Electricity to Shed Buildings: Mains Cable or Solar?
There are two ways to get electricity to shed buildings, workshops and garden offices: run a mains cable from the house, or make the power in the shed with solar. They differ on the rules, on winter performance and on what they can run. Solar Panels for Sheds is an independent UK guide operated by SEO Dons Ltd. We do not sell kits or install anything; send us your load list and we reply by email.
In short: a mains supply to a shed is a new circuit, which is notifiable work under Part P in England, so it needs a registered electrician or a building notice. Solar avoids the new circuit if the system stays self-contained, but winter output is a fraction of summer output, so it suits lights, charging and occasional tools better than heating.
Route one: a mains cable from the house
Running mains power to a shed means a new circuit from the house consumer unit, a cable route down the garden and a small distribution board in the shed. Approved Document P, the government guidance on Part P of the Building Regulations, says the rules apply to electrical installations "in outbuildings such as sheds, detached garages and domestic greenhouses" where the electricity comes from a source within or shared with the house. It lists three kinds of notifiable work: installing a new circuit, replacing a consumer unit, and adding to or altering circuits in a special location such as a bathroom.
A cable to the shed is a new circuit, so it is notifiable. In practice that means one of two routes: an electrician registered with a competent person scheme does the job and self-certifies it, or you notify building control before work starts and they inspect it. Approved Document P also allows a registered third party to certify work done by someone who is not registered. What the regulations do not allow is an unnotified DIY spur.
The cable itself (its type, size and how it is protected along the route) is a design decision for the electrician under BS 7671, the wiring regulations, and depends on the length of the run and what the shed will draw. That is why mains quotes vary so widely between gardens. For the price side, see the cost to run electricity to a shed against the solar tiers.
Route two: make the power in the shed
A self-contained solar system puts the source in the shed: a panel on the roof, a charge controller, a battery and the loads, with nothing connected to the house supply. Approved Document P frames its limits around a building that "receives its electricity from a source located within or shared with a dwelling", which is why a stand-alone low-voltage system is treated differently from a mains spur. Where exactly the line falls, and what you can safely wire yourself, is on our page on shed wiring regulations in the UK. The roof side (planning limits and fixings) is on our guide to solar panels on shed roof builds.
What solar makes through the year
The honest limit of shed solar is winter. These figures are from PVGIS (version 5.3), the European Commission's solar model, for a 1 kW south-facing array at a 35-degree tilt with standard system losses. Scale them to your panel size: a 200 W panel makes about a fifth of these numbers.
| Place | kWh per kWp per year | December, kWh per day | June, kWh per day |
|---|---|---|---|
| London | 1,019 | 1.17 | 4.09 |
| Cardiff | 1,042 | 1.04 | 4.37 |
| Manchester | 884 | 0.88 | 3.69 |
| Glasgow | 853 | 0.62 | 3.67 |
| Penzance | 1,099 | 1.08 | 4.51 |
December output is roughly a quarter to a sixth of June output depending on how far north you are. A shed used for lights and charging in the evenings can run on solar all year with enough battery; a garden office with a heater cannot, because heating needs far more energy than a shed-sized array makes in winter.
Mains or solar: side by side
| Mains cable from the house | Self-contained solar | |
|---|---|---|
| What it is | A new circuit from the house consumer unit to the shed | Panel, charge controller, battery and loads, all in the shed |
| Part P | Notifiable: registered electrician or a building notice before work starts | Outside the notifiable categories when nothing connects to the house supply |
| Winter | Same supply all year | Low output from November to January; size for your worst month |
| Running cost | Billed at your tariff (26.32p/kWh was the GB average cap rate for October to December 2026) | No bill for what the panel makes |
| Best for | Heating, kettles, all-day office use, big tools | Lights, charging, laptops, occasional tools |
What the shed will cost to run on mains
Running costs are simple arithmetic: watts times hours gives watt-hours, and every 1,000 watt-hours is one kWh on your bill. At the 26.32p per kWh GB average cap rate for October to December 2026:
- four 10 W LED lights for four hours an evening use 0.16 kWh, about 4p a night;
- a laptop and monitor drawing 100 W for eight hours use 0.8 kWh, about 21p a day;
- a 2 kW fan heater for four hours uses 8 kWh, about £2.11 a day.
The heater line is the one that changes the answer. A shed that only needs lights and charging costs pennies to run on mains, so the case for solar there is avoiding the new circuit, not the bill. A shed that needs winter heat costs real money on mains, and no shed roof can make that energy in December, which is why heated garden offices usually end up on mains however good the solar is in summer.
Questions to ask before you choose mains
If you are pricing a mains supply, ask the electrician how they will certify the work (competent person scheme or building notice), what cable and protection they propose for your route and why, whether the shed gets its own consumer unit, and whether the design leaves room to add a solar system or an electric vehicle charger later. If you are pricing solar, ask what it will make in December where you live, how many days of battery the design carries, and what happens when the battery runs flat.
How to choose
Start from the loads. List everything the shed will run, its wattage and hours a day, and add up the daily watt-hours; our worked examples on how many solar panels it takes to run a shed show the method. Then compare that figure with the December row for your area.
If the daily need sits comfortably under what a shed roof can make in December, a self-contained shed solar panel kit is usually the simpler route. If the shed needs heating, a kettle or all-day computing in winter, plan for a mains supply, or a grid-tied system that also feeds the house: that is electrician work and, above 16 A per phase (3.68 kW single-phase), needs a G99 application to the network operator before connection; smaller systems are notified under G98. Installed solar and battery storage are zero-rated for VAT until 31 March 2027, then 5%.
Many sheds end up with both answers over time: a small solar system now for lights and charging, and a mains supply later if the shed becomes a full-time office. Nothing in a 12 V solar setup is wasted if you add mains later; the panel and battery can keep running the lighting.
Questions
Can I run electricity to my shed myself?
A mains supply to a shed is a new circuit, and installing a new circuit is notifiable work under Part P of the Building Regulations in England. It must be done by an electrician registered with a competent person scheme, or notified to building control before work starts. Part P applies to outbuildings such as sheds and detached garages.
Do I need an electrician to put solar panels on a shed?
Not always. Part P applies where a building receives its electricity from a source within or shared with the house. A self-contained low-voltage system whose only source is the panel on the shed is a different job from a mains spur; our wiring page sets out where the line falls. Anything connected to the house supply is electrician work.
How much power does a shed solar panel make in winter?
Far less than in summer. PVGIS models a south-facing 1 kW array at a 35-degree tilt producing about 1.17 kWh a day in December in London, 0.88 kWh in Manchester and 0.62 kWh in Glasgow, against roughly 3.7-4.1 kWh a day in June. Size for the month you actually use the shed.
Is mains or solar better for a garden office?
For year-round daily use with heating, a mains supply (or a grid-tied solar system that also feeds the house) is usually the realistic route, because winter solar output is low. For lighting, charging and occasional tools, a self-contained solar kit often avoids the new circuit altogether.
Sources and last checked
Approved Document P (2013 edition incorporating amendments), gov.uk, read 19 October 2026. PVGIS v5.3 (European Commission JRC), 1 kWp, 35 degrees, south, 14% losses, read 19 October 2026. Ofgem price cap October to December 2026, GB average, checked 18 October 2026. HMRC VAT Notice 708/6, checked 18 October 2026. ENA EREC G98/G99 as summarised by the network operators, checked 18 October 2026.
Mains or solar for your shed?
Tell us what the shed has to run, how far it is from the house and how you use it through the year. We reply by email with the route that fits and a sized spec if solar does.