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Solar Degradation Calculator

Project panel output decline over the system lifetime and against warranty terms.

About Solar Degradation Calculator

At 0.5 per cent annual degradation panels retain about 88 per cent of output after 25 years, comfortably above a typical 85 per cent warranty floor. Degradation compounds rather than accumulating linearly. Warranty claims turn on measured output against the guaranteed curve, which makes accurate first-year baseline data valuable.

Formula

Solar Degradation

Remaining capacity = (1 − degradation rate)^years

degradation
Permanent annual capacity loss, typically 0.4 to 0.7% for modern panels
warranty floor
Minimum output the manufacturer guarantees at end of term

Worked example

With the default values below, Solar Degradation Calculator returns Generation in That Year of 5,734.4. Change any input above and every figure here is recalculated in your browser.

Inputs used

First year generationminimum 0 kWh
6,500 kWh
Annual degradation rateaccepts 0–100 %
0.5 %
Years elapsedaccepts 0–50 years
25 years
Warranted output at end of termaccepts 0–100 %
85 %

Results

Generation in That Year
5,734.4 kWh
Remaining Capacity
88.222%
Cumulative Generation
153,114 kWh
Warranty Status
Above the warranted output level
Years Until the Warranty Floor Is Reached
32.42

Step by step

  1. 1Values used
  2. 2Solar Degradation
  3. 3Generation in That Year= 5,734.4 kWh
  4. 4Remaining Capacity= 88.222
  5. 5Cumulative Generation= 153,114 kWh
  6. 6Warranty Status= Above the warranted output level
  7. 7Years Until the Warranty Floor Is Reached= 32.42

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or fees or charges into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Solar Degradation calculated?

Remaining capacity = (1 − degradation rate)^years At 0.5 per cent annual degradation panels retain about 88 per cent of output after 25 years, comfortably above a typical 85 per cent warranty floor. Degradation compounds rather than accumulating linearly.

Why does Solar Degradation matter?

Warranty claims turn on measured output against the guaranteed curve, which makes accurate first-year baseline data valuable.

What values do I need to enter?

This calculator takes 4 inputs: First year generation, Annual degradation rate, Years elapsed, Warranted output at end of term. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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