Choose the Right Size Micro-inverter (Enphase IQ8 Series)
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- Опубликовано: 10 сен 2024
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In this video Joe and Dan explain how to choose the right size micro-inverter to pair with your solar panels. We discuss clipping, DC-AC size ratios, and the difference between STC and NMOT solar panel ratings.
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Joe this is exactly the content we want. Deep dive in technical aspects of solar. Your audience is technical and smart, its great that you arent shying away from technical deep dive discussions.
Yeah it is so easy to find videos where they talk at you like a baby but im building a custom home with a solar system and I agonize over the small stuff like which microinverters i want to use. The solarsales people just want to offload what they have in stock it seems!
i think the best way to evaluate panel and microinverter pairing is to use NREL's PVWatts calculator for your location, use the advanced parameters tab, and adjust the DC to AC size ratio for the panel and inverter configurations you are contemplating and see how the modeled output changes. in my case, I was going to use 485W panels and there was going to be clipping with any of the IQ8s because of the panels' high output. But there was clearly a diminishing returns as I went upward with increased inverter wattage. Ended up using the IQ8H becuase the price difference between it and the lesser models didn't amount to much and I wanted to minimize clipping, but could easily have used the IQ8M or IQ8A which amounted to 420kWh/yr and 155kWh/yr less, respectively, than the IQ8H per PVWatts modeling at my location. Eventually the inverter cost increase outweighs the production increase and you have to determine what makes finianical sense. IQ8+ was 1140 kWh/yr less using PVWatts so you can see that clipping does matter at a certain point so its a needed exercise for proper design.
According to my panel monitoring, most 400W solar panels output well over 300W from 10:15 AM to 3:15 PM if the sun is shining. For my array, this is "Normal", not what it says on the datasheet. Even on mediocre days, the output oscillates between 300W as clouds pass by. You make it sound like 400W solar panels are only going to output 300W, and a lot of people believe you. I'm sorry, it's just not true. Even with 400W panels at just a 10-deg tilt in the NC winter, they output more than 300W and are clipped badly by IQ8+. As you can see, I prefer no clipping unless it's unavoidable. That's why I use and sell Hoymiles HMS-2000-4T-NA high-power microinverters. Their reliability and warranty are as good as Enphase's, but at a much lower cost. Hoymiles is DIY-friendly too.
at 9:00 he goes over the various types of IQ8 inverters including the IQ8M, IQ8A, and IQ8H that all output more than the IQ8+. maybe watch the video before commenting
@@gregorysmith9158 I watched him justify why those higher-power microinverters were not needed twice. I wholeheartedly disagree with that design philosophy now that there is a lower-cost alternative. Clipping is an unnecessary loss of energy.
@@DiySolarHelpDesk Use PVWatts and model what is lost to clipping by adjusting the DC to AC size ratio. you will see that clipping amounts to nothing if you choose the right inverter. using PVWatts, i found that DC to AC size ratio was actually best at 1.1 (ie with clipping; 1 would be no clipping) at my location. Also need to consider the output curve of your inverter (ie its efficiency). they don't all produce optimally at low input powers (although the enphase do go pretty low on the input power before dropping off). so if you size the inverter so that it never clips you may actually have given up a bunch of power in the morning and late afternoons where the input power to the inverter is not near its max and so the inverter is not efficient.
You are correct the inverter curve tells valuable information and should also be considered.
It sure seems true that Enphase has greatly pushed that it’s acceptable to clip VA output.
Other manufactures such as Hoymiles have targeted this VA output as a point of concern/target area which may prove valuable.
Yet there still needs to be concern towards low VA input capacity of the inverter curve to be balanced properly.
i think this is the right approach. the 8M is more suitable and all the talk about the inverter which clips during summer will produce better during other months was applicable to the iq7 models which had different starting voltage for each variant. the iq8 all have the same starting voltage. hence choose the right model based on pv watts.
