Installer guide · 13 min read

The Warm Homes Loan Scheme and Commercial Solar: What Installers Need to Know

By Roman Steer-Love, co-founder of TNW Marketing · published 28 October 2026

Short answer: the Warm Homes Loan Scheme, launched on 27 October 2026, is for homes, not businesses. It lends only to owner-occupiers and private landlords, on a personal basis, and its Scheme Rules say lending to business or SPV type structures is not allowed. For commercial installers it still matters in three places: mixed-use properties such as farmhouses, holiday lets and home businesses, where the domestic part can qualify; landlords who own homes in their own name, who can take a loan for each property; and business customers who may ask about it and need a clear no and a real alternative. This guide takes each rule from the Scheme Rules (v3, September 2026), with section numbers.

• No

  lending to companies or SPVs

  Scheme Rules 3.9

• Yes

  for mixed-use homes, if mainly domestic

  Scheme Rules 4.7

• 1 loan

  per home for private landlords

  Scheme Rules 4.8

• £15k

  cap for solar, and again for a battery

  Scheme Rules 4.19

What the Warm Homes Loan Scheme is, in one paragraph

The Warm Homes Loan Scheme (WHLS) is the loan part of the government's wider Warm Homes Plan (Scheme Rules 1.1). It is a government-backed loan for low carbon home upgrades, run through private lenders. The government gives each participating lender a grant towards every loan, and the lender passes it on as a lower interest rate. The DESNZ factsheet names ten lenders at launch and says rates can be up to 5% lower than regular loans, with some interest free and some repayable over up to 30 years. Eligible measures include roof-top solar, batteries, heat pumps, biomass boilers, heat network connections and small wind or hydro (4.13). The scheme covers domestic property anywhere in the UK (3.7).

Who can and can't borrow under the Warm Homes Loan Scheme

Eligibility turns on two things: who is borrowing, and what the building is used for. The scheme lends to owner-occupiers of existing homes and to private rented sector landlords, on a personal lending basis (4.4). It defines a domestic property as any building used or suitable for use as a dwelling (4.7).

• Limited company or SPV

  No

  Lending to business or SPV type structures is not allowed (3.9)

• Landlord holding homes through a company

  No

  The company is the owner, and the scheme lends only to individuals on a personal basis (3.9, 4.4)

• Private landlord in their own name

  Yes, per property

  Private rented sector landlords are eligible borrowers, and owners of several properties can take a loan for each (4.4, 4.8)

• Owner-occupier with a home business

  Yes

  Running a business from home does not on its own rule a property out (4.7)

• Home with a short-term let or annexe

  Usually

  Incidental business use, such as a short-term let or an annexe, does not on its own rule a property out (4.7)

• Farmhouse on a working farm

  The house, yes

  The installation must be mainly meant to meet the household's energy needs (4.7). Farm buildings are a commercial job

• Shop, office, workshop or unit

  No

  The scheme covers domestic property, meaning a building used or suitable for use as a dwelling (4.7)

Mixed-use jobs: farms, holiday lets and home businesses

Section 4.7 is the one commercial installers will use most. Where a property has both a home and a business use, an installation is eligible if it is principally intended to meet the energy needs of the domestic household. Incidental business use does not on its own rule a property out, and the rules give three examples: short-term lets, secondary but associated buildings such as annexes or converted garages, and someone running a business from home.

In practice that means splitting a mixed site by what each system serves. On a farm, for example:

• Farms. A system on the farmhouse roof, sized to the household, can be a scheme job. Panels on a dairy, grain store or workshop serve the business, so they are a commercial job with commercial finance. The scheme only funds new roof-top mounted solar (4.13), so a ground-mounted array is out either way.
• Holiday lets and annexes. A home with an annexe or a short-term let alongside it is not ruled out by that use alone. A site that is mainly a holiday business, with no household it serves, is harder to fit the rule, so let the lender decide eligibility rather than promising it.
• Home businesses. A home office or small trade run from home does not stop the house qualifying. A separate unit, shop or yard building used only for the business is not a dwelling.

The lender makes the call on each application (3.11), so write the quote so the domestic system and any business system are clearly separate jobs with separate prices.

Landlords with several homes

Private rented sector landlords are one of the two eligible groups (4.4), and an owner of several properties can apply for a loan for each property (4.8). Each home is a separate domestic job, with its own loan and its own measure cap. The catch is ownership: lending to business or SPV type structures is not allowed (3.9), so a landlord whose portfolio sits in a limited company cannot use the scheme for those homes. Ask how the properties are held before you build a proposal around it.

Limits that matter on bigger jobs

• Caps per measure. £15,000 for solar PV and £15,000 for a battery (4.19). Ancillary work such as scaffolding and the grid connection must fit inside the cap (4.16, 4.20).
• No roofing. The scheme will not fund replacement roofing or structural work needed before solar goes on (4.16). A lender may offer a separate ordinary loan for it (4.20). Our guide to roof overcladding or replacement before solar covers that sequencing on commercial roofs.
• MCS for the measure. The installer must be MCS certified for the specific measure at the point of installation, and lenders check it at the quote stage and after installation (4.24).
• No leasing yet. Leasing, subscription and property linked finance are not eligible in the first phase, though the rules say their inclusion will be kept under review (3.10).
• Rules can change. A second lender window is expected to open in late 2026 for onboarding in early 2027 (3.4), and eligibility changes come with at least 30 days' written notice (4.22).

When a business customer asks about it

The scheme was launched with a government announcement and cheaper rates for solar, so business owners may ask about it on site meetings. Answer it early and plainly: the scheme does not lend to companies or SPVs (3.9). Then move the conversation to the routes that do work for a business. A limited company can pay cash, use hire purchase or a lease arranged with a finance company, or sign a power purchase agreement where an investor owns the system. Our guides to offering finance on commercial solar and commercial solar PPAs cover how each works, and when the FCA's credit broking rules apply to sole traders and small partnerships.

If the owner lives on site, the house may be a separate domestic job. Mention it, but keep the two quotes apart, so the business decision does not wait on a personal loan application.

If you do domestic and commercial work

Installers who work on both sides now have two finance stories. On domestic jobs the scheme can bring the monthly cost down; on commercial jobs the case rests on the business's own bill savings, tax position and choice of finance. Point-of-sale finance is allowed under the scheme where lenders offer it with installers (3.8), but introducing a customer to a lender is usually credit broking, which the FCA regulates, so agree the arrangement with the lender first.

For the domestic detail, the lenders, caps, quote rules and when the installer is paid, see our sister site's Warm Homes Loan Scheme guide for installers. For the commercial side of your pipeline, our guide to selling commercial solar covers the business case a finance director needs to see.