We do both halves of this
Depth of Light installs solar, batteries and air source heat pumps across Milton Keynes and Buckinghamshire. The heat pump side is designed, installed, commissioned and MCS certified by MCS-certified heat pump engineers — which is what makes the £7,500 Boiler Upgrade Scheme grant valid — and the grant comes off your price before you pay. One survey, one install, one point of contact.
Heat Pump Calculator Solar Panel InstallationA gas boiler burns fuel to create heat. An air source heat pump moves heat from outside air into your home using electricity — typically producing 3–4 units of heat for every 1 unit of electricity consumed. Solar panels generate free electricity from your roof. Put the two together and you are running a highly efficient heating system largely on energy you generate yourself. That is the combination that is attracting serious interest from UK homeowners in 2026.
Why heat pumps and solar panels work well together
The core logic is simple. A gas boiler creates heat by burning gas — a fuel you buy, a fuel whose price you cannot control, and a fuel that generates carbon emissions. An air source heat pump (ASHP) creates heat using electricity. It does not generate heat directly; it moves heat from the outside air into the home. For every kilowatt of electricity it consumes, a well-installed ASHP delivers 3–4 kilowatts of heat (a coefficient of performance, or COP, of 3–4).
Solar panels generate free electricity from your roof. That electricity can power your heat pump directly when the sun is shining. In spring and autumn — when UK solar generation is reasonable and the heat pump is running at its most efficient (milder outdoor temperatures improve COP) — you can run your heating system largely for free during daylight hours.
This is why the combination attracts attention. Neither system alone is as efficient as the pair. Solar without a heat pump exports surplus electricity cheaply. A heat pump without solar buys electricity at full price. Together, the solar generation fuels the heat pump and the heat pump makes each unit of solar generation go much further than it would powering standard appliances.
How the two systems work together
A typical air source heat pump draws 2–4kW of electricity continuously while running. In heating mode during mild weather, demand sits at the lower end of that range. In very cold weather or when heating a large property, it draws more.
A 4–5kWp south-facing solar system in Milton Keynes generates about 3–4kW at peak on a clear day (roughly 10am–3pm on a clear day). This means that for several hours each day, your solar panels can supply the heat pump’s full electricity demand with no grid draw at all.
The operational picture:
- Clear summer day: Solar panels generate 3–4kW. The heat pump runs on solar during daylight, running the hot water (space heating is usually off in summer) at no electricity cost. Surplus solar charges a battery or exports to grid.
- Mild spring/autumn day: Solar generates 2–3kW for several hours. Heat pump draws 2–3kW. Net grid draw during daylight hours close to zero. More of the day is powered by solar than not.
- Cold winter day: Solar generation lower (1–2kW for fewer hours). Heat pump works harder and draws more power. More grid electricity is consumed. This is when the system is least efficient, but still far cheaper than gas at gas boiler efficiency.
Adding a battery into the system extends the benefit. Instead of exporting unused solar at 10–15p, the battery stores it. In the early evening when the heat pump runs its peak heating cycle (warming the house for the evening) and solar generation has stopped, the battery discharges to power the heat pump rather than the household buying grid electricity at 26.32p.
Sizing solar for a heat pump
A home with an air source heat pump typically uses 3,000–5,000 kWh per year just for space heating and hot water. This is separate from general household electricity (lights, appliances, cooking) which adds another 2,500–3,500 kWh/yr for a typical 3-bed home.
Total annual electricity demand for a heat pump home: 5,500–8,500 kWh/yr.
A 5kWp south-facing solar system in Milton Keynes generates about 4,500 kWh/yr. That covers roughly 55–85% of a heat pump household’s total annual electricity demand, depending on consumption patterns and orientation.
However, the match between solar generation and heat pump demand is seasonal:
- Summer: high solar generation, low heating demand. Large solar surplus — exports to grid or charges battery.
- Winter: low solar generation, high heating demand. More grid electricity required.
- Spring/Autumn: the sweet spot. Moderate solar generation and moderate heating demand overlap well.
This seasonal mismatch is why battery storage is particularly valuable in a heat pump home. A 10kWh battery absorbs daytime solar generation and dispatches it in the evening heating cycle, reducing the amount of expensive grid electricity consumed when demand is highest.
