Result Summary
The calculated result appears here above the form after submission.
Enter the design and operating conditions below, then press calculate to see STC efficiency, corrected efficiency, site losses, performance ratio, and estimated array output.
Calculator Inputs
Plotly Graph
The graph compares nominal efficiency, temperature-adjusted efficiency, net efficiency, and performance ratio.
Example Data Table
| Case | Power (W) | Area (m²) | Irradiance (W/m²) | Cell Temp (°C) | Panels | STC Efficiency | Net Efficiency | Array Output (W) |
|---|---|---|---|---|---|---|---|---|
| Case A | 450 | 2.145 | 900 | 45 | 10 | 20.98% | 17.99% | 3,473.74 |
| Case B | 550 | 2.576 | 1,000 | 35 | 8 | 21.35% | 19.63% | 4,046.07 |
| Case C | 400 | 1.848 | 800 | 50 | 12 | 21.65% | 17.21% | 3,053.07 |
Formula Used
Core equations
Panel area: Area = Length × Width
STC efficiency: ηstc = Rated Power ÷ (1000 × Area) × 100
Temperature factor: Ft = 1 + (Temp Coefficient ÷ 100) × (Cell Temp - Reference Temp)
Loss factor: Fl = (1 - Soiling) × (1 - Shading) × (1 - Mismatch) × (1 - Degradation)
Output equations
Temperature-adjusted efficiency: ηtemp = ηstc × Ft
Net efficiency: ηnet = ηtemp × Fl
Actual panel power: Pactual = Rated Power × (Irradiance ÷ 1000) × Ft × Fl
Array output: Parray = Pactual × Panel Count
Performance ratio: PR = Pactual ÷ (Rated Power × Irradiance ÷ 1000) × 100
How to Use This Calculator
- Enter the rated power for one module under standard test conditions.
- Provide the module length and width to determine the active panel area.
- Input the operating irradiance and cell temperature for the site condition being reviewed.
- Add the reference temperature and the module temperature coefficient from the datasheet.
- Enter soiling, shading, mismatch, and degradation losses as percentages.
- Set the number of panels in the array and press Calculate Efficiency.
- Read the result block above the form to compare STC efficiency, corrected efficiency, and expected array power.
- Use the CSV or PDF buttons to export a shareable engineering summary.
FAQs
1. What does solar panel efficiency mean?
It is the percentage of incoming solar energy converted into electrical power by the module. Higher efficiency means more power from the same panel area under comparable conditions.
2. Why does temperature reduce efficiency?
Most silicon modules lose voltage as cell temperature rises. That voltage drop lowers output power, so the effective operating efficiency falls even when sunlight stays strong.
3. Why is irradiance still included if efficiency can stay similar?
Irradiance directly affects power output and incident solar power. Even if efficiency percentage changes modestly, the absolute watt output of the array depends strongly on available sunlight.
4. What is a temperature coefficient?
It is the percentage change in module power for each degree Celsius away from the reference temperature. A more negative value means output falls faster in hot conditions.
5. What losses should I enter?
Use realistic estimates for dirt, partial shade, wiring or mismatch effects, and long-term degradation. These losses multiply together, so several small losses can noticeably reduce output.
6. Does adding more panels improve efficiency?
Panel count increases total array output and total capture area, but it does not change the single-module efficiency formula. It mainly scales production, not conversion quality.
7. What does performance ratio show?
Performance ratio compares actual output to the baseline output expected at the same irradiance before operational losses. It helps summarize temperature and loss impacts in one percentage.
8. Can this calculator replace a full PV simulation tool?
No. It is excellent for fast engineering estimates and comparisons, but full project design still needs detailed weather data, tilt, azimuth, inverter behavior, and electrical modeling.