Such a great topic. Enphase have a great reputation because of their low unit failure rate and they are field proven to last. That being said, Joe could you debate using Tigo TS4-A-O DC optimizers vs Enphase IQ models. My home is all electric and I have a Tesla model Y. I can not offset my power bill 100% because of my roof size and design. Most of my quotes go with 36 panels 400 watts for a 15.2 kWh system for an 88% offset using 23,781kwh yearly. I need all the power I can get so I’d go with the Tigo optimizers with an EG4 18k inverters with 2 EG4 14.3kwh LiFePO4 batteries, most affordable on the market. Other then having one central failure point, I feel DC optimizers are the way to go because they are rated for 700w panels (and they have a 1000w dual panel model) so 100% no clipping and also you don’t not lose 10% of power like with micro inverters converting from DC➡️AC➡️DC➡️AC with the use of batteries. They are also much cheaper but you do have to include the price for a central inverter. Any input would be greatly appreciated.
Anyone who operates a solar panel knows that the actual output of the panel is pretty much in the middle between the stc and noct value. It is therefore not sufficient to use a 300W micro inverter for a noct 300W module. This is because if the stc value is 400W, the module regularly wants to deliver 350W.
Joe, thanks for the excellent review of this widely (and wildly) misunderstood aspect of solar system design. The comments I read here call for further attempts to clarify this..... I would come out of the box shooting for about a 1.33 to 1 ratio of DC to AC -- solar array output to inverter output. This is the common ratio between the pristine conditions lab output used as an accurate measure to compare one module to another, and what we'd see in the REAL world, where output is whittled down by suboptimal orientation, soiling, degradation, excess heat and sub-perfect irradiance. NREL's yearly roundup of utility scale solar tracks this metric and over the years it has climbed up to and stabilized at this 1.33 to 1 ratio. Yes at this threshold, there is a small amount of clipping. Correction, a tiny amount of clipping, more in Phoenix, less in Duluth. Say about 1%. Negligible. Let's take the example from the presentation and the comment section of a 400 watt panel (or 4000 watt array) feeding into a 300 watt inverter. For single digit hours per day for two weeks of days, you'll waste a pittance of output. For most of the rest of the days of the year, when you are nowhere near filling up the inverter with watts, you are getting 10% or 20% or 30% or very, very often 33% more output than if you had just a 300 watt panel. There is a very popular inverter out there right now with a 3000 watt output that can handle up to 5000 watts PV. Sign me up in a heartbeat. That is a 1.67 to 1 ratio. There will be significant clipping at that ratio for sure. (See @gregorysmith9158's comments about NREL's calculator for the projected amount of clipping.) But so what? Modules are so cheap the economics more and more favor oversizing the array. 40 years ago a watt was like a gold nugget and you could credibly argue for a 1 to 1 ratio. All component prices have tumbled since then but module prices have collapsed. A clipped watt today is a throwaway - relative to what you get in return. Read the part in this comment again where it starts with "yes there is small amount of clipping". And then re-read the part about the huge plusses. Google "oversizing DC to AC ratio" on youtube and you'll get more and more videos examining this very thing. My hope and goal is that the comments following these videos begin to shift from the category of "I don't get this" to the "Got it!" side.
Thanks for this, @gregorysmith9158's, and your comment were VERY valuable in filling-in-the-blanks for me to arrive at "Got it!" :)
i'm so noob on this. A seller offered me to install Sun Power P6 405-410 panels with enphase IQ8MC modules are this combo fine as paring or do i should go for another enphase micro inverter? thanks for any help. Here in Italy enphase is starting now to adv their products i m fine to go in AC power as more safe as i read it. thanks
Due respect, You are optimizing power delivered, Physical size of the solar array and cost. This exactly what most of your customers want, but If cost is secondary Upsizing the Microinverters and using lower capacity panels (more size on roof more rack age…) has no down size. I Live on The Penisula of SF bay CA. I have a 12.4 KWH AC system. I also run my HVAC year round. I put $2,000 per year in my pocket after zeroing out my electrical usage. Ok I have some Tesla power-walls to bridge On peak usage. At 40 % depth of charge It is only on the shortest stormy days that I draw any power from the grid.
