Panel voltage drops in low light when it can't even provide enough power to the electronics it is connected to, like just a meter. A boost converter can not boost your way out of a low voltage condition below power point. Panel voltage drops as you reach the short circuit current for that light intensity. Power point voltage only changes with temperature. I admit I just read that quick, but I have no idea what you are talking about. Why is that? I'll admit I don't have deep experience with PV panels, but it seems to me that the higher the ripple current fraction reflected from a downstream converter the more likely the panel will be pulled below its maximum short circuit current for the intensity of sunlight it is receiving at that time, at which point its output voltage collapses until the converter is cycled off. That MOSFET would still be needed to prevent a parasitic discharge path in a buck topology, so the added cost really is just one more MOSFET (which can be smaller than the others as it only comes into play at low light) and the control circuit to drive it. BTW, if you take a look at a buck-boost topology, you'll note that by keeping the output high side MOSFET on, the circuit degenerates to a buck topology. Built in signal conditioning would be nice to reduce the parts needed to allow the microcontroller to measure voltages and currents.
Design of 500w isolated cuk converter driver#
What I would like to see is a MOSFET gate driver designed to be driven from the PWM output of any microcontroller, with adjustable built in cycle by cycle voltage and current limiting. As long as the output voltage is below the setpoint, the duty cycle would try to go to the maximum supported by the controller, which the microcontroller holds back to do MPPT. One way to do that is to tap into the compensation network of a standard PWM controller and allow a microcontroller to limit the duty cycle.
Any converter topology can be used for MPPT.
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