I sent the following email to Matrix Solar. They manufacture or market Photowatt modules. I have not received a reply to date but would be interested in feed back from the discussion board.
Thanks,
Kudu
In 2003 I purchased two PW750 80 watt solar modules. The accompanying installation manual rated the modules at 17.3 operating volts and 4.6 amps. To date, the maximum amperage achieved is less than 4 amps for both modules combined. I am using a Solar Boost 2000E power point tracking charge controller. Amperage is checked on a clear day between 11:00 and 1:00 CST(such as today, October 26,2005, Fort Worth, Texas, maximum outside temperature about 65F, cloudless sky). During that time the modules were pointed directly at the sun. The modules are mounted atop a pole approximately 15' from the charge controller and batteries(six T105 6 volt Trojans). 10 gauge multi-strand copper wire carries the current from the modules to the charge controller.
Even factoring in as much as 30% module inefficiency, the two modules should still be able to produce in excess of 6 amps.
Is my math faulty? Have I overlooked something?
I have room on the solar mount assembly for an additional module and the wire has already been run. I wish to purchase another 80 watt module to match the other two; however, I am concerned with the inefficiency of the two panels I have.
I would very much appreciate a detailed response addressing my concerns and clarifying this inconsistency.