David, great progress on your quest to go solar. Personally I wouldn’t connect the transformer via the circuit breaker as you did because if something ever causes the transformer circuit breaker to trip it will cause all of your items connected to your neutral terminal to be allowed to float and fight each other. The floating can cause major voltage differences between the L1-N and L2-N connections and permanently damage items connected. I would opt to connect the transformer directly across the buss allowing either the main breaker to protect it or to utilize the temperature protection circuit provided in the transformer to trigger an inverter shutdown as a safeguard for the transformer. Keep up the great work. As a long time service electrician and many years working on industrial equipment I’m quite impressed with your knowledge and improvements you’ve made from your early videos. Good luck!
Great suggestions. Thank you. I appreciate you taking the time to let me know about the potential issue with the auto transformer. I'll have to use your suggestions and modify.
Yeah, I noticed that problem, too. I'm not sure what the best way to handle it is while still providing overcurrent protection. I'm thinking of some sort of double-trip breaker so if the transformer transformer breaker trips the load breaker does, too. I'm not sure if that exists or not. A more practical option might be to put a fast-acting voltage-monitoring relay between the transformer and the loads, but that might have its own problems.
@@warrenridley8723 no because the 240v feed to the transformer is still feeding the transformer (only the split phase L1 and L2 is disconnected not neutral) I never seen a setup like this before, usually you buy 1 (China) inverter that outputs split phase or 2 inverters that support split phase communication data cable between 2 or more inverters (with 2 inverters usually the second slave inverter does the split phase L2 you just have to configure the phase rotation in the settings, if one inverter overloads it will turn both inverters off so both phases go off so not to destroy stuff)
Dave, a small story. One of my hobbies is astronomy, I have telescopes that I can use to look at the sun, the moon, the planets etc. Years ago I was setup in my girlfriends driveway looking at the sun and one of my neighbors came over to ask me what I was doing. I told her and she said "ohhh can I have a look" I said sure and rather than come to where I was standing looking through the eyepiece she ducks down under the telescope and tries to look thru the finder - much smaller telescope you use for finding the general pointing for the bigger telescope. To my horror I yelled at he and said "No, over here." Why? The finder did not have a solar filter on it but thankfully I had had the presence of mind to put the cap on it. If I'd not been paying attention she would have taken the cap off that finder scope and tried to look thru it resulting in instant blindness. Why am I telling you this? Whenever I do high voltage experiments I make sure that I am safe and I don't let anyone else that is not involved into the room, no pets, no one. It takes one lapse of attention for someone to reach into an open box and get electrocuted especially someone that is eternally curious. Please take this message in the spirit that it is meant and be careful. This stuff is no joke. -Vince
What makes you think David is not fully aware of all dangers and, with his apparent casual approach, is not being as careful as needed? Should he be wearing a reflective vest and parrot repeat: "this could kill you" every minute? I applaud David for having fun, for getting excited AND showing his excitement. For sharing his "discovery" with us. For rejoicing about it. That was ABSOLUTELY wonderful. I felt myself smiling and sharing David's excitement. As if being there!!!!! Here in Australia there is an almost genetic fear for electricity and electrical wiring. Almost everything "should" be left to a licensed electrician. Funny enough, across the ocean, in New Zealand, they are allowed to wire their own homes, they have the freedom to legally wire their homes. Amazing difference!!!!! Electricity should be RESPECTED, not FEARED. Those that don't know, should learn before doing, up until they know. And then should do it. The "don't touch approach" is primitive and disappointing. This video is superb, excellent and bring a contagious need to learn more, to research more. To know more and be better. Fear brings civilization back to the cave ... and then, be careful as fire burns as well ... Hope this helps
@@Quarantined_AU Yep. My "eternally curious" hands got burned by the stove top about 30 years ago, because my dad didn't lock me out of the kitchen (or the shop) every time he was working on something. Still thankful for that school of thought today.
If you look at the spec sheet for the Growatt you list in the description, it shows a surge capability at 10kW, they say 10000VA but that's the same thing. That's why you need the 50amp breaker and 8awg wiring.
For non-reactive loads (resistive, like heaters), VA and W are the same, but for reactive loads (motors, etc) the voltage and current are not completely in phase, so the total current in the wires might be larger than you would expect for a given power. The Wikipedia article for Power Factor has a great figure showing this!
@@ericapelz260 what is 'derating' Conductor derating reduces the amount of current that wires are allowed to carry. The idea behind it is to protect the wire's insulation from degradation by excessive heat. As current passes through a wire, heat is produced. As current levels rise, the amount of heat produced also rises.
21.7A at 230VAC is 4991W (5000W output from the inverter - either converted from the battery or AC passthrough) In the US you would set that to 240VAC output (roughly 20.8A) 80A AC charging into a 48V (51.2V) battery is 4096W 4096W at 240VAC input is 17.1A. (17.8A at 230VAC) So the total AC input is up to 21.7A plus 17.1A = 38.8A which is why they spec a 50A input breaker.
I have the same setup and spoke to you after the last video. It has a surge capacity of 10,000VA(watts) which makes the math simple. 240v x 41.67amps equals 10,000VA(watts). I think rounding up to 50amp is just a good measure of safety. Thanks for all your time you dedicate for your viewers! 👍🏼
David, based on your video, I went ahead and bought one of these units from signature solar. No shipping and no state tax charged. You have saved me days of work and much headache of not having to learn things via trial and error about electrical components/batteries/BMS units etc especially with products from battery hookup. On top of that, you saved me money as I could not find any discount code for signature solar and I got a $44.95 discount which brings the total to around $854.04 shipped to my door. Thank you for making these videos.
Beautiful experiment. I'm loving this Growatt inverter. I chuckle at how excited you get, I can only imagine how giddy you were when your child was born. Thank you for sharing this with us. Be safe.
Love your enthusiasm! Thanks for proving that the Growatt has no internal G-N bonding, even it has a Ground terminal. I do always tell people that inverters don't have internal bonding and they need to be bonded in the load panel. I am living in the 3-phase world. Great you have found this Auto-transformer solution. Now the world is open for you for the 240V devices :)
I watched this video and was inspired to visit Signature Solar. I live less than an hour away. I bought about 4kW of used panels at a good price; the next step is to invest in the inverter, transformer and battery; I'll have a little fun testing things out then I plan on expanding.......all of this because I stumbled upon your channel. Very nice work Dave!!
Really helpful Just ordered my 2 unit- LFP200-48 48V/200AH 10KWH Powerwall battery Buit in Smart Patent BMS, Max discharge 100A, Smart LCD 2 unit SNA 5000 WPV OFF Grid Inverter 5KW WPV 48V DC, AC output 230V, Max input power 6000W, Max charging current 100A WIFI and remote monitoring With 18 350 watt panels Was hoping to run a shop and house and after watching your demo I think it will be no problem
Dude! I’ve viewed several of your videos but I found this one at the Perfect time! Thank you So Much for so much useful information. I’m building a new home and got a quote for a Solar Installation and it was over $50,000 bucks! You have shown me that I can build my own system for a Small Fraction of that. Thanks again!
Was watching tutorial videos earlier and the speed was at 1.25x. You think David is exciting at 1x speed, you should see/hear him at 1.25x 🤣 Excellent entertainment and very informative. I actually didn't know about an auto-transformer before or how they worked. I was still puzzled at first until I saw it in action with the meters. Pretty interesting.
I love it! David is so excited he created 120V! And wifey can barely contain her enthusiasm as well LOL. Mine would be the same! Um did we win the lottery or something???
yes, the transformer helps to keep in-rush current under control, it's like a capacitor/limiter combo, protecting the inverter. and nice demo of balancing loads!
@@jlc2345 A 240v deep-well pump should have a start capacitor (along with a smaller run capacitor) in its control box to handle in-rush current. Problem is, David only tested 120v appliances with his auto-transformer. Maybe David (or someone else in RUclips land) will demonstrate an auto-transformer with 240v appliances to answer your question. I'd like to know as well. Another question: Would using a larger start capacitor for a deep-well pump help compensate for having less in-rush current available? That would be a lot cheaper than an auto-transformer! By the way, having a larger tank (and/or a Cycle Stop Valve), will reduce the number of cycles needed in the first place.
@@jlc2345, no. Transformer couldn't supplement extra energy to motor-type load. The best way is use pump's dedicated DIY inverter with VFD-like soft start with gradually increasing voltage and frequency. Like Chinese EGR002 board (microcontroller + 2 x IR2110). Or, use VFD with custom expanded VFD's capacitor bank.
@@charlesrichards5389 It wouldn't do anything at all for 240V loads... since it isn't going through the transformer it would just be a parallel load on the inverter.
Poz, very cool setup .. and great content! Always fun to watch! BTW you answered your own question.. the reason for the 50amp breaker is because of the continuous load, when you factor in the percentage margin it’s over 30amps Keep up with the great 👍 content, I would like to see if this setup continue to work well with multiple parallel inverters.. thanks again..
A few years ago split-phase was nebulous to me, but I eventually figured it out. This is one of the best explanations I've seen. It also makes me reconsider a lot of these simpler 240V single-phase inverters, considering how easy it is, with the added bonus of balancing the legs.
Hi All, Just a few other data points... we've got the ES5000 with the midpoint transformer... we've run a full-sized microwave, an induction cooker, and a concrete saw... not all at the same time... actually the microwave *plus* the induction cooker "blew the circuit", but I think it was the circuit breaker on the *battery*, and not the inverter itself that shut off the power... need to do some more research to confirm. Happy Tuesday!
