Tier 1 automotive component manufacturer · 720kWp solar PV
720 kWp commercial solar PV installation with combined grant + tax relief stack delivering 2.8 years post-tax payback on £720,000 gross capex.
Anonymised composite case study
Names, dates and exact financial figures have been changed to preserve client confidentiality. Project structure, funding combinations, technical configuration, and order-of-magnitude figures are real and based on completed work. Full editorial disclosure on the about page.
Project snapshot
| Sector | Automotive component manufacturer |
| Location | Coventry, West Midlands |
| System size | 720 kWp |
| Battery storage | 480 kWh |
| Gross project capex | £720,000 |
| Grant value | £210,000 (IETF) |
| Year-1 tax relief | £127,500 (Full Expensing yr 1) |
| Net effective cost | £382,500 |
| Annual savings/revenue | £152,600/year |
| Post-tax payback | 2.8 years |
| CO2 saving | 780 tCO2e/year |
| Year commissioned | 2025 |
Context
The site is a 12,000 m² portal-frame manufacturing unit on the Coventry north industrial corridor — a 1980s-built supplier serving the UK Tier 1 automotive market. The site produced precision pressings and welded assemblies for two major OEMs (one German, one UK), with annual revenue around £42m and approximately 280 employees. Energy spend across electricity and gas was £540,000 per year, with electricity import alone at 2.1 GWh.
In Q2 2024, the company's largest Tier 1 customer (a German OEM responsible for 60% of revenue) updated its supplier code to require Scope 1+2 emissions disclosure and a credible decarbonisation roadmap by end-2025. The supplier code change explicitly listed "renewable on-site generation" as an evidence category. The supplier's energy manager — already working on a 2030 net zero pathway — escalated the project to the board.
The challenge
The board's challenge to the project team had three components:
1. Demonstrable Scope 2 emissions reduction sufficient to satisfy the Tier 1 supplier code requirement. 2. Capital cost within available facilities (the firm had £600k of undrawn RCF and limited additional debt headroom). 3. Payback fast enough to support reinvestment in the firm's expansion plans — the board's hurdle was 4 years post-tax.
The site had constraints familiar to industrial brownfield solar: - Roof condition mixed (south-side asbestos cement, north-side modern composite — half the roof needed replacement before solar) - Three-phase electrical service but G99 export limit only 250kW (DNO capacity studies took 11 weeks) - High site daytime electrical load (compressed air, welding, lighting) — strong self-consumption potential - Carbon-intensive welding operations meant the carbon savings narrative was already strong
Funding approach
The energy manager approached us in mid-2024 for an independent eligibility check. We mapped the funding stack across five categories:
1. **Tax relief.** As a profitable limited company, 100% Full Expensing was available — saving 25p per £1 of solar capex. On a £720k project, that's £180k of corporation tax saved in year one. 2. **IETF Phase 4 candidacy.** The site qualified under SIC code 29 (motor vehicles, trailers and semi-trailers) for the Industrial Energy Transformation Fund. We recommended packaging solar with compressed air efficiency, ammonia refrigeration replacement, and VSD compressor upgrades — three energy efficiency interventions that together delivered 24% energy reduction. IETF awarded £210,000 (29% of project capex). 3. **Smart Export Guarantee.** Octopus Outgoing Fixed at 15p/kWh on the 25% of generation exported. 4. **REGO sales.** Above 50kWp, the system qualified for Ofgem REGO accreditation. Annual revenue around £8,200. 5. **Asset finance** for the non-IETF balance, structured as 5-year HP with full Full Expensing in year one.
The combined funding stack made the post-tax-and-grant net cost £382,500 — well within the firm's debt capacity.
Outcome & performance
The project commissioned in Q3 2025. Year-one performance:
- Annual self-consumption: 510,000 kWh (76% of generation) - Annual export: 162,000 kWh under SEG at 15p/kWh = £24,300 - Annual REGO revenue: £8,200 - Annual saved import (28p/kWh blended commercial rate): £142,800 - **Total year-one savings/revenue: £175,300** (versus £152,600 modelled) - CO2 saving: 935 tCO2e (versus 780 modelled) - Tier 1 audit completed in Q2 2026 with no findings — £8m supplier contract retained
Post-installation payback (after IETF grant and Full Expensing): 2.2 years on actual savings versus 2.8 years modelled. The board has approved a second-phase 350 kWp installation on the recently re-roofed south side for delivery in 2027.
Lessons learned
- Pair solar with broader energy efficiency interventions for IETF — solar-alone applications score poorly.
- Don't accept the first DNO export limit — capacity studies can reveal headroom not obvious from initial enquiry.
- Roof refurbishment before solar is often economically justified — it extends asset life and avoids retrofit risk.
- Self-consumption rates beat the model when site behaviour can be tuned to solar generation (we moved evening shift welding to mid-afternoon).
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