Calculate solar cell fill factor from maximum power, open-circuit voltage and short-circuit current, or efficiency from power, area and irradiance.

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Use values measured under the same conditions. Fill factor and efficiency are reported as percentages.

Related Calculators

Fill Factor Formula

The following formula is used to calculate the Fill Factor. 

FF = P / (V × I)

Variables:

  • FF is the dimensionless fill-factor ratio; multiply by 100 for a percentage
  • P is the maximum power from the solar cell (W) 
  • V is the open circuit voltage (volts) 
  • I is the short-circuit current (amps) 

To calculate a fill factor, divide the maximum power of the solar cell by the product of the open circuit voltage and the short-circuit current.

How to Calculate Fill Factor?

The following steps outline how to calculate the Fill Factor.

  1. First, determine the maximum power from the solar cell (W).
  2. Next, determine the open circuit voltage (volts). 
  3. Next, determine the short-circuit current (amps). 
  4. Next, gather the formula from above = FF = P / (V*I).
  5. Finally, calculate the Fill Factor.
  6. After inserting the variables and calculating the result, check your answer with the calculator above. 

Example Problem:

Use the following variables as an example problem to test your knowledge.

maximum power from the solar cell (W) = 30

open circuit voltage (volts) = 3

short-circuit current (amps) = 12. FF = 30 / (3 × 12) = 0.8333, or 83.33%.