i'm venturing into solar power for a small boat with motor... so i bought 2x 100W PV and a $5 Hung Low Charger Controller, it claims as MPPT but looking at the circuit teardown, it should be simple PWM based controller, but so far so good, a lot better than connecting a motor (12V 5A) directly to the PV, the little problem is when prolonged usage, its like throttling the power, not sure how it does that... it doesnt have temperature sensor from the look of it. but thats not the point (we cant expect to much from $5)...
the big deal is actually when its become cloudy and PV cannot fully supply 5A to the motor, so i measured the current is drawn from the battery and slowly depleted. what i really want is i can set to power limit mode (reduce output voltage), ie i dont want power comes from the battery during the day because i want to save the battery power during the night or emergency situation in the middle of the sea. i dont mind if the motor becomes slower operated at lower output voltage, at least i can still move slowly during the day. in case i want to move faster at full motor rating, i can push a button for normal 12V output mode, ie power comes from both PV and battery. is there any such MPPT charger controller like that? at affordable price if possible (10-30A spec 100-200W, for 24-30Voc PV) so i dont have to reinvent the wheel... i tried google no luck, maybe wrong keyword.. cheers.