This is where by pass diodes come into play as shown in the diagram to the right.
Function of bypass diode in solar panel.
Solar modules with bypass diodes are manufactured because of two reasons.
The need for bypass diodes the shadow problems of pv modules are caused by the fact that the solar cells which are unequal current sources are series connected.
Bypass diodes usually schottky diodes are placed on sub strings of a pv panel for example one diode per 10 or 20 pv cells.
In simplest terms a diode can be understood as a two terminal electronic device which allows electrical current to pass in one direction.
Bypass diodes are useless unless the panels are connected in a series fashion to produce high voltage.
Bypass diodes are used in photovoltaic pv panel applications to reduce the effects of shaded conditions on a panel as shaded panels produce a lower solar generated current.
By pass diodes will not be of use unless panels are connected in series to produce a higher voltage.
This causes the solar panel to heat up and have severe power loss.
One way to minimize the effect shading has on a single module in a series string is to use bypass diodes in the junction box.
Function of a bypass diode.
Recently some solar panels are being manufactured by the cells divided into groups with a built in bypass diode in that group.
In multi panel pv strings the faulty panel or string has been bypassed by the diode which provide alternative path to the flowing current from solar panels to the load.
Because current flows from high to low voltage when a solar panel has cells that are partially shaded the current is then forced through the low voltage shaded cells.
Bypass diodes are used to reduce the power loss solar panels experience due to shading.
Diode and unidirectional flow of current.
A blocking diode and bypass diode are commonly used in solar energy systems and solar panels.
The lowest solar cell current is the output current of the pv panel and the surplus current of each solar cell flows back through its diode.
When a module becomes shaded its bypass diode becomes forward biased.
One way to minimize the effect shading has on a single module in a series string is to use bypass diodes in the junction box.
Bypass diodes allow current to pass around shaded cells and thereby reduce the voltage losses through the module.
Now if one panel is shaded the current produced by the unshaded panel can flow through a by pass diode to avoid the high resistance of the shaded panel.
Function of a bypass diode.
