A quiet revolution is happening in UK lending. Several major banks and building societies now let existing mortgage customers borrow up to £20,000 at 0% interest specifically for green home improvements — no personal loan required. Solar panels, heat pumps, battery storage, insulation, EV chargers — all qualify.
Most homeowners have no idea this exists. Here’s everything you need to know.
Why Is Your Mortgage Lender Offering Cheap Money for Green Upgrades?
It’s not charity. Lenders have two very good reasons to offer green additional borrowing at heavily discounted rates.
The first is regulation. Banks are under increasing pressure from the FCA and the government to show they’re actively helping reduce the UK’s housing emissions — residential properties are responsible for around 16% of the country’s total carbon output. Offering subsidised green borrowing is one of the most visible ways a lender can demonstrate that.
The second is that it’s good business. A homeowner who upgrades to solar panels, a heat pump and better insulation typically sees their energy bills fall significantly. That means a lower risk of mortgage arrears, which is genuinely valuable to a lender on a 25-year loan.
The result is an unusual situation: some of the cheapest credit available for home improvements in the UK is sitting quietly inside your existing mortgage offer — if you know to look for it.
Before you look at finance plans from installers or take out a personal loan, check what your mortgage lender offers first. A 0% green additional borrowing product will almost always be cheaper — sometimes by several thousand pounds in interest. This applies whether you’re installing solar panels, a heat pump, battery storage, or all three.
What Is Green Additional Borrowing?
Green additional borrowing (also called a green further advance) is when your mortgage lender lets you borrow more against your home at a preferential rate, specifically because you’re using the money for energy-efficient improvements.
It’s different from a standard further advance and different from remortgaging. It’s a separate, smaller product sitting on top of your main mortgage, priced specifically for green purposes — and your existing deal remains completely untouched.
Eligible improvements typically include:
- Solar panels and battery storage
- Air source or ground source heat pumps
- Loft, cavity wall and solid wall insulation
- Double or triple glazing
- Smart heating controls
- EV charging points
- Boiler upgrades (to electric or heat pump systems)
Both a solar installation and a heat pump installation comfortably qualify under every lender’s criteria.
Which Lenders Offer the Best Rates Right Now?
Here’s every major lender currently offering green additional borrowing as of April 2026, ordered cheapest first. All of these are only available to existing mortgage customers.
| Lender | Rate | Max Borrowing | Max LTV | Green % Required |
|---|---|---|---|---|
| Nationwide Building Society | 0% fixed (2 or 5yr) | £20,000 | 90% | 100% |
| Progressive Building Society | 0% fixed (2yr) | £15,000 | 90% | 100% |
| Co-operative Bank | From 4.10% (2 or 5yr fix) | Varies | 85% | 50%+ |
| Leeds Building Society | From 4.19% (2yr fix) | Varies | 90% | 50%+ |
| Skipton Building Society | From 4.75% (2 or 5yr fix) | £50,000 | 95% | 50%+ |
| Coventry Building Society | Discounted vs standard | £25,000 | — | 50%+ |
| Accord Mortgages | 0.10% below standard range | £40,000+ | 85% | 50%+ |
| Ecology Building Society | Variable discount | Varies | — | 100% |
| Other lenders | Varies | Varies | Varies | Varies |
Rates correct as of April 2026. Always confirm the current offer directly with your lender. Your home may be repossessed if you do not keep up repayments on a mortgage or any other debt secured on it.
Other lenders with green additional borrowing products include Chorley Building Society, Dudley Building Society, Furness Building Society, Hinckley & Rugby Building Society, Leek Building Society, Newbury Building Society and Suffolk Building Society.
The Best Deals in Detail
Nationwide Building Society — 0% Green Additional Borrowing
This is the standout product in the market. Nationwide lets existing mortgage customers borrow between £5,000 and £20,000 at 0% fixed interest for either two or five years — with no product fees whatsoever.
The condition is that 100% of the loan must go towards eligible energy improvements. In March 2026, Nationwide doubled its commitment from 5,000 to 10,000 households after lending around £60 million through the scheme. The average loan has been approximately £13,000 — roughly in line with a typical heat pump installation after the £7,500 BUS grant, or a mid-range solar and battery package.
After the fixed-rate period ends, any outstanding balance moves to Nationwide’s Standard Mortgage Rate (currently 6.49%), so the goal is to repay within the interest-free window. One product per property, and you need at least one monthly payment cleared before applying.