Wow, ...Good to see more info. about how 230vac "single phase" (as per specs on GroWatt's data sheet) can work on 230vac usa split phase. Interesting to see your progression of show and tell testing. Thanks for the lessons :+) Bill
I have three I'm going to stack together. 1 Auto Transformer. 6 batteries eg4 lithium iron phosphate 48-volt 100 amp-hour. 54 235 W Canadian Solar panels. Picked up a 50 gallon heat pump water heater. Soft start for my 3.5 ton Central AC. I will be ready to rock. Hoping to install it the next week or so great video I'm glad to see what these batteries can do.
Any 120 x 120 volt transformer can be connected and used as a 120/240 volt autotransformer. Sourced on the secondary market, they can be had quite reasonably. Normally they will be found as reconnectable with two 120 volt primary windings and two 120 volt secondary windings. They’ll be marked 120/240 x 120/240. The autotransformer used to derive a neutral is interesting not only in as much as it carries only the difference in load current between both lines, but that it also only actually transforms 1/2 of the power it supplies. So, for example, while supplying a single 120 volt, 10 amp (1200 VA) load, the transformer only carries 600 VA. Each of the transformer’s 120 volt windings carries 5 amps. The primary is 5 amps in and the secondary is 5 amps out. The primary is in series with the load, and the secondary is in parallel with the load. So in the case of yours, rated to supply a continuous neutral current of 32 amps, the transformer itself is only ~2 KVA. Technically it would be used with a 4 KVA supply so it could never be overloaded, but they’re stating 5 KVA, figuring, realistically, you’re unlikely to ever have more than 4 KVA imbalance on a 5 KVA supply.
I love load tests like this!! It is really cool to see the Autotransformer working so well! I think you could install that transformer into your current house install because it could do the same for that system and balance the two inverters. I would first add in a bunch of safety's regarding that transformer and the 240v inverter, because what happens when there is a load that trips the breaker of that transformer? L1 and L2 will become extremely unbalanced and you could potentially fry 120v loads with more than 120v on the leg that had the least amount of load. So just make sure to wire an over temperature and disconnect to the logic of the inverter so that if something happens to the transformer the inverter will shutdown immediately. Thanks for sharing! It was a really cool video to watch! I love all of these test panels which clearly show the entire circuit as a whole making it very easy to follow!
I would like to know more about your idea on the overtemp and logic to inverter. For instance, how would you wire that to the inverter? I’m looking for a fail safe idea to keep from frying any 120 loads.
David, we were blessed to buy a 6,500 watt Diesel generator with 74 hours on it for $400. We use it to charge our batteries through our inverter and supply 240 volt AC split phase for big loads like our clothes dryer. We fuel it with used veggie-oil. After settling out the water and solids for two weeks, the clean oil is sent thru 20, 5 and 1 micron cleanable pleated polyester filters. We thin the oil for the winter time with petrol. 10% - 20%. I mention this because you and your brother used to clean used veggie-oil in the past. We have hundreds of gallons from just one restaurant. They put the oil back in the carboy so we don’t have any mess to deal with. Apart from collecting and filtering we have almost free electricity. The rest of the house runs off of the batteries and inverter.
Inductors store current, Capacitors store voltage. The inductor gives you the affect of a shock absorber on the current. the inrush to start a motor on power tool.
From my electrotech classes: "Inductors resist a change in the flow of current". Be it increasing, or decreasing. This is why we put a diode on DC relays. When the power is cut to the relay's coil, it's magnetic field collapses, and a voltage spike can be measured at the coil terminals.
If you go frame by frame when he had the three amp meters on the auto transformer leads, the current spiked up then zeroed out. (The digital meters can't sample fast enough -- three oscilloscope would have been so awesome right there ). The counter EMF across one side of the transformer windings cancelled out the voltage on the other side of the center tap. And the virtual neutral voltage was maintained. It was ssssooooo cool to see Dave have meters on each lead. And that's why we put diodes across coils ! That open circuit voltage (counter EMF) could be way over ten times the supply voltage.
I have a complete SolarEdge system which includes that auto-transformer. My system was professionally installed because I don't possess your diy mojo. Just wanted to let you know I enjoy watching your channel, and I have learned a lot from your explanations of how stuff works.
Impressive results. I didn't see anything about efficiency, other than your mention of the 80 watts used at idle. Based on your meter readings, the best I saw was about 82% when both legs were fairly balanced. I'd like to see some Power Factor tests, especially with all loads on one line. But essentially for times when you are drawing 5KW, your batteries are converting 1 KW into heat. This may not be a big issue if you have 10KW+ of solar and 30KWh of battery storage, but it's a huge deal for those of us with much smaller systems. And 2KW a day just to keep the inverter on with no load whatsoever will run down smaller storage systems pretty fast. Keep the tests coming :)
You saw that correct. I've been checking efficiency randomly and seen anywhere from 80% to 93% (depending on load). In a future video I want to dedicate the time to doing staged loads, and checking efficiency at multiple points, then map the curve. I agree it's a big deal. I don't want to waste more power than necessary.
Nice video Dave. Be aware the auto trans has an imbalance of 25A as well. When building a system it is best to decide what is most important 120 or 240. I would mainly go with a 120v inverter and use the auto trans for only 240 loads.
First, thank you Elena for holding the camera ! Very very helpful ! Visual learner here !! Thank you for the ALL the meter readings ! Thanks for the water heater element. And Dang ! Across one small auto-transformer ! Duuuude! That's a pretty slick trick ! Looking at your drawing, my power distribution instructor, Jack Ice, 35 years ago, would say, "re-draw", "re-draw", "re-draw". The auto-transformer looks like it's directly across the 240 output (source) and you're making a virtual neutral. Very Interesting. (Oh, cool breaker box, btw). So you're telling me: the additional parallel inverters will sense the 60Hz from the others (the primary inverter) and synchronize, across the auto-transformer...? Pretty sneaky sis ! That's either in software or some magic I haven't seen yet ! (Do they require a control cable between the inverters when you add more parallel units?) And the source currents will add up from 5 additional inverters, at the breaker box, across one small auto-transformer, making the virtual neutral with more source current "available" across it. Really?!? That little thing ? I'm thinking where's the current on the virtual neutral going? No voltage, no current. Auto transformer magic self balancing. Or the inverters' are handling it. Duuuude ! Am I seeing this right!? That is ssssooooo freaking cool ! I learned something new this morning !! Thank You very much Dave ! And Growatt. I'm going to do more homework on this ! I wanna check out their warranty and lightning protection recommendations. Niiiiice video Dave! Thanks very much !
You can parallel up to 6 inverters. Each inverter has a built-in communication board and comes with a cable. One inverter is programmed as the master, and all the other inverters are the slave. This keeps the sine waves in sync. As you add inverters the total power available to your house increases. The auto-transformer is 5kva. That limit of 5kva doesn't change no matter how many inverters you have.
@@DavidPozEnergy Wow ! Hi Dave, Thank You ! Hey, my guess was close ! Darn !! I was really hoping, lol, they were using alien technology and didn't have the communications cabling between the units !! Darn, that would have been miraculous ! I would love to see that schematic. I still think that's very doable. Like adding grid tie inverters. The auto-transformer is a very cool trick !!! My boss, way back in the dark ages, was "the GTE man" who was called in, to trouble shoot phantom and ghost telephone circuits. This looks Very similar but simpler than circuits he maintained. It often embarrasses me how smart/learned the very early electrical engineers were. This system looks to be such a system they dug out of the '30's or '40's. It's just such a great idea. It's really exciting to see. Thanks so very much ! Such a great reminder and a great solution !
@@DavidPozEnergy Can you wire in another 5kva auto transformer to get power to produce 10kva ? Trying to get a handle on a larger home system where you want to run big 240v pool pumps, big 120v saws and vacs, and everything in between. Sorry fory nubeness
I have two of these 5Kw inverters in parallel and it is really easy, you just connect the two inverters toghether using the included serial and current cables,with the current cabbles you connect inv 1 left to inv 2 left and then inv 1 right to inv 2 right, best and easy to use inverter on the market,if you want to use lithium batteries with CAN communication you can just splice the two data cables togheter as shown in the manual or see if you can get an analog rj45 splitter as no type of swoych or hub will work
Does the set up change the auto transformer at all. This has really peaked my interest. Are you simply daisy chaining the inverters then sending the power to the transformer?
I don’t get it. Not sure what the auto transformer is doing. I have a 12kw and wired it to the panel with a double pole breaker that splits to two 120 legs. What will the auto transformer do in addition to what I have?
Hello David, I am very glad you did a piece on 120/240 volt systems for solar, as this has been over looked by the majority of the RUclipsrs. As a licensed electrician who holds a valid masters license and a valid contractors license in the Province of Ontario, I have a few concerns regarding the wiring of the auto transformer. Specifically, the bond screw on the panel versus the grounding at the auto transformer. The completion of this ground should go to a ground plate (minimum 18" below grade) or 2 x 10' ground rods or a copper water service, using #6 minimum conductor. The reason for this is that this assembly of components, now represents an "electrical service" by definition. I have spent the majority of my career working in the industrial and commercial sector of the industry and I have wired many isolation transformers and auto transformers. I also have done my share of PV installs with inverters as part of the Province's push for Green energy, all with permits and inspections. I have also been involved with many international production machines that required upgrades to Canadian codes...bonding of neutrals and establishing that ground was common place. Now codes do vary from region to region across the country, but to my understanding, the rule applying to this type of install dies not vary much at all, if any. This has now become a very long post (ugh). I would be very happy to guide you and your subscribers through this process, if you would like. Please let me know.
Thank you for your post. I appreciate it. My fathers side is from Ontario, and that side of the family is still up there. I look forward to the day I can visit them again. I also think grounding is important. I was planning to run a ground wire from the grounding bar of the panel to earth. Are you suggesting that needs to happen at the transformer instead?
