Still Don't Get It (Solar)

BFL, is that a Fawlty Towers reference?

Again, altitude has it's advantages. You might see a hawk soaring around but at 10.000 ft most smaller birds stay on the ground. The bugs sure do like the heat though.

pianotuna wrote:
Hi jrnymn7,

Losses when the panel is at 50 C are about 12%. Raising the panels so that air can flow beneath them easily makes sense because it is a passive fix.

This is my 230w panel where it gets to 44C when ambient is 16C and to 51C when ambient is 25C. Hate to think what panel temp would be if flat on a roof like most installations



BTW photo taken in morning with panel facing Easterly. When twirled to Southerly I lower the tilt, then raise it again for Westerly mid-afternoon. My contraption has some tilt angle options for that reason. The wire across the top is to keep robins off. They poop down the panel.

I laugh at those guys who post they don't have to climb on their roofs once they install the solar. They must not have seagulls bombing them, or else they just don't know what is happening. You don't see any graphs of panel loss vs seagull activity in those insolation guides. Might be bad for the solar business. "Basil, don't mention the seagulls!"

Hi jrnymn7,

Losses when the panel is at 50 C are about 12%. Raising the panels so that air can flow beneath them easily makes sense because it is a passive fix.

I wonder what a thin line, compact cooling design would entail? I'm thinking along the lines of any power supply, but on a larger scale. A shallow sheet metal box mounted to the back of the panel, making it say 3" deep overall. A fan at either end, tunneling air thru a narrow channel. Or even slots on the ends, and a central exhaust fan blowing out the back?

Would there be any significant net gain?

I guess I'll have to experiment with that, next summer.

Yeah, you can't beat portable panels when it comes to output. If a person isn't running any big inverter loads and has energy efficient stuff, I would think 100-200W of portable could handle most situations. I've posted before how I got 56AH from 100W on a sunny March day in AZ. Sunny, that's the key, though. :)

I tested my WFCO 55 in absolute best case wiring conditions, and it only puts out amps in the teens, at 13.6v, during the first couple of hours. So OP's numbers sound right. Poor, but right.

jrnymn7 wrote:
Niner, I pulled the trigger on a wave 3. It's compact size and 1600-3000btu output should do just fine for my little camper.

I'm planning on having a mixture of heating sources; catalytic, hydronic, and a little bit of electric. With 280w of solar, I hope to keep gen charging to a minimum. That little portable set-up of yours puts out quite a bit of power. I'm curious how my numbers will compare to yours, as I am a little ways north/east of Arizona.

Portable panels, aimed 3 to 4x a day, will pull their full rated amps or close, a lot longer than roof mounted panels. Also, because they are in storage when not in use camping, they won't have yearly loss of amps output like solar panels exposed full time to the sun 365 a year.

as I am a little ways north/east of Arizona

boy thats an understatement

Niner, I pulled the trigger on a wave 3. It's compact size and 1600-3000btu output should do just fine for my little camper.

I'm planning on having a mixture of heating sources; catalytic, hydronic, and a little bit of electric. With 280w of solar, I hope to keep gen charging to a minimum. That little portable set-up of yours puts out quite a bit of power. I'm curious how my numbers will compare to yours, as I am a little ways north/east of Arizona.

Gman,

You may be surprised how much even a small load on a fairly discharged pair of 6's can pull down the voltage. Nevertheless, 2 hours of "charging" did not replace your evening and overnight usage. This speaks volumes to some, but seems perfectly normal to others.

The good news is, solar will help significantly. The bad news is, your wfco isn't charging your batteries like it should. A 55a charger, on a 208Ah bank is actually a rather high charge rate of C/3.8. You should be able to do a 50-80% (62Ah replaced) in 2 hours, no problem, and in the example you give, a 66-90%, no problem. So, if you were at 12.4v (~66%), and then charged for 2 hours, you should have been up around (and quite possibly above) 90%. So, to go from 90+% down to ~60% (12.3ish) throughout the evening and over night, that would require over 60Ah usage.

I'm not doubting your estimated usage, but I am doubting your wfco's ability to charge your bank in a reasonable manner. Let's say you used 40Ah's throughout the evening and over night, if the wfco had done its job properly, that should have brought you down from 90% to above 70%, (40Ah = 19% usage), not down to 60%. In this example then, that means the wfco only replaced about 25Ah's in 2 hours. How does a 55a charger replace only 25Ah's in 2 hours on a fairly deeply discharged 208Ah bank?

For comparison, I have done a 50-90%, on a larger bank (215Ah) with a smaller charger (45a) in just over 2 hours.