How do you connect a solar panel and wind generator in parallel?
I have an ~18v solar panel and a ~15v wind turbine. Sometimes one generates more voltage than the other. How would I get both of them to charge one ~12v battery? I can't just connect them in parallel with diodes, because in that case, only the higher voltage source gets used. Is there a special charge controller circuit that will do this?
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There are controllers to do this, but they are very expensive. Why not two batteries, one for each generator and a battery ‘change over’ switch’ on the output. When one battery is low switch to the other.
You could connect them in parallel with diodes because both voltage sources are higher than the 12 v of the battery that you are charging. The battery establishes the 12 v at one side of the diode and both are forward biased by the 15 or 18 v sources. The current drawn by charging the battery will drop the voltage of each source across its internal resistance to bring them both down to the battery voltage plus a diode voltage drop of about 0.7 v
Goober’s idea is correct, though it would be costly to implement at a large power load. The best and simplest way is to buy two charge controllers, each of the proper configuration for the power source, and feed them both into the same battery bank.
Placing diodes in series with each source to the battery would solve your problem. You should use a charge controller on the system to prevent overcharging the battery.
I’ve put together a relatively simple dump load circuit which diverts excess power to high power resistors. It is part of a wind charging system with inputs from wind, solar, and a DC power supply.
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