Can the local grid take heat pumps?
On the network operators' own figures, about 77% of gas-heated homes with an energy certificate in the 3,372 postcode sectors we can check street by street could switch to a heat pump before their local substation runs out of spare capacity, at 1.7 kW added to the winter peak per heat pump. Only 1.4% of the 133,592 local substations of UK Power Networks, SP Electricity North West and Northern Powergrid are already full, but in 137 sectors all gas-heated homes could switch and in 99 fewer than half could. A full substation means the network operator must reinforce it before more heat pumps connect — usually a delay, not a refusal.
By network operator
| Network operator (area) | Local substations | Already full | Spare capacity | Gas homes could switch | Sectors with the answer |
|---|---|---|---|---|---|
| SP Electricity North West (North West England; data 24 March 2026) | 32,799 | 1,003 (3.1%) | 6,976 MVA | 1,193,050 of 1,478,304 (81%) | 678 |
| Northern Powergrid (North East England, Yorkshire and northern Lincolnshire; data 3 August 2026) | 28,043 | 450 (1.6%) | 8,997 MVA | 1,592,550 of 1,871,453 (85%) | 803 |
| UK Power Networks (London, the South East and the East of England; data 15 June 2026) | 72,750 | 478 (0.7%) | 15,244 MVA | 3,189,640 of 4,353,175 (73%) | 1,891 |
Local substations: 11 kV (or 6.6 kV) to 400 V transformers that feed streets. Full: no spare capacity left (UK Power Networks: utilisation of 100% or more). Gas homes: homes whose latest energy certificate shows mains gas heating, on postcodes linked to a substation; “could switch” shares each substation's spare capacity among them.
How many homes could switch, sector by sector
| Gas-heated homes that could switch within local spare capacity | Postcode sectors |
|---|---|
| fewer than 25% | 3 |
| 25% to 50% | 96 |
| 50% to 75% | 934 |
| 75% to just under all | 2,204 |
| all | 135 |
Where local spare capacity runs out first
Postcode sectors where the smallest share of gas-heated homes could switch before their street substations are full.
| Sector | Network operator | Gas homes | Could switch | Substations already full |
|---|---|---|---|---|
| CA24 3 Cumberland | SP Electricity North West | 281 | 30 (11%) | 2 of 15 |
| TS1 3 Middlesbrough | Northern Powergrid | 1,506 | 240 (16%) | 0 of 12 |
| DA18 4 Bexley | UK Power Networks | 1,656 | 400 (24%) | 0 of 9 |
| SK23 6 High Peak | SP Electricity North West | 734 | 180 (25%) | 11 of 26 |
| SW5 9 Kensington and Chelsea | UK Power Networks | 3,083 | 810 (26%) | 1 of 32 |
| CA7 2 Cumberland | SP Electricity North West | 151 | 40 (28%) | 6 of 64 |
| CA6 4 Cumberland | SP Electricity North West | 514 | 160 (31%) | 13 of 124 |
| NW10 5 Brent | UK Power Networks | 3,422 | 1,070 (31%) | 0 of 24 |
| WA3 6 Warrington | SP Electricity North West | 3,092 | 970 (31%) | 11 of 67 |
| CR7 8 Croydon | UK Power Networks | 4,676 | 1,490 (32%) | 0 of 34 |
| NW10 4 Brent | UK Power Networks | 2,703 | 870 (32%) | 0 of 20 |
| SE22 9 Southwark | UK Power Networks | 3,059 | 1,040 (34%) | 0 of 21 |
| CR0 6 Croydon | UK Power Networks | 6,144 | 2,150 (35%) | 1 of 43 |
| BN2 3 Brighton and Hove | UK Power Networks | 3,767 | 1,370 (36%) | 1 of 18 |
| CT11 9 Thanet | UK Power Networks | 2,443 | 890 (37%) | 0 of 22 |
| IG3 8 Redbridge | UK Power Networks | 3,764 | 1,390 (37%) | 0 of 30 |
| SE25 4 Croydon | UK Power Networks | 3,755 | 1,390 (37%) | 0 of 36 |
| LA16 7 Westmorland and Furness | SP Electricity North West | 932 | 350 (37%) | 4 of 23 |
| DA11 0 Gravesham | UK Power Networks | 2,058 | 770 (37%) | 0 of 26 |
| DA10 0 Dartford | UK Power Networks | 1,949 | 730 (37%) | 0 of 13 |
| NW1 9 Camden | UK Power Networks | 2,524 | 950 (38%) | 0 of 26 |
| KT19 7 Epsom and Ewell | UK Power Networks | 436 | 170 (38%) | 0 of 5 |
| RM9 5 Barking and Dagenham | UK Power Networks | 3,142 | 1,210 (39%) | 2 of 25 |
| M11 4 Manchester | SP Electricity North West | 2,916 | 1,130 (39%) | 3 of 21 |
| NW2 3 Camden | UK Power Networks | 2,614 | 1,030 (39%) | 0 of 24 |
SSEN area: primary substations with the least headroom
