Models to represent the behaviour of photovoltaic (PV) solar cells in reverse bias are reviewed, concluding with the proposal of a new model. This model comes from the study of avalanche mechanisms in PV s.
Another strategy is to increase the tolerance of the photovoltaic material against reverse bias: the higher the voltage a cell can withstand before it experiences an electrical breakdown (at the so-called breakdown voltage, Vrb), the lower the reverse-bias degradation.
What are the different types of reverse characteristics in PV solar cells?
It can also be applied to the different types of reverse characteristics found in PV solar cells: those dominated by avalanche mechanisms, and also those in which avalanche is not perceived because they are dominated by shunt resistance or because breakdown takes place out of a safe measurement range.
It can be adapted to PV cells in which reverse characteristic is dominated by avalanche mechanisms, and also to those dominated by shunt resistance or with breakdown voltages far from a safe measurement range. A procedure to calculate model parameters based in piece-wise fitting is also proposed.
What is PV overcurrent protection?
Overcurrent protection, when used, protects PV cells against reverse current and cables against overload. Generally speaking there are three situations that can lead to abnormally high temperatures and the risk of fire in a PV system: insulation fault, a reverse current in a PV module, and overloading cables or equipment.
What causes reverse current in a PV system?
Fig. P11 – Example of leakage capacitance in various PV systems A short circuit in a PV module, faulty wiring, or a related fault may cause reverse current in PV strings. This occurs if the open-circuit voltage of one string is significantly different from the open voltage of parallel strings connected to the same inverter.
This model comes from the study of avalanche mechanisms in PV solar cells, and counts on physically meaningful parameters. It can be adapted to PV cells in which reverse characteristic is dominated by avalanche mechanisms, and also to those dominated by shunt resistance or with breakdown voltages far from a safe measurement range.