Work Out Solar Payback From Your Own Bill — Free
Paste the quote, your annual usage and your tariff, and read the years to payback with the assumptions printed beside it.
The proof surface
Payback claims come from optimistic generation and self-consumption assumptions. Recomputing on the reader's own bill is the only version worth acting on.
Why the flat version breaks
Quoted payback figures
A seven-year claim usually assumes high self-consumption and an export tariff that may change, neither of which appears in the total.
Ignoring the battery
Batteries add cost and improve self-consumption; a quote with and without one produces two very different payback years.
Assuming today's tariff
Import tariffs have risen faster than export rates, so payback computed on today's numbers can move by years.
How to work the payback chart
Quote, grant, usage, tariffs and generation estimate on their own lines.
The chart measures payback against these two figures.
Bars move from negative to positive, with the earlier years shown below the rule.
Reduce the generation assumption by 10% and re-run before committing.
What the chart replaces
| Question | Before | On the chart |
|---|---|---|
| When does it pay back | trust the quote | years computed from your own tariff and usage |
| What if generation is lower | not modelled | bars computed at the saving you supply |
| What to ask the installer | 'is that realistic?' | the generation assumption in writing |
The chart is arithmetic on your own assumptions; it does not model tariff changes, degradation or financing, and it is not financial advice.
Run it on the samples, right here
FIRST-LOAD
Data note: Everything runs in this browser tab on the payback chart: your quote and bill figures stays on this device, nothing is uploaded, and the reading is rebuilt only when you press run.
Go deeper: the companion app files the same reading as a plotted bar chart sheet
The article demo above runs without limits. The companion app keeps a local history, exports the rows as CSV, prints the ready-to-mail packet, and holds your drafts on this device — one free run, then $ 9 one-time for the layer that keeps filing.
The chart and the payback year are free. The paid layer keeps three quotes and prints the comparison for a decision.
Open the solar payback chart companionBoundary
This payback chart works only on the quote, usage and tariff figures you paste you paste. It does not recommend an installer, does not model financing or tax, and does not guarantee a saving. The figures describe what you supplied, not what is true in the world. Confirm anything you plan to act on with your energy supplier and, for a decision this size, an independent adviser without installer commission before you rely on it.
What this is built on
- Every figure comes from the quote, usage and tariff figures you paste you paste; nothing is looked up, scraped or asserted as verified.
- Method: cumulative position = (annual saving × years) − net cost; the payback year is where the cumulative position crosses zero
- Sample values are labelled samples — illustrative by design, not your data and not a quotation of any organisation's policy.
Before: the reader relied on the quote's payback claim. After: they can see payback at year eleven on their own consumption figures.