Solar module performance and expected lifetime

by 00str1

Many consumers interested in using Solar PV for residential or business purposes like to know what the lifetime and performance of the panel will be like over time. The length of life of a photovoltaic unit is a critical element in the financial assessment of solar power. Cash payback may take well over a decade in northern Europe, even with substantial subsidies, such as the proposed new UK tariffs. So adding even a few years of expected life can mean a major difference to the viability of a project.

Below is a small outlay of industry expectancy and why.

Modules are generally rated under standard test conditions (STC) these conditions are below:

  • irradiance of 1,000 W/m² solar spectrum of AM 1.5 and module temperature at 25°C
  • Electrical characteristics include, nominal power, open circuit voltage, short circuit current, maximum power voltage, maxmimum power current, power power and module efficiency (%).

The peak power rating kWp is the maximum output under standard test conditions (not the maximum possible output).

Solar Photovoltaics slowly lose their generating capacity. Although some Solar Panels are still working satisfactorily 40 years down the line, the conventional view is that most will dip below 80% of their rated capacity within about 20 years.

Recent evidence from Japan suggests that life expectancy is longer than expected. A company that reuses old panels reports that it has tested 330 panels made in 1984. 90% of these units can still generate 80% or more of their initial output.

Solar panels must withstand heat, cold, raid and hail for many years. Many crystalline silicon module manufacturers offer a warranty that guarantees the electrical production for 10 years at 90% of rated power output and 25 years at 80%.

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