Solar finance cost calculator: monthly payment by term and APR
Solar finance cost calculator: monthly payment by term and APR
Most finance pages quote an APR and a monthly figure but never show what the term actually costs you in pounds. The longer you borrow over, the lower the monthly payment but the more interest you pay overall. The tables below show representative repayments for three typical system sizes across four terms (3, 5, 7 and 10 years) and four APR bands. These are illustrative figures rounded to the nearest pound, calculated on a standard amortising loan; your actual rate depends on the lender and your circumstances, and finance is subject to status.
£7,500 system (panels only, roughly 4–5kWp)
| Term | 0% APR
monthly / total | 7.9% APR
monthly / interest | 9.9% APR
monthly / interest | 11.9% APR
monthly / interest |
|---|
| 36 months | £208 / £7,500 | £235 / £948 | £242 / £1,199 | £249 / £1,455 |
| 60 months | £125 / £7,500 | £152 / £1,603 | £159 / £2,039 | £166 / £2,487 |
| 84 months | £89 / £7,500 | £117 / £2,288 | £124 / £2,926 | £132 / £3,588 |
| 120 months | £62 / £7,500 | £91 / £3,372 | £99 / £4,344 | £107 / £5,360 |
£11,500 system (panels plus battery storage)
| Term | 0% APR
monthly / total | 7.9% APR
monthly / interest | 9.9% APR
monthly / interest | 11.9% APR
monthly / interest |
|---|
| 36 months | £319 / £11,500 | £360 / £1,454 | £371 / £1,839 | £381 / £2,231 |
| 60 months | £192 / £11,500 | £233 / £2,458 | £244 / £3,127 | £255 / £3,814 |
| 84 months | £137 / £11,500 | £179 / £3,508 | £190 / £4,487 | £202 / £5,501 |
| 120 months | £96 / £11,500 | £139 / £5,170 | £151 / £6,660 | £164 / £8,219 |
£18,000 system (larger home, panels plus larger battery)
| Term | 0% APR
monthly / total | 7.9% APR
monthly / interest | 9.9% APR
monthly / interest | 11.9% APR
monthly / interest |
|---|
| 36 months | £500 / £18,000 | £563 / £2,276 | £580 / £2,879 | £597 / £3,492 |
| 60 months | £300 / £18,000 | £364 / £3,847 | £382 / £4,894 | £399 / £5,969 |
| 84 months | £214 / £18,000 | £280 / £5,491 | £298 / £7,023 | £317 / £8,610 |
| 120 months | £150 / £18,000 | £217 / £8,093 | £237 / £10,425 | £257 / £12,865 |
The honest takeaway: on a £11,500 system, stretching from 5 years to 10 years at 9.9% drops the monthly payment from £244 to £151, but more than doubles the interest from £3,127 to £6,660. A 0% deal over a short term is always the cheapest way to borrow — the trade-off is a higher monthly payment. Run the numbers for your own quote before you sign; finance is subject to status and your APR may differ.
Types of solar finance compared
Types of solar finance compared
"Solar finance" covers several genuinely different products, and the right one depends on whether you want the lowest headline rate, the lowest total cost, or to avoid touching your mortgage. Here is how the main routes compare.
| Finance type | How it works | Best for | Watch out for |
|---|
| Installer 0% APR finance | Interest-free instalment credit arranged by the installer through an FCA-regulated lender, usually over 12–60 months. | Spreading the cost with no interest if you can manage the monthly payment. | Shorter terms and higher monthly payments than interest-bearing loans; check the cash price is the same as a non-finance quote. |
| Personal / green loan | An unsecured loan from your own bank or a green-loan provider, paid directly to you, terms typically up to 7–10 years. | Flexibility and keeping the deal separate from your installer; often allows overpayments. | Interest applies; rate depends on your credit score; total interest adds up over longer terms. |
| Green mortgage / further advance | Borrowing against your home, sometimes at a preferential "green" rate or with an interest-free portion for energy-efficiency works. | Lowest rates and largest sums; spreading cost over the mortgage term. | It is secured on your home; spreading over 25 years can mean far more interest unless you overpay. |
| Government loan (from 2027) | Government-backed 0% or low-interest loans under the planned Consumer Loan Scheme / Warm Homes Plan. | Low-cost borrowing once it launches; see the 2027 section below. | Not yet available; eligibility and terms are still to be confirmed. |
| Subscription / lease / PPA | A third party owns the panels on your roof; you pay a monthly fee or buy the power they generate. | Avoiding any upfront cost — but rarely the best value. | You do not own the system, may not get the export income, and a roof lease can complicate selling or remortgaging your home. We do not recommend these for most homeowners. |
0% routes worth knowing: Nationwide and green mortgages
If you want a true 0% deal beyond installer instalment finance, the most widely available route is a lender's interest-free green borrowing offer. At the time of writing, Nationwide offers eligible mortgage members an additional interest-free green borrowing facility of between £5,000 and £20,000 over 2 or 5 years with no product fee, for qualifying energy-efficiency improvements including solar panels and battery storage. Other lenders, including the Co-operative Bank and Coventry Building Society, offer green mortgage products at preferential rates. These are arranged directly with the lender, not through us — always confirm current terms and eligibility on the lender's own website, as offers change.
