Monday, Jan 02, 2012 at 13:49
Hi Daryl,
yes no worries.
Think gearbox in a car.
An ordinary
solar regulator (PWM, or on/off type) acts like a single speed box.
As long as the clutch is disengaged the motor revs up freely, but the moment the clutch comes on the motor revs drop depending on the actual speed of the car.
Because max motor power has a peak somewhere up high, this power usually won't be available during cruising.
On the other hand, a multi speed gearbox allows the driver to shift the motor revs to the max power point, independent of vehicle speed.
Solar panels, not unlike combustion engines also have a peak in the output power which is visible in the EI diagram of the
panel. The
panel's operating Voltage could be likened to the motor RPM, and the
panel current to the motor torque.
So motor revs are equivalent to the
panel's operating voltage, the gearbox is the DC/DC converter inside the MPPT regulator, the driver is the microcontroller, the clutch are the wires between
solar regulator and battery, and the vehicle speed is the SOC (battery terminal voltage).
Because in a
solar panel, the maximum power point shifts up and down with temperature and insolation, the microcontroller constantly regulates the current through the
panel. The algorithm looks for the maximum in the ExI product.
Hope this isn't too confusing.
cheers, Peter
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