Scotland Regional Winner, Heating Installer Awards 2026Highly Commended, Scottish Energy Efficiency Awards 2025
🎉 Scotland Regional Winner at the Heating Installer Awards 2026
Scotland Regional Winner, Heating Installer Awards 2026Highly Commended, Scottish Energy Efficiency Awards 2025
🎉 Scotland Regional Winner at the Heating Installer Awards 2026
Home / Blog / Solar assisted heat pumps in Scotland
A solar assisted heat pump in Scotland, as installers quote it for ordinary houses, is an air source heat pump that draws part of its electricity from panels on the same roof. The size of that part depends on the month. A 4 kWp array in Glasgow, which is the average size Home Energy Scotland gives for Scottish installations, makes about 438 kWh in June and 77 kWh in December according to the European Commission’s PVGIS model, and your heat pump wants its electricity in the reverse order.
Sean Hogan · Heat Geek engineer · Updated October 2026 · 13 min read
Solar panels can carry a heat pump through long stretches of the Scottish year and cover a slice of it in the coldest months, which makes the useful question how big that slice is in your house. The figures below come from PVGIS for a Glasgow roof, Home Energy Scotland’s funding table and Octopus’s published tariff rates, each with the date we checked it, so you can test any package quote against them.
The phrase covers three different set-ups, and sales literature stretches it to fit all of them. The common one on Scottish houses pairs solar PV panels, which make electricity, with a standard air source heat pump. The panels feed the house wiring, and the heat pump uses that power whenever it runs while the sun is out. The two pieces of kit share nothing except the electrics and, in a good design, the controls.
Two other meanings turn up in manufacturers’ brochures and engineering papers.
Solar thermal collectors heat water themselves, through a coil in the hot water cylinder, and share that cylinder with the heat pump.
PV-T panels make electricity and collect heat in the same panel, and some systems use that heat as the source for a heat pump.
(Few Scottish houses have either.)
Home Energy Scotland funds the three on different terms. Its funding table, which we checked on 13 October 2026, offers an interest-free loan of up to £5,000 for solar thermal and up to £5,000 for PV-T panels, with no grant for either, and lists nothing at all for standard solar PV. The heat pump is funded on its own terms in every case.
We ran a 4 kWp south-facing array on a 35 degree Glasgow roof through PVGIS on 13 October 2026, and it returned 3,401 kWh a year. To set heating demand beside it, we took PVGIS’s typical-year temperatures for the same spot and counted heating degree days, the measure engineers use for how far each day falls below the 15.5°C at which a house starts to need heat.
| Month | Solar output, 4 kWp (kWh) | Estimated share of the year’s heating demand |
|---|---|---|
| January | 89 | 12.8% |
| February | 169 | 11.7% |
| March | 280 | 12.5% |
| April | 411 | 10.2% |
| May | 473 | 6.5% |
| June | 438 | 3.0% |
| July | 439 | 2.9% |
| August | 383 | 1.3% |
| September | 299 | 4.9% |
| October | 211 | 8.8% |
| November | 132 | 11.6% |
| December | 77 | 13.6% |
Solar: PVGIS 5.2 (European Commission Joint Research Centre), 4 kWp, 35 degree pitch, due south, 14% system losses, central Glasgow, pulled 13 October 2026. Heating demand is our estimate: heating degree days at a 15.5°C base, calculated from the PVGIS typical meteorological year for the same location. Space heating only; hot water adds a steadier load on top each month.
The two columns run in opposite directions. November to February brings about half of the year’s heating demand and 13.7% of the year’s solar. May to August turns it round, with 51% of the solar and 14% of the heating.
Take a house whose heat pump draws 3,400 kWh of electricity a year for heating, the same as the array makes (around 10,000 kWh of heat at an efficiency of 300%, an illustrative figure). Over a whole year the panels match the heat pump. Split by month, December asks for about 460 kWh and the roof supplies 77, around a sixth. June asks for about 100 kWh while the roof makes 438, far more than the heating can use.
Winter output has detail of its own, from short days to snow lying on the panels, and our guide to how solar panels perform through a Scottish winter goes through it. For heating, the number to hold on to is that December ratio: the sun pays for a slice, and the grid or a battery covers the rest.
