Online Tool Store
Solar Payback Calculator
Estimate solar payback from install cost, annual generation, self-consumption share, and export rate — with the assumptions made visible.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Finance
Solar Payback Calculator
Frontend preview — no upload or external service.
Payback estimate
5,200 kWh at 55% self-consumed: 177,320 saved on imports plus 51,480 from export, about 228,800 a year. Payback around 6.3 years before any degradation or rate changes.
How the Solar Payback Calculator works
- Enter the installed cost after any grants, and a realistic annual generation figure for your location and roof orientation.
- Set the self-consumption share honestly — it is the single biggest lever and most households overestimate it.
- Read the payback as a range, since electricity rates over a decade are the assumption you cannot know.
The method
Savings come from two very different rates: electricity you no longer buy, and surplus you export at a much lower price.
annual saving = generation × self-consumption × import rate + generation × (1 − self-consumption) × export rate
At 62 import and 22 export, a unit consumed at home is worth nearly three times one exported — which is why self-consumption share dominates the result.
FAQ
What self-consumption share is realistic?
Without a battery or daytime occupancy, often 30-50% for a household, because generation peaks when nobody is home. Working from home, an electric vehicle, or a battery raises it substantially.
Does a battery improve payback?
It raises self-consumption and adds cost, and whether that nets out depends heavily on the gap between import and export rates and on battery price. Model it as a separate scenario rather than assuming.
What about panel degradation?
Output typically declines slowly over decades, which lengthens payback slightly. Rate changes over the same period matter far more and are much less predictable.
How we compare
| Feature | Online Tool Store | A spreadsheet | An advisor consultation |
|---|---|---|---|
| Separates import and export value | ✓ | Often merged | Yes |
| Self-consumption as an input | ✓ | ✗ | ✓ |
| Installer-neutral | ✓ | ✓ | ✗ |
| Nothing stored | ✓ | ✓ | ✗ |
Solar Payback Calculator separates self-consumed from exported units, because they are worth very different amounts and merging them flatters every estimate.