A bypass diode is a diode that is connected across a circuit or module and then conducts as soon as the circuit is supplied with a reverse voltage
or has negative effects on other circuits. In photovoltaic systems, a series connection of several solar modules is called a string. This series connection has the disadvantage that the weakest link, in the case of the solar module the solar cell with the lowest energy yield, determines the current flow
when a solar cell reduces the overall current flow. The bypass diodes protect the solar cells from thermal overload, and the current of the other solar cells is then diverted past this solar cell via the parallel-connected bypass diode without being impaired. Bypass diodes are also available as module bypass diodes and string bypass diodes.