One way diode for solar charging

Hi everyone,
This might be a silly question, I do think it does have merit.

Have fitted 160 watt solar panels to the van supplying 2 x 105 amp hour Gel batteries.
Question should I have a one way diode fitted to the supply line to batteries to eliminate charge to going back into the panels at night from the batteries.
If so what type and were would you locate this diode.

By the way the regulator is a MPPT located near batteries.

Thank you for your input.

Allan and Andrea