What are the most compact, yet affordable panels?

[crotalus]

All the newest technology, highest watt per dollar panels I find are in standard, large panel sizes for large installations. Seems the smaller panels are generally pathetic in watts per pound, per square area and per dollar. Flexible panels for RV/Marine use are dramatically more expensive and have pathetic output per dollar/per area.

What are the most powerful cells that I can find in panels of various sizes? Smaller sizes. 12x24, 16x32, etc? What brands and/or technologies should I be looking for? Hopefully thin, light panels while still having some durability for being hauled down the road.

You didn't define "Affordable" but here is a nice 30 watt panel that will fit your needs.

Mod note - link removed - 8$ per DC watt hardly qualifies as cheap - and linking to competitors of our host is frowned upon.

I believe that BP is getting out of the market so these may be hard to find.

[dylanear]

A couple of places you mentioned printed on crystalline - just for the record.

I didn't mean to claim I never used the words and I have certainly quoted others using the term. I've never made the claim, 100% that any of these products were printed crystalline. Early on in the conversation I was less clear on what these flexible panels were. I may have speculated that the flexible panels might be some kind of printed crystalline tech, or at least pointed to claims by others.

From what I can tell now, while there is very credible evidence there are "printed on crystalline" cells. From what I can tell, in actual mass produced cells the printed part is screen printed circuitry on the traditional crystalline cells. Not the cells themselves. Yes indeed, as you say, it would be pretty amazing if you could print a substance and have it organize into large scale crystals. You say, "Printed on crystalline my aching butt - the two terms contradict each other. " You may think so, and I think I understand you logic, but they are used together by credible sources. That GA Tech paper says MOST commercial cells use printed technology. So it seems it's important to understand what those term used together mean. Circuits printed rather than using silicon lithography.

http://www.ece.gatech.edu/research/UCEP/papers/31ieee/HIGH%20EFFICIENCY%20SCREEN-PRINTED%20PLANAR%20SOLAR%20CELLS%20ON%20SINGLE.pdf

http://www.schottsolar.com/global/news/top-news/article/more-than-20-percent/

A very detailed explanation of Screen printed circuits on crystalline silcon:

http://pveducation.org/pvcdrom/manufacturing/screen-printed

While I'm pretty darn sure the Sunflex use solid, if very thin crystalline cells the HQRPs are a bit of a mystery. They advertise crystalline, but they look printed (they look amorphous, if they are crystalline, they are trimming any curves on the cells. They look completely rectangular. The comment by the customer who said "printed on crystalline structure" only adds to the mystery. He obviously isn't sure what he's looking at. Crystals thin enough to look printed? Amorphous that look crystalline? Since they are advertised as mono crystalline, good chance they are, just like the Sunflex.

Since it seems I can't get the Sunflex any time soon, I may order an HQRP panel from Amazon since I can have that overnight. Just to have a look up close, perhaps test if it's rating is anywhere close to accurate. The 30 watt is only $150. I'm at the point where I'd pay that just to satisfy my curiosity and hopefully, at least make up for battery storage losses, maybe even a bit of actual charging. If I do I'll post some close ups of the cells with a high quality macro lens. Perhaps even order a small panel and take it apart and look at one of these cells up close.

[russ]

A couple of places you mentioned printed on crystalline - just for the record.

I'm not 100% convinced the printed monocrystalline panels are super exotic/expensive tech at this point.

I am just speculating here, but they look printed, they claim to be monocrystalline.

The web-site picture that shows the panel semi-folded is roughly 1 or 2 degrees from the point where you start damaging the printed-on crystalline structure.

[dylanear]

Printed on crystalline my aching butt - the two terms contradict each other. Your friend is smoking something and spreading BS.

I never said, my friend never said, and the maker nor seller ever said anything about the sunflex being printed. As I've said they are very thin crystalline cells laminated on a metal sheet.

The HQRP panels that are all over the Internet, those may be printed, may be crystalline, I've never seen them. The only reference to them being printed is that online review by a customer. The maker does claim monocrystaline. Who knows.

[russ]

Sadly I'm having no luck getting a reply from the US reseller of the Sunflex panels. My friend has received his panel after 3 weeks, so they are still selling and shipping panels. But answering any questions seems to beyond their capability these days. Sad. They seem to have the best panels for my needs, I just don't know if I have the time or patience to deal with such lousy customer service. If they've had some business issue preventing communication a boiler plate message would suffice. Perhaps they are selling all they can make and have no need for customer service. Ah, modern international business!

Printed on crystalline my aching butt - the two terms contradict each other. Your friend is smoking something and spreading BS.

[dylanear]

Sadly I'm having no luck getting a reply from the US reseller of the Sunflex panels. My friend has received his panel after 3 weeks, so they are still selling and shipping panels. But answering any questions seems to beyond their capability these days. Sad. They seem to have the best panels for my needs, I just don't know if I have the time or patience to deal with such lousy customer service. If they've had some business issue preventing communication a boiler plate message would suffice. Perhaps they are selling all they can make and have no need for customer service. Ah, modern international business!

[dylanear]

Sadly, we are speaking from real life experience, that the effort & expense, to install small, flexible panels, is way beyond the power you (ok, what I would expect) could expect to harvest from them.

The amphorus cells they are made from, degrade rapidly in a couple years, you need to see if the power spec is when NEW, or what it is expected to degrade to in 5 years. Often, that's a 50% difference.

