iv/power curve
Questions, smallish PWM portable When a PWM controller limits voltage to 15v, the panel must be operating at 15v+ (blue area) to make up for any voltage drop? If conditions are such that Vmp has...
Forum Discussion
The Imp has no meaning with PWM, Imp is an MPPT thing. You care about Isc. Isc is what you get at the battery minus a titch for wiring etc. If the panel is getting enough light, you will get rated Isc, such as the 8.2 amps of my 130w panel.
You only get that many amps when the sun is higher mid-day when you can point the panel all day. if the panel is just left pointing south, you will only see that full Isc briefly at noon.
Now as battery voltage rises, you go right on the IV curve and Isc tapers a little. Say to 8.0 from 8.2 by 14v. Still lots. But also by the time the batts are up to 14.7 they are nearly full, so now you also get amps tapering from the battery acceptance rate falling.
So before you get to the dreaded 15v cliff, you are all done anyway--batts near full and amps have tapered right down from that.
I can only get the battery voltage to 15 anyway by disconnecting the controller and going panel-direct because the controller is set to limit the voltage in the 14s.
You only get that many amps when the sun is higher mid-day when you can point the panel all day. if the panel is just left pointing south, you will only see that full Isc briefly at noon.
Now as battery voltage rises, you go right on the IV curve and Isc tapers a little. Say to 8.0 from 8.2 by 14v. Still lots. But also by the time the batts are up to 14.7 they are nearly full, so now you also get amps tapering from the battery acceptance rate falling.
So before you get to the dreaded 15v cliff, you are all done anyway--batts near full and amps have tapered right down from that.
I can only get the battery voltage to 15 anyway by disconnecting the controller and going panel-direct because the controller is set to limit the voltage in the 14s.
