Solar Panel Blocking Diode Installation

If you have two 175 watt panels each at 42 volts you will need two 8 amp 45 volt diodes.

Solar panel blocking diode installation.

Blocking diodes are used to prevent your batteries from discharging backwards through your solar panels at night. But at night if the solar panel is connected directly to a battery the voltage of the solar panel is going to be lower than the voltage of. Not only will that panel not be producing any significant power but it will also have a high resistance blocking the flow of power produced by the unshaded 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.

Now let s consider what happens if one of the panels in the above diagram is shaded. The diode needs to have a voltage and amperage rating above that of the panel. It is always installed in series with the solar panel. Blocking diodes are usually included in the construction of solar panels so further blocking diodes are not required.

Blocking diodes will be of benefit in any system using solar panels to charge a battery. To prevent this from happening a blocking diode is installed. It allows the current to flow from the panel to the battery but blocks the flow in opposite direction. Again current flows from high to low voltage so during a sunny day the voltage of a solar panel will be higher than the voltage of a deep cycle battery and the current will naturally flow from the panel to the battery.