If you place them on the outside of the windshield, it could serve two functions at once. Direct sunlight for production, but also an excellent shield for the interior. Perhaps even put a cloth backer that is tailored to your windshield with some attachment mechanism. Jeez, might try that myself.
I just happened to run across your video today.(I think you did a good job) i’ve been in the Glass business for a little over 50 years. This is just my humble opinion, but I believe the reduction and output of those panels is due to the polyvinyl butyral interlayer (PVB) Which is actually capable of filtering about 99% of the ultraviolet that passes through it. I believe that is the primary cause in the output, reduction. Keep up the good work.
Thank you Professor Proton for running this experiment. When I retire to a truck camper I had planned on using a solar panel inside the windshield to trickle charge a backup power supply but if it only generates 40% the output as when it is deployed outside I might pass on this idea.
I think car windshields are doing some spectrum filtering to attempt to limit at least UV to keep interior cooler, but I don't know anything specific. Also aren't windshields two layers with plastic/glue to make them safety rated? again, no clue how this affects things. That said, I like this test. I've thought about using a flexible(not foldable panel) as part of a window sun block, but never worked out any details. So again, very interesting test and my blind guess at the start with 50% at best for the reasons you mentioned, dirty window, non-optimal angle/car position. That said, flat mounted roof panels are facing these same issues. If someone had a jackery like device up front while on a day hike(or day job), this would be helpful way get some power while unattended charging. I've been thinking of an ways I could trickle charge my starter battery while boondocking for days in same spot. Modern vehicles have parasitic power draw that's really annoying. You see notes in owners manual about starting car every 2-4weeks to top off battery.
I bought a small battery tender panel on Amazon (probably 20-30w). I just leave it on the dash in my truck and it works great. The truck is under a carport so it only gets direct sun to about 11:30 and it still works great.
@@atomicsmith Thanks for the tip. Was looking at the little 50w panel but did not work out which controller I'd use to regulate the voltage for starter battery charging, but not over charging. Once those are figured out, wiring for ease of use. What do you use control the panel voltage?
@@Chris-ut6eq been using a 60w folding panel in my windscreen for a few years now to help combat parasitic draw from car alarms. PWM solar voltage regulators are very cheap (£10 to £30 for the cheap Chinese ones readily available) but approximately 30% less efficient than MPPT type regulators. I use Victron mppt more expensive but well worth it for adjustable within there app. Just remember to buy the right type Victron do make Bluetooth and non Bluetooth versions
@@Chris-ut6eq The panel I bought has a battery tender circuit built in. I just plug it in to the cigarette plug and it does its thing. Very convenient.
At trailheads, I hang a couple of 130 watt flexible panels on the side of my van or on the windshield during my day hike. Thief would need to have a mc4 disconnect tool or wire cutters in his pocket. If he uses wire cutters, he has to reinstall MC4 connectors. Too much hassle for too little return. But thanks for doing this experiment.
Thanks for doing this, and thanks for putting the main answer early in the video. Follow-up question: what if you face the van east on a cool morning? As panels get cheaper, "questionable" stuff like this begins to make sense, especially if you use some power to ventilate the vehicle. (I have had various plastic things fail in the interior heat, over the years, here in Alabama.) Finally, some have suggested UV or IR-blocking windshield layers are the problem, but most panels are tuned for visible light, because the most energy is there.
Same results I noticed using a smaller panel to maintain a 12v battery...putting inside the windshield made it more or less useless. It had to be mounted outside of the glass to get enough irradiation to actually work.
If it's a cool day and you want the extra heat, the inside option makes the panels 'dual output' devices for the good. However, if you expect a hot day and want cool comfort, the heat needs to be kept OUT to reduce the load on cooling appliances. So, seasonal considerations indicate some days where the outside panel is best.
Great video, guess we know why window shade manufactures didn't already do this. I wonder if securely mounted solar panels on to the side of camper van bodies will help increase the amount of solar power generated. I see some solar panels can be mounted on the front hoods of Sprinters but I wonder if the heat from the engines reduce their efficiency?
Ha Ha I've done this for years especially placing them on the inside when I'm gone to prevent theft. If the panel doesn't cover the whole window, I'll put the shade behind it to keep the vehicle cooler in the summer. They are on the outside when I'm present.
Did you look into the effects of coatings on windshields? I’m guessing you just assumed most windshields will act similarly enough? Wasn’t sure if different manufacturers might use different coatings, or even none at all in some cases, which could potentially affect results. Might have to try this on my own van and see how it compares. Thanks for the interesting content!
