Flexible solar panels

[Dirtdoctor]

For 100 watts itIs t worth it when you can buy 300 plus watt panels and mount them for about the same $$$.

[Sharee100]

Ross Lukeman has a van conversion course and a solar course. When he first started he put in flexible solar panels. They malfunctioned quickly. Research has been done that shows the early flexible panels were poor quality and malfunctioned quickly. They were recalled from the market. I have not checked for updates on quality in the past year. So, if you are ordering panels from China, where the original flex panels were made, do lots of research. I plan to get rigid panels, which while more expensive, have a longer warranty.

[taw9]

Wow, this thread has definitely gone around the barn and back again. After living off grid with solar as my only power source for a decade, I can say it is silly to separate out the components to examine pros and cons. It is a total unit which functions together and affects the other components...one must consider the affect of heat on the batteries, and of course that is determined by the type of batteries you have. You cannot separate out the panels without considering the charge controller, the inverter and the batteries. As far as heat goes, it seems more of a concern to batteries which need water than the solar panels, and of course, if you have closed cell batteries, you do not face that same heat issue. Irregardless of flexible or rigid, it all is a total system rather than the sum of its parts.

[sproutroot]

Originally Posted by dzl_

In the system you sketched, you would at a minimum need a water pump and a radiator fan, these things take power...

Also, unlike a water cooled engine where the cooling system needs to cool something from 'ridiculously hot' down to 'very hot', the cooling system for the pv panels would need to cool something down from 'pretty damn hot' to 'close to ambient.' Could water that is somewhere between ambient and panel temperature make a meaningful difference, and could it both heat water by a meaningful amount, and cool the panels at the same time?

Think less like a radiator and more like an AC unit or a refrigerator. To get good thermal efficiency from this system I think you'd need a compressor and an expansion valve to get a phase change (liquid to vapor) between the two sets of coils.



You could have a secondary condenser coil on a thermostatically controlled loop, which could act as a water heater.

Then you could lord over the skoolie community like the wizard you are.

[john61ct]

Originally Posted by taw9

I can say it is silly to separate out the components to examine pros and cons

Not true. Yes, you need to select the right pnels and the right controller to optimize, but more important than specs are build quality, reliability and functionality.

"Kits" are usually way sub par, if not a waste of time.

Heat's impact on batteries whether lead flooded, sealed or lithium is always the same, higher temps means shorter lifespan, and usually not much to be done unless you have aircon'd space anyway.

Inverter is not even in the picture, just another load, nd afaic optional.

And flex version panels, does not matter how well built, just do not last as long as rigid framed.

[Unpluggedone]

Originally Posted by Iceni John

Standard PV panels have a 25-year performance warranty. How long (if any) warranty do flex panels have? The general consensus of opinion is that flex panels simply don't last very long.

Solar panel warranties are typically void when mounted on moveable structures like busses, TVs and semis. But they are so cheap compared to flexible that warranty should not be the biggest concern

[dzl_]

Originally Posted by Unpluggedone

Solar panel warranties are typically void when mounted on moveable structures like busses, TVs and semis. But they are so cheap compared to flexible that warranty should not be the biggest concern

Good point, still though, even if the warranty won't cover mobile, its still reassuring to know a manufacture designs and stands behind their product for 20-30+ years, vs what 1-3yrs for flexible?

[john61ct]

The only makers of flexible I've heard of actually being responsive to warranty claims is super expensive ones like Solbian, and only when installed by an authorized dealer

Talking like $10 per watt all up

and even then at most 4-5yr average lifespan.

When top notch ~70Voc 300+W house / commercial panels can be found for 60-90¢ per watt and IRL last twice to four times as long even bouncing on down the road. . .

[AndiW]

One thing you can do is paint the roof with cooling/reflective roof paint. There's an issue of heat being reflected back up into rigid solar panels through the space between the roof and the panels, but with the flexible panels right up against the roof there's not so much reflection going on. Mostly you have a cushion between the metal and your panel to keep it from heating up so much. It's still not most desirable way to mount panels. Best is air flow underneath, I believe.