Well I learned something new today, thank you. Did not know you could use a transformer like that, always thought you to connect Inverter > Transformer > Loads
I would like to see that on an oscilloscope. I am betting their is a slight phase shift between Inverter and auto-transformer. Perhaps that is why they put them together to sync?
I bought the inverter before finishing the video! It would also be interesting to see a video with running the inverter without the batteries as it should be able to do. Thanks again for the great content
After Hurricane Maria here in PR we are using this type of configuration. I think that we depleted solar edge AT in the warehouses in Main Land. Also we use Victron AT and others.
Thank you David for the careful review - really helpful. I am sorry to potentially disturb the party ;-) - but 70 W idle according to my understanding is insanely high - 3 inverters = 210W idle. Think of that. if you have 12h of non-producing (during winter with overcast, etc) that's around 2.5 KWh/day just for running the inverters without using any power within the house. That's maybe why the idle wattage usage is not published on Growatt's data sheet. Even chineese inverters like e.g. the EASun inverter type (see aliexpress - there are many different brands which offer the same hardware) which has comparable power output and similar PV MPPT input power and voltage capabilities like this Growatt inverter - seem to have lower idle power consumption (from what I learned from tests by other people, it is around 50w per inverter). According to Victron (a European Inverter brand), their inverters with similar power output have even much lower idle power consumption (7w per inverter - but I didn't find any independent tests which prove this number). For David's high-power solar array the 2.5KWh/day is a peace of cake (15 mins of full sun radiation and it is recharged) but for smaller PV arrays this may be a real issue.
I agree that idle loss can be a big deal. As you said, it's not a problem with my system given how large my solar array is. For someone with a small solar array, they are probably not buying 3 inverters, but one, or maybe even one smaller. So it might be a relative problem. Victron and SMA both make beautiful equipment with extremely small idle loss. This would matter more if you have limited area for solar (van/boat). But for me, I can afford the space in the backyard to mount the extra panels needed.
@@DavidPozEnergy So if I'm going to use 2 inverters and 1 autotransformer what is the minimum number of panels needed to overcome the idle loss of the 3 devices?
Given that most american homes have relatively few 240v loads, it kinda makes more sense to me to have a 240v inverter feeding a 240v split phase breaker box that you move all those loads into (HVAC, water heater, pump) and then run a 2:1 step down transformer from an extra breaker on that panel. That transformer will produce 120v which you can feed to your home's existing panel box. The only modification to that panel box would be to bridge the two phases. So all the 120v loads would be on one phase and the full power of the inverter would be available to all 120v loads. The auto transformer seems like a bandaid for the kooky split phase we use. You can find a 10kva transformer new pretty easily. When I first installed a 24v 120v 4kw inverter on the critical loads in my house, I actually installed an extra panel box and bridged the phases.... labeled it 120v only.
Using an autotransformer to turn the inverter 240v into a single 120v leg to feed regular household loads doesn't really make sense to me because then the transformer needs to handle all your loads. If you keep it split phase the transformer only needs to handle the unbalanced loads, so the system will be more efficient.
Put an o-scope on it, see what the sine wave looks like under load. Can this Growatt inverter run without a battery? Your large solar array should prove that it can. With that high of solar voltage range you can hookup it up directly to a hybrid vehicle battery instead of panels too, flexibility. Possibilities are becoming numerous.
Re: Your idea; With that high of solar voltage range.. hookup it up directly to a hybrid vehicle battery instead of panels too, flexibility." ... I am looking forward to when EV batteries can be paralleled, or somehow be integrated to the home solar system battery bank, for supplying home loads during cloud cycles, and automatically topping up when the sun is shinning; for max flexibility ;+) Note: I hear from an experienced buddy that some higher end battery banks operate and integrate to some higher end solar systems at around 350vdc; matching some EV battery setups.
Great video! In watching this video I was intrigued yet slightly worried about the results, reading Matt’s reply I was thinking that the potential unbalanced and tripping may fry the inverter. I was impressed with growatts 110% 💪 flex The company that I am partners with builds 100 homes a year. As the solar program manager We get around half of those homes to come with solar and battery back up in the build. GroWatt is something I have considered using however we mainly use duel Sol-Ark 12 kw and 4 to 6 EG4 lithium Ion phosphate 20kw /30kw cabinets. This adds around 28k to the price of the house however it’s a total offset of electrical usage with around 12kw of solar depending on the roof and orientation etc etc. Point being is that finding a balance to the load per phase is been tough. Every home owner is different and their energy needs vary greatly. Finding that equipment cost versus bankable funding for draws in construction and also getting a end result in value from the appraiser was the struggle at first. After two years we found a solution for pre construction solar that Works.
Great video If it is possible can you get a second inverter and put it in series and test everything again, would like to see the power draw on your whole system
SYNCHRONIZE THE inverters OUTPUT PHASE OR PROBLEMS ARISE. (Some units have this feature built in and Grid Tie Units usually by default ) Not as simple as it first looks, HOWEVER a transformer intrinsically achieves this ! PS. For GRID CONNECTED INVERTERS An AUTO transformer does NOT PROVIDE GALVANIC ISOLATION so I"d be inclined to go for an ISOLATING TRANSFORMER 240 volt to 0 - 120 - 240 volt with FULL POWER CAPABILITY on the secondary winding's 0 to the 120 volt tap (~40 amps) and the 240 volt tap ~(20 amps).
We like being able to toast our bread or cook pancakes on a flat grill with bacon next to the tub while we're taking a bath here in America without accidentally killing ourselves. That's freedom.
Lol, I bought a 5000VA autotransformer from Newark. The thing cam on a palette and weighs 140lbs. I had to use a scissor lift table to get it to the right height and mount it on the wall. The entire transformer is gunked into its metal box. This unit you used subverted my expectations. Mine has multiple taps for different voltages 480, 240, 208, 120-0-120, etc.
@@JM-yx1lm Do you have a model number of a Growatt that is transformerless design with an auto transformer in it ? There older transformer design has a large idle draw 140-200 watts and low pv input voltage .
I have one of these www.ginverter.com/Off-Grid-Storage-Inverters/44-622.html in a 12kW model, and it pulls ~70W idle. I also get between 80-92% efficiency out of it. I paid $2600 for it about 18 months ago, but you can find them all around for $2k now.
Merci David, très belle expérience et merci de partager avec nous toutes ces possibilités et techniques. Bonne continuation et à bientôt ! je suis impatient de regarder une nouvelle vidéo.
I am happy and grateful for what you do! I learn much from you.... and Wow your child has grown up! I guess children do that :-) Please keep your DIY channel going,
I love your positive attitude thanks for all your help. a little theory of how and why a neutral is needed and how your transformer provides it would be great
The answer to your question on why the manual is suggesting a 50A breaker is because of the surge current. The inverter is capable of surging to 10KVA for a full 5 seconds which is about 42A at 240V. Infact in can surge upto 7.5KVA for 10 seconds which would cause a 30A breaker to trip before reaching these 5 or 10 seconds.
Thanks for writing me back Battery bank is 51.4 volts 600 AH But i am using 4 gage wires I thought the battery connected should power up Your video make things so simple and easy Not easy connecting that thing And i have done many inverters in my life Thank you Nit sure what to do Maybe contact Amazon to return it
Hi David, I love your videos. Lots of enthusiasm and lots of fun stuff to play with! Thumbs up. A couple of safety things- you didn’t say if the power was off when you tested for continuity between neutral and ground in your panel. Either way, you would always want to first test with a known good meter that there is no power present before using an ohmmeter. Your meter *may* have protection against that, but people have been killed this way (albeit on much higher power). The proper protection of autotransformers used to derive a system neutral is very important. Specifically, it is crucial that the transformer not be cut out of the circuit without also shutting down all of the power. Loss of neutral would mean that some connected 120 volt equipment could be exposed to as much as full line to line voltage. An electrician friend accidentally did this at a customer’s home, and destroyed several pieces of equipment.
Great comment. Thank you. 1. I tested continuity with the inverter off, and with the inverter on. In the video I only showed one clip due to time. I edit down tons of raw footage to make a video. 2. Good point on the auto transformer. A few people have said this today and it is something I didn't consider. I'll have to modify it somehow.
Hi David You might want to check the Growatt inverter for a setting to do the bonding from N to ground when the inverter is working. Most inverters has this built in. The reason as far as I know is that one should only have a single return path via N to the utility when the inverter is bypassing to utility power. This might happen when your battery is drained or when the inverter is overloaded. If you do the bonding inside the DB, it will create a return path via the ground wire to the utility as well when the inverter is bypassed. Grounding wires are usually not designed to handle this current continuously and are only to keep equipment grounded so that people don't shock themselves when touching the outside metal surfaces of equipment. So, the inverter should do the bonding internally only when the inverter is running. If, however you are not planning to connect to utility power I guess the bonding inside the DB does not matter so much. I personally would still use the inverter bonding relay in that instance since it feels safer to me. >o{
As another commenter pointed out, the inverter is rated for 10 kVA surge. In AC circuits, VA and W are not the same thing because the voltage and current are not necessarily in phase. They are only in phase for non-reactive loads. Inductive and capacitive loads will cause the current to lag and lead the voltage, respectively. The first 2 figures on the "Power Factor" Wikipedia page illustrates this nicely. So for some hypothetical reactive load, like a motor, the load could be pulling 1 kW of power. For a DC circuit, this would mean the motor is pulling 4.2 A at 240 V, but for an AC circuit, because of the inductance in the motor, there might be 6 A flowing in the wires, so 1 kW, but 1.44 kVA. This is why you need 50 A capable wires/breaker for a 10 kVA system even if it can only supply 5 kW continuous. I'm really enjoying you DIY videos! Looking forward to more.
