Hi,
I routinely get 7 amps out of a possible 17 in leafy shade. It is a properly designed MPPT system with shade tolerant panels. The panels have diodes between every cell.
To put it another way--your panels do 28% in poor conditions and mine do 41%.
Further, because the input voltage on my system is 33, charging starts sooner in the early morning and runs later in the day.
I do recommend folks look at PWM vs MPPT on the basis of total system cost per watt. 7 years ago MPPT was a no brainer because panel cost was $5.50 per watt. Now with lots of panels under $1 per watt PWM generally makes more sense.
It is good to use a diversion load (for example, water heating with a 12 volt element) if there is going to be excess power. Many PWM controllers have this as an option. Blue Sky has it on MPPT controllers. Morningstar, for some reason, does not on MPPT, but does on PWM.
I used to handle it by turning on the inverter and water heater for 15 minutes. Now that I full time, I rarely get to that place.
Chandalen wrote:
This is TOTALLY backwards. MPPT will never out perform a PWM in low light conditions.
