DIY Shed Solar or an Installer? How to Decide

The legal line comes first

Start with what you are allowed to choose. A fully off-grid DC system — panels, controller, battery, 12V/24V loads, even an isolated 230V inverter — is yours to build; Part P does not apply to extra-low-voltage islands, as set out on the wiring and Part P page. The moment the project connects to the house supply, adds a fixed mains circuit, or feeds the grid, the choice disappears: that is registered-electrician work, and grid-tied systems additionally need MCS certification for Smart Export Guarantee eligibility and a G98 notification to the network operator — paperwork an accredited firm like MCS installer Green Hat Renewables handles as a matter of routine. Nobody DIYs Tier 4. The real decision space is Tiers 1–3.

Where DIY wins

For a £200 lighting kit, an installer's day rate would triple the project cost for work a careful adult can do with a spanner and the instructions. Even at the £1,200 workshop tier, self-installation saves £300–£600 of labour and — more valuably — leaves you understanding a system you will inevitably want to modify. Off-grid systems grow: a second panel next spring, a bigger inverter when the pillar drill arrives. The owner who built it upgrades it in an afternoon; the owner who had it installed phones for quotes. The component knowledge in the kit guide and battery guide is genuinely sufficient for these tiers.

Where DIY quietly fails

The failure pattern is consistent and worth naming. It is almost never electrocution — extra-low voltage protects you there. It is fire and roof damage. Unfused battery positives run through timber walls; 30A flowing through 2.5mm² cable because the kit shipped it; self-tappers through the roof felt without sealing washers, found two winters later as a rotten purlin; panels held by adhesive pads that let go in a February gale. Every one of these is avoidable with the practices on the wiring page, and every one appears weekly on shed forums. The honest self-test: if crimping a ring terminal, sizing a fuse, and sealing a roof penetration all sound like things you would do carefully rather than look up reluctantly, you are a DIY candidate. If not, paying a professional £300 to do the mounting and wiring on parts you supply is a respectable middle path many people never consider.

Four questions that settle it

One: does the system touch the mains? If yes, installer, no further discussion. Two: is the roof high, steep, fragile, or the panel array heavy? Working at height turns cheap jobs expensive the moment it goes wrong — a single-storey pent roof is one thing, a two-storey gable over a patio another. Three: is the building insured or insured-adjacent? A garden office holding £3,000 of computer equipment deserves professional-grade wiring sign-off even where the law does not demand it, if only for the insurance conversation after any incident. Four: do you actually want the project? Some people light up at the prospect of a weekend with a crimping tool; others want light in the shed by Friday. Both are valid, and pretending otherwise wastes either money or enthusiasm.

Costs for both routes are itemised on the costs page. If you are still split, describe the project through the contact form — we will tell you plainly which side of the line it sits on, including when the answer is "pay someone."