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Utility Solar Annual Output Calculator

This calculator estimates the annual electrical output of a utility solar project from its nameplate capacity and expected capacity factor. A loss adjustment accounts for wiring, inverter, availability, soiling, curtailment, and other reductions not already embedded in the capacity factor.

Developers, analysts, and project stakeholders can use the result for early-stage energy budgeting, revenue scenarios, and comparisons between sites. The page reports gross theoretical energy, estimated delivered energy, and average output across the year.

Utility solar production assumptions

kW
%
%
Result
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Estimated annual electricity generation
Gross annual energy—
Loss-adjusted annual energy—
Average continuous output—
Monthly average—

1. Enter nameplate capacity

Use the project’s rated AC or DC capacity consistently with the capacity-factor assumption.

2. Set the capacity factor

Enter the expected average output as a percentage of nameplate capacity over a full year.

3. Add separate losses

Include only losses that are not already reflected in the capacity factor.

4. Review annual generation

The main result shows estimated loss-adjusted megawatt-hours per year.

5. Check supporting values

Use gross energy and average output to validate the scale of the estimate.

Gross annual energy (kWh) = Capacity (kW) × 8,760 hours × Capacity factor
Net annual energy = Gross annual energy × (1 − losses)

Capacity factor and losses are entered as percentages and converted to decimals. The model uses a 365-day year and assumes the selected capacity factor represents normal long-run operation.

What the result means

The result is the estimated electricity produced over one year after the separately entered losses.

For bankable forecasts, use site-specific irradiance, equipment, degradation, availability, and curtailment studies.

Given: 1,000,000 kW capacity, 27% capacity factor, and 10% additional losses.

Calculation: Gross energy = 1,000,000 × 8,760 × 0.27 = 2,365,200,000 kWh. Net energy = 2,365,200,000 × (1 − 0.10) = 2,128,680,000 kWh.

Result: 2,128,680.0 MWh per year.

This is the modeled annual delivered energy under the stated utilization and loss assumptions.

Should I use AC or DC capacity?

Use the same capacity basis used to derive the capacity factor. Mixing a DC rating with an AC-based factor can distort the estimate.

What does capacity factor represent?

It is actual or expected annual energy divided by the energy the plant would produce at nameplate power every hour of the year.

Can losses be set to zero?

Yes, when the capacity factor already reflects all expected losses. Otherwise, enter only the incremental loss percentage.

Does the estimate include solar degradation?

Not automatically. For a future operating year, reduce the capacity factor or add an appropriate degradation adjustment.

Why is annual output less than capacity times daylight hours?

Capacity factor already captures changing irradiance, weather, nighttime, and operational limitations across the full 8,760-hour year.