Do All Solar Panels Have Blocking Diodes

There are two functions a diode can perform in 12volt solar systems either as a blocking diode or as a bypass diode.

Do all solar panels have blocking diodes.

All the energy is in the battery and it wants to escape. Bypass diodes inside the junction box of a solar panel provide a low resistance path for the current to go around a series of solar cells that have been shaded. Most solar panels have bypass diodes built in these days so you don t have to worry about that anymore. Not only will that panel not be producing any significant power but it will also have a high resistance blocking the flow of.

Now the night time comes and the sun goes in. This causes the solar panel to heat up and have severe power loss. In real life this is mostly not the case. Blocking diodes in solar panel arrays.

Since you have a basic understanding of the blocking diodes let s move on to the solar panel arrays that are much more complicated. However if you have multiple solar panels wired together in series and you consistently have shading on one or more of the solar panels wiring a bypass diode in parallel across the shaded panel can prevent the current from being forced. The diodes are to prevent the battery discharging into the panel at night. This is where a solar panel blocking diodes is used.

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. Most folk connect the panels to an inverter which sometimes have their own blocking diode some simple checks with a current meter will indicate if you need one in your setup or not. The energy flow is now reversed and escapes out through the solar panel. In the above example you only had to deal with a single solar panel.

Now let s consider what happens if one of the panels in the above diagram is shaded. Blocking diodes are usually included in the construction of solar panels so further blocking diodes are not required. You may come across multiple strings as well. Bottom line is with blocking diodes you will avoid 2 4w being wasted in the shaded panel but will waste 4w in each of the unshaded panels all the time the panels are in full sun.

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. If you have two 175 watt panels each at 42 volts you will need two 8 amp 45 volt diodes. Blocking diode when a solar panel is shaded the output current reduces dramatically and when it s dark it actually absorbs current. Those shaded solar cells become consumers of electricity instead of producers.

2 4w will be wasted in the shaded panel without a blocking diode in place. With the other panels operating at max power voltage of 18 4v approx.