I tried maintaining my car battery with a 65w panel and a 240wh Jackery battery pack. Had the panel inside. Don't have your numbers, but it kept both batteries maintained. Not sure if windshields have a UV blocker if that has anything to do with a lower output since my photochromatic glasses won't change very much through the windshield even w/ direct light or that solar panels need ultraviolet light to work properly. Apparently, they do for the reason why they don't work as good through the windshield.
VRM online let you export data in csv.. And 40% is not so bad I thought worse. It could differ with type of glass used for wind shield but 0,4 is better than i thought. Thanks!
Yet another you tuber who makes really great content but hardly ever replies to comments. On this there is 42 comments, as I write this comment, over the last day since posting and not one reply. Yep, great video, and you have answered a question I had thought about...so I thank you. Just saying though....reply to comments and maybe you'd have 100K or more subs and 10X views. just my opinion folks....once again, great video :)
So the 40% result is mainly due to temperature of the panels inside the van. Dramatically illustrated the impact of temperature on panel efficiency doesn't it!
vehicle glass especially windshield is a layered composite which is laminated with a plastic layer. this means it reflects more than even regular window glass, and is also likely to block close to 100% of UV, possibly other wavelengths as well. im sure the temperatures reduced the efficiency, but i would expect the largest reduction to come from the glass itself reflecting and filtering various wavelengths.
Modern windows and windshields are designed to block thermal radiation to keep the inside cooler. That's where the 60% went.
True true!
Also many of them are polarized, like our sun glasses or CPL filters for camera's, cuts the light quite a bit.
If you place them on the outside of the windshield, it could serve two functions at once. Direct sunlight for production, but also an excellent shield for the interior. Perhaps even put a cloth backer that is tailored to your windshield with some attachment mechanism. Jeez, might try that myself.
Just casually snacking on some desiccant! LOL
I just happened to run across your video today.(I think you did a good job) i’ve been in the Glass business for a little over 50 years. This is just my humble opinion, but I believe the reduction and output of those panels is due to the polyvinyl butyral interlayer (PVB) Which is actually capable of filtering about 99% of the ultraviolet that passes through it. I believe that is the primary cause in the output, reduction. Keep up the good work.
Like# 198 - I actually do this as a sun shade here in AZ as well as to keep my 12volt battery topped off
I absolutely love your videos. Found your channel from the lightweight cabinets, and i'd love to see more of that as well.
Can you do a quick review on the free snacks they packed in there? 😃
the do not eat snacks! 😁
Thank you Professor Proton for running this experiment. When I retire to a truck camper I had planned on using a solar panel inside the windshield to trickle charge a backup power supply but if it only generates 40% the output as when it is deployed outside I might pass on this idea.
This is a nice experiment, thank you for the information 👌🏼
I think car windshields are doing some spectrum filtering to attempt to limit at least UV to keep interior cooler, but I don't know anything specific. Also aren't windshields two layers with plastic/glue to make them safety rated? again, no clue how this affects things.
That said, I like this test.
I've thought about using a flexible(not foldable panel) as part of a window sun block, but never worked out any details. So again, very interesting test and my blind guess at the start with 50% at best for the reasons you mentioned, dirty window, non-optimal angle/car position. That said, flat mounted roof panels are facing these same issues.
If someone had a jackery like device up front while on a day hike(or day job), this would be helpful way get some power while unattended charging. I've been thinking of an ways I could trickle charge my starter battery while boondocking for days in same spot. Modern vehicles have parasitic power draw that's really annoying. You see notes in owners manual about starting car every 2-4weeks to top off battery.
I bought a small battery tender panel on Amazon (probably 20-30w). I just leave it on the dash in my truck and it works great. The truck is under a carport so it only gets direct sun to about 11:30 and it still works great.
@@atomicsmith Thanks for the tip.
Was looking at the little 50w panel but did not work out which controller I'd use to regulate the voltage for starter battery charging, but not over charging. Once those are figured out, wiring for ease of use. What do you use control the panel voltage?
@@Chris-ut6eq been using a 60w folding panel in my windscreen for a few years now to help combat parasitic draw from car alarms. PWM solar voltage regulators are very cheap (£10 to £30 for the cheap Chinese ones readily available) but approximately 30% less efficient than MPPT type regulators. I use Victron mppt more expensive but well worth it for adjustable within there app. Just remember to buy the right type Victron do make Bluetooth and non Bluetooth versions
@@Chris-ut6eq The panel I bought has a battery tender circuit built in. I just plug it in to the cigarette plug and it does its thing. Very convenient.
