GREAT DEAL on 'discontinued' Flex Panels...

[rickst29]

For those owners who want Solar, but want to avoid the weight, Ebay seller 'recycledgoods.com' is selling 90W CIGS panels (just 4.6 lbs each!) at about $1.50 per Watt. These are from a bankrupt Oregon company 'Solopower' which, like the notorious Solyndra, went bankrupt while trying to use 'exotic' technology to build thin panels.

http://www.ebay.com/itm/SoloPower-SP1-90-SoloPanel-90-Watt-Flexible-Lightweight-24V-CIGS-Solar-Panel/191414606314

In comparison, other lightweight panels (form Chinese companies) are going for $2.20 per Watt and higher. (Note that the even cheaper 136W Uni-Solar panels are built too long to fit any model of TM roof, so they don't count).

Note that the sun is never at a good angle for roof-mounted panels. Therefore, with a new installation intended for actual boondocking, I would recommend 3 or 4 of these, not just 1 or 2. I pondered doing an upgrade to 4 * 90W myself, but my current 200 Watts would become leftover junk - and my wife would not be pleased by seeing me "toss them" on Craigslist, or the local newspaper.
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There are two disadvantages with this implementation. First, flex panels are said to wear out faster (a lifespan 10-15 years on a roof at 80%+ of original power, versus 25+ years for heavyweight panels under glass).

And 2nd: These panels require an MPPT controller, at additional cost of $150 - $350. (They are 24 volt panels, and the TM uses a 12 volt battery configuration.) A $30 "PWM" Controller would only get a maximum about 50W from each of the panels. (In the "real world", with rooftop panel angles - maybe 30W).

[scrubjaysnest]

Saw a flex panel mounted to a pvc frame to get portability. It was a 100 watt 12 volt. This is while we were at Big Bend.

[tentcamper]

Nice. since they are so thin, I wonder if you could lay them on the rear shell froward and have the front shell close up on the majority of the panel? If so you could put up to 4 panels back there?

[LoveToCamp]

Well, from my viewpoint, for my purposes, I would not think you would want to cover them while folded. I like having my panels charge my batteries when in storage, so they are always topped-off. If you covered part of the panels, doesn't that almost negate the input from the exposed panels?

I don't know enough about solar to say one way or another, but I have seen many people comment that partially covering a panel will render it virtually worthless. And, with multiple panels, covering one can render the other(s) worthless. Not saying this is the case, but that would need to be checked before designing a layout. What do you think, rickst29?

[Bill]

I'm not rickst29, and I am not an expert. But - if the panels are wired in series, and one panel is covered, then my understanding is that the total output would be spoiled.

But these are high voltage panels, and you would probably wire them in parallel. If so, and if you laid the panels crosswise on the rear roof, and arranged them so that when the trailer is closed, one panel is still fully exposed, then I believe that the uncovered panel would continue to produce output as if the others were not there.

Is a single 90-watt panel enough to charge your batteries while on the road? That is a different question. Probably not, since the refrig draws something on the order of 120 watts. But maybe two 90-watt panels exposed?

Bill

[LoveToCamp]

If the panel is charging on the road, and one has a 10 ga. wire to charge through the Bargman, would that suffice?

[Bill]

If the panel is charging on the road, and one has a 10 ga. wire to charge through the Bargman, would that suffice? I'm not sure where you are going with this. You can't disconnect the Bargman from the tow vehicle, since the Bargman carries lights and brakes to the trailer. And I'm not sure how you would connect the solar charge current to the Bargman while it is still plugged into the tow vehicle.

Also not clear on what it means to "suffice". Can you define what you are looking for a bit?

Bill

[rickst29]

Nice. since they are so thin, I wonder if you could lay them on the rear shell froward and have the front shell close up on the majority of the panel? If so you could put up to 4 panels back there?
Bad idea- because they don't have THICK tempered glass on the top-side, they'd become damaged relatively fast. 4 panels would best be mounted on the front shell, length-wise (2 along each side the center joint).

[rickst29]

I'm not rickst29, and I am not an expert. But - if the panels are wired in series, and one panel is covered, then my understanding is that the total output would be spoiled.

But these are high voltage panels, and you would probably wire them in parallel. If so, and if you laid the panels crosswise on the rear roof, and arranged them so that when the trailer is closed, one panel is still fully exposed, then I believe that the uncovered panel would continue to produce output as if the others were not there.

Is a single 90-watt panel enough to charge your batteries while on the road? That is a different question. Probably not, since the refrig draws something on the order of 120 watts. But maybe two 90-watt panels exposed?
Bill
With panels having just one to four "strings" of diode-separated segments, and shade on most of on panel, there is often a big advantage in setting them up parallel - exactly as Bill describes.
But these are 24V panels- you need an MPPT in any case, and nearly every MPPT can handle at least 100W of maximum Open Circuit voltage. (In this particular scenario, two panels @ 33.6V is about 67V; it would become a bit higher in cool, clear conditions at any significant altitude). I suspect that, overall, a pair would best be wired in Series instead - less wire loss on the "PV side" wiring, and a bit of extra power yield at the start and end of the day.

A bigger configuration (for boondocking), 4 * 90W, would probably need to be wired as 2 parallel strings of 2 panels in series, at the same 'Open Circuit' voltage.
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My comments on the "different question": SInce this would be an MPPT configuration, you really could expect to get a full 90W while driving down the road near noon in early Summer. (Maybe even more, in mountains.) One panel wouldn't charge the batteries, but it would greatly assist the TV in preventing Fridge operation from digging a hole into the batteries so quickly. The TV, and it's very long wiring to the Converter's Distribution panel (and then to the Fridge), would need to provide only 30-50W to keep the batteries from becoming depleted, instead of the whole 120-140W. (Don't forget, the Norcold Fridge element is a simple resistor, which will consume MORE power when voltage is high.

The Amps and voltage drop on the TV-to-TM-Panel wiring would both be greatly reduced, in comparison to running from TV and TM batteries alone. In the latter configuration, the batteries can often be drained quite fast, because the wire length (and possibly thin gauge) form the alternator can't "hold up" to the battery voltage, as seen at the DC distribution panel, at higher levels of current. The total current can end up coming primarily form TM batteries, rather than the TV alternator. ;)