Source: MDPI

Understanding Mismatches in Photovoltaic Modules

Open Circuit Voltage Mismatch for Series-Connected Cells

A mismatch in the open-circuit voltage of series-connected cells is a less critical type of mismatch. At short-circuit current, the overall current from the PV module remains unaffected. However, at the maximum power point, the overall power output decreases because the weaker cell generates less power. Since the cells are connected in series, the current passing through them is the same, and the total voltage is the sum of the individual cell voltages at a specific current.

Short-Circuit Current Mismatch for Series-Connected Cells

In contrast, a mismatch in the short-circuit current of series-connected solar cells can have a significant impact on the PV module, depending on the degree of mismatch and the operating point. At open-circuit voltage, the effect of a reduced short-circuit current is relatively minor due to the logarithmic relationship between open-circuit voltage and short-circuit current. However, when the module operates at low voltages, the overall current cannot exceed that of the weaker cell. This can lead to severe power reductions, especially if the weaker cell produces less current than the maximum power current of the stronger cells. Operating the module at short circuit or low voltages can also cause irreversible damage to the module due to high power dissipation in the weaker cell.

Conclusion

Understanding and minimizing mismatches in photovoltaic modules are essential for maximizing their efficiency and longevity. While open-circuit voltage mismatches are less critical, short-circuit current mismatches can significantly impact the overall performance and durability of the PV system. By addressing these mismatches through proper system design and maintenance, the efficiency and reliability of solar power generation can be greatly enhanced.

Source: Battery Guy

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