HeatPumpHeat Pump with Solar Panels: The Ultimate Energy Combo
A heat pump and solar panels together create the most cost-effective, low-carbon heating system available to UK homeowners. Solar generates cheap electricity during the day, and the heat pump uses it to heat your home and water. Here's exactly how the numbers work.
Why They're a Perfect Match
A heat pump's only running cost is electricity. Solar panels generate free electricity from daylight. Combine them, and you're heating your home for almost nothing during the sunniest months.
Even in winter when solar output drops, the panels still contribute. And with a smart tariff or battery storage, you can shift cheap energy to when you need it most.
The Numbers: System Sizing
Typical Combined System
- Heat pump: 8–10kW air source heat pump (suits most 3-bed homes)
- Heat demand: ~12,000 kWh of heat per year
- HP electricity use: ~3,750 kWh/year (at COP 3.2)
- Solar array: 4kW system (10 panels) — generates ~3,400 kWh/year
- Solar self-consumption: 35–45% without battery, 70–80% with battery
Combined Savings Calculation
| Scenario | Annual Electricity Cost | Savings vs Gas Boiler |
|---|---|---|
| Gas boiler (baseline) | £1,100–£1,400/year | — |
| Heat pump only (grid electricity) | £700–£1,100/year | £200–£500 |
| Heat pump + solar (no battery) | £400–£700/year | £600–£900 |
| Heat pump + solar + battery | £200–£450/year | £800–£1,200 |
Based on electricity at 24.5p/kWh (Ofgem cap, Q1 2026) and gas at 6.76p/kWh. Actual savings depend on your tariff, home size, insulation level, and location.
Seasonal Reality Check
The mismatch is important to understand: solar generates most electricity in summer (when you need least heating), and least in winter (when the heat pump works hardest).
- Summer (Apr–Sep): Solar covers 60–70% of HP electricity. Hot water heating is essentially free.
- Winter (Oct–Mar): Solar covers 15–25% of HP electricity. You'll still pay for most heating from the grid.
- Annual average: Solar offsets roughly 35–45% of heat pump running costs without a battery.
Should You Add a Battery?
A home battery (typically 5–10 kWh capacity, costing £3,000–£6,000) stores excess daytime solar for evening and overnight use. This increases self-consumption from around 40% to 70–80%.
The payback on a battery alone is 8–12 years. But when combined with an agile/time-of-use tariff (like Octopus Agile), you can charge the battery at 7p/kWh overnight and use it during expensive peak periods — shortening payback to 5–7 years.
Combined System Costs
| Component | Cost | Grant / VAT Relief | Net Cost |
|---|---|---|---|
| Air source heat pump | £8,000–£15,000 | £7,500 BUS grant | £500–£7,500 |
| 4kW solar array | £6,000–£8,000 | 0% VAT (saves ~£1,200) | £6,000–£8,000 |
| Battery (optional) | £3,000–£6,000 | 0% VAT | £3,000–£6,000 |
| Total (HP + solar) | £14,000–£23,000 | ~£8,700 | £6,500–£15,500 |
Smart Tariff Optimisation
Time-of-use tariffs make this combo even more powerful. With Octopus Agile or similar, you can:
- Run the heat pump during cheap overnight periods (often 7–10p/kWh)
- Store solar in the battery during the day
- Use battery power during expensive peak periods (30–50p/kWh)
- Export excess solar at 15p/kWh via the Smart Export Guarantee
What to Install First
If your boiler has failed or is near end of life, install the heat pump first — it's the bigger quality-of-life improvement. If your boiler still works, consider installing solar first: it's cheaper, starts saving money immediately, and helps you understand your electricity consumption before sizing a heat pump.
Ideally, plan both together. Your installer can size the solar array to match the heat pump's electricity demand, and the insulation level of your home will determine how much heat (and therefore electricity) you actually need.
Related Guides
Frequently Asked Questions
Can solar panels power a heat pump?
Yes. A typical 4kW solar array generates around 3,400 kWh per year. A heat pump heating a well-insulated home uses roughly 3,750 kWh of electricity annually. Solar can cover 60–70% of that during summer months, significantly reducing your electricity bill.
Should I install solar panels or a heat pump first?
Install the heat pump first if you are replacing a broken boiler. Otherwise, solar panels are cheaper and start saving money immediately. Ideally, plan both together so the solar array is sized to match the heat pump's electricity demand.
How much can I save with solar and a heat pump combined?
A combined system can save £1,200–£1,800 per year compared to a gas boiler with grid electricity. The exact figure depends on your electricity tariff, solar generation, and how much you use during daylight hours.
Do I need a battery with solar panels and a heat pump?
A battery helps but is not essential. Without a battery, you export excess solar during the day and buy electricity at night. A battery (£3,000–£6,000) lets you store daytime solar to run the heat pump in the evening, increasing self-consumption from around 40% to 70–80%.
Can I get grants for both solar and a heat pump?
The £7,500 BUS grant covers the heat pump. Solar panels have no direct UK government grant, but they are VAT-free (0% VAT) until March 2027, saving roughly £1,200–£1,600 on a typical system.