The short answer: on 12 October 2026, 1,808 fields of 0.5 to 2 hectares were within 1 km of a substation with at least 5 MW of spare capacity both ways. For a grid-scale battery, 207 fields of 2 to 5 hectares were within 1 km of a substation with 20 MW both ways. Outside Dublin, Sligo has the most.
A battery is different from a solar farm. It takes power from the grid as well as sending power to it, so the substation needs spare capacity in both directions. ESB's heatmap shows the two separately. This post joins them, then joins the result to every field in the State.
Counted on 12 October 2026, on ESB Networks' heatmap compiled on 12 December 2025 and published in July 2026.
What counts here
- Spare both ways: the smaller of the spare capacity to export and the spare capacity to import, at one substation, medium voltage or higher, and not constrained further up the network.
- The field: a freehold Land Registry title, clear of mapped flood extents and designated sites (SAC, SPA, NHA and proposed NHA), with buildings on under 2.5% of it, and not already a solar farm.
- The distance is measured from the field's boundary to the substation.
| Search | Fields | Hectares |
|---|---|---|
| 0.5-2 ha, 5 MW both ways within 1 km | 1,808 | 1,906 |
| The same, within 500 m | 595 | 645 |
| 2-5 ha, 20 MW both ways within 1 km | 207 | 641 |
Small sites: 0.5 to 2 hectares, 5 MW
| County | Fields | Hectares |
|---|---|---|
| Dublin | 323 | 316 |
| Cork | 280 | 271 |
| Roscommon | 198 | 220 |
| Mayo | 170 | 193 |
| Galway | 94 | 101 |
| Sligo | 89 | 104 |
| Limerick | 74 | 80 |
| Cavan | 67 | 74 |
| Westmeath | 59 | 60 |
| Kilkenny | 53 | 51 |
| Wicklow | 52 | 58 |
| Waterford | 52 | 53 |
| Tipperary | 50 | 53 |
| Kerry | 40 | 40 |
| Wexford | 39 | 43 |
| Laois | 30 | 32 |
| Louth | 22 | 25 |
| Offaly | 22 | 25 |
| Clare | 22 | 23 |
| Longford | 20 | 22 |
| Kildare | 20 | 24 |
| Donegal | 17 | 22 |
| Meath | 9 | 11 |
| Leitrim | 2 | 3 |
Four fields have no county on the Land Registry. Carlow and Monaghan have none at this setting.
Grid-scale sites: 2 to 5 hectares, 20 MW
| County | Fields | Hectares |
|---|---|---|
| Dublin | 59 | 169 |
| Sligo | 49 | 150 |
| Cavan | 23 | 76 |
| Wexford | 19 | 66 |
| Offaly | 17 | 54 |
| Tipperary | 12 | 40 |
| Cork | 12 | 34 |
| Donegal | 6 | 21 |
| Kilkenny | 4 | 13 |
| Waterford | 3 | 9 |
| Leitrim | 3 | 9 |
Only 11 counties have any. 20 MW both ways is scarce, because one substation has to have that much spare in each direction.
We looked at 20 of them from the air
A database cannot tell a field from a road verge. So we picked 20 of the 207 grid-scale fields at random and looked at each on satellite imagery, with the title boundary drawn on.
11 of the 20 were open farmland. The other nine were a golf course, a strip of motorway verge, a road and riverbank, common ground in a housing estate, a playing pitch in a town, a field cut by a new road, disturbed ground on an industrial site, a strip of bog and scrub, and rough hill grazing on bog.
Where they were mattered more than anything else:
- All four Dublin fields failed. Dublin tops both tables because its substations have the most spare capacity, but the land titles near them are mostly verges, estates and sports grounds, not fields.
- All six Sligo fields passed. They were ordinary farmland.
So read the Dublin row as substations, not sites. Outside Dublin, a field on this list is more likely than not to be real land, but you still have to look.
Beside a solar farm
Added 22 October 2026.
On 21 October RTÉ reported new EirGrid figures: more than 13% of the wind and solar electricity available in the first nine months of 2026 could not be used. Wind Energy Ireland put the loss at enough for around 496,000 homes. Energy Storage Ireland said putting batteries with renewable generation would let developers make better use of existing grid connections.
So we asked a second question: which fields could take a battery beside a solar farm?
- The farms: 64 built solar farms of a hectare or more, mapped on OpenStreetMap (1,556 ha of panels), and 458 solar farms granted planning permission since 2021.
- The fields: the same rules as above. Freehold, 0.5 to 2 hectares, clear of flood and designated sites, under 2.5% built on, and not already solar.
| Search | Fields | Hectares |
|---|---|---|
| 0.5-2 ha, a solar farm built or permitted within 500 m | 2,063 | 2,270 |
| The same, a built farm within 500 m | 356 | 399 |
| The same, and 5 MW both ways within 1 km | 174 | 193 |
OpenStreetMap shows about half the State's solar farms, so a field can be next to a farm we do not know about. The list can miss fields, but every field on it really is near a farm. A permission is placed at the application's map point, so that distance is approximate. And being beside a farm is not an agreement to share its connection. That is for the farm's owner and ESB Networks.
What this does not tell you
- It is not a connection offer. The heatmap is ESB Networks' indication of headroom, as of the end of 2025. Only a connection application tells you what a site can connect and on what terms. It says nothing about projects already queued for the same capacity.
- Substation positions are mapped, not surveyed. We moved ESB's substations to where OpenStreetMap shows them, which matched 538 of 548.
- A field that passes still needs planning. This does not check zoning, access, noise neighbours or fire safety rules.
Where Precedent fits
This post is three searches, run once. In Precedent you run them yourself, for any county:
- Battery sites as a search of their own, with "both ways" headroom, the size you need and a distance of 500 m to 5 km. (Grid capacity)
- Battery sites beside a solar farm, built or with planning permission, within 250 m to 2 km. (Fields & farmland)
- Add the other checks: flood, designated sites, power lines, slope and buildings on the land. (Fields & farmland)
- Open a field to see its Land Registry title, the substations behind the match, with names and distances, and farmland prices for the region.
For renewables developers, here is the whole toolkit. It shows ESB's published heatmap, not a connection offer, and it cannot tell a field from a verge, so look at the imagery before acting on one.
Sources: ESB Networks' availability capacity heatmap (compiled 12 December 2025, published July 2026); Tailte Éireann Land Registry titles and building outlines; OPW flood extents; NPWS designated sites; OpenStreetMap (ODbL) for solar farms and substation positions; granted solar-farm planning applications from the national planning register; Esri World Imagery for the photo check. Read 12 October 2026; the solar-farm section 22 October 2026.
A battery needs the capacity both ways
Precedent reads ESB's heatmap for spare capacity to export AND to import at the same substation, and joins it to every Land Registry title, the flood maps, designated sites and building outlines. Pick the size, the distance and the megawatts, and get the fields.