For your question about the AC input wire suggestion, if you look at the name plate on the side of the inverter you'll find that the AC input current from the grid can go up to 40A. They recommend a bigger wire and circuit breaker so they would be at 80% of their capacity.
From the 40A taken from the grid, the inverter can both supply the 22A to your equipment and charge the batteries at the same time with the 18A AC, that becomes 80A at the DC side.
Super impressive. I love this project and congratulations on a successful build. Scares me a bit to think of DIYers now playing with AC circuits as high voltage! Stay safe.
High voltage - you mean 10K and above ;-) 220v is not high voltage. We call a 40kv transformer low voltage depending on your viewpoint. But 220 for sure is not HIGH voltage ;-)
@@defenderred1212 so a mistake at 405v will definitely +€)" me up in some way. Good to know. 220v is indeed physically quite manageable. Less manageable after working outside and being sweaty without shoes on though... But perfectly survivable :). I'm not going to make that mistake with 405v that these growatts can handle for pv
Excellent. Another option for me. Convert from 240v to split phase... Very nice. It's not clear in my head yet but I think I would want a separate wiring box with a singular breaker for the transformer. A to B to C. That way if the breaker for the transformer tripped the main box would not be powered. I also don't like the way you eventually have all the inverters going into the breaker box; I would personally like them to combine in a separate box.
Today, there are many inverters with 240 VAC split-phase output for the North and South American market (I bought EG4 6000XP). There are less-expensive 240 VAC single-phase inverters for the Euro/Asia market like the Growatt inverter shown, but costly and cluttered to add the autotransformer shown to form split-phase. Another approach is to buy two 120 VAC single-phase inverters and wire their outputs to realize split-phase (some allow that).
Would love to see how panels hook up and interact with the inverter and load. Growatt makes a big deal of its ability to switch between available sources.
Hi DavidPoz. I am really enjoying the experiments you are trying with the Growatt 5kW Inverter, the new breaker panel, the auto transformer and your power tools. I had a few questions I would like to ask, via email. But first, I will watch the rest of the Solar themed videos in case my questions do get answered. Thanks for sharing.
Note: Whenever inserting circuit wiring into the breaker box, always provide enough lead wiring, so if in the future you want to rearrange the breakers, the wiring will be able to be extended anywhere inside in any position.. Dutchman loops make a nice termination.. Does it make for a crowded box.?? Yes, it does, but you won' be compromised in he future trying to balance the load on each 120vac buss as you add more demand...
likewise - new information for me and I'm glad to see this on your channel. Is there any other research you did with autotransformer setups that you can point at?
Another super cool review. Love it! Please consider, letting us know why standby draw is important. I know but some other folks may not. I would also learn about inductance etc so you could briefly go over it. Can’t wait for solar review on growatt. Thanks for sharing.
Awesome 👌. I dont know why I love this stuff .I want to run my apartment with 240v of grid and I want a situation with maximum output to be safe . It seems like the battery set up you have is plenty, but the conversion is my main issue.
Probably already answered, but the only reference I see to a 50 amp breaker in my manual is the AC *input* protection (page 9), from a generator or what have you. Regardless, you really helped me make a decision on my setup and I'm largely copying your approach. Thanks man, big help.
Why the Auto transformer? In the US Neutral and Ground are tied together. Out of the inverter you are using you already have 120 N to Ground and Phase to Ground. If you would reference the neutral coming out of the inverter as phase 1 and the L as Phase 2 and the Ground as neutral you wouldn't need the Autotransformer right?
you should now test the autotransformer on all the other inverters aswell, looking at the inside of the Growatt inverter 5000ES, it looks exactly the same as one side of the split phase MPPSolar/EASun. Btw, the autotransformer is acting as a load reactor, this is the term you were looking for.
I bought this auto transformer and I just connected to a 120v receptacle through a kilowatt meter. it was pulling 14W but 68VA and showing a power factor of 20.
@DavidPoz First of all, I want to thank you for making these videos. These were very helpful to me, since I'm also making home solar system using growatt inverters. I think, according growatt user manual we've to use AC 50A circuit breaker only for AC Input. We don't need to use 50A cb with AC output. Thing I can't understand is, inside growatt, it already has 40A AC input circuit breaker, but it user manual instructs to use 50A cb outside it
if you configure your panel correctly so that 120v loads are divided between left side and right side of panel they will cancel each other out which will cause way less load on the auto transformer. only voltage indifference uses the auto transformer. that means for every 120 breaker in left side have one on right side and try to balance the load from each accordingly. some breaker panels switch every other breaker from left to right for you. Hope you all understand what I said. signature solar did a video on this.
Correct me if I'm wrong! But the reason for the next step up breaker and wire size has to do with code requirements. If the load is rated as continuous, it can't be rated any more than 20% of the breaker rating. Ex: a 30A breaker for a continuous load can only have 24A going through it. A 40A by code would be acceptable, but I'm not sure why Growatt is spec'ing a 50A breaker. Maybe it has something to do with peak surges? Usually they're rated for 2x the inverter output rating. As for the wire size, the wire is not allowed to be rated lower than the breaker (the breaker is meant to protect the wire). Maybe the reason for such a large breaker and wire size is in case 1 line is pulling all 5000W off the inverter? Just guessing at this point. I too am curious!
I noticed that Signature Solar has the ATS 5000T -US transformer. It seems to not have the worry of tripping the transformer circuit breaker. I was hoping you could show wiring that one into your system.
Its being used as a balancing transformer. Thats the reason a transformer less inverter meaning most of the hybrid all in one inverters are not able to handle large 120v loads on the same leg or but also the reason they generally cannot handle large startup loads even 240 v . The transformer acts kinda like a small high amp battery for a short time aiding the startup.
FYI your Neutral to Ground test proves the autotransformer doesn't have Neutral and Ground bonded. If the inverter has any Ground bonding it will be one of the Lines so you get +240 for one leg and 0 for the other (in relation to ground). Some inverters have a jumper to do this others have an internal relay and a setting to bond a leg to ground.
As an inverters nominal output is considered continuous, the breaker and conductor need to be rated for 80% of of continuous output. As 1.25 is the inverse of 80%, we multiply the 25 amp output by 1.25, equaling 31.25Amps. Since this is more than 30 Amps, the next higher breaker and wire size is then chosen. And since the equipment manufactures instructions have final say, we follow them, but in this case, they are the same as the calculations.
David, great progress on your quest to go solar. Personally I wouldn’t connect the transformer via the circuit breaker as you did because if something ever causes the transformer circuit breaker to trip it will cause all of your items connected to your neutral terminal to be allowed to float and fight each other. The floating can cause major voltage differences between the L1-N and L2-N connections and permanently damage items connected. I would opt to connect the transformer directly across the buss allowing either the main breaker to protect it or to utilize the temperature protection circuit provided in the transformer to trigger an inverter shutdown as a safeguard for the transformer. Keep up the great work. As a long time service electrician and many years working on industrial equipment I’m quite impressed with your knowledge and improvements you’ve made from your early videos. Good luck!
Great suggestions. Thank you. I appreciate you taking the time to let me know about the potential issue with the auto transformer. I'll have to use your suggestions and modify.
Mr Poz please do the video with the modify thanks
Yeah, I noticed that problem, too. I'm not sure what the best way to handle it is while still providing overcurrent protection. I'm thinking of some sort of double-trip breaker so if the transformer transformer breaker trips the load breaker does, too. I'm not sure if that exists or not. A more practical option might be to put a fast-acting voltage-monitoring relay between the transformer and the loads, but that might have its own problems.
Do you not lose Neutral if the transformer breaker trips hence 120v phases loosing power anyway?
@@warrenridley8723 no because the 240v feed to the transformer is still feeding the transformer (only the split phase L1 and L2 is disconnected not neutral)
I never seen a setup like this before, usually you buy 1 (China) inverter that outputs split phase or 2 inverters that support split phase communication data cable between 2 or more inverters (with 2 inverters usually the second slave inverter does the split phase L2 you just have to configure the phase rotation in the settings, if one inverter overloads it will turn both inverters off so both phases go off so not to destroy stuff)
Dave, a small story. One of my hobbies is astronomy, I have telescopes that I can use to look at the sun, the moon, the planets etc. Years ago I was setup in my girlfriends driveway looking at the sun and one of my neighbors came over to ask me what I was doing. I told her and she said "ohhh can I have a look" I said sure and rather than come to where I was standing looking through the eyepiece she ducks down under the telescope and tries to look thru the finder - much smaller telescope you use for finding the general pointing for the bigger telescope. To my horror I yelled at he and said "No, over here." Why? The finder did not have a solar filter on it but thankfully I had had the presence of mind to put the cap on it. If I'd not been paying attention she would have taken the cap off that finder scope and tried to look thru it resulting in instant blindness. Why am I telling you this? Whenever I do high voltage experiments I make sure that I am safe and I don't let anyone else that is not involved into the room, no pets, no one. It takes one lapse of attention for someone to reach into an open box and get electrocuted especially someone that is eternally curious. Please take this message in the spirit that it is meant and be careful. This stuff is no joke. -Vince
What makes you think David is not fully aware of all dangers and, with his apparent casual approach, is not being as careful as needed?
Should he be wearing a reflective vest and parrot repeat: "this could kill you" every minute?
I applaud David for having fun, for getting excited AND showing his excitement. For sharing his "discovery" with us. For rejoicing about it.
That was ABSOLUTELY wonderful. I felt myself smiling and sharing David's excitement. As if being there!!!!!
Here in Australia there is an almost genetic fear for electricity and electrical wiring. Almost everything "should" be left to a licensed electrician.
