Calculator Inputs
Enter the baseline system rating, energy production, degradation assumptions, warranty threshold, and energy price. The grid becomes three columns on large screens, two on smaller screens, and one on mobile.
Example Data Table
This sample shows how the calculator can be used for a commercial system scenario.
| Initial Capacity | Baseline Annual Energy | First-Year Loss | Annual Degradation | Analysis Years | Warranty Threshold | Energy Price | End Capacity | Retained Capacity | Cumulative Energy Lost |
|---|---|---|---|---|---|---|---|---|---|
| 100 kW | 160,000 kWh/year | 2.00% | 0.55% | 25 | 80% | $0.12 | 85.85 kW | 85.85% | 328,133.16 kWh |
Formula Used
1. Retained fraction in year y:
Retained Fraction = (1 − First-Year Loss) × (1 − Annual Degradation)(y − 1)
2. Remaining capacity in year y:
Remaining Capacity = Initial Capacity × Retained Fraction
3. Annual energy in year y:
Annual Energy = Baseline Annual Energy × Retained Fraction
4. Cumulative energy lost:
Cumulative Energy Lost = (Baseline Annual Energy × Years) − Sum of degraded yearly energy
5. Revenue loss estimate:
Revenue Loss = Cumulative Energy Lost × Energy Price
6. Warranty crossing year:
First year where Retained Capacity ≤ Warranty Threshold
Use percentages as percentage inputs in the form. The calculator converts them into decimal factors internally before applying the yearly geometric decline model.
How to Use This Calculator
- Enter the starting system capacity in W, kW, or MW.
- Provide the baseline annual energy expected without degradation.
- Set the first-year loss and the ongoing yearly degradation rate.
- Choose the analysis period and the warranty threshold you want to test.
- Add the energy price to estimate lost value from reduced output.
- Press Calculate Degradation to show results above the form.
- Review the summary cards, Plotly graph, and yearly table.
- Use the CSV or PDF buttons to save the report.
FAQs
1) What is solar degradation?
Solar degradation is the gradual loss of module output over time. This calculator separates first-year drop from later annual decline because early aging is often larger than the long-run rate.
2) What annual degradation rate is typical?
Many systems assume about 0.3% to 0.8% annual degradation after the first year. Actual values depend on module type, climate, installation quality, and operating stress.
3) Why is first-year loss entered separately?
First-year loss represents early settling and light-induced effects. Later degradation is usually slower and reflects long-term aging from heat, humidity, thermal cycling, and material fatigue.
4) Does degradation reduce energy and revenue equally?
Lower retained capacity usually reduces annual energy almost proportionally. Revenue follows that drop if energy price stays fixed, though weather, shading, downtime, and inverter behavior can change real outcomes.
5) How is the warranty year estimated?
The calculator finds the first year when retained capacity falls to or below your selected warranty threshold. If that never happens during the chosen period, it reports that the threshold was not reached.
6) Should I enter DC size or AC rating?
Use the rating basis that matches your production model. DC module rating is common for degradation analysis, but AC rating also works if the baseline annual energy uses the same basis.
7) Are weather and shading losses included?
No. Weather, soiling, shading, clipping, and downtime are not degradation. Include them inside your baseline energy estimate or analyze them separately to avoid double counting.
8) When should modules be replaced?
Replacement depends on economics, warranty support, output needs, safety, and maintenance costs. Many systems continue operating beyond warranty when production and balance-of-system components remain acceptable.