Solar panels and batteries: costs and choosing an installer

Hiring solar panel and battery installers means checking permissions, sequencing professionals correctly, and vetting quotes carefully to avoid costly mistakes.

SP-01What the job actually involvesSolar panels sit on your roof and generate electricity from daylight. An inverter turns that into power you can use, and a battery stores spare power for the evening or for days with less sun. Some households also add an EV charger to the same system. You're not doing any of this yourself — you're hiring a team to survey, design, and fit it.

SP-02Permissions you need to checkMost houses, and since August 2026 most blocks of flats, can have panels fitted under permitted development. You need planning permission if the building is listed, if panels would go above the highest part of the roof, or in a conservation area if they would sit on a wall or roof facing the road. Building Regulations cover the electrical work, which an installer registered with a competent person scheme certifies, and the roof's ability to take the weight. Your electricity network operator (DNO) must be told about the system: for a typical home system within 28 days of it being connected, and for a larger one, before connection.

RULES

KNOW THE RULES

Planning permission may be required outside permitted development rights. Building Regulations cover structural and electrical safety, and a registered electrician should self-certify the electrical work. Telling the network operator is a required step, not optional. HomeGraft has a separate 'Know the rules' guide on this.

SP-03Who to hire, and in what orderStart with an MCS-certified solar installer for a site survey — they'll check your roof's condition, orientation, shading and your existing electrics. If the survey flags a weak roof, old slates, or a flat roof, bring in a structural engineer before anyone commits to a price. If repairs are needed, a roofer should finish those before panels go up. The installer's own Part P-registered electrician handles the wiring, and the installer notifies the DNO before connection.

RULES

KNOW THE RULES

Electrical work connected to solar and battery systems falls under Part P. It must be done or certified by a registered electrician.

SP-04Realistic costs and timescalesFor an average three-bedroom house outside London, expect roughly £6,500-£8,500 for solar panels alone (around 4kWp), or £10,000-£14,000 with a battery added. Larger systems, EV charger integration, or a three-phase electrical upgrade can push this past £18,000. London and the South East typically cost more. What pushes a job to the top of the range: roof reinforcement, scaffolding for a complex or steep roof, a bigger battery, and difficult access. From first survey to switch-on usually takes 4-12 weeks, mostly survey, design and scheduling, plus network operator approval for larger systems; the physical installation is normally 1-3 days. Residential solar installations currently qualify for 0% VAT — check the current rules on GOV.UK before you budget.

SP-05What a good quote should containA proper quote names the system size in kWp, the exact panel, inverter and battery models, and separate warranty lengths for each (panels often 20-25 years, inverters and batteries usually shorter). It should state the installer's MCS certification number, confirm who carries out the structural check, and show scaffolding costs as a separate line. It should also confirm who registers you for the Smart Export Guarantee, which pays you for power you export — check current payment rates on Ofgem or GOV.UK, not from the installer's sales pitch.

SP-06Questions to ask, and red flagsAsk: can I see your MCS certificate and number, who checks my roof's strength, what happens if the DNO limits or rejects my connection, and what's the exact warranty on the battery and inverter? Red flags: cold-calling or door-knocking salespeople, pressure to sign the same day, a deposit above 25-30%, no MCS certification, vague 'estimate' pricing instead of a fixed quote, and no mention of an insurance-backed guarantee.

SP-07What commonly goes wrongThe most common problem is discovering after installation that the roof wasn't strong enough, which should have been checked beforehand. DNO delays or capacity limits in your area can stall connection for weeks. Batteries fitted in unventilated spaces or near escape routes create fire-safety problems that should have been spotted at survey stage. Underperforming systems are often down to shading that wasn't properly assessed, and disputes over scaffolding costs are common when they weren't itemised in the quote.

SP-08If you live in Wales, Scotland or Northern IrelandIn Wales, permitted development and Building Regulations rules are broadly similar to England, but check with your local planning authority if you're in a conservation area or listed building. In Scotland, a building warrant usually isn't needed if the roof can take the extra weight; if it needs strengthening, it is. In Northern Ireland, Building Regulations (NI) apply and planning rules differ, so check with your local council before booking any work.

RULES

KNOW THE RULES

In Scotland, a building warrant is needed if the roof has to be strengthened. Northern Ireland has its own Building Regulations and planning system. Confirm requirements with the relevant local authority before work starts.

KNOW THE RULES

Before you start: Do I need planning permission for solar panels? · Which electrical jobs can I do myself? Part P explained

Save this as a project

Back to all guides