Why Do I Need Blocking Diodes For Solar Panels

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Why do i need blocking diodes for solar panels. Blocking diodes are usually included in the construction of solar panels so further blocking diodes are not required. For solar panels we recommend you put one blocking diode on each solar panel inside an abs project box the diode needs to have a voltage and amperage rating above that of the panel. 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. Now let s consider what happens if one of the panels in the above diagram is shaded.

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 is able to stop this backwards flow and ensures that the energy collected is safely stored. If you have two 175 watt panels each at 42 volts you will need two 8 amp 45 volt diodes. Nowadays most solar power systems have a charge controller between the solar panel and the battery and this charge controller prevents this backflow of electricity eliminating the need for a blocking diode.

This is where a solar panel blocking diodes is used. This is common on sailboats with a solar panel on both the port and the starboard sides. There may be however some instances when a blocking diode can still be helpful. Now you re thinking brilliant i will just get a 12v solar panel blocking diode hold your horses.