As long as the sun shines, voltage is produced by the Solar Panel panels connected to your battery in your Solar Power System but come night time in the dark, when no voltage is being produced by the panels, the voltage of the battery would cause a current to flow in the opposite direction through the panels, discharging the battery, if it was not for the blocking diode in the circuit. What is a Solar Panel Blocking Diode?
Because current naturally moves from high to low, a Solar Panel Blocking Diode uses a semiconductor material, that prevents batteries from releasing voltage in reverse through the solar panels during the evening when no energy from the sun is being produced and moving through to the battery.
In the world of Solar Power, all the components involved in the system need to function for the system to do what it’s supposed to do, which is to make Solar energy and move it in one direction to charge your batteries, where it can be stored then used when it’s needed.
What is a Blocking Diode
A Diode uses a semiconductor material, usually silicon, with two terminals attached. Its function in its simplest form is to allow electricity to pass in one direction but not the other. In plumbing, a Diode works like a check valve keeping water moving one way so it won’t back -up.
Blocking diodes are used to keep batteries from releasing power in reverse through the solar panel boards during the evening when no energy from the sun is moving through to the battery.
Current streams from high to low voltage, so on a bright day, the voltage of a panelboard will be higher than the voltage of a profound cycle battery and this energy will normally spill out of the PV panel to the battery.
By function, all diodes block electrical current; however, blocking diodes are used specifically to prevent a reverse flow of electrical power in order to protect batteries, charging systems, or power generation systems. Blocking diodes are used heavily in green-energy systems such as solar or wind-powered electrical generators. Most Diodes are involved in Solar Systems and wired in Solar Panels these days but not all. All Solar Systems now use a Charge Controller as a block between the Solar Panels and the Battery
A Blocking and By-pass Diodes are basically the same things it’s just how they’re wired and what their function is that makes them different. By-Pass Diodes are used to reduce the power loss that happens when shading occurs in the Solar System this is because current flows from high to low voltage. By-pass diodes will not be of use unless Solar Panels are connected in series to produce a higher voltage.
When a solar panel has cells that are partially shaded it creates high resistance and the current will be forced through those lower voltage shaded cells. This will cause the cell on the panel to heat up and creates power loss. Those shaded cells become consumers of solar panel energy instead of being providers of energy.
However, at night, if the panel board is associated specifically with a battery, the voltage of the panel board will be lower than the voltage of the battery, so there is a probability of some retrogressive stream, which means it draws power out of the battery. It will not be as much as the stream in the day, however. This figure shows the By-Pass Diode in a PV panel, which shows the wiring position for preventing the backward flow of voltage.
How to Test a Diode in a Circuit