a) High conversion efficiency
If your photovoltaic system comes with a large solar array, MPPT would be the best choice to boost the solar energy conversion, especially in cold weather, since the panel voltage will rise as the temperature drops. The MPPT conversion rate could rise from 20% to 40%. That’s green and free energy that really saves money on your bill.
Solar panel array in distance
b) Lower energy loss in cables or lower cost for purchasing cables.
Please remember Ohm’s law formula
V (Volts) = R (Ohm) x I (Amps)
Output power PO (Watts) = V (Volts) x I (Amps)
So Resistance loss PR(Watts) = R (Ohm) x I2 (Amps)
Then, if your PV panels are installed a long distance from your battery bank, the power loss of cable resistance is considerable ( PR = R x I2 ). Here R represents the resistance of cables. R increases as cable length increases:
Cable resistance formula
But if we double the Voltage of the solar array by wiring them in more series, according to PO = V x I, there is no change of total power outputPO , so the current through cable I should be half.
Finally, the resistance PR(Watts) = R (Ohm) x I2 (Amps) will be a quarter than before.
In fact, with MPPT, you could raise the voltage of the solar array even higher to reduce the current flow.
In this case, we increase the panel’s voltage to reduce the resistance loss through cables, and since we are using MPPT, which always tracks to harvest maximum power from panels, we have no voltage waste as PWM may have.
We could review this topic from another aspect. If you cannot raise the panels voltage, then you have to find out some solution to reduce cable resistance, as resistance = resistivity × length / area, it seems the only way is to use cables with large transverse areas, and that will be another huge sum of money to spend.
To recap, when it comes with small systems, PWM is a good solution since it is inexpensive, but for large systems, in order to improve conversion rates and not waste the solar panel capacity of harnessing solar energy, MPPT is preferable. MPPT would always be applied to higher power systems.
