Enter the initial power output of the solar panel, the annual degradation rate, and the number of years the panel has been in use into the calculator to determine the annual power loss. This calculator can also evaluate any of the variables given the others are known.

Solar Panel Loss Formula

The following formula is used to calculate the annual solar panel power loss. 

PL = P * r * n

Variables:

  • PL is the annual power loss (kWh)
  • P is the initial power output of the solar panel (kWh)
  • r is the annual degradation rate (decimal)
  • n is the number of years the panel has been in use

To calculate the annual solar panel power loss, multiply the initial power output of the solar panel by the annual degradation rate, then multiply the result by the number of years the panel has been in use. This will give the total power loss over that period.

What is a Solar Panel Loss?

Solar panel loss refers to the decrease in the efficiency and power output of a solar panel over time. This can be caused by various factors such as degradation of materials, dust and dirt accumulation, shading, temperature changes, and improper installation. The standard performance loss for solar panels is about 0.5-1% per year. This means that after 25 years, a solar panel may operate at around 80-90% of its original capacity.

How to Calculate Solar Panel Loss?

The following steps outline how to calculate the Solar Panel Loss.

  1. First, determine the initial power output of the solar panel (P) in kWh.
  2. Next, determine the annual degradation rate (r) as a decimal.
  3. Next, determine the number of years the panel has been in use (n).
  4. Next, gather the formula from above = PL = P * r * n.
  5. Finally, calculate the Solar Panel Loss (PL) in kWh.
  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.

initial power output of the solar panel (P) = 500 kWh

annual degradation rate (r) = 0.05

number of years the panel has been in use (n) = 10