learningsolar wrote:
okay so directly hooked to battery amerage remains same while voltage drops...now i get it....and i assume an mppt controller will give me allot more then that as it reduces voltage and increases amps??
Why not a voltage increase from zero to 12v? Isc is at zero volts.
Look at a IV curve and a power curve (at each end there is zero power). The panel is capable of so much power in any give light conditions. Hooked to a load the panel only outputs the voltage needed for that load and the IV curve generally shows current is flat at ~Isc up to the Vmp.
An MPPT has the ability to track max power (Vmp, Imp) and transforms the power for battery charging. If max power is 240w @ 30v, the MPPT transforms that to battery voltage and (240/v =) x amps. (Example: 240/13 = 17 amps vs 9).
Controller also limit charging voltage to avoid overcharging, prevent the panel from draining the battery at night ...
