In article ,
Eric F. Richards wrote:
m II wrote:

Anyone hooked up any photovoltaic panels for battery charging? I've been
offered two 75 watt panels and it might be fun to power some small loads
through a battery storage setup.

Major pitfalls? Clouds?

(off to do some research...)
....
I'd tell you how to do it if you weren't such a hateful ****head. In
other words, you're on your own.

So anyone with a concern for truth and justice, (and a bit of a flippant
attitude) is hateful?

Solar cells have a voltage vs. current curve that's roughly square.

|___ Open Circuit voltage
| ====____. maximum power point
V| \ \
| \ \ "Constant" Current
| \ \
| \ \
|---------------
I ^ available current depends on incident light

The no load voltage is determined by quantum physics and is roughly
constant. The current available is determined by the cell area and
the incident sunlight.

In practical terms, if you don't put the cells in a situation where
they're outputting enough current to damage their internal wiring,
you can hook them up and they'll provide a roughly constant current for
charging a battery. You wouldn't want to use too high a voltage array,
as you could damage the battery. And if the sunlight goes away, as it
does every day, leakage back through the cell can discharge the battery.
So the simple "chargers" I've seen where switches to disconnect the
battery when its voltage got too high, or there wasn't enough sunlight.

If you want to be cost effective, you get a fancy charger that
transforms the load on the solar array to the maximum power point
to get the most bang for the buck.

Mark Zenier Washington State resident