Panels peak in summer, heating peaks in winter
The two technologies pull in opposite directions through the year. In central Wigan, PVGIS puts a south-facing panel at its best angle at 113 kWh per kW in June and 28 kWh in December, so a December makes about 25% of a June, by our arithmetic from figures averaged over 2005-2023 (PVGIS 5.3). A heat pump does most of its work in the colder months, when the home needs heat, which is exactly when the panels have least to give. This guide puts no figure on a heat pump's use: that depends on the house, and the heat pump installer should work it out for yours.
Add the months up and the pattern is starker. October to March brings 31% of a year's output from the same panel, and April to September the other 69%, by our arithmetic from the same PVGIS months (PVGIS 5.3). Panels can still help on bright days in spring and autumn, and in summer, when a heat pump has less heating to do. Anyone promised that a roof of panels will run a heat pump through a Wigan winter should ask to see the month-by-month sums. The table below uses PVGIS's best angle for central Wigan, 40°, which gives 929 kWh per kW over a year; a south roof at the more usual 35° gives 927 kWh, almost the same. Other directions and other parts of the borough are on output across the borough.
| Month | kWh per kW | 4 kW system, kWh |
|---|---|---|
| January | 31 | 124 |
| February | 50 | 200 |
| March | 82 | 328 |
| April | 109 | 436 |
| May | 119 | 476 |
| June | 113 | 452 |
| July | 113 | 452 |
| August | 102 | 408 |
| September | 85 | 340 |
| October | 59 | 236 |
| November | 40 | 160 |
| December | 28 | 112 |
The Boiler Upgrade Scheme is for heat pumps, not panels
The Boiler Upgrade Scheme helps with the heat pump and nothing on the roof. GOV.UK sets out £7,500 towards an air source or ground source heat pump, with an extra £1,500 until March 2027, making £9,000, where oil or LPG heats the property and there is no mains gas connection (GOV.UK). Solar panels are not on its list of what it pays towards.
The rules around it are worth knowing before talking to installers. The scheme is open to people in England and Wales (GOV.UK). You must own the property, most new builds are excluded, and having already had funding to insulate the home does not stop you applying (GOV.UK); there is one grant per property, and it cannot go towards a hybrid system that pairs a heat pump with a gas boiler or replace an existing low-carbon heating system (GOV.UK). The installer applies on your behalf on Ofgem's website, and the value of the grant is taken off what you pay for the installation and shown on the quote and the invoice (GOV.UK). A combined quote should therefore show the heat pump, the grant and the panels as separate lines, so you can see that no part of the grant has drifted onto the solar.
Because the installer makes the application, there is never a reason to sign a grant form for a seller at the door, and a pitch that bundles panels and a heat pump under one "grant" deserves a second look. Ask which scheme pays for which item, check the answer against the GOV.UK pages linked here, and see doorstep sellers for the lines to watch for.
Finding certified heat pump installers
Heat pumps are their own trade. GOV.UK's advice is to contact suitable MCS certified installers to get quotes (GOV.UK), and MCS says that if you live in England or Wales its installer search also lets you look for installers registered for the Boiler Upgrade Scheme (MCS). Search by the technology you want, and if one firm is quoting for both, check that it is listed for each.
Certification is worth more than a logo. MCS says its certification includes added protections, such as warranties and an independent complaints service (MCS), and each installation gets its own MCS certificate, so a home with panels and a heat pump should end up with two. Keep both, and keep the warranty papers for each system separately.
One firm or two is your choice. One firm can make the paperwork and the layout of roof and garden simpler; two firms means two contracts, two consumer codes and two sets of warranties to keep track of. Either way, the checks on checking a solar installer apply to each, and each quote should stand on its own figures, with the panels compared against the North West prices on the costs page.
GMCA's grant and low-carbon heating
For households on lower incomes, GMCA's Warm Homes: Local Grant has a low-carbon heating part alongside its energy performance part, which is where solar PV and batteries sit (GMCA). The heating measures it lists are air source and ground source heat pumps, high heat retention storage heaters and shared ground loops; gas and oil boilers are not eligible. The home must be owner-occupied at EPC D to G, or privately rented at D or E, and the household must meet one route: a postcode in the two most deprived income deciles, a listed means-tested benefit, two of six listed proxies such as a referral from AWARM Wigan, or a combined gross income below £36,000.
For a home and household that qualify, GMCA's page lists each part at up to £15,000 for an owner-occupier, £30,000 in all (national guidance has since raised the caps to £16,600 per part, DESNZ), and offers measures in the order a retrofit assessment recommends, aiming at EPC band C. It does not list the boroughs it covers, and Wigan appears only through the AWARM Wigan referral route, so ask its Retrofit Team whether your address is covered, and how its heating help would sit alongside the Boiler Upgrade Scheme, before planning on either. Households who can pay have no solar grant in England (Warm Homes Plan); help with the cost has the full picture.
Telling Electricity North West about both
Both end up on the network's records. MCS tells installers that solar PV under G98 must be notified within 28 days of commissioning, and that a heat pump which keeps the home's maximum demand at or below 60 A can be connected and then notified within 28 days of installation. Where the new maximum demand would be between 60 A and 100 A, the installer must apply before installation, and the network assesses supply capacity within 10 working days (MCS).
Electricity North West runs that network across the borough (Electricity North West). When both are planned, ask each installer which notice or application it will send, and when, so that neither job is held up by the other. Electricity North West and your panels explains the G98 and G99 routes for the solar side. Put copies of both notices in the same folder as the two MCS certificates; anyone who later adds a battery or an electric car charger will need to know what is already connected.
Order of work, and what to ask each installer
GMCA's scheme follows a retrofit assessment towards EPC band C, which is a sensible way to look at any home: what the house loses, then how it is heated, then what the roof makes. Of the borough's homes with an EPC, 53.6% are at band C or above, but only 26.9% of those built before 1929 (ONS), and the older stock is where that assessment has most to say.
Then ask each installer for its working. From the heat pump installer: how it sized the heat pump, and how much electricity it expects the heat pump to use in a year, by month if it can. From the solar installer: the yearly estimate in kWh for your roof, by month, as what a quote should include describes. Set the two side by side, and the overlap between them, mostly in spring, summer and early autumn, is the part of the heat pump's use the panels can realistically meet. A battery shifts some daytime output into the evening, but it cannot carry summer sunshine into January; batteries covers what one can and cannot do.