FAQs & tips

Why is my installer's payback different?

Installers may use a different generation figure for your roof, a different self-use share, or future tariff assumptions. Ask them to show generation, self-use, export, price, and feed-in tariff separately, then enter those same figures here to compare like with like.

Does a battery always help?

No. A battery can raise self-use, but it adds thousands of dollars upfront. Add the battery cost to the system cost in this calculator and see whether payback actually shortens for your usage pattern.

What if I am rarely home during the day?

Daytime self-use will be lower, so more solar is exported at the lower feed-in rate. Shifting flexible loads to daylight, or using timers, can change the result more than a slightly larger system.

Should I trust a single payback number?

No. Run at least three scenarios: pessimistic (lower generation, lower self-use), central, and optimistic. If payback only works in the optimistic case, the investment is riskier than it first looked.