Fill factor

The fill factor means the quotient of the maximum power of a solar cell at the maximum power point and the product of open circuit voltage and short circuit current. The fill factor is therefore dimensionless.

In this chart, the fill factor is to be regarded as the ratio of blue to yellow area. The ideal solar cell provides a constant current source is (up to its maximum voltage ), its current-voltage diagram is a rectangle and the space factor is equal to 1, Therefore, it is adjacent to short-circuit current and open-circuit voltage is a measure of the quality of the cell. The lower the fill factor, the lower is the efficiency of the solar cell, since a lost part of the power generated at the internal resistance of the cell.

For crystalline solar cell values ​​from 0.75 to 0.85 are achieved with amorphous cells, the fill factor is between 0.5 and 0.7.