Sources and data
The primary sources we work from, what each licence lets us do with them, and the terms we publish our own data under.
How to read a source list
Every page that makes a factual claim carries a source list at the foot, with the publisher and the date we last accessed it. If a page makes a claim without one, that is a defect — please report it.
Three things you will see in those lists, and what they mean:
An issue or version number — for standards and engineering recommendations we name the issue and the document’s own internal date, not just the title. Publishers' websites are unreliable guides to which version is current, so the number is how you tell whether we read the same document you would find today. This is rule 7.
A licence — where we reuse public sector information we say so, and the page carries the required attribution.
An access note — where a source is paywalled, gated behind registration, or where we read a freely available copy rather than the publisher’s own, we say that. You should know what a link will ask of you before you click it.
The sources we work from
We use primary sources: the body that made the rule, published the standard, or collected the data. Where a figure comes from a dataset rather than a document, we say which release.
The categories we draw on:
- Regulators and government departments — for scheme rules, tariff obligations, price controls and policy
- Statutory registers and certification schemes — for installation counts, certification status and scope
- Standards bodies — for the technical standards installations must meet
- Network operators and the Energy Networks Association — for connection requirements
- Open datasets — for energy performance, generation and deployment statistics
- Modelling tools — for location-specific generation estimates
Specific sources are cited on the pages that use them, with the access date, so a claim can be checked at the point it is made rather than through a general list.
What each licence lets us do
This is not housekeeping. The licence on a source decides whether a page can carry a table, a summary or a download, and it explains why some of our pages give you the data and others send you elsewhere for it.
| Type of source | Example | What we can do |
|---|---|---|
| Open Government Licence | Ofgem reports, government guidance | Republish in full with attribution |
| Legislation | legislation.gov.uk | Quote and link. We never mirror it |
| Restricted, with a public model behind it | MCS generation tables | Run the model ourselves and publish our own output |
| Restricted, no public model | MCS self-consumption tables, ENA engineering recommendations | Read, quote sparingly to explain, link to the source |
| Our own modelling | Our generation dataset | Publish freely under CC BY 4.0 |
Open Government Licence material
Where we reuse public sector information, the page carries this attribution:
Contains public sector information licensed under the Open Government Licence v3.0.
We take the licence conditions seriously, including the condition that reuse must not suggest official status or endorsement. We are not a government service and we never present ourselves as one.
This is why our SEG tariff table exists as a full table rather than a summary: Ofgem’s annual report is OGL material, so we can republish it with attribution instead of paraphrasing it and asking you to trust us.
Legislation
We quote and link, and we never mirror. legislation.gov.uk serves point-in-time
versions and permanent URLs, which a static copy cannot — a mirrored copy of a
statutory instrument is a snapshot that silently goes stale.
Restricted material we can model around
MCS publishes the UK method for estimating solar generation, and states that its own figures are drawn from the Climate-SAF-PVGIS dataset multiplied by 0.8. The method is public and the underlying model is public; the compiled tables are not free to redistribute.
So we run the model ourselves, at the loss factor that 0.8 factor corresponds to, and publish our own output. That is why our generation dataset can be given away as a CSV while MCS’s own tables cannot be mirrored.
Restricted material with no public model
Some documents have nothing behind them to reproduce independently. MCS’s self-consumption lookup tables in MGD 003 are one; the Energy Networks Association’s engineering recommendations G98, G99 and G100 are another — ENA reserves all rights and requires written consent for reproduction.
For these we read the document, quote the load-bearing sentences for the purpose of explanation, describe the method, and link to the source. We do not reproduce the tables or the forms, and we say plainly on the page when we are quoting rather than republishing.
Sources that are hard to reach
Two of the most important document sets in UK solar are free but awkward. ENA’s engineering database requires registration to download; its asset server refuses automated requests entirely. Where a freely accessible copy of the identical document exists — the GB Distribution Code site publishes G98 and G99 as direct PDFs — we link to the one you can actually open, and name the publisher’s own index alongside it.
Where we could not obtain a document at all, the page says so rather than implying we read it. Our export limiting page carries exactly that notice about G100.
Our own data
Datasets we compile and maintain are published free for public, academic, journalistic, commercial and personal use. Each dataset carries its licence on its own download page.
Currently published:
- UK solar generation by location, pitch and orientation — 625 modelled values, CC BY 4.0. Attribute as solar.org.uk, modelled from PVGIS 5.3 (European Commission, Joint Research Centre)
Provenance, method and caveats travel inside the file as header comments, so a figure cannot be separated from the assumptions that produced it.
Giving the data away is deliberate. A maintained, citable dataset is worth more to us as something people can quote than as something we could charge for. There is no sign-up and no email address in exchange.
Archived copies
Where a claim rests on a government publication, we keep a copy of the version we read, with the retrieval date and an integrity hash, on our source documents page. Government documents get withdrawn and replaced — one of the specifications behind our plug-in solar guidance was withdrawn within weeks — and a citation that cannot be checked is not much of a citation.
We do not archive material we are not licensed to redistribute. Restricted standards are read and cited, not stored for you.
Corrections to sources
If you maintain a source we cite and something has changed, or we have represented it inaccurately, tell us. We will correct it and log the correction publicly.
If you have access to a document we have said we could not obtain, that is worth sending too. It is on the corrections page when it changes what we publish.
Sorry to hear that. What was the problem?