Blocking Diodes For Solar Panels In Parallel

Mainly we use two kinds of diodes for effective solar panels bypass and blocking diodes.

Blocking diodes for solar panels in parallel.

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. If your panels are a grouping of other panels then you won t need a diode. It is always installed in series with the solar panel. When a solar panel is shaded the output current reduces dramatically and when it s dark it actually absorbs current.

Blocking diodes will be of benefit in any system using solar panels to charge a battery. Also we should consider bypass diodes in this. I recall reading somewhere that one should also install a blocking diode for each parallel string. Store bought panels will typically have a protection diode already in place.

Now let s consider what happens if one of the panels in the above diagram is shaded. 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 usually included in the construction of solar panels so further blocking diodes are not required. You may be wondering what is the difference.

Blocking diodes are used to prevent your batteries from discharging backwards through your solar panels at night. 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. There are two functions a diode can perform in 12volt solar systems either as a blocking diode or as a bypass diode. The blocking diodes are connected in series while the bypass diodes have a parallel connection.

There is a possibility of the current flowing from the battery to the solar panel thereby discharging the battery overnight. This is a real problem at night because we could lose all the power we gained during the day. Difference between bypass and blocking diodes source. To prevent this from happening a blocking diode is installed.

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. This is to prevent current flow from branches in high sunlight feeding current into those in shadow.