Solar Panel Finance UK: Payment Plans & Loans

1. 0% Interest Finance (from installer): - APR: 0% - Term: 3–5 years - Monthly payment (4kW system at £6,750): £113–£188/month - Total repayable: £6,750 (same as cash price) - Pros: No interest — you pay exactly the cash price - Cons: Shorter terms mean higher monthly payments; not all installers offer this - Availability: Some larger installers (check during quoting)

2. Personal Loan (bank/building society): - APR: 3–7% (depends on credit score and lender) - Term: 3–10 years - Monthly payment (4kW at £6,750, 5% APR, 7 years): £95/month - Total repayable: £7,985 (£1,235 interest over 7 years) - Pros: Widely available, competitive rates, flexible terms - Cons: Interest adds to total cost; requires good credit score for best rates

3. Green Home Improvement Loan: - APR: 2–5% (subsidised by some lenders) - Term: 5–15 years - Availability: Limited — some building societies and specialist lenders - Pros: Lower rates than standard personal loans; longer terms available - Cons: Limited availability; may require property valuation

4. 0% Purchase Credit Card: - APR: 0% for 12–24 months, then 20–30% - Best for: Small systems or deposits only - Risk: If not paid off within the 0% period, interest is very high - Only suitable if you can definitely repay within the interest-free period

Source: UK finance market data; installer finance terms.

Here is the key insight that makes solar finance attractive:

4kW system on 0% finance over 5 years: - Monthly payment: £113 - Monthly electricity saving: £48–£68 - Monthly net cost: £45–£65 - After 5 years: payments stop, £48–£68/month savings continue for 20+ years

4kW system on personal loan (5% APR, 10 years): - Monthly payment: £72 - Monthly electricity saving: £48–£68 - Monthly net cost: £4–£24 - Nearly cash-flow neutral from month one - After 10 years: payments stop, savings continue for 15+ years

The point: With a 10-year loan at 5%, your monthly payment (£72) is almost identical to your monthly saving (£48–£68). You are essentially paying for the system with the money it saves you.

After the loan is paid off, you keep saving £48–£68 per month — that is £580–£820 per year of pure profit for the remaining 15+ years.

Source: Loan calculation at 5% APR; savings based on Ofgem Q1 2026.

Paying cash is always cheapest — you avoid all interest costs. But finance can still be a smart choice:

Choose cash if: - You have the funds available without depleting your emergency savings - You prefer zero debt - You want the simplest arrangement

Choose finance if: - You do not have £5,000–£8,000 in savings - Your savings earn less interest than the loan costs (often the case) - You want to start saving on electricity immediately without waiting to save up - You find a 0% interest deal (no cost difference vs cash) - You prefer to keep cash liquid for other needs

The maths of waiting to save up: - Saving £200/month takes 2.5–3.3 years to reach £6,000–£8,000 - During those years, you miss £1,450–£2,700 in solar savings - A 5% loan on £6,750 over 7 years costs £1,235 in interest - Borrowing now saves more (£1,450–£2,700) than it costs (£1,235)

Finance is financially rational when the missed savings from waiting exceed the interest paid.

Source: Savings calculation with Ofgem Q1 2026 rates.