Embedded generation: the third of the grid you can't see

Not all power stations are wired into the national transmission grid. Around 29% of Great Britain’s generating capacity connects instead to the fourteen regional distribution networks - closer to homes, at lower voltages. The industry calls it embedded (or distributed) generation, and it has a strange property: the system operator cannot see it. There is no real-time meter on your neighbour’s roof.

What’s embedded?

Every solar panel in Great Britain. From a 4 kW rooftop to a 70 MW solar farm, all GB solar is distribution-connected - which is why the “live” solar figure is an estimate (the PV Live model from the University of Sheffield) rather than a meter reading, and why our solar pages say so. Alongside it: thousands of smaller onshore wind farms, landfill gas engines, anaerobic digesters and small hydro. Of the ~3,400 stations in the fleet, only about 113 are transmission-connected with a live feed - the rest are embedded and honestly shown capacity-only on their pages.

The accounting quirk that confuses everyone

Embedded generation doesn’t reduce what the grid generates - it reduces what the grid sees as demand. Power made and used behind the local substation never touches the transmission system, so national demand (INDO) is net of embedded generation by definition.

Consequences worth knowing:

• Summer middays show oddly low demand - embedded solar is serving it invisibly. The all-time lowest demand was a sunny spring lunchtime.
• “Generation + imports” on the dashboard can exceed demand by tens of gigawatts without anything being wrong - the two are measured on different bases. That is why no naive “surplus” figure appears on this site.
• The official generation mix does include embedded estimates - skipping them would understate renewables on every sunny, windy day.

Why it matters

The grid’s centre of gravity is moving outward: from a few hundred big stations to millions of small ones. Forecasting what the transmission system will need to supply now means forecasting the weather over every rooftop in Britain - one reason the demand forecasts and carbon forecasts are genuinely hard problems, and one more reason this site labels estimates as estimates.