PowerFilm R-21 rollable solar chargers.

[VanGo]

"Back on track"- means waiting out 4 week back order. I'll keep you guys posted in the intrim let's continue with discussion. How about a mounting solution for these rollable panels? I am considering a (2) short tent poles to create an arch effect so the panels can me moved with the sun.

 

[teotwaki]

"Back on track"- means waiting out 4 week back order. I'll keep you guys posted in the intrim let's continue with discussion. How about a mounting solution for these rollable panels? I am considering a (2) short tent poles to create an arch effect so the panels can me moved with the sun.

I like the tent pole approach. Maybe add a 3rd "leg" to make it a tripod so that it can stand on its own?

 

[Corey]

I just hung mine over the windshield in the morning and got the 18+ volts out of it, and later in the day when the sun was not directly on it, it still pumped out 16+ volts.

I thought about hanging it from my awning to get more sun, but I was to impressed with the voltage it was still churning out.

 

[charlieaarons]

I just hung mine over the windshield in the morning and got the 18+ volts out of it, and later in the day when the sun was not directly on it, it still pumped out 16+ volts.

I thought about hanging it from my awning to get more sun, but I was to impressed with the voltage it was still churning out.

The true test of solar panels is amperage output against a low resistance or short circuit, not voltage output presumably on an open circuit.

Charlie

 

[Corey]

All I know is it works great.
It better had for the price I paid for it

 

[teotwaki]

The true test of solar panels is amperage output against a low resistance or short circuit, not voltage output presumably on an open circuit.

Charlie

IIRC, the typical specs show max unloaded voltage output and max short circuit current. Much like batteries, solar panels have a theoretical optimum internal resistance that a maximum wattage can be developed on a resistor of the same value as the internal resistance. If the vendor has voltage and current curves with wattage you can pick out the point from their data. I think that they usually publish the max perfect Wattage for optimum conditions.

In the real world you'll have some sort of charge controller and some wiring resistance and a battery load with a certain charge state that are nowhere near the optimum load, so YMMV. That is one reason why you'll try to get a panel that delivers more current than a perfect situation requires. It also helps to make up for less than optimum sunlight due to pointing, sun angle and clouds.

Corey,

how did you measure the voltage? Was the panel connected to the charge controller? Would it be easy to insert the DVM as an Ampmeter?

For my setup I have a charge controller that can display Volts or Amps, similar to what the good folks at Adventure Trailers show at their web site.

I also searched around to find your Solar power thread
http://expeditionportal.com/forum/showthread.php?t=28712

 

[Corey]

Jim, you can see the charge controller I have in my writeup on the forum.
Same one Scott Brady is running.

I unplugged the cable that goes to the charge controller and put the + - leads from my amp/voltage meter to the same inputs that go right to the panel.

I may upgrade in the future to the other controller that Martyn sells.
This is my first experience with solar, so I wanted to keep it simple the first time around.

It will be easy to swap out my controller for the better one like you have or Martyn sells.

 

[teotwaki]

Jim, you can see the charge controller I have in my writeup on the forum.
Same one Scott Brady is running.

I unplugged the cable that goes to the charge controller and put the + - leads from my amp/voltage meter to the same inputs that go right to the panel.

I may upgrade in the future to the other controller that Martyn sells.
This is my first experience with solar, so I wanted to keep it simple the first time around.

It will be easy to swap out my controller for the better one like you have or Martyn sells.

When you unplug the cable the panel is operating without any load. It would be better to measure the voltage with the charge controller and battery connected.

 

[VanGo]

Just received an update on my PF order, complete order is shipping minus 1 panel. Should have some pics and specs up soon.

Van