Worked example: 720kWp PPA for a Coventry Auto-parts Factory
An illustrative 720 kWp factories solar PPA: at 12.2 p/kWh over 20 years, the modelled year-1 saving is £82,000.
Illustrative example — not a real deal
This is a hypothetical worked example, written to show how a solar PPA's numbers work for this kind of site. The site, the operator and every figure are illustrative: the tariff and term sit inside this site's indicative bands and the saving is modelled from them. It does not describe any real organisation, and no contract is claimed.
| Worked example — modelled figures | |
|---|---|
| Sector | Factories |
| System size | 720 kWp |
| PPA tariff (year 1) | 12.2 p/kWh |
| Contract term | 20 years |
| Year-1 saving (modelled) | £82,000 |
A representative auto-parts factory
This composite, anonymised example comes from the automotive supply chain: a Tier-2 components manufacturer in Coventry, occupying a 12,000 m² portal-frame factory that imports about 2.1 GWh of electricity a year. The trigger was commercial, not idealistic. A German OEM further up the chain wanted Scope 1 and 2 disclosure by the end of 2024, and the site's £8m supply contract depended on passing that audit.
The capital clash
The complication was timing. The business had already committed a £2m capital programme to a production-line upgrade and had no appetite to divert funds into a rooftop array. A PPA resolved that tension by keeping the solar entirely off the capital budget — the provider funds, builds, owns and maintains, while the factory simply buys the output. For anyone comparing that trade-off against buying outright, the side-by-side comparison lays out where each route wins.
Fixing the tariff and adding storage
In this scenario a corporate-PPA specialist delivers 720 kWp on the factory roof over 20 years at 12.2 p/kWh — and unusually, the rate was fixed with no escalator, giving the finance team a flat unit cost to model for two decades. A 480 kWh battery was bundled in for peak-shaving, trimming demand charges during the most expensive periods. How a fixed rate compares with an inflation-linked one is worth modelling before you sign; the pricing explainer covers both.
What it delivered
The headline outcomes for this illustrative site:
- Around £82,000 saved in year one against the previous grid rate.
- Roughly £15,000 shaved off TNUoS peak charges through battery-led load management.
- The OEM audit passed, protecting the £8m contract that justified the project.
The strength of that OEM relationship is also what let the provider price keenly — see the covenant guide. It was not friction-free, though: integrating the battery triggered a higher fire-risk classification, and the site's insurance premium rose by about 8% afterwards — a reminder that on-site storage carries its own compliance and cost tail, separate from the PPA itself.
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