Secured vs unsecured: the difference that matters
Installer instalment finance and personal/green loans are normally unsecured — they are not tied to your property, so your home is not at risk if you fall behind (though missed payments still affect your credit file). A green mortgage, further advance or remortgage is secured on your home, which is why the rates are lower but the consequences of non-payment are more serious: your home could be repossessed. Borrowing more on your mortgage also stretches the cost over a long term, so unless you overpay, a "cheap" rate can cost more in total interest than a shorter unsecured loan. Speak to a qualified mortgage adviser before securing solar costs against your property.
A note on regulation
Midland Solar is a credit broker, not a lender. We are authorised and regulated by the Financial Conduct Authority. We work with a panel of FCA-regulated finance partners and may receive a commission for introductions. Finance is subject to status, affordability checks and minimum loan amounts set by the lender; rates quoted are representative and your personal rate may differ.
The 5 things to check before signing any solar finance deal
The 5 things to check before signing any solar finance deal
Solar finance is a Your Money or Your Life decision — you are taking on a credit agreement that can run for a decade. A reputable installer will be relaxed about you checking the detail. Before you sign anything, confirm these five points.
- The broker and lender are FCA-regulated. Anyone arranging credit in the UK must be authorised by the Financial Conduct Authority. Ask for the firm's FCA registration and check it on the FCA Register at register.fca.org.uk. If a salesperson is vague about who regulates them, walk away.
- It is not a roof lease, rent-a-roof or PPA dressed up as finance. With genuine finance you own the system outright once it is paid off, keep the Smart Export Guarantee income and can sell your home freely. A lease or power purchase agreement means a third party owns the panels — that can block a sale or remortgage. Make sure the contract clearly states you own the equipment.
- There is no early-repayment penalty. Check whether you can settle the balance early or make overpayments without a fee. Most regulated instalment and personal loans allow this; some agreements charge an early-settlement fee. If you might pay off the export income or a future windfall against the loan, this matters.
- The rate is fixed, not variable. A fixed APR means your monthly payment never changes for the life of the agreement. A variable rate can rise. For a multi-year solar loan, a fixed rate gives you certainty over your total cost.
- The total amount repayable is written on the agreement. Before you sign, the pre-contract information must state the cash price, the APR, the monthly payment, the number of payments and the total amount payable. If "0% finance" comes with a higher system price than the cash quote, the interest has simply been built into the headline — always compare the cash price with and without finance.
If a deal cannot pass all five checks, it is not the deal for you. We are happy to put any of our finance options in front of these tests.
More solar finance questions answered
More solar finance questions answered
Is 0% solar finance really free, or does it inflate the system price?
Genuine 0% APR finance means you repay exactly the cash price with no interest added — the lender, not you, absorbs the cost. The honest check is simple: ask for the cash price and the finance price side by side. If they are the same, the 0% is real. If the financed price is higher, the interest has been built into the headline. We quote the same cash price whether or not you take finance, so you can compare freely.
Do I need a deposit to finance solar panels?
It depends on the product. Many instalment and personal loan options can finance the full amount with no deposit, while some agreements ask for a deposit (often 10%) to reduce the amount borrowed and the monthly payment. A deposit lowers your total interest on an interest-bearing loan. We will set out the deposit options for your specific quote; all finance is subject to status and lender affordability checks.
Can I make overpayments or settle the loan early?
Most FCA-regulated instalment and personal loans let you overpay or settle early, which reduces the interest you pay on an interest-bearing agreement. Some agreements apply an early-settlement charge, so always confirm this before signing. Many homeowners use their Smart Export Guarantee income and energy bill savings to overpay and clear the balance sooner.
Is there a minimum loan amount for solar finance?
Yes — most lenders set a minimum, commonly around £1,000 to £3,000, and a maximum that depends on affordability. As most domestic solar-and-battery systems fall between roughly £7,000 and £18,000, the minimum is rarely an issue. The exact limits depend on the lender; we will confirm them for the option that suits you.
Will solar finance affect my mortgage or ability to remortgage?
An unsecured solar loan is not tied to your property, so it does not put your home at risk, but like any credit it appears on your credit file and is counted in affordability when you apply for or renew a mortgage. A green mortgage or further advance is secured on your home, which means lower rates but more serious consequences if you cannot pay. Crucially, a lease or PPA — where someone else owns the panels — can complicate a sale or remortgage, which is why we recommend owning your system outright.
What government solar finance is coming in 2027?
The government has set out plans for a Consumer Loan Scheme as part of the Warm Homes Plan, backed by around £1.7 billion, to provide 0% or low-interest loans for home energy improvements including solar panels, with a planned launch in April 2027. Full eligibility and terms are still to be confirmed. Separately, domestic solar and battery installations remain 0% VAT-rated until 31 March 2027 (then 5%), so installing before that date avoids VAT on the equipment. We will update this page as scheme details are published.
Finance availability, rates and third-party scheme details are correct to the best of our knowledge at the time of writing and may change. Midland Solar is a credit broker, not a lender, and is authorised and regulated by the Financial Conduct Authority. Finance is subject to status.