How to apply for a commercial solar grant in the UK — step by step.

Step 1 — Identify the right route for your project

The first and most important decision in any commercial solar grant application is choosing the right scheme. Wrong-scheme applications waste 8-12 weeks of effort and assessor goodwill. The active 2026 routes by sector and geography:

• UK manufacturers (English/Welsh) — IETF closed. Use the Annual Investment Allowance alone or with a competitive PPA. No grant application needed.
• UK manufacturers (Scottish) — the Scottish IETF (SIETF) is closed (last call March 2025) and never funded solar PV; use the AIA and the 50% special-rate FYA.
• Public sector bodies (NHS, councils, schools, FE) — PSDS closed. Apply for Salix interest-free loans via Salix Finance portal. LCSF for HDP funding.
• Rural enterprises (farms, food processors, country hotels) — Apply for REPF via your local council’s economic development team.
• Businesses in 11 Mayoral Authority areas — Apply for Local Growth Fund via the relevant Mayoral Authority investment plan.
• Community-led organisations (charities, faith buildings, social clubs) — Apply for GBE Community Fund via Great British Energy.
• Welsh manufacturers — Apply for Welsh Industrial Decarbonisation funding via Welsh Government.
• Northern Irish businesses — Apply for Invest NI Capital Grants (case-by-case).
• Tax allowances (the Annual Investment Allowance, AIA) — No application; claimed automatically.

Step 2 — Pull half-hourly meter data and run the energy audit

Every UK commercial solar grant application requires energy data. The standard expectation is 2-4 years of half-hourly meter data, broken down by load type. This is what funders use to validate that the project sizing is sensible and that solar will actually displace material electricity.

Not sure which grants apply to your business? Use the grant eligibility checker to find out in 60 seconds. Half-hourly data is typically obtained from your electricity supplier (Octopus, EDF, British Gas, etc.) on request. Larger commercial sites have it as standard with their MIC (Maximum Import Capacity) contracts. We pull this data as the first step of any client engagement and run an energy audit identifying load patterns, daytime vs overnight demand, weekend operation, seasonal variation. The audit informs system sizing and the funder narrative.

Step 3 — Build the MCS-compliant system design

Funders want to see a properly engineered design — not a back-of-envelope sizing. The standard documentation:

• System sizing rationale tied to half-hourly demand profile
• Module and inverter selection (Tier 1 modules, commercial-grade inverters)
• PVsyst yield assessment for the specific site latitude, orientation and shading
• Mounting structure specification
• Single-line electrical diagram showing AC connection
• G99 DNO application status
• Structural assessment (engineer’s report on roof load capacity)

Step 4 — Build the financial model

Funders score on net economics, not gross. The financial model must show:

• Headline capex broken down by line (panels, inverters, mounting, DNO, install, design, contingency)
• Annual generation (kWh/year, year by year for 25 years with degradation)
• Self-consumption rate from half-hourly modelling
• Annual savings (electricity displacement + SEG export)
• Tax effects (the Annual Investment Allowance/AIA on net of grant)
• Three energy price scenarios (base, upside, downside)
• NPV at funder-specified discount rate (HM Treasury Green Book 3.5% real for public sector)
• IRR and payback period
• Sensitivity analysis

Step 5 — Write the funder-specific narrative

This is the highest-leverage part of the application. Each scheme rewards different scoring criteria:

REPF

Productivity outcomes — jobs created or supported, contract revenue enabled, GVA contribution, rural enterprise diversification. Decarbonisation is a secondary factor. We have written REPF narratives that anchored on contract grain-drying enabling 2 seasonal jobs as the primary scoring driver.

Local Growth Fund

Local economic outcomes aligned to the relevant Mayoral Authority’s investment plan themes. Cluster fit — for sites in named clusters (Aire Valley logistics in WYCA, Atom Valley in GMCA, AMRC in SYMCA), narrative alignment with cluster strategy strengthens scoring. Authority-specific net zero milestones if the authority has a target ahead of 2050.

Salix BAU loans

Loan repayment from energy savings — the financial model must show savings cover repayments with margin. Savings calculation methodology aligned to Salix preferred metrics. Project timeline tied to public sector procurement frameworks.

Scottish IETF

SIETF assessors scored carbon savings per pound of grant; the fund closed in March 2025 and solar PV was never an eligible deployment. Bundled measures (PV + heat + process electrification) score higher than standalone PV. Deep Decarbonisation route requires specific narrative on pathway alignment.

Step 6 — Submit and manage clarifications

Submission is via the funder’s portal (each scheme has its own). After submission, expect 4-12 weeks of funder review. Most funders raise clarification questions during review — typically focused on energy data interpretation, monitoring methodology, and supplier quotation quality. Most clarifications resolve within 48 hours of being raised. Award decisions come as a batch at window close.

Step 7 — Award, contract and milestone delivery

On award, the funder issues a grant funding agreement covering deliverables, milestones, monitoring requirements and clawback conditions. Project delivery typically runs 12-16 weeks for sub-1MW commercial rooftop projects. Grant funding draws down against actual milestones, with monitoring & verification (M&V) continuing for 18-36 months post-commissioning.

What we do for clients

The free funding review takes 4 minutes. We reply by email with a written shortlist of routes you would credibly use, the documentation needed for each, and the realistic timeline. Engagement fees only kick in if you ask us to write the application — initial scoping is always free.