Solar PV now costs roughly four times more to install than solar thermal but can earn over three times more in annual savings and payments
If you are weighing up solar PV and solar thermal for your home, the headline numbers point clearly in one direction. A typical 4 kWp solar photovoltaic (PV) system costs between £5,500 and £7,500 to install in 2026, while a solar thermal system with two panels and a 300-litre cylinder comes in at £4,000 to £5,500 (Energy Saving Trust, 2026; Energy Saving Trust, 2026).
Solar PV is better for most homes, saving £600-£1,100 per year versus solar thermal's £150-£300. PV costs £5,500-£7,500 to install, while thermal costs £4,000-£5,500, but PV's long-term returns far outweigh the higher upfront cost.
- Solar PV costs £5,500-£7,500 for a 4 kWp system in 2026.
- Solar thermal costs £4,000-£5,500 with two panels and a cylinder.
- PV saves £600-£1,100 per year on bills plus SEG payments.
- Solar thermal saves just £150-£300 per year on water heating.
- Choose PV for better long-term returns unless roof space is limited.
- Solar PV now costs roughly four times more to install than solar thermal but can earn over three times more in annual savings and payments
- The core difference between solar PV and solar thermal technology
- Which system qualifies for the 2026 home energy grants
- Quick numbers key performance and cost comparisons
- The direct answer solar PV is better for most UK homes in 2026
- Eligibility and installer verification for both systems
- How to confirm your home's eligibility for a specific grant before buying
The better investment for most households is solar PV. Annual savings from a PV system, combining electricity bill offset with Smart Export Guarantee (SEG) payments, range from £600 to £1,100, whereas solar thermal saves just £150 to £300 per year by displacing gas or oil for water heating (Energy Saving Trust, 2026; Ofgem, 2026).
This article sets out the practical differences between the two technologies, the grants available in 2026, and the key numbers that should drive your decision. Which system suits your home depends on your energy priorities, your roof space, and whether you qualify for any government support.
The core difference between solar PV and solar thermal technology
Solar PV (photovoltaic) panels convert sunlight directly into electricity that can power lights, appliances, and anything else in your home. Solar thermal panels capture the sun’s heat to warm water stored in a cylinder, which is then used for taps, showers, and baths. They are fundamentally different technologies serving different purposes (DESNZ, 2026).
Solar PV generates electricity year-round, even on overcast days, though output peaks in summer. A typical 4 kWp system produces around 3,400 to 4,200 kilowatt-hours (kWh) of electricity per year (MCS, 2026). Solar thermal is most effective in summer months when the sun is stronger, and typically delivers 1,500 to 2,500 kWh of heat per year for hot water only (MCS, 2026).
Solar PV requires an inverter to convert the direct current (DC) electricity into alternating current (AC) for household use, and you can pair it with a battery to store excess power for evening use. Solar thermal needs a twin-coil cylinder or a thermal store to hold the heated water, and it works best alongside a conventional boiler or immersion heater for backup when the sun is weak.
Which system qualifies for the 2026 home energy grants
The grant landscape in 2026 strongly favours solar PV, but only in specific circumstances. The Great British Insulation Scheme (GBIS) does not cover solar thermal or solar PV directly. The ECO4 scheme, which runs until March 2026, can fund solar PV only when it is installed alongside a low-carbon heating system such as a heat pump, and only for low-income households in properties with an EPC rating of E, F, or G (DESNZ, 2026).
The Boiler Upgrade Scheme (BUS) covers heat pumps but does not cover standalone solar thermal. Solar PV is eligible under BUS only if it is installed alongside a heat pump as part of the same application, and the overall system must meet the scheme’s requirements (Ofgem, 2026).
The Smart Export Guarantee (SEG) is available for solar PV installations up to 5 MW, paying you for electricity you export to the grid. Solar thermal has no equivalent export payment scheme, meaning you cannot earn any income from the heat it produces (Ofgem, 2026).
Quick numbers key performance and cost comparisons
| Metric | Solar PV (4 kWp system) | Solar Thermal (2-panel system) |
|---|---|---|
| Typical installed cost (2026) | £5,500–£7,500 | £4,000–£5,500 |
| Annual electricity/hot water output | 3,400–4,200 kWh (electricity) | 1,500–2,500 kWh (heat) |
| Annual savings + SEG payments | £600–£1,100 | £150–£300 |
| Payback period (no grant) | 8–14 years | 15–25 years |
| Lifespan | 25–30 years | 20–25 years |
| Space required | 20–30 m² (roof area) | 4–6 m² (roof area) |
Sources: Energy Saving Trust, 2026; Energy Saving Trust, 2026; MCS, 2026.
The direct answer solar PV is better for most UK homes in 2026
For the vast majority of UK households, solar PV is the better investment. It provides higher annual savings, a shorter payback period, and eligibility for the Smart Export Guarantee, which can turn your roof into a small income stream. Solar PV also gives you flexibility to add a battery later, store cheap off-peak electricity, and reduce your reliance on the grid (DESNZ, 2026).
Solar thermal remains viable only in a narrow set of circumstances. If you have very high hot water demand, such as a household of four or more people using a lot of showers and baths, and you have no space for more PV panels, solar thermal can still cut your gas or oil bill. But it cannot offset electricity bills, earn export income, or power your appliances, and its payback period is much longer (Energy Saving Trust, 2026).
guide to solar panel battery storage
Eligibility and installer verification for both systems
For solar PV, your installer must be MCS-certified to qualify for SEG payments and any grant. You can check current certification on the MCS Register at mcsregister.co.uk (MCS, 2026). For solar thermal, the installer must also be MCS-certified and the system must meet MIS 3001 standards. If the solar thermal system connects to a gas boiler or cylinder, the installer must be registered with the Gas Safe Register (Gas Safe Register, 2026).
For either system, check TrustMark for broader consumer protection covering workmanship and warranties (TrustMark, 2026). If your installation involves any roof windows or glazing changes, you may also need a FENSA-certified installer (FENSA, 2026).
How to confirm your home’s eligibility for a specific grant before buying
Before you commit to any system, use the Energy Saving Trust’s online “Home Energy Grant Checker” tool. Enter your property details, including your EPC rating, household income, and heating type, and it will tell you which grants you qualify for (Energy Saving Trust, 2026).
For ECO4, your property must have an EPC rating of E, F, or G, and you must be on a qualifying benefit. You can check your EPC rating at gov.uk/find-energy-certificate (GOV.UK, 2026). For the Boiler Upgrade Scheme, you must own your home and have a valid EPC with no outstanding cavity-wall or loft-insulation recommendations. Check full eligibility criteria at ofgem.gov.uk (Ofgem, 2026).
how to read your EPC certificate
Frequently Asked Questions
Solar PV is better for most homes, saving £600-£1,100 per year compared to thermal's £150-£300, according to the Energy Saving Trust (2026). Choose thermal only if you have limited roof space and high hot water demand.
A typical 4 kWp solar PV system costs between £5,500 and £7,500 to install in 2026, based on Energy Saving Trust figures.
Solar thermal with two panels and a 300-litre cylinder costs £4,000 to £5,500 in 2026, per the Energy Saving Trust.
Yes, solar PV can heat water via an immersion diverter or heat pump, but it is less efficient than solar thermal for that purpose. Solar thermal directly heats water but only for taps and showers, not space heating.
The Boiler Upgrade Scheme (BUS) offers £7,500 off an air source heat pump, which can pair with solar PV. Solar thermal is not covered by BUS, but ECO4 may help low-income households. Check Ofgem and GOV.UK for eligibility.
