Shed Solar Kits: 12V, 24V, or Grid-Tied?
Almost every shed solar decision collapses into one question: which of three system architectures fits your loads? Get that right and the component choices mostly make themselves. This page sets out what each kit type is, what it genuinely runs, and the point at which it stops being the right answer.
The 12V off-grid kit — where nearly everyone should start
A 12V kit is the bicycle of shed solar: simple, cheap, and hard to get badly wrong. A typical package pairs a 100–200W panel with a PWM or MPPT charge controller, a 12V battery, and a fused distribution block feeding DC loads directly — LED light strips, USB charging sockets, a small fan, a PIR security light. Because everything runs at extra-low voltage and never touches the house mains, the whole installation is a legitimate DIY job; the Part P guide explains why.
Sizing is forgiving at this scale, but the winter rule still applies. A 100W panel in southern England produces around 60–80Wh on a grim December day — enough for three hours of LED lighting and a phone charge, and not much else. If the shed gets evening use all year, step up to 200W of panel and 100Ah of battery from the start; the extra £80–£120 is far cheaper than replacing an exhausted undersized battery in February.
The ceiling of a 12V system is current. Power equals volts times amps, so a 600W inverter on a 12V bank pulls 50A and demands genuinely thick cable, proper crimped lugs, and close attention to fusing. Once your ambitions pass roughly 300W of panel or 500W of continuous load, the physics is telling you to change architecture.
The 24V workshop system — for tools and serious storage
Doubling system voltage halves the current for the same power, which is the entire argument for 24V. Cable gets thinner, fuses get saner, charge controllers handle twice the panel for the same amp rating, and inverters run more efficiently. A representative workshop build is 400–800W of panel on the shed roof, a 24V/100Ah LiFePO4 battery, an MPPT controller, and a 1,500–2,000W pure sine wave inverter feeding a small consumer unit with 230V sockets.
That system runs a chop saw, a router, battery chargers for cordless tools, decent lighting, and a laptop — though not all simultaneously, and the inverter surge rating decides which motors will start at all. Budget £700–£1,500 depending mostly on battery chemistry, and read the battery options guide before choosing, because the battery is half the spend and nearly all of the regret potential.
One honest warning: heating. A 2kW fan heater flattens a 100Ah/24V battery in under an hour and a half. Off-grid solar heat is a fantasy at shed budgets — insulate the building, wear a jumper, or take the grid-tied route below.
The grid-tied route — when the shed is really a second room
If your garden building is an office, studio, or gym in daily use, off-grid stops making sense and a professionally installed grid-tied system takes over. Panels on the outbuilding (or house) roof feed a string or micro-inverter, power flows into your home's supply, and surplus exports to the grid under the Smart Export Guarantee — typically earning 4–15p per kWh depending on tariff. Because it is supply-and-install on a residential property, the whole job carries 0% VAT until 31 March 2027, which materially narrows the price gap against DIY kit bought at 20% VAT.
Expect £2,500–£4,500 for a 2–3kWp installation depending on scaffold access and inverter choice, and insist on an MCS-certified installer — without MCS paperwork most SEG tariffs will not sign you up. The economics, including payback against a £1,000 mains-spur alternative, are worked through on the garden office power page and the costs page.
The three shed solar architectures compared
| 12V kit Lights & charging | 24V system Workshop tools | Grid-tied Garden office / daily use | |
|---|---|---|---|
| Typical panel array | 100–200W | 400–800W | 2–4 kWp |
| Installed cost | £150–£300 | £700–£1,500 | £2,500–£4,500 |
| Legal DIY install | |||
| Runs 230V power tools | |||
| Works in a power cut | Usually not | ||
| SEG export income | |||
| 0% VAT | |||
| Needs MCS installer |
What to check before buying any kit
Four quick filters separate decent kits from landfill. First, controller type: MPPT controllers harvest 20–30% more from the same panel than PWM, and matter most in winter — worth the premium beyond 100W. Second, inverter waveform: pure sine wave only, because modified sine wave inverters cook motor windings and confuse electronics. Third, battery chemistry honesty: any kit quoting lead-acid capacity without mentioning 50% depth of discharge is marketing to you, not engineering for you. Fourth, cable and fuse sizing in the box — a kit that ships 2.5mm² cable for a 30A circuit has already told you everything about its designer.
If you would rather send us your load list and get a straight answer on which tier you are in, use the contact form — we reply within one working day with a spec, not a sales pitch.