The Solar League is compiled entirely from official public registers, and every figure can be traced to a dated source. This page explains where the data comes from, how we attribute each solar system to an organisation, and where the limits lie.
We catalogue commercial rooftop solar across Great Britain and attribute each system to the occupier of the building and to its owner or landlord. We then rank those organisations by the share of their estate that carries registered solar. The reporting threshold is systems of 50 kW and above, recorded on every published table.
We do not detect panels from satellite or aerial imagery, and we do not cover domestic solar or ground-mounted solar farms.
The "has solar" signal comes from three official registers, taken as dated snapshots:
Because each register brackets a different size range, bringing them together gives a fuller picture of the commercial rooftop band than any one of them alone.
The registers we use cover Great Britain. Northern Irelandruns a separate electricity network with its own registers and is out of scope, so where we say "UK" as everyday shorthand, the underlying coverage is Great Britain.
Ownership attribution is strongest in England and Wales, where HM Land Registry's corporate and overseas datasets apply. Sites in Scotland can be harder to attribute from those sources and are more likely to fall into the unverified group.
We match each solar site to the organisation that owns or occupies the building, using HM Land Registry's corporate and overseas ownership data and Companies House. Each attribution carries a confidence level, shown openly on the tables:
Only systems recorded as connectedcount towards an organisation's headline figure. Systems that are approved but not yet energised (accepted to connect) are shown separately, so a landlord whose newest arrays are still in the pipeline is not made to look absent, and un-energised capacity is never counted towards the headline figure.
Before the league is published, every organisation in it is invited to review its own entry, confirm what is right, correct what is wrong, and add any systems we have not captured. Every confirmation, edit and addition is logged with the submitter and the date, and reviewed against the registers and any evidence before it changes a published figure. That review is what keeps the league auditable.
The published table shows which entries an organisation has confirmed and which remain unconfirmed, so readers can see at a glance which figures have been checked by the organisation itself and which still rest on the registers alone.
Every published table is tied to dated snapshots of its source registers, so any figure can be reproduced from the exact versions it was built from. We publish counts, shares and rankings, not the raw register rows.