Solar payback period calculator
See how many years until your solar system pays for itself, accounting for power prices likely rising over time.
Savings vs system cost
Cumulative savings climbing over 25 years — payback is where the line crosses your system cost.
What this means for you
See how many "free" years of generation you get after payback, within the 25-year window shown here.
Compare price-rise assumptions
Rising electricity prices speed up payback — see how the result shifts between flat and rising price assumptions.
| Scenario | Price rise | Payback period |
|---|---|---|
| Flat prices | 0%/year | 0 years |
| Current | 3%/year | 0 years |
| Higher rises | 6%/year | 0 years |
Nobody knows future electricity prices for certain — this shows the range of outcomes rather than a single confident prediction.
Assumptions & sources
Historical NZ retail electricity price trends (roughly 30-50% cumulative rise over the past decade) used to inform the default price-rise assumption.
1 July 2026
17 July 2026
Cumulative savings compound at your chosen annual price-rise rate until they exceed the system cost; that crossover year is the payback period.
System cost, year-1 savings, and an assumed annual electricity price rise, projected over 25 years.
Panel output degradation (~0.5%/year), maintenance costs, and any inverter replacement typically needed once during a 25-year system life.
Related reading
Is solar really worth it?
Solar panels cost thousands upfront — here's when the payback maths actually works in your favour, and when it doesn't.
Read article →
How does NZ stack up against Australia in residential solar?
Australia has one of the highest rooftop solar rates in the world. Here's why NZ lags behind — and whether that's changing.
Read article →Why rising power prices work in solar's favour
NZ retail electricity prices have climbed roughly 30-50% over the past decade, driven by network upgrades and rising demand from EV charging and heat pump adoption — and most forecasts expect that trend to continue. Once your solar system is paid for, your generation cost is effectively locked at zero for the remaining 15-20+ years of its life, while the electricity you're no longer buying keeps getting more expensive. That's why payback calculations that ignore rising prices tend to understate solar's real long-term value.
There's also a dry-year risk factor specific to NZ: because the grid leans heavily on hydro generation, low-rainfall years can spike wholesale (and sometimes retail) prices — a risk solar households are partially insulated from.
Frequently asked questions
Most well-sized systems pay for themselves in 6-9 years, with less optimal setups (poor orientation, low self-consumption, southern locations) taking up to 12 years. After that, panels keep generating for 13-19+ more years, essentially free.
Yes, favourably. NZ retail prices have risen 30-50% over the past decade and are projected to keep climbing. Since solar locks in your cost at effectively zero, rising prices speed up your effective payback compared to a flat-price assumption.
