A 4kW solar panel system saves £600-£900 per year on electricity bills and costs £5,000-£7,500 installed; for a 4.5 kWp system the Energy Saving Trust estimates £740-£930 a year including export payments (July 2026 prices). An air source heat pump saves £200-£400 per year compared to a gas boiler and costs £10,000-£16,000 before the £7,500 Boiler Upgrade Scheme grant (Ofgem). Solar panels pay back in 6-9 years. Heat pumps pay back in 10-15 years after the grant. If you can only afford one, install solar panels first. If budget allows, install both: solar powering a heat pump can cut total energy costs by 70-80%.
How do solar panels and heat pumps compare in 2026?
| Feature | Solar Panels (4kW) | Air Source Heat Pump |
|---|---|---|
| Installed cost | £5,000-£7,500 | £10,000-£16,000 |
| Government grant | 0% VAT (until March 2027) | £7,500 BUS grant |
| Net cost after grant | £5,000-£7,500 | £2,500-£8,500 |
| Annual savings | £600-£900 | £200-£400 vs gas boiler |
| Payback period | 6-9 years | 10-15 years (after grant) |
| Lifespan | 25-30 years | 20-25 years |
| Lifetime savings | £15,000-£25,000 | £4,000-£10,000 vs gas |
| Maintenance cost | £0-£100/year | £100-£200/year |
| Planning permission | Usually not needed | Usually not needed |
| Works with existing system | Yes | Replaces boiler |
Solar savings assume 35-40% self-consumption without battery, 26.32p/kWh electricity (the October to December 2026 price cap), plus Smart Export Guarantee income. Heat pump savings versus a gas boiler at 7.97p/kWh gas and 26.32p/kWh electricity with COP of 3.0-3.5. Sources: Energy Saving Trust, Ofgem.
Which saves more money: solar panels or a heat pump?
Solar panels deliver higher annual savings and faster payback than a heat pump for most UK homeowners in 2026. The numbers are straightforward: a 4kW solar system generates 3,400-3,700 kWh per year. At the current price cap rate of 26.32p/kWh, self-consuming 35-40% of that generation saves £310-£390 directly on your electricity bill. The remainder exported under the Smart Export Guarantee earns another £150-£250 per year, with the best SEG tariffs now paying 12-15p/kWh (Ofgem).
Adding a battery (£2,500-£5,000 for 5-10kWh) increases self-consumption to 60-80%, pushing total annual savings to £700-£1,000.
Heat pump savings are more variable and depend heavily on what you are replacing:
- Replacing an old gas boiler (60-70% efficient): Save £300-£400/year
- Replacing a modern gas boiler (90% efficient): Save £100-£250/year
- Replacing oil heating: Save £400-£600/year
- Replacing direct electric heating: Save £500-£800/year
The heat pump savings calculation is sensitive to the gas-to-electricity price ratio. With gas at 7.97p/kWh and electricity at 26.32p/kWh, a heat pump with a COP (Coefficient of Performance) of 3.0 effectively heats at 8.77p per kWh of heat, barely cheaper than gas at 8.86p from a 90% efficient boiler. If electricity prices fall relative to gas, heat pumps become significantly more attractive.
What does each one actually cost after grants?
The Boiler Upgrade Scheme grant of £7,500 dramatically closes the cost gap, making heat pumps competitive with solar on upfront investment. Here is the real-world cost comparison for a typical 3-bed semi-detached home:
Solar panels
- 4kW system: £5,000-£7,500 installed
- VAT: 0% (until March 2027)
- Battery (optional, 5kWh): £2,500-£4,000
- Total without battery: £5,000-£7,500
- Total with battery: £7,500-£11,500
Air source heat pump
- Installation: £10,000-£16,000
- BUS grant: -£7,500
- Potential radiator upgrades: £0-£3,000
- Total after grant (no radiator work): £2,500-£8,500
- Total after grant (with radiator upgrades): £5,500-£11,500
Homes heated by oil or LPG with no mains gas connection can claim an enhanced grant of £9,000 from July 2026 to March 2027 (GOV.UK). The heat pump must be installed by an MCS-certified installer; since 28 April 2026 you don’t need an EPC.
