Unisolar flexible 68W $99 ea.!!!

Does this interest anybody? Unisolar went out of business, but there are good reports of their efficiency and I plan to mount 4 on the back roof.

9'4" x 15" come with 3ft. MC-3.

From here

They are on ebay for $115....but $99 seems pretty great!

[scrubjaysnest]

These wouldn't fit our TM

I don't know why you had a problem...I have 11+ ft. of bare back roof; room for 5 or 6 of these.

These 68w panels are 9ft. 4" long x 15" wide.

$400 for 4 = approx. 250 watts - with no mounting hassles and much less paranoia about theft concerns seemed like a good solution (w/MPPTcontroller).

Sure, if I was as handy as Harveyrv, I'd look into standard panels with the innovative mounting latches and braces he built to make them removable......maybe he should market them. I am so impressed with all the cool upgrades you guys have done.

[Bill]

When the TM is set up, you have 11 feet of room for the panels. When you close the TM, though, you have only about 4 feet. The back edge of the front shell will come down on the panels more or less at their center. You must protect the panels somehow. Otherwise, the bag seal along the back edge of the front shell will rub the surface of the panels, which will destroy them. That bag seal has rubbed the paint off my TM ...

Bill

[ThePair]

I looked into these some time in the past, and my understanding is that their construction allows for damage without any output loss outside of the actual cells that are damaged. So, if there were to be a line of cells damaged by the bag seal, it would only lose the output of that single line of cells, and not the rest of the panel. That may be an acceptable loss for the convenience of the install, especially if the output is 250 -> 240 (or whatever). They were quite clear that shadowing (which basically causes the same thing) would only affect those cells that were shaded, not the global panel output -- which is a weakness of some traditional panels, IIRC. In addition, they state that you can walk on these without damage. I agree the bag seal would likely rub and harm that line, but it may not dramatically affect the installation.

Then again, I'm not the one taking the risk!!

[scrubjaysnest]

The way solar panels are constructed, flexible or not, when shaded; called a hotspot; this greatly reduces the total panel output.
We use a pvc frame work and store the panels on the couch when moving the camper. This maybe adds 10 minutes to set up moving the panels to where they will get good sun light.
When not in use at a camp site they are stored under the TM.

The manufacturer's wording is very clever. Yes shading only impacts the output of the cells shaded ( or damaged) BUT the total output of the panel is impacted significantly by the reduced output of those cells. The panel is the physical size it is because it must contain a certain number of cells to attain the performance desired. The output of most panels is greater than the required charging input to account for losses and inefficiency of wiring and controllers. If the output is reduced, you get a reduced charging capacity. If you shade 25% of a working panel, you will find that you get a greater than 25% loss of power out. Also remember if the panels were as good as the marketing says, the company would still be in business. I would be more inclined to get something such as this: http://www.solar-electric.com/poup65wa12vo.html

[Bill]

Solar panels in partial shade is a topic that is difficult to understand, and the manufacturers intentionally cloud the issue. But at the bottom line, both of the previous two posts are correct. A small amount of shade causes a power reduction that is much larger than you would intuitively expect. For anyone who wants to know more, I would suggest Googling "solar panel shade". You will get dozens of hits, all confirming this counter-intuitive behavior. For example, try
http://solaroregon.org/residential-s...els-are-shaded or
http://www.wholesalesolar.com/Inform...fficiency.html
And for purposes of this discussion, a damaged cell is the same as a shaded cell, since neither one produces power.

The story is this. As you visualize it, remember that the concept is exactly the same as hooking up 6-volt and 12-volt batteries in series and parallel, which many of us have done on our TMs.

A solar "panel" is made up of a bunch of solar "cells". On crystalline (rigid) panels, a "cell" is usually about 2 inches by 2 inches. Each cell can generate about 1 volt. Since you need about 18 volts to charge a 12-volt battery, the manufacturer will connect 18 cells in series. The series is sometimes called a "string". A "string" produices the correct voltage, but not very much current. In order to get more current, the manufacturer will connect several strings in parallel. If you look at a picture of a solar panel, you can usually see cells in groups of 9, and two groups make 18 cells.

[As I was writing this, I lost a factor of 2. A solar cell produces a bit more than a half volt, and so to get 18 volts, a string is typically made up of 36 cells, often in 4 groups of 9. My apologies.]

On amorphous (flexible) panels, the cells can be larger, though I don't know the limits. But the concept of a "string" of cells still applies.

A "string" is like a series string of Christmas tree lights - if you break one "cell", then the entire "string" goes out. When I say that you break a cell, I mean that you either damage it physically, or you shade it. Either way, it stops generating electricity, and takes out the entire string.

If there are several strings in parallel, and you take out one string, then the other strings continue to make power. But if you damage one cell in each string, thereby taking out all the strings, the entire panel stops producing. You can see a good picture of this on the web site linked above, where an entire panel is taken out by a band of shade that covers only about 5% of the panel.

For this particular discussion, the Unisolar picture of the flexible panel appears to show a single string of large cells (11 of them?) running the length of the rolled-up panel. If you damage the panel across its width, you take out the entire string (remember the Christmas lights analogy) - and since there is only one string, the entire panel dies.

I don't know if this description helps. Hope so.

Bill

As far as abrasion from the seals, the panel surface is supposed to be very durable. I could easily overlay a thin sheet of clear laminate (plastic or plexiglass) to protect that strip of area.

Efficiency as per sq.ft. is moot here; there is plenty of room. Stick them on and forget about it.

I go with $ per watt. (roughly $1.50/watt)

First trip out with the 2720 and new solar panel setup. Very good results.

1 x Blue Sky Solar Boost 2512i 25A, 12V 3 Stage Charge Controller () = $178.06
4 x Unisolar PVL-68 68W, 12V Thinfilm Roof Laminate (PVL-68T) = $396.00
------------------------------------------------------
Federal Express (1 x 50lbs) (Home Delivery (1 days)): $19.82
Sub-Total: $574.06
Tax: $44.49
Total: $638.37

Plus my 2 FullRiver 6v 200Ah batteries. Bought slightly used for $200. These are held down to the floor under the dinette.
Trimetric 2025RV Battery System Monitor w/Shunt: 500 Amp , Cable: 35 Ft. Meter to Shunt Cable Price: $199.50 for all.

2- 4-way MC3 Y cables for the panels in parallel.

Total system cost w/ batteries and misc. cables: $1300.

When I arrived at the campground the Trimetric showed 43% battery power remaining. I had a phantom draw - TM closed up since December.

Would that be the Carbon Monoxide Detector??

I forgot to turn off my master switch that I just installed under the batteries, reachable from the outside.

One day of sun brought the batteries back to 100%!! Average power generated 13-16 amps. I'm very happy.

There is no noticeable wear from the TM roof seal on the panel from 4 hours of driving.

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