Funny enough, across the ocean, in New Zealand, they are allowed to wire their own homes, they have the freedom to legally wire their homes.
Amazing difference!!!!!
Electricity should be RESPECTED, not FEARED.
Those that don't know, should learn before doing, up until they know. And then should do it.
The "don't touch approach" is primitive and disappointing.
This video is superb, excellent and bring a contagious need to learn more, to research more. To know more and be better.
Fear brings civilization back to the cave ... and then, be careful as fire burns as well ...
Hope this helps
@@Quarantined_AU Yep. My "eternally curious" hands got burned by the stove top about 30 years ago, because my dad didn't lock me out of the kitchen (or the shop) every time he was working on something. Still thankful for that school of thought today.
If you look at the spec sheet for the Growatt you list in the description, it shows a surge capability at 10kW, they say 10000VA but that's the same thing. That's why you need the 50amp breaker and 8awg wiring.
For non-reactive loads (resistive, like heaters), VA and W are the same, but for reactive loads (motors, etc) the voltage and current are not completely in phase, so the total current in the wires might be larger than you would expect for a given power. The Wikipedia article for Power Factor has a great figure showing this!
Wow that must be a very well built inverter inside!
You need to derate for continuous loads as well, which always bumps us a least one wire and breaker size.
@@ericapelz260 what is 'derating' Conductor derating reduces the amount of current that wires are allowed to carry. The idea behind it is to protect the wire's insulation from degradation by excessive heat. As current passes through a wire, heat is produced. As current levels rise, the amount of heat produced also rises.
21.7A at 230VAC is 4991W (5000W output from the inverter - either converted from the battery or AC passthrough)
In the US you would set that to 240VAC output (roughly 20.8A)
80A AC charging into a 48V (51.2V) battery is 4096W
4096W at 240VAC input is 17.1A. (17.8A at 230VAC)
So the total AC input is up to 21.7A plus 17.1A = 38.8A which is why they spec a 50A input breaker.
I have the same setup and spoke to you after the last video. It has a surge capacity of 10,000VA(watts) which makes the math simple. 240v x 41.67amps equals 10,000VA(watts). I think rounding up to 50amp is just a good measure of safety. Thanks for all your time you dedicate for your viewers! 👍🏼
You are correct. Due to the surge rating, a larger breaker is required otherwise the 30A would trip every time something larger (like an AC) kicks on
David, based on your video, I went ahead and bought one of these units from signature solar. No shipping and no state tax charged. You have saved me days of work and much headache of not having to learn things via trial and error about electrical components/batteries/BMS units etc especially with products from battery hookup. On top of that, you saved me money as I could not find any discount code for signature solar and I got a $44.95 discount which brings the total to around $854.04 shipped to my door. Thank you for making these videos.
Your welcome. Enjoy your new energy system.
@@DavidPozEnergy kindly drop your mail address. I have a whole lot to share with u
Beautiful experiment. I'm loving this Growatt inverter. I chuckle at how excited you get, I can only imagine how giddy you were when your child was born. Thank you for sharing this with us. Be safe.
Love your enthusiasm! Thanks for proving that the Growatt has no internal G-N bonding, even it has a Ground terminal. I do always tell people that inverters don't have internal bonding and they need to be bonded in the load panel. I am living in the 3-phase world. Great you have found this Auto-transformer solution. Now the world is open for you for the 240V devices :)
This is awesome.. Ive been looking for a solution for my 240v boat to run 110v items.. This auto transformer to apply a neutral..
@@JoJoRocks5 I definitely can meet your requirement of solar inverter in competitive price，sir
Well this comment didn't age well 😂
I watched this video and was inspired to visit Signature Solar. I live less than an hour away. I bought about 4kW of used panels at a good price; the next step is to invest in the inverter, transformer and battery; I'll have a little fun testing things out then I plan on expanding.......all of this because I stumbled upon your channel. Very nice work Dave!!
It's addictive to start creating your own power.
I think autotransformers are my new favorite thing. Thanks for the great demonstration of how it handles unbalanced loads!
Really helpful
Just ordered my
2 unit-
LFP200-48
48V/200AH 10KWH Powerwall battery
Buit in Smart Patent BMS, Max discharge 100A, Smart LCD
2 unit
SNA 5000 WPV
OFF Grid Inverter 5KW WPV
48V DC, AC output 230V, Max input power 6000W, Max charging current 100A WIFI and remote monitoring
With 18 350 watt panels
Was hoping to run a shop and house and after watching your demo I think it will be no problem
Cool stuff. Making your own neutral...I'm feeling empowered with knowledge. Thanks, David.
Dude!
I’ve viewed several of your videos but I found this one at the Perfect time!
Thank you So Much for so much useful information.
I’m building a new home and got a quote for a Solar Installation and it was over $50,000 bucks!
You have shown me that I can build my own system for a Small Fraction of that.
Thanks again!
Your welcome. Thanks for checking out my channel.
Was watching tutorial videos earlier and the speed was at 1.25x. You think David is exciting at 1x speed, you should see/hear him at 1.25x 🤣 Excellent entertainment and very informative. I actually didn't know about an auto-transformer before or how they worked. I was still puzzled at first until I saw it in action with the meters. Pretty interesting.
or 1.75!
I love it! David is so excited he created 120V! And wifey can barely contain her enthusiasm as well LOL. Mine would be the same! Um did we win the lottery or something???
His excitement reminds me of the first time i saw penthouse magazine.
R.I.P. penthouse and playboy, they are both long dead
I know - its so hard to find good role models now a days
yes, the transformer helps to keep in-rush current under control, it's like a capacitor/limiter combo, protecting the inverter. and nice demo of balancing loads!
Would this eliminate the need for a soft starter for a well pump, for example?
@@jlc2345 A 240v deep-well pump should have a start capacitor (along with a smaller run capacitor) in its control box to handle in-rush current. Problem is, David only tested 120v appliances with his auto-transformer. Maybe David (or someone else in RUclips land) will demonstrate an auto-transformer with 240v appliances to answer your question. I'd like to know as well. Another question: Would using a larger start capacitor for a deep-well pump help compensate for having less in-rush current available? That would be a lot cheaper than an auto-transformer!
By the way, having a larger tank (and/or a Cycle Stop Valve), will reduce the number of cycles needed in the first place.
@@jlc2345, no. Transformer couldn't supplement extra energy to motor-type load. The best way is use pump's dedicated DIY inverter with VFD-like soft start with gradually increasing voltage and frequency. Like Chinese EGR002 board (microcontroller + 2 x IR2110). Or, use VFD with custom expanded VFD's capacitor bank.
@@charlesrichards5389 It wouldn't do anything at all for 240V loads... since it isn't going through the transformer it would just be a parallel load on the inverter.
Poz, very cool setup .. and great content! Always fun to watch!
BTW you answered your own question.. the reason for the 50amp breaker is because of the continuous load,
when you factor in the percentage margin it’s over 30amps
Keep up with the great 👍 content, I would like to see if this setup continue to work well with multiple parallel inverters.. thanks again..
A few years ago split-phase was nebulous to me, but I eventually figured it out. This is one of the best explanations I've seen. It also makes me reconsider a lot of these simpler 240V single-phase inverters, considering how easy it is, with the added bonus of balancing the legs.
I've been hoping someone would make this video...THANKS David!!!!
Hi All, Just a few other data points... we've got the ES5000 with the midpoint transformer... we've run a full-sized microwave, an induction cooker, and a concrete saw... not all at the same time... actually the microwave *plus* the induction cooker "blew the circuit", but I think it was the circuit breaker on the *battery*, and not the inverter itself that shut off the power... need to do some more research to confirm. Happy Tuesday!
Wow, ...Good to see more info. about how 230vac "single phase" (as per specs on GroWatt's data sheet) can work on 230vac usa split phase. Interesting to see your progression of show and tell testing. Thanks for the lessons :+) Bill
I have three I'm going to stack together. 1 Auto Transformer. 6 batteries eg4 lithium iron phosphate 48-volt 100 amp-hour. 54 235 W Canadian Solar panels. Picked up a 50 gallon heat pump water heater. Soft start for my 3.5 ton Central AC. I will be ready to rock. Hoping to install it the next week or so great video I'm glad to see what these batteries can do.
Any 120 x 120 volt transformer can be connected and used as a 120/240 volt autotransformer. Sourced on the secondary market, they can be had quite reasonably. Normally they will be found as reconnectable with two 120 volt primary windings and two 120 volt secondary windings. They’ll be marked 120/240 x 120/240.
The autotransformer used to derive a neutral is interesting not only in as much as it carries only the difference in load current between both lines, but that it also only actually transforms 1/2 of the power it supplies. So, for example, while supplying a single 120 volt, 10 amp (1200 VA) load, the transformer only carries 600 VA. Each of the transformer’s 120 volt windings carries 5 amps. The primary is 5 amps in and the secondary is 5 amps out. The primary is in series with the load, and the secondary is in parallel with the load.
So in the case of yours, rated to supply a continuous neutral current of 32 amps, the transformer itself is only ~2 KVA. Technically it would be used with a 4 KVA supply so it could never be overloaded, but they’re stating 5 KVA, figuring, realistically, you’re unlikely to ever have more than 4 KVA imbalance on a 5 KVA supply.
Wonderful videos Mr. P. I've a EE and do IT (~29 years now) and enjoy/appreciate your vids. Thank you.
Your welcome, and thanks for watching.
