In short as diode only passes current in one direction so the current from solar panels flows forward biased to the battery and blocks from the battery to the solar panel.
Installing blocking diode solar panel.
A blocking diode and bypass diode are commonly used in solar energy systems and solar panels.
In simplest terms a diode can be understood as a two terminal electronic device which allows electrical current to pass in one direction.
The diode needs to have a voltage and amperage rating above that of the panel.
If you have two 175 watt panels each at 42 volts you will need two 8 amp 45 volt diodes.
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.
In this video you will learn the importance of a bypass diode in solar panel learn how to connect a bypass diode to your own solar cells to improve the eff.