Blocking Diodes For Solar Panels In Parallel

Blocking diodes will be of benefit in any system using solar panels to charge a battery.

Blocking diodes for solar panels in parallel.

I recall reading somewhere that one should also install a blocking diode for each parallel string. When a solar panel is shaded the output current reduces dramatically and when it s dark it actually absorbs current. In short the blocking diodes only provide a single path for current from the solar panel to the battery and block the currents from the battery to the solar cells during night as solar cells are acting as a load instead of generating energy. Mainly we use two kinds of diodes for effective solar panels bypass and blocking diodes.

Also we should consider bypass diodes in this. You may be wondering what is the difference. It is always installed in series with the solar panel. The blocking diodes are connected in series while the bypass diodes have a parallel connection.

If your panels are a grouping of other panels then you won t need a diode. This is to prevent current flow from branches in high sunlight feeding current into those in shadow. There is a possibility of the current flowing from the battery to the solar panel thereby discharging the battery overnight. To prevent this from happening a blocking diode is installed.

There are two functions a diode can perform in 12volt solar systems either as a blocking diode or as a bypass diode. This would prevent current flowing from one parallel string into a lower current string possibly due to shading and therefore helps minimize mismatch losses in parallel connected arrays. I was told recently that panels in parallel should have blocking diodes in each branch. Now let s consider what happens if one of the panels in the above diagram is shaded.

It allows the current to flow from the panel to the battery but blocks the flow in opposite direction. 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. Difference between bypass and blocking diodes source. Blocking diodes are used to prevent your batteries from discharging backwards through your solar panels at night.

A solar panel it a grouping of cells in a series parallel configuration of one form or another typically inside a housing. Store bought panels will typically have a protection diode already in place.