As to your friend with full batteries by noon, I can't explain that, except maybe he did not use much that night.

A small genset & battery charger still looks to be the best option, after a good DC wire from the tow vehicle.

A: I never said exactly how much power I expect, perhaps I said how much I'd like. My goal for this stage is simply get as much power from a lightweight and low profile installation on the trailer roof. ANY other suggestion is not helpful. I may need more power later on from big movable panels or a generator. BUT THAT'S NOT WHY I STARTED THIS THREAD!

B: They are not amorphous, they are crystalline.

[billvon]

Nope, not even close. I have three areas on the roof, one about 16" x 34", two about 24"x36".

The old BP 590's were quite efficient and were 20x46 inches. If you can tolerate some overhang they might be a good option.

[Mike90250]

Sadly, we are speaking from real life experience, that the effort & expense, to install small, flexible panels, is way beyond the power you (ok, what I would expect) could expect to harvest from them.

The amphorus cells they are made from, degrade rapidly in a couple years, you need to see if the power spec is when NEW, or what it is expected to degrade to in 5 years. Often, that's a 50% difference.

As to your friend with full batteries by noon, I can't explain that, except maybe he did not use much that night.

A small genset & battery charger still looks to be the best option, after a good DC wire from the tow vehicle.

[billvon]

How go you get flexible crystaline silicon cells? It may be a different product but I don't see anyway to make a sliced cell flexible.

I've used two versions of them. The original ones were made by Solarex, and were crystalline cells laminated onto stainless steel. Later version ones (forget the manufacturer) were laminated onto fiberglass which was also fairly flexible. Flexible enough to conform to boat hulls, not flexible enough to roll up or anything.

[Naptown]

That is amazing because Sanyo HIT Double is what science claims as the highest efficiency panel on the market today @ around 20%..

They are talking individual cell efficiency not module efficiencyr.

[Sunking]

The flexible photovoltaic panels of SP series with "Sunpower technolgy" are made with monocrystalline cells with efficiency greater then 22,5%

That is amazing because Sanyo HIT Double is what science claims as the highest efficiency panel on the market today @ around 20%..

[dylanear]

I asked my friend who originally recomended the Sunflex panels about the cells in his panels. He's built his own panels from cells in the past, so he has a clue. He says they are semi-ridgid, very thin crystalline cells, not dramatically different from what he's used to build his own panels, but thinner. They bend slightly because they are so thin, he suspects if you tried to bend them more than slightly they'd crack, but the way they are mounted that's not easy. There's an aluminum backing and several layers of polymers over and under the cells. So the whole thing is flexible but not a lot, you'd have to try to bend it more than it was designed to. Apparently some heavy duty outdoor tape is often used to hold these down and my friend says his lays flat and flush on the slightly curved fiberglass roof of his trailer. No problems in hail, hitting branches, they are holding up and staying attached after 8 months, 10000 miles of towing. Who know after a few years, but they seem like an excellent solution other than a possibly sort lifespan. You might get 5 years out of them, probably not 10, but I think I'm ok with that.

I'm not 100% convinced the printed monocrystalline panels are super exotic/expensive tech at this point. I suspect that's what the HQRP panels are. It may be newer tech, but once a Chinese factory gets the new tooling and starts cranking out millions of panels sold all over the internet, prices will be lowish. The whole point of printed cells/panels is cheap mass production. And that's what the Chinese tech firms do, take new tech and make cheap bits and bobbles that can be sold for a pittance by the millions. I am just speculating here, but they look printed, they claim to be monocrystalline. And there's this reference in a Amazon review:

"Why not that (coveted) 5th star?
The web-site picture that shows the panel semi-folded is roughly 1 or 2 degrees from the point where you start damaging the printed-on crystalline structure. You are NOT going to roll that thing up to store it, but so far, that has not been an issue on my boat."

http://www.amazon.com/HQRP-Flexible-Mono-crystalline-Stainless-Radiation/dp/B003DVY27U

Seems the reviews are generally very good for a bargain flexible panel. I may order a smaller HQRP panel to play with, may end up a battery topper in one of my lesser used vehicles or something.

[inetdog]

How go you get flexible crystaline silicon cells? It may be a different product but I don't see anyway to make a sliced cell flexible.

And so far all I have seen agrees with you on that. I have not seen any mention of flexible "cells" in the Sunpower description. Just semi-flexible panels. To me that suggests that all the bending happens between the cells.

The resulting panel will not mount tightly to a curved surface, but it will follow the curvature with small airspaces. Each individual sliced cell's area is tangent to the curve, but flat. What I do not see clearly is how you protect the cells from accidental breakage. For that, a thicker cell would be better than a thin one, since silicon does not flex worth a darn. Or else a rigid substrate under each cell. (Silicone does bend, but that is a compound, and very different from the element silicon.)

According to the German group, printed polycrystalline rather than amorphous cells have been in production for awhile, but the printed monocrystalline cell is still the bleeding edge of research, and therefore probably NOT cheap, if you could get one. (And no, I do not understand the technology of printing a monocrystalline cell, but I am willing to give it the benefit of the doubt for now.)

[russ]

I think the chinese panels, at least the HQRP ones are printed. The Soliban and maybe the Sunflex panels seem to use very thin, but solid crystal cells.

How go you get flexible crystaline silicon cells? It may be a different product but I don't see anyway to make a sliced cell flexible.