Some installers will calculate this for you, but the answer depends on the assumptions they make. If you use only about 30% of the electricity you produce it could be 20 years. This would reduce to about 15 years if you heat water with excess electricity, or if you secured a reasonable SEG payment, and would reduce further if you did both. If you also install a battery and maximise the benefits of storing your generated electricity and off-peak grid electricity, this could drop to 10 years. This is based on electricity prices and solar PV prices in early 2022 – changes in these prices affect the payback period. More info in the financial calculations below.