Edinburgh makes more in the same model, 3,661 kWh a year from an identical array, and follows the same curve. On a Glasgow sandstone villa or tenement flat, our heat pump installations across Glasgow start from the heating side of that sum, the heat loss on a cold day, before anyone decides how many panels go on the roof.
“Changing from gas central heating to renewables isn’t simple but, having asked four companies to quote to convert our system, Sean stood out as someone who cared about getting the design right, optimising it for our house while clearly explaining how and why. He helped us understand how heat pumps, solar panels and batteries all work together and gave us confidence that the conversion would be possible and relatively simple.”
Alison Hyde, ★★★★★ Google Review
Hot water in summer is the closest match an air source heat pump and solar panels ever get. Heating a 200-litre cylinder from 10°C to 50°C takes about 9.3 kWh of heat, which a heat pump makes from 3 to 4 kWh of electricity (assuming it runs at 250% to 300% while heating water). The Glasgow array in the table averages 14.6 kWh a day in June. Schedule the cylinder to reheat in the early afternoon and the sun pays for most of a summer day’s hot water with power left over.
A PV diverter sends surplus power to the immersion heater instead, and Home Energy Scotland’s own advice is that the surplus alone is unlikely to meet all your hot water needs.
With a heat pump in the house, its hot water cycle gets more from the same sunshine, because an immersion turns one unit of electricity into one unit of heat and the heat pump turns it into two or three.
March, April, September and October do the most useful work for space heating.
April brings 12.1% of the year’s solar and still 10.2% of the year’s heating demand, so the panels and the radiators are busy in the same weeks.
October is weaker on both counts, 6.2% of the solar against 8.8% of the heating, and the overlap thins from there into winter.
Daytime pre-heating uses that overlap on a smaller scale. Raise the thermostat a degree through the sunny hours of a spring afternoon and the heat pump does its extra work in the warmest part of the day, when an air source unit runs at its best, on power from the roof. Solid stone and brick walls hold that warmth into the evening, which leaves the heat pump less to do after sunset. Controls that read the inverter’s output can handle this for you; a timer set to the early afternoon gets you part of the way.
A heat pump, solar panels and battery together let you use daytime power after dark. In summer the battery fills from the roof at midday and runs the house through the evening. On a short winter day the roof cannot fill it, so the battery earns its keep from cheap grid hours instead.
Cosy Octopus, a tariff for homes with a heat pump, shows how wide the gap between cheap and peak hours runs. On 13 October 2026 Octopus’s published South Scotland rates, including VAT, were 12.19p a unit from 4am to 7am, 1pm to 4pm and 10pm to midnight, 37.28p from 4pm to 7pm, and 24.85p at other times.
A battery charged in a cheap window and emptied into the heat pump between 4pm and 7pm saves about 24p on every unit it delivers, once you allow for the 10% or so a battery loses between charging and discharging (the price gap itself is 25.09p). The 1pm to 4pm window also overlaps the hours a winter array generates, so on a dull December afternoon the battery tops up from cheap grid power before the evening peak. Those rates also carry the temporary 0% VAT on domestic electricity that HMRC applies from 1 October 2026 to 31 March 2027, so they rise when it ends, and Octopus revises them through the year in any case.
A house in Gartcosh shows the combination at work. Christine’s family already had an air source heat pump, but nobody had ever set it up right, and their electricity bills reached around £600 in some months. We fitted a 10.5 kWp solar array with 20.8 kWh of battery storage, re-commissioned the heat pump with the correct flow temperatures, and the monthly bill dropped to £24.79. The heat pump fix did part of that work, and the array is well over twice the Scottish average, so read it as what a large system, set up right, can reach.
“We’ve had very attentive customer service from Sean, and are very happy with the outcome of the installation of solar panels & batteries. We are also grateful for his knowledge and input into adjusting our heat pump and currently our bills are massively reduced.”
Christine C, ★★★★★ Google Review
Solar panels never change the size of the heat pump. The heat pump comes from a room-by-room heat loss calculation at your area’s winter design temperature, because it has to carry the coldest week with or without sunshine. Our air source heat pump sizing guide sets out how that calculation works.