[john61ct]

Yes, fixing flex panels directly to a metal roof would just be stupid, for so many reasons.

[kidharris]

Originally Posted by Highwaygirl1078

Has anyone tried the flexible solar panels that adhere to the roof with an adhesive as opposed to brackets? I’ve just started looking into them so know nothing about cost, companies, installation etc. I’m just at the beginning of my fact finding mission. Thanks!

I don't know much about PV, but, from what I have heard the flexible panels are amorphous silicon and are cheaper, but way less efficient, therefore not a good choice for max power from a limited area, except... relative to other types they perform better on cloudy days. I think that the 4 panel, 100 watt, system sold by Harbor Freight is amorphous rigid panels

[kidharris]

Originally Posted by john61ct

On a cold winter morning with good reflection from surrounding snowy surfaces, is when panels can produce way over their standardized ratings, to the point you need to give some cushion when shopping for a controller if your usage may involve such conditions.

In warm weather they very rarely even come close to hitting those numbers.

Not true, at all.

Just that you should install them so that they don't get much **hotter** than that.

The PV chemical reaction is what generates the damaging heat, needs to be dissipated via the underside, where yes it often gets hot enough to fry eggs.

ok
did my 2 min google, but indecisive results, so how hot (to you) is "hot enough to fry eggs"? LOL



Does this info apply equally to monocrystalline, polycrystalline, and amorphous panels?


Also, does this mean that we can increase the collectors output with reflectors if we can keep the bottom of the panels cool (77degree F) and would keeping them colder than 77 further increase output?


Question for the engineers among us - could a small solar powered 12vdc thermostat controlled fan/fans cool the bottom of the panel enough so that the extra panel output would compensate for its draw and then some and thereby increase output from a specific amount of area. Consider that it would also help lower indoor heat gain from poorly insulated bus metal roofs. Too many variables?


I can see where sloped panels could benefit from passive air flow (hot air rises) as well as solar gain but probably not workable for a moveable bus. I think that a 1/4 inch per foot slope is considered the absolute minimum slope for draft or good drainage so could this minimum slope be satisfied by the curvature of the bus roof?. Maybe with a little help from the fans? Maybe even exit thru a plenum with a finned water coil and make hot water? I'm thinking that is simple to do and a solid maybe on working. Comments?



I am not completely sold on the idea of storing as much energy as possible in batteries and I am interested in how to use electricity as created to run (automated or timed) hvac, hot water, and appliances during peak production so it seems relevant to consider the effects of temperature control on the panels and even other forms of energy use/storage as pertains to buses.


Maybe it is my imagination but it seems to me that panel prices are decreasing and battery prices are rising. Problem is you only have a very limited space to mount panels and need to increase panel output to cut system lifetime costs. Which is better - increased output or increased storage? Is it true that batteries have to be replaced much more often than panels and have more maintenance, not to mention that the occupy premium storage space and weight.


Using more efficient panels on a buses small flat roof seems like a no brainer. Maybe even zombie like. Maybe.


I like this thread. I think that I might be learning something.

[sproutroot]

~160 degrees

[kidharris]

Originally Posted by john61ct

I just meant for cooling purposes.

If you got passive HWS out of it by pumping down to a heat exchanger, that would be so cool who cares if it's practical or not 8-D

Call me stupid, I DuckDuckGo'ed "8-D" and I basically got 2 answers and a few acronyms



1. A typographical penis with the number of - or = indicating size



https://www.urbandictionary.com/define.php?term=8%3DD


2. A corporate team approach to problem solving


https://asq.org/quality-resources/eight-disciplines-8d
https://www.isixsigma.com/dictionary/8-d-process/
https://en.wikipedia.org/wiki/Eight_...roblem_solving


Do you mean one of these 2 answers or is it something only Google knows?

