Calc4Living

Home Energy · Free calculator

Solar Savings Calculator

Estimate solar production, avoided electricity purchases and export credits using your local sunlight, system and tariff assumptions.

Your inputs

All fields are required. Prefilled values are an editable example, not local price or usage recommendations.

No exchange rates or conversion. Enter electricity prices in the selected currency per kWh, not in cents or pence. Changing currency clears the result.

Installed DC peak capacity of the panel array, not inverter AC rating.

Equivalent full-sun hours, 0–24; use a local value for your period.

Fraction of ideal production remaining after combined losses. 0.80 is 80%.

Share of generation used on site, 0–100. The remainder is treated as exported.

Enter major currency units per kWh: for example, 0.20 means 20 cents or pence, not 20.

Major currency units paid per exported kWh. Enter 0 if there is no export credit.

Whole days, 0–366. The period result uses this value; monthly and annual comparisons use 30 and 365 days.

Your estimate

Energy & savings

Review the example inputs, enter your local electricity price, then calculate. Results clear when inputs change so an old estimate is never shown for new values.

How are solar electricity savings and export credits estimated?

Daily generation (kWh) = system size (kWp DC) × peak sun hours/day × performance factor. Daily value = generation × [self-consumption fraction × import rate + (1 − self-consumption fraction) × export rate]. Multiply by days for the period.

Worked example

A 5 kWp system with 4 peak sun hours/day and performance factor 0.80 generates 16 kWh/day. With 60% self-consumption, import price 0.20/kWh and export price 0.05/kWh, daily value is 2.24. Over 30 days: 480 kWh, 57.60 avoided purchases + 9.60 export credits = 67.20.

Example amounts use whichever currency you select; they are arithmetic illustrations, not quoted local rates.

Assumptions & limitations

  • Peak sun hours are equivalent hours at 1 kW/m² irradiance on the panel plane, not daylight duration. Use a local average appropriate to the period.
  • The performance factor is the fraction remaining after overall losses (for example 0.80 means 20% combined losses). Include losses such as inverter, temperature, shading and wiring effects in your assumption without double-counting effects already included in the sun-hour estimate. This simplified estimate is not a weather-based PV simulation.
  • Self-consumption is the fraction of generated energy used on site, not the fraction of household demand covered. Choose a share your demand can actually absorb. All remaining energy is assumed exportable at your entered rate; use zero export price when it has no value.
  • Actual savings depend on local conditions, seasonal weather, self-consumption, export limits and tariffs. No batteries, degradation, installation costs, financing, incentives or payback are modeled. This is gross bill benefit, not net investment profit.

Further reading