For solar panels we recommend you put one blocking diode on each solar panel inside an abs project box.
Installing blocking diode solar panel.
Learn how and why blocking diodes and bypass diodes are used.
Blocking diode in a solar panel is used to prevent the batteries from draining or discharging back through the pv cells inside the solar panel as they acts as load in night or in case of fully covered sky by clouds etc.
The diode needs to have a voltage and amperage rating above that of the panel.
Blocking diodes installation instructions sm 335 issue c 03 11 05 marlec engineering co ltd blocking diodes a blocking diode is required in each series string of solar modules between the modules and regulator battery to prevent current flowing back through the modules when the modules are shaded or during darkness.
If you have two 175 watt panels each at 42 volts you will need two 8 amp 45 volt diodes.
A blocking diode and bypass diode are commonly used in solar energy systems and solar panels.
Diode and unidirectional flow of current.