payback period ends up being less than the life of the battery then I'm in front
But that assumes a couple of things.
1)The cost of using the battery for the house is less than using the grid at the time the battery is used
2)The income from Fit is more than the cost of using the battery for export.
My suspicion is that 24c/kWh is less than the cost of using the battery on cents/kWh basis. If 24c/kWh is equal to the cost of using the battery to export, then the actual income that can be attributed to the payback period will be Zero.
My 48kWh battery has a cost of 23c/kWh. The cost of charging it from solar is about 5cents/kWh usingthe same calculation. But because I also have free 3 hours, I attribute half of the battery charging at Zero cents. So net 2.5c/kWh
This means the electricity that comes out of the battery is 25.5c/kWh.
This means that if the annual average Fit is 24c/kWh, exporting through amber actually cost me 1.5c/kWh and is a financial loss.
It is easy to amortise the capital over the warranty period
Use an
amortisation calculator. Enter the capital amount of battery and opportunity interest rate - offset home loan rate for example.
Use 10 years or whatever the warranty period is
Use monthly as Amber has monthly bills.
Find the warranted kWh in the warranty.
Divide the total monthly payments by the warranted kWh to bet the $/kWh and convert to cents/kWh
Only export from the battery when the FiT is greater than the battery c/kWh (including the cost to charge the battery)