What are the most compact, yet affordable panels?

In those physical sizes the per watt cost is high.
What are these to be used for?

A small travel trailer (13' Scamp). The usable panel mounting area is quite small and since my tow vehicle is very small weight is critical.

This is looking like the best solution so far, but I'd love a higher wattage for a similar surface area.

The thin film like your link are the least efficient - probably by 50%. A silicon cell panel gives you much more for the same space and should have a much better life.

Better to buy from a real dealer rather than Amazon - the guarantee from Amazon sales is most likely finished once the item touches your door step.

Find me a 30+ watt panel that will fit in a 16" x36" area and I'll be grateful, I'm not finding any others. Perhaps if there's a place that will do custom panels, I'm not sure I feel like buying cells and making my own, but I suppose that's possible.

The thin film while not ideal for panel efficiency and durability is a great match for the application, mildly curved fiberglass. Plus a thin surface mount will be better for aerodynamics. They weigh next to nothing, much less than glass/metal panels. But as I said, I'd be happy with a more traditional panel if I can find ones that fits.

I'd be happy to use a dealer, but I'm finding few with good selections of smaller panels. And I have to say in general, from coffee makers to cameras I'm usually very happy with my Amazon transactions. I've been looking for a dealer who want to take the time to listen to my requirements and then find be the ideal panels, electronics. But each dealer I find is either all about standard sized panels for residential/industrial applications, or if they handle small, off grid, portable systems they have a limited selection, are more interested in selling their current inventory than finding me the right products. If you have suggestions I'd welcome them.

30 w thin film panels, you may as well not bother. They will barely keep up with the battery self discharge. You would be better off getting a honda eu1000 generator and a beefy battery charger to run off it's AC outlet. 30 minutes (500Wh) would be the same as 4 days worth of power from the PV, and you could run the electric kettle at the same time you are charging the batteries.

My best suggestion is a couple of "sandwich board" arrangements, with a 120W panel (easy to handle size) that you can pull out. Or figure some some sort of awning with a panel or 2 on it.

Are you assuming I'm only going to use 1 30 watt panel? Or is 90 watts from the 3 thin film panels (3x30=90 watts) not going to be close to 90 watts of silicon cell based panels? Is that because the thin films don't reach their peak output under as many conditions? Or is that because the cheap makers don't realistically, accurately rate their panels?

I have an acquaintance with a similar trailer to mine, he says he has a full battery by noon most days using 2 40 watt flexible panels. Granted I don't think he has huge demands. These panels specifically.

The company is American, but they manufacture and ship from Hong Kong. One interesting thing about these is they say they can custom make different sizes. It's expensive and longevity is questionable, but the mounting and weight saving is a huge plus for these. My friend says he's had them less than a year, but no problems so far, towed 10000 miles, seen very high temps, snow storms, weeks of rain, sand storms with very high winds, etc. If they only last 5 years I'll be a bit disappointed, but at the rate solar tech is getting better there will be something much cooler to upgrade too. If I was making a $20,000 investment in a huge installation I'd be more concerned about efficiency per dollar and longevity. As it is, I want convenient power and don't need tons and tons of it. I'd love to find light weight, well sized silicon cell panels, but I'm not finding those.

Waste of time to look for solar that small IMO. Better off using a generator, panels that small are a lot pricier because there's far more limited demand for them, the numbers really don't add up, in some cases you can pay 2-3 times as much for a smaller panel.


What you want is high efficiency but you're looking at the "bare cupboard" section of the industry, you're not going to find anything remotely close to having high efficiency, especially not thin film, those lower-end thin film panels can have efficiencies that barely reach 6%.......your conventional silicon panel has about 15% efficiency and the high-end panels have 19%+ efficiency. In short, what you're looking for really doesn't exist.

OK, maybe I need to go to a forum that specializes in portable (RV/Marine) set ups.

Being compact and fitting on the roof is the paramount specification. So telling me I should get bigger panels is not helpful to me. I know I'm going to have a hard time getting the most efficient cells in smaller panels, that's why I'm asking. I may end up with a large movable panel eventually, but the first panels I'm putting on WILL be on the roof and standard sizes are not going to fit. If they end up being little more than a $1000 glorified trickle charger so be it, I understand the disadvantages and I'm ok with them. But I do want to try to get the best panels I can afford that will fit into my specifications. If I find that I'm getting no where near the power I want to use I'll consider additional options. But I want basic battery charging without setting anything up, unpacking a loose panel and securing it at every stop is not something I want to mess with.

What I don't understand is I've found options that work by the numbers. They'll fit on my roof and are rated at 90-120 watts depending on the panels (HQRP vs Sunflex). That should be in the ballpark of what is a decent match for my 80ah battery. But I'm being told I shouldn't even bother?

No one is saying why, but it seems people think that 90 watts of thin panels is not even comparable to 90 watts of traditional panels. Can someone show me testing that indicates thin film panel ratings are consistently more optimistic than traditional panels?

And I'm not even sure these "flexible" panels should be lumped in with "thin film" panels, they claim to be monocrystaline cells and I've heard first hand reports they work quite well.

Has anyone actually tried them? The Sunflex or the cheap HQRP panels available all over online? I think the $140 Amazon panels may be worth the money just to test one!

Do you have an area that is say 64x39?

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

Very small areas, it's a tiny trailer. Therein lies the rub.

The more I look the more I think the monocrystaline flexible panels are not inherently inefficient.

I found a seemingly respected, certainly expensive variation on the chinese panels made in Italy I believe. They claim very high efficiency.



The flexible photovoltaic panels of SP series with "Sunpower technolgy" are made with monocrystalline cells with efficiency greater then 22,5% embedded in polymers with high-resilience technology developed in collaboration with CNR of Parma. These materials make the panels flexible, walkables with a weight of about 1 / 8 compared to traditional glass panels. Their specific technologies makes them particularly resistant to the marine environment and therefore suitable for application in the marine industry.

A US reseller.

Featuring high-output, semi-flexible, lightweight solar panels made by SOLBIAN (Italy) and MPPT controllers by GENASUN. Previous high-output panels have been heavy, cumbersome and armed with dangerously sharp corners. Other flexible panels have been very low-output.

Solbian has made a significant advance with these new solar panels in both power and light weight. They have been proven in use by top short-handed racers like Giovanni Soldini (Telecom Italia), Marc Guillemot (Safran), and many high-performance cruisers.

The high-power versions (SP-50L, SP-50Q, and SP-100L) are the highest output (per sq. ft.) and lightest weight solar panels available. They use the new SUN POWER BLACK CELL, with efficiency greater than 22.5%, increasing the amount of power you can get from a given size panel. The SP-40L, SP-40Q, and SP-80L represent a great value for their output and low weight.

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.

A link showing printed monocrystaline cells can in theory be very efficient.

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.)

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."


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.