PWM Reverse current

[Snowgoose-1]

PWM solar working fine but noticed voltage at deck plug reading 12.9 v multimeter when duskand no charge registered at PWM. I thought that PWM would stop charge from house batteries reaching solar panels thanking any ideas.

 

[noelex]

Most, but not all solar regulators will disconnect the solar panels at night. Some cheaper models simply use a blocking diode. If the panel is not disconnected or the blocking diode defective the current flow with most, but not all solar panels is small.

So I would measure the current. If it is more than very small, I would replace the solar controller. It is likely a model that does not disconnect the panels, nor incorporate a blocking diode. You could just add an extra blocking diode, but this is not the ideal solution.

One caution is make sure it is completely dark, or the solar panels are very well covered when doing these tests. Solar panels can still produce significant voltage (not current) with very little illumination. Many solar regulators use solar panel voltage to trigger disconnecting, so this can occur after dusk and long after the current has dropped to zero.

 

[Graham376]

I used to have 2 separate battery banks with two (Chinese cheap) controllers in parallel, one to each bank. By morning, banks would be balanced so inserted diodes into feeds from panel which cured the problem with no noticeable difference in charge rate.