SSEN Distribution does not publish spare capacity for street substations, so in its southern England area (853 sector pages) the answer is given for the primary substation (33/11 kV) that feeds the district — a much coarser view. Primary substations with at least 500 gas-heated homes, by the share that could switch within the 2027 winter headroom (lowest of SSEN's scenarios):
| Primary substation | Headroom 2027 | Gas homes in its area | Room for heat pumps | Sectors |
|---|---|---|---|---|
| East Howe | −0.3 MVA | 9,432 | none | BH10 4, BH10 5, BH11 8, BH11 9 |
| Vicarage Farm Road (upstream constraint) | −16.9 MVA | 9,299 | none | TW3 3, TW3 4, TW4 6, TW4 7 |
| Ashling Road (upstream constraint) | −2.2 MVA | 8,589 | none | PO18 8, PO19 3, PO19 5 |
| Ashton Park (upstream constraint) | −7.5 MVA | 8,112 | none | BA14 0, BA14 6, BA14 7 |
| Chichester (upstream constraint) | −5.7 MVA | 7,285 | none | PO18 0, PO20 3, PO21 5 |
| Frimley | −1.4 MVA | 7,015 | none | GU15 1, GU16 7, GU16 8, GU16 9 |
| Wootton Road (upstream constraint) | −1.9 MVA | 6,122 | none | OX13 6, OX14 1, OX14 2 |
| St Cross | −6.3 MVA | 6,032 | none | SO22 4, SO22 5, SO23 9 |
| St Johns | −10.5 MVA | 6,019 | none | RG14 5, RG14 6, RG14 7, RG19 8 |
| Bilsham (upstream constraint) | −2.1 MVA | 5,880 | none | BN18 0, BN18 9, PO22 0, PO22 6 |
| Rose Hill | −8.8 MVA | 5,691 | none | OX4 3, OX4 4 |
| Yarnton (upstream constraint) | −13.4 MVA | 5,408 | none | OX5 1, OX5 2 |
| Grove (upstream constraint) | −8.5 MVA | 4,909 | none | OX12 0, OX12 9 |
| Emsworth (upstream constraint) | −1.3 MVA | 4,867 | none | PO10 7, PO10 8 |
| North Fareham (upstream constraint) | −3.6 MVA | 4,836 | none | PO15 6, PO16 7, PO17 5, PO17 6 |
SSEN Network Scenario Headroom Report 2026 and Primary Supply Areas (19 October 2026). Across all 425 SEPD primary substations, 30 have no winter headroom for 2027 in the lowest scenario.
How this is calculated
- Spare capacity: each network operator's published demand headroom of its local substations — UK Power Networks (utilisation band × transformer rating; we take the low end of the band), SP Electricity North West (transformer headroom, kVA) and Northern Powergrid (transformer headroom, kW, from last year's maximum demand). kVA and kW are treated as equal.
- Which homes a substation feeds: UK Power Networks — postcodes whose centre lies inside the substation's published supply area; Northern Powergrid — the postcodes it lists as fed by the substation; SP Electricity North West — the nearest substation to the postcode centre (within 1 km), because supply areas are not published. A postcode linked to several substations is shared equally between them.
- Gas-heated homes: homes whose latest energy certificate (EPC register) shows mains gas heating; homes without a certificate are not counted.
- Heat pumps per substation: spare capacity ÷ 1.7 kW. That is the average extra winter peak of a heat pump once many are spread over a street (after diversity maximum demand of about 700 heat pumps in the government's Renewable Heat Premium Payment trial; Love et al., Applied Energy, 2017). In a cold snap a heat pump can add more, so each sector page also shows the answer at 3 kW.
- A sector shows the answer when at least 70% of its gas-heated homes with a certificate are on postcodes linked to substations and there are at least 30 of them. Sectors served by National Grid Electricity Distribution or SP Energy Networks (the Midlands, the South West, Wales, Merseyside and Cheshire) are not covered: those operators do not publish street substation capacity openly.
Caveats
- This is not a connection offer. Installers must tell the network operator about each heat pump; when a substation is full, the operator reinforces it, usually at its own cost — the risk is a delay, not a refusal.
- Substations are also limited by their cables and by the network upstream; electric cars, batteries and new homes compete for the same capacity.
- The capacity figures are the operators' latest published estimates, not live readings.