I love load tests like this!! It is really cool to see the Autotransformer working so well! I think you could install that transformer into your current house install because it could do the same for that system and balance the two inverters. I would first add in a bunch of safety's regarding that transformer and the 240v inverter, because what happens when there is a load that trips the breaker of that transformer? L1 and L2 will become extremely unbalanced and you could potentially fry 120v loads with more than 120v on the leg that had the least amount of load. So just make sure to wire an over temperature and disconnect to the logic of the inverter so that if something happens to the transformer the inverter will shutdown immediately. Thanks for sharing! It was a really cool video to watch! I love all of these test panels which clearly show the entire circuit as a whole making it very easy to follow!
I would like to know more about your idea on the overtemp and logic to inverter. For instance, how would you wire that to the inverter? I’m looking for a fail safe idea to keep from frying any 120 loads.
My solution is to use 2 auto transformers. Very unlikely that both would trip or fail.
David, we were blessed to buy a 6,500 watt Diesel generator with 74 hours on it for $400. We use it to charge our batteries through our inverter and supply 240 volt AC split phase for big loads like our clothes dryer. We fuel it with used veggie-oil. After settling out the water and solids for two weeks, the clean oil is sent thru 20, 5 and 1 micron cleanable pleated polyester filters. We thin the oil for the winter time with petrol. 10% - 20%. I mention this because you and your brother used to clean used veggie-oil in the past. We have hundreds of gallons from just one restaurant. They put the oil back in the carboy so we don’t have any mess to deal with. Apart from collecting and filtering we have almost free electricity. The rest of the house runs off of the batteries and inverter.
That's awesome. Do you have any videos or blogs about your setup? I'd love to see it.
@@DavidPozEnergy I could pm some of what I have videoed
That would be great. I checked Facebook, but there seems to be 100+ Steven Fraziers. I'm at DavidPozEnergy
Inductors store current, Capacitors store voltage. The inductor gives you the affect of a shock absorber on the current. the inrush to start a motor on power tool.
From my electrotech classes: "Inductors resist a change in the flow of current". Be it increasing, or decreasing. This is why we put a diode on DC relays. When the power is cut to the relay's coil, it's magnetic field collapses, and a voltage spike can be measured at the coil terminals.
If you go frame by frame when he had the three amp meters on the auto transformer leads, the current spiked up then zeroed out. (The digital meters can't sample fast enough -- three oscilloscope would have been so awesome right there ).
The counter EMF across one side of the transformer windings
cancelled out the voltage on the other side of the center tap. And the virtual neutral voltage was maintained. It was ssssooooo cool to see Dave have meters on each lead.
And that's why we put diodes across coils ! That open circuit voltage (counter EMF) could be way over ten times the supply voltage.
I have a complete SolarEdge system which includes that auto-transformer. My system was professionally installed because I don't possess your diy mojo. Just wanted to let you know I enjoy watching your channel, and I have learned a lot from your explanations of how stuff works.
Impressive results. I didn't see anything about efficiency, other than your mention of the 80 watts used at idle. Based on your meter readings, the best I saw was about 82% when both legs were fairly balanced. I'd like to see some Power Factor tests, especially with all loads on one line. But essentially for times when you are drawing 5KW, your batteries are converting 1 KW into heat. This may not be a big issue if you have 10KW+ of solar and 30KWh of battery storage, but it's a huge deal for those of us with much smaller systems. And 2KW a day just to keep the inverter on with no load whatsoever will run down smaller storage systems pretty fast. Keep the tests coming :)
You saw that correct. I've been checking efficiency randomly and seen anywhere from 80% to 93% (depending on load). In a future video I want to dedicate the time to doing staged loads, and checking efficiency at multiple points, then map the curve. I agree it's a big deal. I don't want to waste more power than necessary.
well said!!
Thank you for posting.
@@DavidPozEnergy
I’m definitely going to be interested in these newer brands when they can achieve Victron / Magnum levels of efficiency.
You are blame I just bought 2 Growatt Inverters :-) I just love you're excitement in testing them
Nice video Dave. Be aware the auto trans has an imbalance of 25A as well. When building a system it is best to decide what is most important 120 or 240. I would mainly go with a 120v inverter and use the auto trans for only 240 loads.
First, thank you Elena for holding the camera ! Very very helpful ! Visual learner here !!
Thank you for the ALL the meter readings ! Thanks for the water heater element.
And Dang !
Across one small auto-transformer !
Duuuude! That's a pretty slick trick !
Looking at your drawing, my power distribution instructor, Jack Ice, 35 years ago, would say, "re-draw", "re-draw", "re-draw". The auto-transformer looks like it's directly across the 240 output (source) and you're making a virtual neutral. Very Interesting. (Oh, cool breaker box, btw).
So you're telling me:
the additional parallel inverters will sense the 60Hz from the others (the primary inverter)
and synchronize, across the auto-transformer...? Pretty sneaky sis ! That's either in software or some magic I haven't seen yet !
(Do they require a control cable
between the inverters when you add more parallel units?)
And the source currents will add up from 5 additional inverters,
at the breaker box, across one small auto-transformer, making the virtual neutral with more source current "available" across it. Really?!? That little thing ?
I'm thinking where's the current on the virtual neutral going?
No voltage, no current.
Auto transformer magic self balancing. Or the inverters' are
handling it.
Duuuude ! Am I seeing this right!? That is ssssooooo freaking cool !
I learned something new this morning !!
Thank You very much Dave !
And Growatt.
I'm going to do more homework on this !
I wanna check out their warranty and lightning protection recommendations.
Niiiiice video Dave! Thanks very much !
You can parallel up to 6 inverters. Each inverter has a built-in communication board and comes with a cable. One inverter is programmed as the master, and all the other inverters are the slave. This keeps the sine waves in sync.
As you add inverters the total power available to your house increases.
The auto-transformer is 5kva. That limit of 5kva doesn't change no matter how many inverters you have.
@@DavidPozEnergy Wow !
Hi Dave, Thank You ! Hey, my guess was close !
Darn !! I was really hoping, lol, they were using alien technology and didn't have the communications cabling between the units !! Darn, that would have been miraculous !
I would love to see that schematic.
I still think that's very doable.
Like adding grid tie inverters.
The auto-transformer is a very cool trick !!! My boss, way back in the dark ages, was
"the GTE man" who was called in, to trouble shoot phantom and ghost telephone circuits.
This looks Very similar but simpler than circuits he maintained. It often embarrasses me how smart/learned the very early electrical engineers were. This system looks to be such a system they dug out of the '30's or '40's. It's just such a great idea. It's really exciting to see. Thanks so very much ! Such a great reminder and a great solution !
Wow my neighbor is sold. So if I buy one of these, you'll help me install it aye?
@@erichibar4746 Nope. I'm hanging up my tools.
@@DavidPozEnergy Can you wire in another 5kva auto transformer to get power to produce 10kva ? Trying to get a handle on a larger home system where you want to run big 240v pool pumps, big 120v saws and vacs, and everything in between. Sorry fory nubeness
Do you have a video on, or can you show us how to wire up an extra inverter? Being able to expand seems really cool!
I have two of these 5Kw inverters in parallel and it is really easy, you just connect the two inverters toghether using the included serial and current cables,with the current cabbles you connect inv 1 left to inv 2 left and then inv 1 right to inv 2 right, best and easy to use inverter on the market,if you want to use lithium batteries with CAN communication you can just splice the two data cables togheter as shown in the manual or see if you can get an analog rj45 splitter as no type of swoych or hub will work
@@tiaan1587 yeah it sounds so easy that I don't understand it
Does the set up change the auto transformer at all. This has really peaked my interest. Are you simply daisy chaining the inverters then sending the power to the transformer?
I don’t get it. Not sure what the auto transformer is doing. I have a 12kw and wired it to the panel with a double pole breaker that splits to two 120 legs. What will the auto transformer do in addition to what I have?
This is so cool. I was really stumped on how to go from 240V to 120 split phase. Thanks so much!
The 50 amp breaker for the inverter is likely due to the fact that it can handle a surge current (motor starts) for a short time.
Hello David,
I am very glad you did a piece on 120/240 volt systems for solar, as this has been over looked by the majority of the RUclipsrs.
As a licensed electrician who holds a valid masters license and a valid contractors license in the Province of Ontario, I have a few concerns regarding the wiring of the auto transformer. Specifically, the bond screw on the panel versus the grounding at the auto transformer. The completion of this ground should go to a ground plate (minimum 18" below grade) or 2 x 10' ground rods or a copper water service, using #6 minimum conductor. The reason for this is that this assembly of components, now represents an "electrical service" by definition. I have spent the majority of my career working in the industrial and commercial sector of the industry and I have wired many isolation transformers and auto transformers. I also have done my share of PV installs with inverters as part of the Province's push for Green energy, all with permits and inspections. I have also been involved with many international production machines that required upgrades to Canadian codes...bonding of neutrals and establishing that ground was common place. Now codes do vary from region to region across the country, but to my understanding, the rule applying to this type of install dies not vary much at all, if any. This has now become a very long post (ugh). I would be very happy to guide you and your subscribers through this process, if you would like. Please let me know.
Thank you for your post. I appreciate it. My fathers side is from Ontario, and that side of the family is still up there. I look forward to the day I can visit them again.
I also think grounding is important. I was planning to run a ground wire from the grounding bar of the panel to earth. Are you suggesting that needs to happen at the transformer instead?
Well .. What if it is going in an RV? What do I need to do then?
“Is smaller than in the pictures”
That’s what she said moment. :P
Great video. :)
In your case
@@late4dinner268 shazam
I can see the uncertainty, and anticipation of pops and sparks in your wobbly hands :D.
I know your feeling!
Well I learned something new today, thank you. Did not know you could use a transformer like that, always thought you to connect Inverter > Transformer > Loads
I would like to see that on an oscilloscope. I am betting their is a slight phase shift between Inverter and auto-transformer. Perhaps that is why they put them together to sync?
