# Solar Panel Calculator Derby | Cost, Savings, Payback

> Free solar panel calculator for Derby: generation from PVGIS, savings at the East Midlands price cap and payback from published Derby prices, all sourced.

URL: https://ecosolarpanelsderby.co.uk/tools/solar-panel-calculator/

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# Solar Panel Calculator for Derby

[Eco Solar Panels UK](https://ecosolarpanelsderby.co.uk/) built this calculator from PVGIS generation figures for Derby, the East Midlands price cap and published Derby prices. Four questions show what a system would make, save and cost, and every figure has its source.

_[Interactive tool: open the web page to use it.]_

Transparency

## How the estimate works

-   Generation: the system size multiplied by PVGIS v5.2's yearly figure for Derby, 979 kWh per kWp facing south or 773 kWh facing east or west, rounded to the nearest 10 kWh.
-   Share used at home, as an example: out most of the day 30%, someone home for part of the day 50%, home most of the day 60%, and at least 70% with a battery.
-   Saving: the power used at home multiplied by 25.36p per kWh, the [Ofgem price cap, electricity by Direct Debit, 1 October to 31 December 2026 (East Midlands)](https://www.ofgem.gov.uk/your-energy-supply/your-energy-bill/energy-price-cap-unit-rates-and-standing-charges).
-   Cost: the published Derby range from Checkatrade, plus the published battery range if you add one.
-   Payback: the cost divided by the yearly saving, at both ends of the range, before any export income.

Questions

## About the calculator

### How accurate is the estimate?

Generation uses PVGIS v5.2 figures for Derby: typical-year estimates for an unshaded roof at a 35 degree pitch. Shade, a different pitch and the weather all change the real figure. The saving depends on how much of the power you use at home, which the calculator estimates from your answers.

### Why is the installation cost the same for every system size?

Checkatrade's published Derby range covers jobs of different sizes and isn't broken down by kWp, so the calculator shows the whole range instead of inventing a price per kWp. A quote for your roof gives a fixed figure.

### Why doesn't it include export income?

Export tariffs vary by supplier and each has its own eligibility rules, so the calculator leaves export income out. Any export payment you do get would shorten the payback.