For a heat pump home, aim for at least 5kWp of solar. If budget allows, 6–8kWp better covers the winter months when solar generation is proportionally lower relative to heating demand. A battery of 10kWh+ provides meaningful daily storage that shifts enough solar generation to cover a large portion of evening heat pump usage.
Boiler Upgrade Scheme: the £7,500 grant
The Boiler Upgrade Scheme (BUS) is the UK government’s primary grant for replacing fossil fuel boilers with low-carbon heating. In 2026, the grant for an air source heat pump is £7,500.
Key conditions:
- Available in England and Wales only (Scotland has its own schemes).
- The heat pump must replace an existing fossil-fuel (gas, oil or LPG) or direct-electric heating system.
- The heat pump must be installed by an MCS-certified heat pump installer.
- The grant applies to the heat pump installation cost, not to solar panels.
- Runs to 2030. The Warm Homes Plan committed about £2.7bn to the scheme to 2029/30 at the 2025 Autumn Budget (GOV.UK summary business case, checked 11 October 2026). The budget is still set year by year, so it is not unlimited.
The grant is claimed by the installer, not the homeowner. Your MCS-certified heat pump installer submits the application. You simply pay the net cost (total minus £7,500). There is no paperwork burden on you beyond providing property details.
You can claim the £7,500 BUS grant on your heat pump and also benefit from 0% VAT on solar panels. The two incentives are completely independent. Installing solar does not affect your BUS eligibility and vice versa.
Planning a heat pump and want to size the solar correctly? We advise on solar system sizing across Milton Keynes and Buckinghamshire.
Solar Panel InstallationCombined costs in 2026
Let us put real numbers to a full heat pump + solar + battery installation in 2026:
| Component | Cost Range | Notes |
|---|---|---|
| Air source heat pump | £9,000–£13,000 | Before BUS grant |
| BUS grant | –£7,500 | Deducted at point of installation |
| Net heat pump cost | £1,500–£5,500 | After grant |
| 5.58kWp solar panels | £5,900–£6,900 | 0% VAT applies |
| 11.52kWh battery storage | £3,700–£4,300 | 0% VAT applies |
| Total after BUS grant | £11,100–£16,700 | Full system: heat pump + solar + battery |
These are indicative ranges. A smaller property with a straightforward installation will sit toward the lower end. A larger property, more complex roof, or premium equipment adds cost. The solar and battery elements can be installed in phases if budget requires: solar first, battery later.
Savings: what to expect
Payback depends entirely on which part of the system you are asking about, so here it is split three ways rather than blended into one number. Blending them charges the cost of the solar and battery against the heating saving, which makes the heat pump look far worse than it is — the heat pump is only about an eighth of the package cost once the grant is applied.
The assumptions
- Gas use before: 9,500 kWh/yr, boiler at 85% — about 8,075 kWh of heat
- Heat pump SCOP 4.0 — the top of the 3–4 range above, which a properly sized and commissioned system on correctly sized radiators should reach — so about 2,000 kWh/yr of electricity
- A heat pump tariff with cheap overnight windows, blending out at 16–20p/kWh. This one matters: see below
- Household electricity 2,700 kWh/yr; 5 kWp solar in MK ≈ 4,500 kWh/yr
- Rates: gas 7.97p, electricity 26.32p, standing charges 29.68p and 54.83p a day (Ofgem cap, Oct–Dec 2026)
1. The heat pump
Gas for heating and hot water costs about £865/yr (9,500 kWh at 7.97p, plus the £108 standing charge). At SCOP 4.0 the heat pump needs about 2,000 kWh of electricity instead — and what that costs depends almost entirely on your tariff:
- On a heat pump tariff, blending out at 16–20p: about £320–£400 a year — a saving of £460–£540 a year
- On the standard price cap at 26.32p: about £530 a year — a saving of about £334 a year
Electricity costs roughly 3.3× what gas does per unit, so the whole case rests on the heat pump using three to four times less energy than a boiler and on buying a good share of that energy in a cheap window. A heat pump left on a standard tariff still saves money, but roughly £200 a year less. We will say which tariffs are worth moving to before you commit, not after.
