Resources / Heat pumps
Heat Pump, Solar and Battery Combined
Three technologies, three jobs. They stack well when each is sized for the building — not when they are sold as a single “energy independence” bundle.
Quick Answer
Heat pump delivers efficient heat. Solar PV cuts daytime imported electricity. Battery shifts energy in time. Winter heat demand peaks when solar is weakest — a battery helps shoulder seasons more than it “runs the heat pump all January.”
Design the heat pump from heat loss and emitters first. Size solar for the roof and residual electricity use. Add storage only when occupancy and tariffs justify the capital. BUS support applies to the heat pump (£7,500, or £9,000 for many oil/LPG off-gas homes) — not to the whole stack.
View printable checklist Planning aid — not a quote
Give each technology a job
| Technology | Primary job | Does not do |
|---|---|---|
| Heat pump | Space heat and hot water efficiently from electricity | Create free electricity; erase a leaky building |
| Solar PV | Generate daytime electricity on site | Heat the house in midwinter by itself |
| Battery | Store surplus or cheap units for later use | Increase annual solar generation |
Bundles that skip heat loss and emitter design are sales packs. The stack only performs if the heating system is competent on its own terms.
The winter gap (be honest)
In Devon and Cornwall, winter days are short and heat demand is high. Solar output is lowest when the heat pump works hardest. A typical domestic battery (often in the ~5–10 kWh class) cannot cover weeks of heating load.
What the stack does well:
- •Cut imported kWh in spring, summer and autumn
- •Raise self-use of PV when you are out during the day
- •Shift some evening heat-pump and household load off peak tariffs
- •Reduce annual electricity cost even if January still needs the grid
“Off-grid all winter from solar and a wall battery” is marketing, not engineering for a normal heated home.
Self-use is the economic hinge
Exported units usually earn less than the price of imported units. Raising the share of PV you use on site — live or via battery — is what improves payback. A heat pump adds winter electricity demand (when PV is weak) and can also absorb surplus on brighter cold days if controls allow.
Daytime occupancy, EV charging and hot water timing all change the picture. See solar payback and is a battery worth it.
Controls and tariffs
Without a simple strategy you can export solar at noon and import at peak while the battery sits idle or the heat pump ignores surplus. Useful ingredients:
- •A tariff that rewards flexibility (heat-pump or time-of-use products)
- •Hot water and heating schedules that can lean into cheap or solar-rich periods where comfort allows
- •Battery set up for self-use first, not only backup theatre
- •Installer commissioning across PV, battery and heat pump — not three isolated apps
From our running-cost work, a well-matched electricity tariff alone is often worth in the region of £150–£300/year versus a poor default rate — before solar is even counted.
Sequencing: what to decide first
- Fabric and heat loss — reduce the load the heat pump must meet.
- Heat pump and emitters — size and design for comfort and SCOP.
- Solar — size to residual electricity use and roof reality.
- Battery — only if daytime export and evening import justify it.
Sometimes scaffold or a failed boiler forces a different order. That is fine — just re-size assumptions when the missing piece arrives. More: solar before or after a heat pump.
Cost realism
A full stack is major capital. The Boiler Upgrade Scheme supports the heat pump only — not the solar array or battery. Planning bands below are indicative for Devon and Cornwall domestic work; surveys and quotes always win.
| Element | Indicative installed band | Notes |
|---|---|---|
| Air source heat pump (full system) | Often ~£12,000 – £18,000+ before grant | Cylinder, controls, electrics, commissioning — not the outdoor unit alone |
| BUS grant | − £7,500 or − £9,000 | £7,500 standard; £9,000 oil/LPG with no mains gas (confirm GOV.UK window) |
| Net heat pump (typical 3-bed planning) | Often ~£4,000 – £7,500 after £7,500 BUS | Can land lower on simple jobs; higher with full radiator/pipework upgrades |
| Solar PV (domestic roof) | Wide range — often mid £000s to low £10,000s | Depends on kW, scaffold, electrics, roof complexity |
| Battery storage | Often several £000 extra | Us and brand dependent; lengthens simple payback vs solar-only |
| Full stack (HP + PV + battery) | Substantial five-figure total after grant | Phasing is normal; one programme can save scaffold/disruption |
Bands for orientation only. Heat pump net figures align with our 2026 costs guide (typical 3-bed after grant). Solar/battery vary too much for a single headline number without a roof survey.
Grant reminder: £7,500 in most eligible cases; £9,000 where replacing oil or LPG and the property has no mains gas connection (time-limited uplift — confirm live GOV.UK rules). Paid to the MCS installer, not claimed as cash by the householder.
Running costs are separate from capital: a good heat pump on a typical 3-bed often sits around £800–£1,400/year for heat and hot water in our published bands, with tariff and fabric moving the result. Solar then chips away at the electricity import side of that bill.
Detail: heat pump costs 2026 · running costs · grants.
When the full stack fits — and when it does not
- Decent roof resource and electrical capacity
- Heat pump correctly sized and emitted
- Daytime export with evening demand (or EV)
- Budget and appetite for a multi-year energy plan
- Poor roof / heavy shade
- Heating design still unresolved
- Expecting winter off-grid comfort from a small battery
- Cash needed for fabric first
Honest bottom line
Heat pump + solar + battery is a strong direction of travel for many South West homes — when the heat pump is designed properly, the roof is a real solar candidate, and storage is justified by how you use power.
It is not a single product that cancels winter physics. Grid electricity in January is normal. Lower annual imports and better comfort are the realistic win.
Frequently asked questions
Will solar make my heat pump free to run?
No. It can cut annual imports significantly. Midwinter heating still draws from the grid on most homes.
Should I buy all three at once?
Only if design ownership is clear and the budget is real. Phasing fabric → heat pump → PV → battery is often wiser.
Does a battery let me size a smaller heat pump?
No. Peak heat loss on a cold evening is a kW problem. Batteries store energy (kWh); they do not replace outdoor unit capacity.
Next step
Get a realistic planning band for your home, then use the checklist when you speak to installers.