Here's the label that matches the specs I've seen..
I've got two of these panels in the mail..
I had been planing on using them to charge batteries with a
Xantrex C40 3-Stage PWM Charge Controller, 40 Amp, 12, 24, or 48 Volt.
http://www.solarcellsales.com/techin...controller.pdf
I wanted to charge a 48v battery pack. But, after looking at the C40 specs,
I'm thinking that my PV
Voltage @ Peak Power is very close to being too low.?.
28.9v times 2 = 57.8 volts. This is
just inside the C40 48v Bulk charge range.
Will it work?
If it fails to charge a 48v pack, the fallback plan is to rewire the pack to 24v,
and use the same Series PV configuration. (57.8 volts)
Since, if the C40 fails at 48, it would likely fail at 24 with half the PV voltage..
Or, am I wrong? Will running a 48v system with 57.8v be just dandy?
The nearly matched voltages will make it almost like MPPT??
~~~
Idea #2
If I were just using four old junk car batteries, maybe I could just wire them directly (using diode) to the series panels.?.
And then wire in a Dump-Load to keep the battery pack from over-charging.
The Dump-load could be set at the Max power voltage of the panels. 57.8V.
Allowing 14.45 volts (a somewhat high?) Float on each battery.
Idea #2 Operation theory:
In the morning, the batteries start charging up.
When their voltage reaches >57.8v, the Dump-Load circuit kicks in
and connects the pack (& PV) to a load.
The load would be matched (8.35 ohms), so it could consume 400w at 57.8v.
So, it would handle everything from the panel (while the sun was out),
and keep the battery pack from absorbing any more power.
Comments please..
Thanks,
Rich
Update:
Thanksgiving Day, at 6:30 AM, the panels were at the local UPS depot!