Maybe it needs a lot of panels and space🤣🤣🤣🤣
I just want to make a comment regarding the 3 inverter configurations that are possible and a comparison of their respective clipping losses. I designed and installed my first solar PV system in 1999. The next 3 systems I purchased (2 I designed) are representative of what is available in the US. The second system I designed is a ground mounted commercial Sunpower system that uses a Fronius Galvo 3.1 kW central string inverter and 8 Sunpower 425 watt modules. So the DC rating of the system is 3.4kW (8 x 425 watt). I have seen this system generate 3.2kW AC for 10 minutes and 3.53 kW AC for 10 seconds. So central inverter systems do NOT CLIP, at least not until the time has passed to risk reliability issues with over heating. So, especially with cool ground mounted modules these systems can exceed their power ratings without clipping losses. The third system I designed (also ground mounted) uses 10 REC 365 watt modules with a Solar Edge SE3800H inverter and 10 370 watt power optimizers. I have seen this system output 3.6 kW for several minutes without clipping as well. The 4th system I specified uses 16 REC 405 watt modules (roof mounted) and 16 Enphase IQ8M inverters. This system went on line on Aug 19th in Pismo Beach CA and has been clipping at 5.2 kW AC every day from 1 to 2 PM. So you do get some clipping losses with micro inverter systems. You do have easier expandability and redundancy with micro inverter systems but they have compromises too.
clipping has nothing to do with the type of inverter you use (central string or micro). it has to do with the panel output vs the inverter input. all inverters have a power input limit - central string inverters will have something like 5kW, 10kW, 15kW, etc. If you pare 20 - 500W panels (so10kW total max) with a 5kW string inverter, you will get clipping (i'm not suggesting this just an extreme example to prove the point).
Microinveters are just that - smaller versions of a central string inverter intended to be used for individual panel input (vs central string fed by multiple panels). Hook a 500W panel up to a 280W microinverter and you will get clipping.
The opposite is also true of both central string and microinverters. Hook up panels that don't maximize the inverter input (like 5 - 500W panels and a 10kW string inverter or a 380W microinverter on a 200W panel) and there will be no clipping with either the central string or the microinverters. Use PVWatts to understand what your location produces and the best configuration of panels and inverters.
@@gregorysmith9158 I'm simply saying that the power limit for string inverters is NOT a hard limit, it can be exceeded until temperature or other factors reduce the power- the power rating is very conservative. Micro inverters have a hard limit which can't be exceeded for long without damage to the circuitry.This is based on real world experience- I can show you the data if you wish.
clipping isn't the difference between an inverter's maxium short term output and its rated continuous output. clipping has to do with pairing panels to an inverter(s) where the panels have a rated output greater than the inverter rated output.
your original comment describes two systems with panel DC output paired with string inverter AC output ratings that are approximatley equal (system 2 - 3.6kW DC with 3.1kW AC so DC/AC ratio of 1.16; system 3 - 3.65kW DC with 3.8kW AC so DC/AC 0.96) and one system with panel rating > microinverter rating (system 4 - 405W DC with 325W AC so DC/AC 1.25)). System 2 should clip slightly mid-day in full sun, system 3 will never clip, and system 4 will clip mid-day in full sun more than system 2 (assuming these are all located in the same exact place on earth) Its no surprise that you are getting the inverter rating on the string systems and you see clipping on the microinverter system - its a product of the pairings not what type of inverter you used. Any inverter (micro or string) that is 100% saturated (so panel output wattage > than inverter output wattage) will produce the rated continuous output of the inverter(s) and not the panels.
@@gregorysmith9158 System 2 (Fronius Galvo 3.1 kW AC string inverter with 8 x 425 watt Sunpower modules- 3.4 kW DC) Has never clipped.The peak AC power of the Fronius recorded last year during a cold spring morning was 3.56 kW AC! So the string inverter can greatly exceed its continuous rating and the SunPower modules do exceed their STC ratings due to conservative output ratings and the cooler temperatures. The Fronius regularly records continuous power of 3.2 kW AC for several minutes during the spring. The module tilt (30 degrees) and the azimuth (180 degrees) mean that during the spring and summer the output has 2 peaks during the day- I am at 37 degrees n latitude. Generally central string inverters do not limit output power as much as micro inverters.
Great video. With the IQ8 480w version to come out soon, clipping will become even more of a non issue.