Me too, so an auto transformer is slave to the sine wave generated by the growatt inverter
@@TallTexasGMan referred to as Power Factor
@@jaydekeyser referred to as Power Factor
These videos are PRICELESS!!! It's videos like these that help me make a decision to buy one of these units. THANK YOU for posting it!
I bought the inverter before finishing the video! It would also be interesting to see a video with running the inverter without the batteries as it should be able to do. Thanks again for the great content
After Hurricane Maria here in PR we are using this type of configuration. I think that we depleted solar edge AT in the warehouses in Main Land. Also we use Victron AT and others.
Your videos are very informative, but your wife was like Get me out of here LOLL
I'm stoked with this video. This is exactly my need.....
Thank you David for the careful review - really helpful. I am sorry to potentially disturb the party ;-) - but 70 W idle according to my understanding is insanely high - 3 inverters = 210W idle. Think of that. if you have 12h of non-producing (during winter with overcast, etc) that's around 2.5 KWh/day just for running the inverters without using any power within the house. That's maybe why the idle wattage usage is not published on Growatt's data sheet. Even chineese inverters like e.g. the EASun inverter type (see aliexpress - there are many different brands which offer the same hardware) which has comparable power output and similar PV MPPT input power and voltage capabilities like this Growatt inverter - seem to have lower idle power consumption (from what I learned from tests by other people, it is around 50w per inverter). According to Victron (a European Inverter brand), their inverters with similar power output have even much lower idle power consumption (7w per inverter - but I didn't find any independent tests which prove this number). For David's high-power solar array the 2.5KWh/day is a peace of cake (15 mins of full sun radiation and it is recharged) but for smaller PV arrays this may be a real issue.
I agree that idle loss can be a big deal. As you said, it's not a problem with my system given how large my solar array is. For someone with a small solar array, they are probably not buying 3 inverters, but one, or maybe even one smaller. So it might be a relative problem. Victron and SMA both make beautiful equipment with extremely small idle loss. This would matter more if you have limited area for solar (van/boat). But for me, I can afford the space in the backyard to mount the extra panels needed.
@@DavidPozEnergy So if I'm going to use 2 inverters and 1 autotransformer what is the minimum number of panels needed to overcome the idle loss of the 3 devices?
Given that most american homes have relatively few 240v loads, it kinda makes more sense to me to have a 240v inverter feeding a 240v split phase breaker box that you move all those loads into (HVAC, water heater, pump) and then run a 2:1 step down transformer from an extra breaker on that panel. That transformer will produce 120v which you can feed to your home's existing panel box. The only modification to that panel box would be to bridge the two phases. So all the 120v loads would be on one phase and the full power of the inverter would be available to all 120v loads. The auto transformer seems like a bandaid for the kooky split phase we use. You can find a 10kva transformer new pretty easily.
When I first installed a 24v 120v 4kw inverter on the critical loads in my house, I actually installed an extra panel box and bridged the phases.... labeled it 120v only.
Using an autotransformer to turn the inverter 240v into a single 120v leg to feed regular household loads doesn't really make sense to me because then the transformer needs to handle all your loads. If you keep it split phase the transformer only needs to handle the unbalanced loads, so the system will be more efficient.
You WILL want to wire a monitor into the Temp sensor lead in that Autoformer.. and keep an eye on it :)
That auto transformer really is the magic piece there
Put an o-scope on it, see what the sine wave looks like under load. Can this Growatt inverter run without a battery? Your large solar array should prove that it can. With that high of solar voltage range you can hookup it up directly to a hybrid vehicle battery instead of panels too, flexibility. Possibilities are becoming numerous.
Re: Your idea; With that high of solar voltage range.. hookup it up directly to a hybrid vehicle battery instead of panels too, flexibility." ... I am looking forward to when EV batteries can be paralleled, or somehow be integrated to the home solar system battery bank, for supplying home loads during cloud cycles, and automatically topping up when the sun is shinning; for max flexibility ;+) Note: I hear from an experienced buddy that some higher end battery banks operate and integrate to some higher end solar systems at around 350vdc; matching some EV battery setups.
Great video! In watching this video I was intrigued yet slightly worried about the results,
reading Matt’s reply I was thinking that the potential unbalanced and tripping may fry the inverter. I was impressed with growatts 110% 💪 flex
The company that I am partners with builds 100 homes a year. As the solar program manager We get around half of those homes to come with solar and battery back up in the build. GroWatt is something I have considered using however we mainly use duel Sol-Ark 12 kw and 4 to 6 EG4 lithium Ion phosphate 20kw /30kw cabinets. This adds around 28k to the price of the house however it’s a total offset of electrical usage with around 12kw of solar depending on the roof and orientation etc etc.
Point being is that finding a balance to the load per phase is been tough.
Every home owner is different and their energy needs vary greatly.
Finding that equipment cost versus bankable funding for draws in construction and also getting a end result in value from the appraiser was the struggle at first. After two years we found a solution for pre construction solar that Works.
Great video
If it is possible can you get a second inverter and put it in series and test everything again, would like to see the power draw on your whole system
SYNCHRONIZE THE inverters OUTPUT PHASE OR PROBLEMS ARISE.
(Some units have this feature built in and Grid Tie Units usually by default )
Not as simple as it first looks, HOWEVER a transformer intrinsically achieves this !
PS. For GRID CONNECTED INVERTERS An AUTO transformer does NOT PROVIDE GALVANIC ISOLATION so I"d be inclined to go for an ISOLATING TRANSFORMER 240 volt to 0 - 120 - 240 volt with FULL POWER CAPABILITY on the secondary winding's 0 to the 120 volt tap (~40 amps) and the 240 volt tap ~(20 amps).
You want the inverters in parallel, not in series
Awesome video dude!!!.. please do a review of felicity lithium batteries with the growatt inverter
Cool - still glad I don't have to deal with split phase stuff over here.
We like being able to toast our bread or cook pancakes on a flat grill with bacon next to the tub while we're taking a bath here in America without accidentally killing ourselves. That's freedom.
@@FaceTubeU Hahahaha yep !
I'm the poster child ! ADHD at its best !
Lol, I bought a 5000VA autotransformer from Newark. The thing cam on a palette and weighs 140lbs. I had to use a scissor lift table to get it to the right height and mount it on the wall. The entire transformer is gunked into its metal box. This unit you used subverted my expectations. Mine has multiple taps for different voltages 480, 240, 208, 120-0-120, etc.
Hey Growatt...in the future, can you just build the transformer into your all-in-one unit so they don't need to be separate like this?
They already do. He just happened to get the one that needs the transformer.
@@JM-yx1lm Do you have a model number of a Growatt that is transformerless design with an auto transformer in it ? There older transformer design has a large idle draw 140-200 watts and low pv input voltage .
just move to a real integer 50hz 240v country & use all the generic 240v power tools ,fridges, heater etc..
I have one of these www.ginverter.com/Off-Grid-Storage-Inverters/44-622.html in a 12kW model, and it pulls ~70W idle. I also get between 80-92% efficiency out of it. I paid $2600 for it about 18 months ago, but you can find them all around for $2k now.
@@captainobvious9188 your telling me that a 12kw low frequency inverter only pulls 70watt idle? I’ll have to see it before I believe it!!
Merci David, très belle expérience et merci de partager avec nous toutes ces possibilités et techniques. Bonne continuation et à bientôt ! je suis impatient de regarder une nouvelle vidéo.
I am happy and grateful for what you do! I learn much from you.... and Wow your child has grown up! I guess children do that :-) Please keep your DIY channel going,
I love your positive attitude thanks for all your help. a little theory of how and why a neutral is needed and how your transformer provides it would be great
If it has AC charging they want the breaker to be large enough to do both at the same time just a guess as that is how Outback does it.
The answer to your question on why the manual is suggesting a 50A breaker is because of the surge current. The inverter is capable of surging to 10KVA for a full 5 seconds which is about 42A at 240V. Infact in can surge upto 7.5KVA for 10 seconds which would cause a 30A breaker to trip before reaching these 5 or 10 seconds.
Poz: -120V! 120V!
Wife: smirk, smirk...
Thanks for writing me back
Battery bank is 51.4 volts
600 AH
But i am using 4 gage wires
I thought the battery connected should power up
Your video make things so simple and easy
Not easy connecting that thing
And i have done many inverters in my life
Thank you
Nit sure what to do
Maybe contact Amazon to return it
Impressive how well it handled the low power factor loads from the motor starts!
At time stamp 20:45, I liked the way your battery monitor voltage went from previously 53.2vdc no-load to 60.1vdc with 103 amp load on battery.
Hi David, I love your videos. Lots of enthusiasm and lots of fun stuff to play with! Thumbs up.
A couple of safety things- you didn’t say if the power was off when you tested for continuity between neutral and ground in your panel. Either way, you would always want to first test with a known good meter that there is no power present before using an ohmmeter. Your meter *may* have protection against that, but people have been killed this way (albeit on much higher power).
The proper protection of autotransformers used to derive a system neutral is very important. Specifically, it is crucial that the transformer not be cut out of the circuit without also shutting down all of the power. Loss of neutral would mean that some connected 120 volt equipment could be exposed to as much as full line to line voltage. An electrician friend accidentally did this at a customer’s home, and destroyed several pieces of equipment.
Great comment. Thank you.
1. I tested continuity with the inverter off, and with the inverter on. In the video I only showed one clip due to time. I edit down tons of raw footage to make a video.
2. Good point on the auto transformer. A few people have said this today and it is something I didn't consider. I'll have to modify it somehow.
This video is the best! Very explanatory!
