Solar Panel Degradation Forecast Tool — Project Future PV Output
Forecast how annual solar production changes as photovoltaic module output declines over the years, and identify when a selected production threshold may be reached.
Degradation forecast inputs
How solar panel degradation is forecast
The calculator treats annual production as changing by a compound percentage each year. This is different from subtracting the same number of kilowatt-hours every year.
Why compound modeling matters
A percentage degradation rate applied to the remaining production creates a gradually declining curve. The output therefore depends on both the annual rate and the number of years modeled.
Why real modules need more context
Observed system production also changes with weather, soiling, inverter behavior, shading, availability and other operational factors. A production forecast should not automatically attribute every year-to-year change to module degradation.
What the threshold means
The production threshold is a planning marker. It can represent a minimum annual output that makes a system attractive to continue operating, a target for review or another project-specific threshold. Crossing it does not itself prove that replacement is necessary.
Frequently asked questions
Can degradation be zero?
Yes. The forecast then stays flat unless another growth or improvement assumption is entered.
Can the model include improvement?
Yes. The optional improvement field lets you test a scenario that offsets part of the modeled decline.
Does production always decline smoothly in reality?
No. Actual annual generation can fluctuate because operating conditions and weather vary.