Joe, thank you for this educational video. I was questioning a quote that uses a Silfab SIL-400HC+ panel that's rated NOCT of 298. He was pairing it with the IQ8M, I was thinking it should be the IQ8A. This shows me he is pairing the system correctly. Again, thanks for the excellent content. I'm in Ocala, Florid and I'm heavily leaning to a ground mounted system as I have ample room in my backyard.
Glad this was helpful. The SilFab 400W is a little underpowered compared to some of the newer 2023 solar panels. Also, ground mount systems can be problematic in Florida due to high wind ratings and water setback requirements. Please reach out if you need a comparison quote: solarsurge.net/
Hello, I live in central Pennsylvania. I am working with a solar contractor that utilizes Enphase inverters. He is specifying your iQ8+ inverter for a 30 panel system with REC 405 pure panels. I was looking at the output of the panel compared to the continuous power input for the iQ8+ and it looks to me like the panel put out more than the inverter can handle continuously. I asked if they thought I would be better off with the iQ8a which looks to exceed what the panel can put out. I was told that the iQ8a isn’t as good with low light power as the iQ8+ and that because I live in the north east the iQ8+ would not likely clip or have the panel exceed the inverter. Does this sound correct?
Sounds like they're absolutey spot on my friend
I find this talk a bit misleading. You don't design for clipping, in order to optimize for other seasons. You simply accept clipping, as a trade off in cost: a well designed system is in the optimal point of optimizer cost versus return on investment over the life time of the system. There is no benefit in clipping. The only positive about a smaller inverter is that it may start a few minutes earlier in the morning. It needs about 5 percent of it's power rating to boot. This start up power (not start up voltage btw) is slightly higher in bigger inverters. Other than that: the optimizers will perform the same in the winter spring and fall.
Thank you for making this video!
I currently have a system spec with 420w panels and IQ8M. I am getting mixed information if that's OK. Some say I should be using IQ8A instead? Any input would help thanks.
Yes the IQ8A would give you better performance. Depends on the cost difference though. I would ask the installer to quote both options.
"Minimum performance" at normal operating conditions is what I read. So these microinverters "clip" everything above the bare minimum for a 400w panel ? is there not a better option ? at least the iQH goes up to 380w, I mean if I'm spending this kinda money I would not want to lose 30% solar energy even when it is available. Doesn't make sense to me.
Me neither, I use a 2000W microinverter so there is no clipping at all with 400W modules.
find my comment about using PVWatts to model this for an overview. you are thinking of this as some steady state analysis and its anything but. weather, sunlight angle, panel angle, season, etc are litterllaly changing every second and all have a huge effect on the system output. 400W panels are rated at STC as he states. No one achieves STC in the real world - its just a way to compare differnt products in laboratory conditions. Use NWOT on the data sheets for real world use but even better, use PVWatts and model specifically for your location.
Upvote for gregory. @@gregorysmith9158
That was an excellent explanation, and reassured me that the 405 watt panels paired with iq8+ shouldn't result in much clipping. I just got the system installed a few weeks ago and was a bit swcond guessing my install.
What do you think about 440 or 470w panels ? Not suitable ?
@@defaultHandle1110 You'll definitely experience some clipping. I first noticed it in March. I probably lose about 3-5% year round as a result of clipping.
On a string inverter, on any normal nice day my QCell array delivers 85% and 90% of the nameplate, for hours on end and have even hit as high as 110% of nameplate on cold days.
How does this compare to a dc system. Do the optimizers give you the full wattage without having to pick the right pairing from panel to inverter?
2 Silly questions:
(1)
How do you make these Micro-inverters work if your home is single phase? I live in an old home and only have have 1 hot 1 neutral coming form the pole, instead of 2 hots. 2 hots would give me 240V in my panel, but I only have 120V throughout the whole house. Will Enphase Micro-inverters work at all in this scenario? I have zero plans on a panel upgrade.
(2)
If the grid is active, and your solar is active as well, how does the house "know" to use solar electricity instead of grid electricity? How does the house pick which power to use?
I have 365 watt with iq7+ in texas with a 1.25 dc to ac ratio. Virtually zero clipping. With a little dust and annual degredation it is negligible.
What’s an acceptable ratio of dc to ac
My Dc to ac ratio is 1.44, you are saying 1.2 is recommended?