Comparing prices from multiple installers?
Should you install solar panels or a heat pump first?
Install solar panels first if you are choosing one at a time. Solar panels are non-disruptive, work with your existing heating system, and start generating returns from day one. A heat pump is a larger project requiring potential radiator upgrades, hot water cylinder installation, and changes to your heating controls.
The strategic case for solar first:
1. Faster payback funds the heat pump later: 6-9 years vs 10-15 years
2. No disruption to your current heating: solar bolts onto your roof without changing anything inside
3. Solar prepares the ground for a heat pump: once installed, solar electricity can power the heat pump, making the combined system far cheaper to run
4. Electricity prices matter most for heat pump economics: solar reduces your effective electricity cost, improving the heat pump business case when you add it later
The exception is if your gas boiler is about to fail. Replacing a broken boiler is urgent; solar panels can wait. In that scenario, claim the £7,500 BUS grant for a heat pump now and add solar when budget allows.
What happens when you install both?
Combining solar panels with a heat pump can reduce total home energy costs by 70-80%, approaching near-zero energy bills in summer and drastically lower bills in winter. This is the optimal long-term setup for UK homeowners.
A typical combined system for a 3-bed home:
- 5kW solar array + 10kWh battery + air source heat pump
- Total cost: £18,000-£26,000
- After BUS grant: £10,500-£18,500
- Annual savings: £1,200-£1,800 compared to gas boiler + grid electricity
- Payback: 8-12 years
- 25-year savings: £30,000-£45,000
The solar panels generate free electricity during the day. The battery stores excess for evening use. The heat pump uses this free or stored electricity to heat the home and hot water at a COP of 3.0-3.5, effectively tripling the value of every kWh of solar generation used for heating.
In summer, solar generation typically exceeds total household demand including hot water heating via the heat pump. In winter, solar covers 20-30% of the heat pump’s electricity demand, with the grid supplying the rest.
FAQ
Can solar panels power a heat pump directly?
Not directly in real time, because a heat pump draws 2-4kW continuously while solar output fluctuates. However, a battery storage system bridges the gap. Without a battery, solar still offsets the grid electricity your heat pump consumes, reducing your bills. The system works through your meter, not through a direct physical connection.
Do I need planning permission for solar panels or a heat pump?
Solar panels on a pitched roof fall under permitted development for most houses and do not need planning permission. In England, an air source heat pump on a house also has permitted development rights provided the outdoor unit is no bigger than 1.5 cubic metres and its sound is no more than 37 dB at 1 metre from the window or door of a neighbour’s habitable room (GOV.UK). Since 29 May 2025 it no longer has to be one metre from the property boundary, and the 37 dB limit under MCS 020 a) replaced the old 42dB calculation. Wales, Scotland and Northern Ireland have their own rules. Listed buildings and conservation areas may have additional restrictions.
What is the Boiler Upgrade Scheme and how do I apply?
The Boiler Upgrade Scheme provides a £7,500 grant towards air source, ground source or water source heat pumps in England and Wales. Your MCS-certified installer applies on your behalf and the grant is deducted directly from your invoice. You no longer need an EPC (since 28 April 2026), but you must be replacing fossil fuel or electric heating (storage heaters and electric boilers count). The scheme runs until 31 March 2030 (Ofgem).
Are heat pump running costs really cheaper than gas?
At current UK energy prices (gas 7.97p/kWh, electricity 26.32p/kWh), a heat pump with a COP of 3.0 delivers heat at around 8.77p per kWh. A 90% efficient gas boiler delivers heat at 8.86p per kWh. The margin is tight. Heat pumps become clearly cheaper when powered partly by solar panels, when electricity tariffs drop (e.g., Octopus Agile off-peak rates), or if gas prices rise.
How long do solar panels and heat pumps last?
Solar panels are warranted for 25 years and typically produce 80%+ of original output at that point, often lasting 30-35 years. The inverter needs replacing once at 10-15 years (£500-£1,000). Air source heat pumps last 20-25 years with annual servicing. Both outlast a gas boiler (12-15 year average lifespan).
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