The heat pump costs £1,500–£5,500 after the grant. A replacement gas boiler is typically £2,500–£4,000, so if your boiler is due for replacement anyway, a heat pump can cost about the same or less — and then takes money off the bill every year rather than adding to it. If the boiler still has years left, you are paying the full £1,500–£5,500, which comes back in roughly 3 to 12 years depending on your tariff and where in that cost range you land.
2. The solar
5 kWp costs £5,900–£6,900 and generates about 4,500 kWh a year. A heat pump home uses more of that directly than most, because the heat pump runs during the day: roughly 45% self-consumed without a battery. That is about £719/yr in avoided imports and export income, so 10 to 12 years.
3. The battery
A 10 kWh battery adds £3,700–£4,300. On self-consumption alone it does not pay for itself quickly. Its value is in charging cheaply overnight and running the house and the heat pump on that stored electricity through the peak — which is also what makes the heat pump tariff figure above achievable. Whether it is worth it depends on your tariff more than your roof.
The heat pump is the part the grant makes cheap, and against a boiler you were going to replace anyway it is close to cost-neutral on day one, then saves £460–£540 a year on a heat pump tariff. The solar is a solid 10–12 year investment. The battery is a tariff decision. Anyone quoting you one payback figure for all three together is answering a question that does not match how you would actually buy them. A survey replaces every assumption here with your own numbers.
What Depth of Light does
We handle air source heat pump installation across Milton Keynes and the surrounding counties, alongside the solar and battery side.
We handle heat pumps too. One survey covers the heat pump, the solar and the battery together, so the three are planned as one system rather than three separate jobs.
Your heat pump is designed, installed and commissioned by MCS-certified heat pump engineers. We manage the whole job — survey, quote, scheduling and handover — and you deal with us throughout. Depth of Light is MCS and NAPIT certified for solar panels, battery storage and EV charger installation.
- One survey for the heat pump, solar and battery, rather than three visits
- The solar sized around what the heat pump will actually use
- Battery capacity chosen so daytime solar covers the evening heating
- The Boiler Upgrade Scheme grant applied for by the MCS-certified installer and taken off your price before you pay
See air source heat pump installation, our solar installation service, battery storage options and solar + battery packages. For the grant, see the Boiler Upgrade Scheme guide.
Planning a heat pump, solar or both?
One free survey covers all three. We are based in Milton Keynes and cover Buckinghamshire, Bedfordshire and Northamptonshire.
Book a free survey Heat pump calculatorFrequently asked questions
Yes. A heat pump runs on electricity, and solar panels generate free electricity. A 4–5kWp solar system generates 3–5kW during peak daylight hours, enough to run an air source heat pump effectively for several hours per day at no electricity cost. In spring and autumn, when the heat pump runs most efficiently and solar generation is reasonable, the combination works particularly well. Adding a battery extends the benefit into the evening heating cycle.
A heat pump home typically uses 3,000–5,000 kWh/yr for heating and hot water. A 5kWp solar system generates about 4,500 kWh/yr in Milton Keynes. That covers a significant proportion of annual heating demand. We generally recommend at least 5kWp for a heat pump home, with 6–8kWp providing better winter coverage. A 10kWh battery complements the solar by storing daytime generation for the evening heating cycle.
Yes. The BUS grant of £7,500 applies to air source heat pump installations in England and Wales and is entirely separate from solar panel incentives. You can claim the BUS grant on your heat pump and benefit from 0% VAT on solar panels in the same project. The two are completely independent. The BUS grant is claimed by the heat pump installer and deducted from your invoice.
A full system — air source heat pump (after £7,500 BUS grant), 5.58kWp solar panels, and a 10kWh battery — costs approximately £11,100–£16,700 in 2026. The heat pump alone costs £9,000–£13,000 before the grant (effectively £1,500–£5,500 after), solar adds £5,900–£6,900 (at 0% VAT), and battery storage adds £3,700–£4,300. Exact costs depend on property size and chosen equipment.
Yes. Your heat pump is designed, installed and commissioned by MCS-certified heat pump engineers, and we manage the whole job from survey to handover — you deal with us throughout. One survey covers the heat pump, the solar and the battery together, so the three are sized as one system. The Boiler Upgrade Scheme grant is applied for by the MCS-certified installer and taken off your price before you pay.