The array is sized the other way round, from the roof and the year. Sizing it to cover winter heating fails on any normal house: in the illustration above, matching December’s 460 kWh would take about 24 kWp of panels, six times the Scottish average and far more than a semi’s roof holds. A sensible array matches the household’s yearly electricity use with the heat pump included, fits the roof’s orientation and shading, and leaves summer surplus for the cylinder, a battery or export.
The battery follows your evenings. Add up what the house uses between teatime and breakfast in winter, the hours the heat pump keeps running included, and size the battery to that figure.
Then the electrics have to carry all three. The survey checks the main fuse and the consumer unit against a heat pump, an inverter and a battery running at the same time, and the network operator has to approve solar and battery systems above a set export size before they go in. One design answers those questions once, where two separate installers would each answer them for their own kit.
“Aventus Eco fitted solar panels, battery storage and an air-source heat pump, and the whole experience has been great… The solar panels were a no brainer, but Aventus suggested right sizing the solar panels and adding battery storage.”
Duncan Livingstone, ★★★★★ Google Review
Buying the heat pump and solar panels as one package changes the paperwork and the bill. One survey covers the heat loss, the roof and the electrics, the scaffold goes up once, and one company answers for the whole system under a 5-year workmanship guarantee. Each unit of solar the heat pump uses replaces a unit you would otherwise buy from your supplier. Our heat pump and solar package page sets out what the package includes and what it costs.
The heat pump itself works as before. Its efficiency depends on the outdoor air and the flow temperature to the radiators, and the source of its electricity changes neither; solar lowers what each unit costs you. Its size stays the same, and in December you still buy most of its electricity from the grid or a battery.
Funding sits under two sets of rules. Home Energy Scotland funds the heat pump with a grant of up to £7,500, or £9,000 for homes in remote rural, island and off-gas accessible rural areas, plus an optional interest-free loan of up to £7,500, provided the heat pump supplies 100% of the heating and hot water; a heat pump that replaces an existing one gets the loan of up to £7,500 and no grant. Panels on the roof make no difference to that test, so a hybrid that keeps a boiler stays ineligible with or without solar. Standard solar panels and batteries get no Home Energy Scotland grant or loan. HMRC zero-rates the installation of solar panels, batteries and air source heat pumps until 31 March 2027, with the rate set at 5% from 1 April 2027.
Summer surplus that the heat pump, the cylinder and any battery cannot absorb goes to the grid, and the Smart Export Guarantee pays for it at a rate your supplier sets.
The sum that matters for your house sets its heat loss, month by month, against what your roof can make, then decides what a battery and a cheap-rate tariff should carry. A £0 survey measures the heat loss, checks the roof and the electrics, and sizes the heat pump, the panels and any battery in one design.
Solar covers a small part of a heat pump’s winter use in Scotland. PVGIS puts a 4 kWp Glasgow array at about 77 kWh in December, around a sixth of the heating electricity in our illustration, so the rest comes from the grid or a battery charged at cheap-rate times.
A 4 kWp array, about ten panels of 400 W, makes around 3,400 kWh a year in Glasgow, which can match a heat pump’s yearly use. An ordinary house roof cannot cover a Scottish December, so size the array to the roof and your year, never to winter.
Each solar unit your heat pump uses replaces one you would buy. On Cosy Octopus in South Scotland, the 1pm to 4pm cheap window (12.19p on 13 October 2026) overlaps peak solar, so solar mostly replaces 12.19p or 24.85p units. The value sits in spring, autumn and summer hot water.
A first heat pump can attract a Home Energy Scotland grant of up to £7,500, or £9,000 in eligible rural and island areas, plus an optional £7,500 loan; a replacement heat pump gets the loan only. There is no Home Energy Scotland grant or loan for solar PV, and its installation carries 0% VAT until 31 March 2027.
No. Panels and a heat pump work together without one. A battery moves summer daytime power into the evening and, in a Scottish winter, stores cheap-rate grid power for the 4pm to 7pm peak.
Solar thermal heats the water in your cylinder, PV-T makes electricity and heat in one panel, and solar PV makes electricity the heat pump uses. In Scotland, Home Energy Scotland offers loans of up to £5,000 for solar thermal and PV-T and nothing for standard PV.
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