Nice I'm moving to Ghana building a off grid home. So all this information is good.
Hi David
You might want to check the Growatt inverter for a setting to do the bonding from N to ground when the inverter is working. Most inverters has this built in. The reason as far as I know is that one should only have a single return path via N to the utility when the inverter is bypassing to utility power. This might happen when your battery is drained or when the inverter is overloaded. If you do the bonding inside the DB, it will create a return path via the ground wire to the utility as well when the inverter is bypassed. Grounding wires are usually not designed to handle this current continuously and are only to keep equipment grounded so that people don't shock themselves when touching the outside metal surfaces of equipment.
So, the inverter should do the bonding internally only when the inverter is running. If, however you are not planning to connect to utility power I guess the bonding inside the DB does not matter so much. I personally would still use the inverter bonding relay in that instance since it feels safer to me.
>o{
As another commenter pointed out, the inverter is rated for 10 kVA surge. In AC circuits, VA and W are not the same thing because the voltage and current are not necessarily in phase. They are only in phase for non-reactive loads. Inductive and capacitive loads will cause the current to lag and lead the voltage, respectively. The first 2 figures on the "Power Factor" Wikipedia page illustrates this nicely.
So for some hypothetical reactive load, like a motor, the load could be pulling 1 kW of power. For a DC circuit, this would mean the motor is pulling 4.2 A at 240 V, but for an AC circuit, because of the inductance in the motor, there might be 6 A flowing in the wires, so 1 kW, but 1.44 kVA. This is why you need 50 A capable wires/breaker for a 10 kVA system even if it can only supply 5 kW continuous.
I'm really enjoying you DIY videos! Looking forward to more.
It can work totally without battery missing this test. Overall great Chanel all the time keep forward
For your question about the AC input wire suggestion, if you look at the name plate on the side of the inverter you'll find that the AC input current from the grid can go up to 40A. They recommend a bigger wire and circuit breaker so they would be at 80% of their capacity.
From the 40A taken from the grid, the inverter can both supply the 22A to your equipment and charge the batteries at the same time with the 18A AC, that becomes 80A at the DC side.
Yes super exciting! Loving everything about these Growatt inverters! Excellent stuff! Thanks for the walk through David! Cheers and sunny days 🌞
Dear David
Your work is awesome.
Please, don't forget to active your captions Languages on video.
Many thanks,
FR from Switzerland.
And for us hard of hearing folks too !
You can really see the 'flywheel effect' in the surge amps when you start the miter saw :-)
Super impressive. I love this project and congratulations on a successful build. Scares me a bit to think of DIYers now playing with AC circuits as high voltage! Stay safe.
High voltage - you mean 10K and above ;-) 220v is not high voltage. We call a 40kv transformer low voltage depending on your viewpoint. But 220 for sure is not HIGH voltage ;-)
@@mmeuwese Yup! 220V will bite you but not take a limb or your life. 480V and up will grab you and take limbs and/or your life.
@@defenderred1212 so a mistake at 405v will definitely +€)" me up in some way. Good to know. 220v is indeed physically quite manageable. Less manageable after working outside and being sweaty without shoes on though... But perfectly survivable :). I'm not going to make that mistake with 405v that these growatts can handle for pv
Excellent. Another option for me. Convert from 240v to split phase... Very nice.
It's not clear in my head yet but I think I would want a separate wiring box with a singular breaker for the transformer. A to B to C. That way if the breaker for the transformer tripped the main box would not be powered. I also don't like the way you eventually have all the inverters going into the breaker box; I would personally like them to combine in a separate box.
Today, there are many inverters with 240 VAC split-phase output for the North and South American market (I bought EG4 6000XP). There are less-expensive 240 VAC single-phase inverters for the Euro/Asia market like the Growatt inverter shown, but costly and cluttered to add the autotransformer shown to form split-phase. Another approach is to buy two 120 VAC single-phase inverters and wire their outputs to realize split-phase (some allow that).
Would love to see how panels hook up and interact with the inverter and load. Growatt makes a big deal of its ability to switch between available sources.
I just finished wiring up my solar array to the inverter. It's going to be a few weeks to collect the info, film, and edit.
@@DavidPozEnergy Looking forward to it. Bingeing your channel rn. Thanks!
Hi DavidPoz. I am really enjoying the experiments you are trying with the Growatt 5kW Inverter, the new breaker panel, the auto transformer and your power tools. I had a few questions I would like to ask, via email. But first, I will watch the rest of the Solar themed videos in case my questions do get answered. Thanks for sharing.
I'm on facebook if you want to try there.
Way to go, David, I think you gave it 110% with this one! Thanks!
Note: Whenever inserting circuit wiring into the breaker box, always provide enough lead wiring, so if in the future you want to rearrange the breakers, the wiring will be able to be extended anywhere inside in any position.. Dutchman loops make a nice termination.. Does it make for a crowded box.?? Yes, it does, but you won' be compromised in he future trying to balance the load on each 120vac buss as you add more demand...
Great information, this will save me from upgrading a marginal sized inverter, the balancing feature will give more total output. Thanks
Don't be surprised the power factor of Growatt is 1, that means you can get 100percent of it's CAPACITY.... I just love that brand.
Good work. I didn't know about the transformer and inverter balancing of 120V phases. Thanks
likewise - new information for me and I'm glad to see this on your channel. Is there any other research you did with autotransformer setups that you can point at?
Another great video David.. I like how humble you are. Keep it up.
Another super cool review. Love it! Please consider, letting us know why standby draw is important. I know but some other folks may not. I would also learn about inductance etc so you could briefly go over it. Can’t wait for solar review on growatt. Thanks for sharing.
Awesome 👌. I dont know why I love this stuff .I want to run my apartment with 240v of grid and I want a situation with maximum output to be safe . It seems like the battery set up you have is plenty, but the conversion is my main issue.
Probably already answered, but the only reference I see to a 50 amp breaker in my manual is the AC *input* protection (page 9), from a generator or what have you. Regardless, you really helped me make a decision on my setup and I'm largely copying your approach. Thanks man, big help.
Why the Auto transformer? In the US Neutral and Ground are tied together. Out of the inverter you are using you already have 120 N to Ground and Phase to Ground. If you would reference the neutral coming out of the inverter as phase 1 and the L as Phase 2 and the Ground as neutral you wouldn't need the Autotransformer right?
you should now test the autotransformer on all the other inverters aswell, looking at the inside of the Growatt inverter 5000ES, it looks exactly the same as one side of the split phase MPPSolar/EASun.
Btw, the autotransformer is acting as a load reactor, this is the term you were looking for.
My friend, Ben, used a transformer on a MPP Solar brand and it worked well.
I bought this auto transformer and I just connected to a 120v receptacle through a kilowatt meter. it was pulling 14W but 68VA and showing a power factor of 20.
Great job. It would be interesting to see a similar test done on the Sigineer 6000 watt 48-volt inverter
This is a video I made with an Aims 6000W 48V. Very similar architecture to the Sigineer: ruclips.net/video/dfHb5tZErTs/видео.html
@DavidPoz First of all, I want to thank you for making these videos. These were very helpful to me, since I'm also making home solar system using growatt inverters. I think, according growatt user manual we've to use AC 50A circuit breaker only for AC Input. We don't need to use 50A cb with AC output. Thing I can't understand is, inside growatt, it already has 40A AC input circuit breaker, but it user manual instructs to use 50A cb outside it
my bad... I think that 40A circuit breaker on inverter is for output short circuit protection.. it'll make sense, wouldn't it?
I kind of have an idea of what you are doing but great video showing solar battery power in action.
if you configure your panel correctly so that 120v loads are divided between left side and right side of panel they will cancel each other out which will cause way less load on the auto transformer. only voltage indifference uses the auto transformer. that means for every 120 breaker in left side have one on right side and try to balance the load from each accordingly. some breaker panels switch every other breaker from left to right for you. Hope you all understand what I said. signature solar did a video on this.
Correct me if I'm wrong! But the reason for the next step up breaker and wire size has to do with code requirements. If the load is rated as continuous, it can't be rated any more than 20% of the breaker rating. Ex: a 30A breaker for a continuous load can only have 24A going through it. A 40A by code would be acceptable, but I'm not sure why Growatt is spec'ing a 50A breaker. Maybe it has something to do with peak surges? Usually they're rated for 2x the inverter output rating. As for the wire size, the wire is not allowed to be rated lower than the breaker (the breaker is meant to protect the wire).
Maybe the reason for such a large breaker and wire size is in case 1 line is pulling all 5000W off the inverter? Just guessing at this point. I too am curious!
I noticed that Signature Solar has the ATS 5000T -US transformer. It seems to not have the worry of tripping the transformer circuit breaker. I was hoping you could show wiring that one into your system.
Its being used as a balancing transformer. Thats the reason a transformer less inverter meaning most of the hybrid all in one inverters are not able to handle large 120v loads on the same leg or but also the reason they generally cannot handle large startup loads even 240 v . The transformer acts kinda like a small high amp battery for a short time aiding the startup.
FYI your Neutral to Ground test proves the autotransformer doesn't have Neutral and Ground bonded. If the inverter has any Ground bonding it will be one of the Lines so you get +240 for one leg and 0 for the other (in relation to ground). Some inverters have a jumper to do this others have an internal relay and a setting to bond a leg to ground.
As an inverters nominal output is considered continuous, the breaker and conductor need to be rated for 80% of of continuous output. As 1.25 is the inverse of 80%, we multiply the 25 amp output by 1.25, equaling 31.25Amps. Since this is more than 30 Amps, the next higher breaker and wire size is then chosen. And since the equipment manufactures instructions have final say, we follow them, but in this case, they are the same as the calculations.