Estimate solar energy production over a chosen period with conservative, expected and optimistic resource cases.
This is an energy screen, not a site-specific hourly yield forecast. Weather, shade, orientation, temperature, clipping and downtime can change production. Trust level: engineering estimate; verify site and equipment assumptions before purchase or installation.
| Scenario | Peak sun hours | Generation |
|---|---|---|
| Conservative | 4 | 3,504 kWh |
| Expected | 5 | 4,380 kWh |
| Optimistic | 6 | 5,256 kWh |
Method: generation = array kW × peak sun hours × days × (1 − system loss)
Inputs used: 3 × 5 × 365 × (1 − 20%) = 4380 kWh
Assumptions: Peak sun hours Combined system loss Solar-resource scenario spread
Scope and warnings: This is an energy screen, not a site-specific hourly yield forecast. Weather, shade, orientation, temperature, clipping and downtime can change production.
National Renewable Energy Laboratory · PVWatts supported locations; use a location-specific model for a site estimate · effective PVWatts version 5 documentation · reviewed 2026-09-12
high confidence · Engineering estimate
Supports the transparent solar energy relationship and system-loss planning reference.
Exclusions: Not a structural, electrical or financing assessment. ToolMitra does not query PVWatts automatically.
Generation equals DC array capacity multiplied by equivalent peak sun hours, days and the usable fraction remaining after combined system losses. Scenario cases vary only the entered solar resource by the visible spread, keeping capacity and losses unchanged.
A 3 kW array with 5 peak sun hours, 20% combined losses and 365 days produces an expected 4,380 kWh. A 20% resource spread shows 3,504, 4,380 and 5,256 kWh without presenting any case as a forecast.
No. It is a transparent first-pass equation. PVWatts uses location weather data and a fuller system model. Use a site-specific service or designer before treating annual generation as bankable.
Calculations run on your device. Review your results before exporting or sharing them.
Peak sun hours are equivalent full-sun energy, not daylight duration. Use the expected case for a representative resource estimate, then set a spread that reflects uncertainty you can explain. Combined losses should reflect the proposed orientation, shade and equipment.
The three scenarios change solar resource only. They do not simulate hourly clipping, seasonal load matching or a probability distribution. Carry the appropriate annual result into the cost tool and keep the scenario name attached.
Published by ToolMitra — methods and editorial approach.