Can I Run Plug-In Solar Into a Garden Room or Summer House?
Garden rooms and home offices are where I get the most interesting solar questions. You have a structure with its own electricity supply, panels on the roof or nearby, and a real desire to offset the running cost. Here is how it works and what to check.
Two scenarios: connected to house supply or standalone
Most garden rooms installed in the last decade have their own sub-consumer unit fed from the main house consumer unit via an armoured cable buried in the garden. Electrically, the garden room is part of the same installation as the house — same meter, same supply, same DNO connection. A plug-in solar system feeding generation into the garden room circuits reduces what the whole property draws from the grid, not just the garden room. Generation from the garden room roof is as useful as generation from the fence next to the house.
A truly standalone garden room with no mains connection and its own battery is a different scenario — effectively off-grid. In that case, none of the G98 or SI 2026/848 grid-connection rules apply.
For a garden room connected to the house supply
The one-per-household limit applies to the whole property. If you already have a certified socket-connected system in the main house, adding another in the garden room counts as a second system and is not currently permitted under the socket-connection rules. A hardwired installation on a dedicated circuit is the route for a second system — see our multiple systems article for detail.
If this is your first system and you want it in the garden room: the garden room circuit is part of your installation, G98 notification covers the property address, and the process is identical to any other install.
Panel positioning for a garden room
A flat or low-pitched garden room roof is often the best solar resource on the plot — more accessible than the house roof, typically less shaded. Ballast-weighted frames at 10 to 15 degrees tilt work well on flat roofs. Mount the microinverter on the garden room wall or roof fascia directly below the panels, then run the AC output cable into the garden room and back to the house through the existing armoured cable connection. The DC cable stays short; the AC cable runs back through existing infrastructure.
For flat roof mounting and wind loading, see our flat roof article. For DC cable length and voltage drop, see our DC cable guide.