The best photovoltaic solar panels
Thought I would share some information on what are rated as the best/most efficient panels available. Sanyo HIT Power N Series. The cells are hybrids of monocrystalline silicone, surrounded by ultr...
Forum Discussion
BFL13 wrote:
For the same watts you can have high V and low A or low V and high A. Same watts. So it means nothing which way you go?
If your MPPT controller has a flat efficiency vs. voltage curve (which it does not quite), then that is correct. You need to go to the max power point for your panel. It does not matter if the panel makes it at high or low voltage.
Volts determines amps, or amps determines volts. You can pick one and that forces you to a point on the curve, which picks the other. There is exactly one point on the curve where the box drawn by dropping a vertical and horizontal line maxes that out to make the biggest box. That an only that combination of Voltage and Amperage is the maximum on that curve. It's the sweet spot.
Now if you know your particular MPPT controller is 96% efficient at 36 volts but only 90% at 70v, you want the panel with the closest V(mpp) to the most efficient voltage (36v) for your controller.
In PWM you are matching the solar panel to the battery, looking for good wattage output at the battery voltage (which simplifies down to the most current provided at the battery's voltage, often close to I(sc)).
In MPPT you are matching the solar panel to the controller's characteristics rather than the battery's.
Jim
