As discussed in the previous post, an 'MPPT' Solar Controller can utilize power which a 'PWM' controller must always leave within the panels by rapidly disconnecting and reconnecting to the panel array.
The power increase typically varies in the range of 18-35%, depending on the number of panels in the Solar Array, their "maximum power point" Voltage values, and their configuration).
The main advantage occurs in all configurations. Even when Batteries are being charged at 14.4 Volts, the Voltage of "12V" panels operating under good sunlight is typically between 17.8 and 19.5 volts. A 'PWM' Controller will only accept power equivalent to 14.4 Volts, while the MPPT controller can accept all of it. The MPPT controller starts with an advantage of about 25-30%, just from the advantage of operating at the "maximum power point" Voltage instead of the average battery charging voltage.
But this initial advantage must be discounted by power consumption and waste heat within the MPPT controller itself, typically 4-10%. We therefore obtain the lower limit of about 18% "better", with typical "12 Volt" panels operating at a maximum power point voltage of about 18 volts.
How do some configurations enjoy greater benefits? They use higher Voltage panels, or they use "12V" panels wired in Series. Large Solar panels tend to run at high voltages 20V and even higher - and they enjoy a greater advantage.
But even with typical "12 Volt" panels, the change in Voltage between "Solar Input" and "Battery/TM Output" can be made very large.[/B]. With an MPPT controller, Solar Panels may be wired in Series (while a "PWM" controller must
always work only with panels wired in a parallel configuration). In Series wiring (with all identical panels), the CURRENT remains constant, while the VOLTAGE of the panels is increased with each additional panel. In Parallel wiring, the VOLTAGE remains constant, while the CURRENT is increased with each additional panel.
The amount of power which is lost in the Solar wires is proportional to the amount of current,
squared. Double the current makes 4x the wire losses, and triple the current creates 9x larger losses in power - lost before even reaching the Solar Controller.
Example: In an MPPT-compatable array of solar panels like mine (currently 4 panels wired together in Series), the amount of current in the wires is about 5.5 Amps. The VOLTAGE increases with each panel, from about 19.6V (at the end of the first panel) to 39V, 59V, and finally about 78 Volts at the end of the Series "String". My lost power is only about 0.3%.
If I were using a PWM controller and forced to wire in Series, my Voltage would be only 19.6 Volts. But my total current would be about 5.5 Amps * 4, or 22 Amps total. I would lose about 4% of my power within the Solar wires, before ever getting to the Controller.
The larger the number of panels, the larger the additional MMPT "parallel wiring" advantage becomes.