At trailheads, I hang a couple of 130 watt flexible panels on the side of my van or on the windshield during my day hike. Thief would need to have a mc4 disconnect tool or wire cutters in his pocket. If he uses wire cutters, he has to reinstall MC4 connectors. Too much hassle for too little return. But thanks for doing this experiment.
Thanks for doing this, and thanks for putting the main answer early in the video.
Follow-up question: what if you face the van east on a cool morning?
As panels get cheaper, "questionable" stuff like this begins to make sense, especially if you use some power to ventilate the vehicle.
(I have had various plastic things fail in the interior heat, over the years, here in Alabama.)
Finally, some have suggested UV or IR-blocking windshield layers are the problem, but most panels are tuned for visible light, because the most energy is there.
Interesting idea.
Whoa .... that is a lot of van you got there.
Thank you that's always been a question I had in the back of my mind and you just answered it, awesome job
Same results I noticed using a smaller panel to maintain a 12v battery...putting inside the windshield made it more or less useless. It had to be mounted outside of the glass to get enough irradiation to actually work.
I too have always wondered whats shown here in the video. Thanks
If it's a cool day and you want the extra heat, the inside option makes the panels 'dual output' devices for the good. However, if you expect a hot day and want cool comfort, the heat needs to be kept OUT to reduce the load on cooling appliances. So, seasonal considerations indicate some days where the outside panel is best.
Very interesting… great video.
Great video, guess we know why window shade manufactures didn't already do this. I wonder if securely mounted solar panels on to the side of camper van bodies will help increase the amount of solar power generated. I see some solar panels can be mounted on the front hoods of Sprinters but I wonder if the heat from the engines reduce their efficiency?
Ha Ha I've done this for years especially placing them on the inside when I'm gone to prevent theft. If the panel doesn't cover the whole window, I'll put the shade behind it to keep the vehicle cooler in the summer. They are on the outside when I'm present.
Did you look into the effects of coatings on windshields? I’m guessing you just assumed most windshields will act similarly enough? Wasn’t sure if different manufacturers might use different coatings, or even none at all in some cases, which could potentially affect results. Might have to try this on my own van and see how it compares. Thanks for the interesting content!
Very useful video. Thanks!
Been there done that with s battery tender…
NO BUENO AT ALL
Glass have UV cut, IR cut… bad for solar panel…
I tried maintaining my car battery with a 65w panel and a 240wh Jackery battery pack. Had the panel inside. Don't have your numbers, but it kept both batteries maintained. Not sure if windshields have a UV blocker if that has anything to do with a lower output since my photochromatic glasses won't change very much through the windshield even w/ direct light or that solar panels need ultraviolet light to work properly. Apparently, they do for the reason why they don't work as good through the windshield.
VRM online let you export data in csv.. And 40% is not so bad I thought worse. It could differ with type of glass used for wind shield but 0,4 is better than i thought. Thanks!
Yet another you tuber who makes really great content but hardly ever replies to comments. On this there is 42 comments, as I write this comment, over the last day since posting and not one reply.
Yep, great video, and you have answered a question I had thought about...so I thank you.
Just saying though....reply to comments and maybe you'd have 100K or more subs and 10X views.
just my opinion folks....once again, great video :)
Not to mention the thermal transfer into the cab of the vehicle...
thank you!
So the 40% result is mainly due to temperature of the panels inside the van. Dramatically illustrated the impact of temperature on panel efficiency doesn't it!
vehicle glass especially windshield is a layered composite which is laminated with a plastic layer. this means it reflects more than even regular window glass, and is also likely to block close to 100% of UV, possibly other wavelengths as well. im sure the temperatures reduced the efficiency, but i would expect the largest reduction to come from the glass itself reflecting and filtering various wavelengths.
@@ensom Very good. Thanks for the info.
Probably the same reason my eye glasses don’t get dark while inside the van
Thank you very much for your video and very usefull informations!
Don’t have to watch this to know that the greenhouse effect of sun rays going through glass will cook that panel . Way too hot inside a vehicle .
I'm concerned about a cracked windshield!
Of course they would work BUT I winder about the long term "COOKING" of the cells from the heat coming I with the light.
the wndow itself is prob taking away half the power lol
And you need to take into account that the windshield is tinted.
No way a frige can be ran on one 100w panel and 100Ah battery, i must have misunderstood.
prob a dc fridge, not a home appliance ac one
Suboptimal
the reason nobody ever done a video on this before is because it not worth showing lol