[sproutroot]

it's a smiley face

8 is the eyes. D is the mouth.

don't worry about it, man. digital society is constantly confusing everyone. you've got a lot of catching up to do, so do we all - and you probably weren't the only one here who didn't get it.

[kidharris]

Originally Posted by Unpluggedone

Solar panel warranties are typically void when mounted on moveable structures like busses, TVs and semis. But they are so cheap compared to flexible that warranty should not be the biggest concern

Even so I think some type of useful information as refers to quality can be inferred from how long the manufacturer is willing to warranty the product depending on what is actually covered in the warranty.

[kidharris]

Originally Posted by sproutroot

it's a smiley face

8 is the eyes. D is the mouth.

don't worry about it, man. digital society is constantly confusing everyone. you've got a lot of catching up to do, so do we all - and you probably weren't the only one here who didn't get it.

this is copied from the typographical page---------

https://www.urbandictionary.com/define.php?term=8%3DD



8=D
I though it was a smiley face. I used it everywhere. Now I'm banned from lots of forums. =(
Me: I'm so happy! 8=D

Admin: Why, you like penis? *BANNZOR*
by Meijer's! July 20, 2005

[dzl_]

Originally Posted by kidharris

ok
Does this info apply equally to monocrystalline, polycrystalline, and amorphous panels?

Good question.

and would keeping them colder than 77 further increase output?

Definitely yes, the colder the better.


Its common for power output to increase by about 0.3% for every degree *C below 77*F, at 0*F, PV power output could be 10-15% higher than its rated output. The opposite is also true for every degree *C above 77*F output should decrease by the same amount.

Question for the engineers among us - could a small solar powered 12vdc thermostat controlled fan/fans cool the bottom of the panel enough so that the extra panel output would compensate for its draw.

My guess is a 12v fan would not make a meaningful difference in most situations. Especially when compared to raising the panels an extra inch or two to get more natural airflow. But this is just an uninformed guess, I'm not an engineer, and have no idea how to run the numbers. Would be an interesting experiment or thought experiment though.

I am not completely sold on the idea of storing as much energy as possible in batteries and I am interested in how to use electricity as created to run (automated or timed) hvac, hot water, and appliances during peak production

I think you are on the right track here, As I understand it, its generally much cheaper to produce the energy than to store large amounts in batteries. More productive capacity and less storage capacity makes financial sense.

Maybe it is my imagination but it seems to me that panel prices are decreasing and battery prices are rising.

I think you are right about the first part but not the second. Can't speak to lead acid, but lifepo4 raw cell prices seem to be coming down-- far from cheap though.

Is it true that batteries have to be replaced much more often than panels and have more maintenance

I think this is an unequivocal yes if you are using decent quality panels. Warranties are 20-30 years, and they are still expected to have 70-90% output after that amount of time. Lead acid batteries will last a few years, longer if you oversize your battery bank and baby them, LiFePO4 can last 8-10+ years if you treat them well, possibly significantly longer if you baby them but they are new enough that that might still be an open ended question.

One variable though is that none of this data is based on being thrown on top of or underneath a skoolie and driven all over the country. So its unclear how that use-case will change things, and its unlikely they will ever test for it, probably the closest thing would be the marine industry.

[sproutroot]

Originally Posted by kidharris

8=D
I though it was a smiley face. I used it everywhere. Now I'm banned from lots of forums. =(
Me: I'm so happy! 8=D
Admin: Why, you like penis? *BANNZOR*

In this forum's "smilies" selection, the dude with the sunglasses uses a parenthesis instead of a D for the mouth. That's the only difference. Easy mistake to make.

Using an equals sign instead of a hyphen for the nose and calling it a dick is not something I was familiar with (thanks for the heads up, btw), but I'm pretty sure that's not what John meant.

Like I said, digital society is constantly confusing everyone.

[john61ct]

Yes smiley with glasses

never heard of an emoticon dick

emoji eggplant [emoji533] being the closest