Yes. You will have clipping at 1.44
Wow, Great video! Will I loose much if I pair REC405AA Pure panels with enphase iQ8M microinverter vs iQ8A microinverter? Could iQ8M more clip? Panels are going to face South and will be located in Maryland. Thanks guys!
Some panel data sheets don't list the Power at MPP or NOCT rating.
At 8:00 the guest states “ fall, spring, summer“ where he meant to say, “fall, spring, winter“.
What micro inverter would be best for an REC390?
We have a JINKO solar panel with 580watts can micro inverter work?thank you
It will work, but will clip down to the level of the microinverter, so maybe a mismatch.
excellent
Since an IQ8A has one of the highest output rating, why so most just use the 8plus or the 8m, which has lower output rating, and to me more clipping. Do I understand this correctly?
You pay extra for the higher model inverters, but the amount you gain by not clipping may not be worth it
$ difference is about $40, over time I believe the $40 would be worth it.
Can the clipping be sold to the electric company?
Great video Joe; how does this comparison relate to Solar edge inverters , likewise ?
And why exactly can't Enphase, AP Systems, BlueSun etc design microinverters that can achieve the optimal output of higher rated solar panels? Is the increase in solar panel wattages simply outstripping the ability of microinverter companies to keep up?
What are the downsides to oversizing your microinverter? Is it just cost or are there other factors?
That's a good question. Will an IQ8+ perform better than an IQ8m at lower light levels?
13:36 Sorry to be such a pedant but there are instances in which solar panels will perform better than standard test conditions. Out here in Colorado ,we tend to have fairly cold but extremely sunny days in the winter and with less atmospheric effects, we're capable of producing up to 20% more than standard test conditions.
i'm in Georgia and for a few minutes in the morning I have seen as much as 10% higher then the panel was rated for on really cold days when the sun first hits it.
Exactly, 1000W/m2 can be exceeded.
Can you please tell me what is the biggest competitor of enphase in the microinvertors market?
AP Systems is the 2nd place competitor but Enphase is by far and away the market leader in the US.
@@SolarSurge thanks you!
Clipping has ZERO advantage! Why are you condoning this BAD practice?
I agree why would you want clipping . Just buy a bigger micro inverter . Like Hoymiles had a 500-1000-1600 or 2000. The cost upgrade is minimal . Clipping makes zero sense
The clipping logic is basswards. Why would I want the power generation to be clipped in the highest peak of year generation? The inverter power (voltage/current) rating should be higher than the solar panel. Where did that guy learn electricity? That's not even electricity, just capacity deisgn. Many people take your info, and they did not know any better.
This may be relevant. As inverter capacity increases the amperage requirements on the main service panel change perhaps requiring that panel to be changed at great expense.
Because your system will be only optimized for summer months and not be rest of the year. Efficiency drops if you pair too high inverter that doesn’t produce enough watts in the winter. You need a happy medium. Pay attention to what he’s saying
So if I switch my IQ7s to IQ8’s I hit Nem 3 faster than you can spit.
I am so tired of this entire "clipping" rationalization! Why not just market a microinverter that can handle the power that is coming from a 400 watt panel and be done with it?! Please do not insult our intelligence with all of this pseudo technical mumbo jumbo!!
Why would this be a mumbo jumbo, when it is normal even with string inverters to oversize the panels to get more from the inverter in times when the solar energy is not at it peak. That type of system will also get clipping and everybody is ok with that. But when you do the same with micro inverter it or regarded as mumbo jumbo.
BULLSHIT! Stop making rationalizations for microinverter manufacturers who are too lazy to make the proper size inverter! If clipping was so great then why do the manufacturers keep increasing the size of their microinverters? According to your rationalization, a 250 watt microinverter shouid work just fine with a 575 watt solar panel! BULLSHIT!
Joe, your young money grubbing employee, playing games with inverters, should be fired. Joe, if I did business with you, no way, would buy from anyone in your company beside you. This plaid suited Miami sales machine time share type person you had on, his immediate wrong/disrespectful view of his customer, was immediate turn off. No way any excuse for how he excused away clipping issues rip off parts of the industry uses to increase gross margins (while selling under engineered systems).
Scam company!