Solar budget variance calculator
Splits the gap between budgeted and actual energy into irradiance, availability and a residual, and shows how much of the availability gap a guarantee could cover.
A design aid, not financial or legal advice. The starting values are the invented plant on the asset management page. Replace every input with your own budget, meter and contract figures.
| Result | kWh | % of budget |
|---|---|---|
| Budget energy | - | 100.00% |
| Irradiance effect | - | - |
| Availability effect | - | - |
| Other (residual) | - | - |
| Total versus budget | - | - |
| Total in USD at the price above | - | |
| Irradiance / availability effect if availability is taken first | - | |
| Energy per availability point (kWh) | - | |
| Availability gap to budget (points) | - | |
| Points below the guarantee after exclusions | - | |
| Energy under the guarantee (kWh and USD) | - | |
Method: budget energy = size x budget sunlight x budget performance ratio. Irradiance effect = budget energy x (actual sunlight / budget sunlight - 1). Availability effect = energy at 100% availability x change in availability. Other = actual energy minus the first two steps. The split depends on the order and on the sunlight sensor. Availability must be energy-based and use the budget's own definition. The guarantee line uses lost energy at the price above, not any contract's own formula. Numbers accept 6,250,000 or 0,06 style input; 1.000 is rejected as ambiguous.