Retro-fit Battery Payback Calculator

*The following calculator is for reference only.

Lets calculate the total cost of installing a battery system
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
To calculate payback period lets input the below values
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 (eg: 8c as 0.08)
General or Import Tarrif (eg: 25c as 0.25)
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
$$\ =\frac{Total\ cost}{Total\ savings\ per\ day\ *\ 365} $$