I want my MPPT charger to use solar power OR mains power.

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PaulVdB

Joined Jan 7, 2016
2
Maybe I should start a new thread, but my question is also about MPPT chargers.
I want my MPPT charger to use solar power OR mains power. I made a circuit that starts the mains charger for about 2 hours when the (24V)battery voltage gets dangerously low. For the moment I use 2 diodes from a rectifier bridge. One AC input is connected to the (60V) solar panel, the other connected to the charger. But even with very low light conditions, the panel still has an output voltage of about 50Volts because the MPPT controller doesn't draw any current. The mains charger has an output voltage of about 30 Volts. So as long there's more than 30(.7) Volts coming from the panel, the mains charger does not provide any current to charge the battery. I could use a relay or MOSFETS instead of the diodes, but then when the sun begins to shine I want to block the (timed) charger and let the solar panel deliver the power again. I can't use a common ground for the charger/panel and the battery ground (minus) because then the current limiting/measuring of the MPPT doesn't work anymore.
Someone has a solution, an idea to solve this "problem" ?
In advance : THANKS !
 
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