question

gadget007 avatar image
gadget007 asked

Can current flow from battery to PV inputs when PV cabling is shorted?

I have been asked by engineering company if it is possible for current to flow from batteries through the solar charge controller (Smart Solar MPPT 150|85) in the case of a fault within the solar panels or cabling.

The system will have circuit breakers on the batteries and on the incoming solar input. I guess they are being over cautious as to the correct cable sizing.

I would have thought that there would have to be a fault with the charge controller for this to occur, as at night there isn't any current

any input would be appreciated

MPPT Controllers
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1 Answer
wkirby avatar image
wkirby answered ·

Under normal operating conditions, there is no Voltage on the PV input terminals if no PV is available. For example, if the PV input terminals are open, no PV connected, there is no Voltage at these terminals even when that battery is connected. Therefore, under normal conditions, no current flows from the battery to the PV array.

If a fault occurred within the MPPT charge controller, then it may be possible for the battery Voltage to appear at the PV input terminals.
Protection against such unlikely events should be provided externally.

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