Question 1

How long do solar panels take to pay back in the UK?

Accepted Answer

A typical 4 kWp system installed for around £7,000–£9,000 pays back in 10–14 years, depending on your electricity usage, self-consumption rate, and the SEG rate your supplier offers. Higher electricity prices and better self-consumption shorten the payback period.

Question 2

How much does a 4 kWp solar panel system cost in the UK?

Accepted Answer

A 4 kWp solar panel system typically costs £7,000–£9,000 installed in 2026. Solar panels benefit from 0% VAT in the UK since April 2022. Larger systems of 5–6 kWp cost £9,000–£12,000. Costs vary by region, installer and panel brand.

Question 3

How much electricity does a solar panel system generate?

Accepted Answer

A 1 kWp system generates around 850–950 kWh per year in the UK, depending on location and roof orientation. A south-facing 4 kWp system generates roughly 3,400–3,800 kWh per year. The calculator uses a UK average of 900 kWh per kWp.

Question 4

What is the Smart Export Guarantee (SEG)?

Accepted Answer

The Smart Export Guarantee is a UK government scheme that requires licensed electricity suppliers with 150,000 or more customers to offer tariffs to small-scale generators. You get paid for every unit of electricity you export to the grid. Rates vary by supplier — typical fixed rates range from 5p to 20p per kWh, with some variable rates higher. There is no government-set minimum beyond requiring the rate to be above zero.

Question 5

Does adding a battery improve solar ROI?

Accepted Answer

A battery storage system lets you self-consume more of your solar generation (typically 70–90% instead of 40–50%), which is more valuable than exporting at SEG rates. However, batteries cost £2,000–£6,000 and have a lifespan of 10–15 years, so the ROI calculation is more complex. Use our self-consumption slider to model different battery scenarios.

Question 6

Do I need to own my home to benefit from solar panels?

Accepted Answer

You generally need to own the property, or at minimum have a very long lease (typically 25+ years remaining) and explicit landlord permission. Solar panels are a permanent fixture that cannot easily be moved. Renters cannot install panels without landlord consent. If you own a flat in a shared building, you would also need freeholder or management company permission, and the available roof space may be shared with other leaseholders.

Question 7

What maintenance do solar panels require?

Accepted Answer

Solar panels are largely maintenance-free. Rain washes most dirt away, but an annual or biannual clean with a soft brush or squeegee on a single-storey roof is beneficial in dusty or bird-affected areas  -  dirty panels can lose 5–10% of output. Inverters (which convert DC solar power to AC mains) typically last 10–15 years and cost £500–£1,500 to replace. The panels themselves usually come with a 25-year performance warranty and require no routine servicing.

Solar Panel ROI Calculator UK 2026