Do All Solar Panels Have Blocking 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.

Do all solar panels have blocking diodes. If you have two 175 watt panels each at 42 volts you will need two 8 amp 45 volt diodes. You will find out about bypass diodes in detail below this heading. So during a sunny day the voltage of a solar panel will be higher than the voltage of a deep cycle battery so current will naturally flow from the panel to the battery. As a result in the days before charge controllers people would put a blocking diode in series between the battery and the solar panel only allowing power to go into the battery.

Blocking diodes will be of benefit in any system using solar panels to charge a battery. There are two functions a diode can perform in 12volt solar systems either as a blocking diode or as a bypass diode. 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. Again current flows from high to low voltage.

If your panels are a grouping of other panels then you won t need a diode. For solar panels we recommend you put one blocking diode on each solar panel inside an abs project box. A solar panel array has more than one branch or strings connected in parallel consisting of solar panels bypass diodes and blocking diodes. A solar panel it a grouping of cells in a series parallel configuration of one form or another typically inside a housing.

Blocking diodes are used to prevent your batteries from discharging backward through your solar panels at night. When a solar panel is shaded the output current reduces dramatically and when it s dark it actually absorbs current. 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 reverse biased.

This way your existing equipment batteries and you newly purchased 12v solar panel charger will be protected and give you a long reliable working life. This is a real problem at night because we could lose all the power we gained during the day. One last point do not confuse a blocking diode with a bypass diode.