Progressive Building Society — 0% Energy Efficient Additional Borrowing
Progressive matches Nationwide on rate but lends a smaller maximum of £15,000, with a £250 arrangement fee and a two-year fixed term. Important caveat: Progressive only lends on properties in Northern Ireland. If that’s where you are, this is well worth a call.
Co-operative Bank — from 4.10%
For customers who don’t have a Nationwide mortgage, the Co-operative Bank is currently the best mainstream alternative. Their two-year fixed rate is 4.10% at up to 60% LTV, rising to 4.39% at up to 85% LTV. Five-year fixed rates are also available. No product fees, minimum loan of £5,000, and at least 50% of the borrowing must go towards qualifying green works — which means you can combine a heat pump or solar installation with other home improvements in a single loan.
Leeds Building Society — from 4.19%
Leeds launched their green additional borrowing product in November 2025. Residential rates start at 4.19% up to 75% LTV or 4.69% up to 90% LTV, both on two-year fixed terms. No product fee and a free standard valuation is included. Leeds also offers a free Home Energy Saving Tool in partnership with the Energy Saving Trust — worth using before you apply.
Skipton Building Society — from 4.75%
Skipton sits higher on rate but offers the largest maximum loan in this category — up to £50,000 — which suits anyone planning a larger renovation that includes green improvements. Residential products are available up to 95% LTV. At least 50% of the loan must go towards qualifying green improvements, with the remaining 50% available for other home works. No product fees, and Skipton provides eligible members with a free EPC Plus report to help identify the most impactful improvements for your property.
How to Stack Grants and Green Borrowing for Maximum Impact
The real opportunity is combining multiple incentives at once. Both solar panels and heat pumps benefit from 0% VAT on installation (confirmed until March 2027), and heat pumps also attract the £7,500 BUS grant.
Heat pump example
A typical Vaillant aroTHERM Plus installation in the North East comes in at around £14,500 all-in. The BUS grant removes £7,500, leaving £7,000. Borrow that £7,000 at 0% over five years through Nationwide and your monthly repayment is just £116.67 — with zero interest. The same loan at 8% APR on a personal loan would cost around £142 per month and add roughly £1,520 in interest over the term.
Solar panels and battery storage example
Solar doesn’t have a grant equivalent to the BUS scheme, but 0% VAT and green additional borrowing together still make it highly accessible. A typical 4kW solar system with battery storage runs to around £9,000–£12,000 installed. Borrow £10,000 at 0% over five years through Nationwide and your monthly cost is £166.67. A well-sized system in the North East typically saves £600–£900 a year on electricity bills, meaning the monthly saving can comfortably offset the repayment from day one.
How to Apply — Step by Step
- Check your lender. Log in or call your mortgage provider and ask whether they offer a green additional borrowing product.
- Get a written quote. Your installer provides an itemised quote — your lender needs this to confirm the works and amount. At Amp Renewables, we provide finance-ready quotes as standard.
- Submit your application. Apply online or through a mortgage broker. Affordability is assessed on the full new loan amount.
- Book the installation. Once funds are released, your installer completes the work and the savings start.
Most lenders require at least six months of consecutive payments on your existing mortgage, no recent arrears, and a maximum LTV within their green product limits. Allow two to four weeks from application to funds release in straightforward cases.
Is This Right for Me?
It works well if:
- You’re already with one of the lenders listed above
- You have at least 10% equity in your home
- You’ve made at least six months of mortgage payments without issues
- You’re planning solar panels, a heat pump or battery storage and want to spread the cost without paying interest
- You want to combine green works with other home improvements in a single loan
It may not be the right route if:
- Your current lender doesn’t offer a green product
- You’re close to your LTV ceiling
- You’ve missed mortgage payments recently
- You need the money quickly — a mortgage application takes longer than a personal loan
- The amount you need is below the lender’s minimum (typically £3,000–£5,000)
Even if your lender isn’t on this list, it’s worth a quick call. The green mortgage market is growing fast — several new products launched in late 2025 — and your lender may have added something recently.
We Can Help With the Quote
Both solar panels and air source heat pumps are among the most common eligible works across every lender’s scheme, and they can be combined into a single loan where at least 50% goes towards the green measures.
If you’re thinking about either — or both — get in touch with us at Amp Renewables. We’re MCS certified, Heat Geek Approved for heat pump installations, and we provide itemised, written quotations suited to your mortgage lender’s application process. We also handle the £7,500 BUS grant application for heat pumps directly.
Rates and product availability correct as of April 2026. Green mortgage schemes can change or be withdrawn at any time — always verify directly with your lender before making financial decisions. This article is for informational purposes only and does not constitute financial advice.