Use this rooftop solar capacity factor calculator to turn operational assumptions into a clear planning estimate. Enter values that match your own workload or site, then review the main result, supporting metrics, and interpretation. The calculation runs locally in your browser and exposes every major variable, making it useful for scenario comparison, budgeting, and early-stage design. Results remain estimates and should be checked against measured performance and project-specific constraints.
Capacity factor compares actual energy with the energy the rated system would generate if it ran at full power for every hour. It is not panel conversion efficiency.
Planning estimate only. Confirm important decisions with measured data, provider documentation, equipment specifications, and qualified professionals where appropriate.
10,512 kWh from an 8 kW system over 8,760 hours gives 10,512 ÷ (8 × 8,760) × 100 = 15.00%.
Solar output varies with night, weather, sun angle, temperature, losses, and downtime.
No. Capacity factor compares energy over time with continuous nameplate production.
Use the same rating basis used for your performance comparison and document it consistently.
Yes. Enter monthly energy and the exact hours in that month.
It usually indicates mismatched energy, capacity, period, or units; this calculator flags that case.
| Item | Meaning |
|---|---|
| Period | Typical hours entered |
| 365-day year | 8,760 |
| 366-day year | 8,784 |
| 30-day month | 720 |
| 24-hour day | 24 |