Retro-fit Battery Payback Calculator

*The following calculator is for reference only.

Costs / Discount in $
Batteries
Support/Racking systems
Inverter
Labour
Any other cost
Discount or Rebates
? Do not enter negative sign. System will deduct this figure from the total cost.
Total Cost
Calculate Payback
Battery Size in kWh
? Enter size of the battery in kWh
Usable battery percentage
? Do not enter % sign. Simply enter 100 if battery is fully (100%) usable or 90 if battery is 90% usable
Feed-in Tariff
General or Import Tarrif
Result
Difference in Tarrif
Total KWh Saved (Usable Battery Capacity)
Total savings per day by the new system
Payback period in years
Equations
Difference in Tariff
$$\ =General\ or\ Import\ Tariff\ – Feed\ in\ Tariff $$
Total KWh Saved
$$\ =\frac{Battery\ Size\ in\ kWh * Usable\ battery\ percentage}{100} $$
Total savings per day
$$\ =Total\ KWh\ Saved\ * Difference\ in\ Tariff $$
Payback period in years
$$\ =\frac{Total\ cost}{Total\ savings\ per\ day\ *\ 365} $$