“How long does a solar panel installation take?” is really two questions. The first is how long will you be on my roof — for most houses, one to two days. The second is how long from enquiry to the panels generating — and that is a matter of weeks, because the on-site work sits inside a chain of survey, design, paperwork, scaffolding and a network operator who may need to answer before anyone climbs a ladder. Here is the chain, and the steps that stretch it.
The short answer: a day or two on site, several weeks door to door
A typical residential installation is on site for one to two days. The Energy Saving Trust describes a typical domestic system as around 4.5 kWp — around 12 panels over 20 to 30 m² of roof — and a system of that size takes a day for the roof work, with the electrical work and commissioning the same afternoon or the following morning. A bigger roof, awkward access or a battery fitted at the same time pushes it towards two.
The weeks come from everything around it: a survey, a design and quote to agree, scaffolding to book, and a network operator who has to be told about — or, for larger systems, approve — the new generator. That is why “a day or two” and “several weeks” are both honest answers.
The free survey: what it looks at
Everything downstream depends on the survey. It is free, it books through our residential solar panel installation page, and it checks five things.
The roof. Pitch, orientation, tile or slate type, the condition of the covering, and where the rafters run — panels are fixed to the rafters, not the tiles.
Shading. Chimneys, dormers, aerials, neighbouring buildings and trees, and how their shadows move through the day and the year. Shading changes a system’s output more than which town it is in.
The loft. Access, rafter spacing, where the inverter can go and how the cable gets to it.
The consumer unit. Whether it has a spare way for a dedicated circuit, its condition, the main fuse rating and the earthing arrangement.
Your usage. Annual electricity use from your bills, when in the day you use it, and whether an electric car is on the way. That sizes the system to the household rather than to the roof.
Design and the written, itemised quote
From the survey comes a design: panel count and layout, inverter size, whether a battery is included, cable routes and any consumer-unit work. The quote that follows should be written and itemised, so each of those is a line you can read rather than one number for “solar installed”. We have set out what each line means in what is in a solar quote, line by line, and what moves the total on our solar panel installation cost page, with a county worked example in solar panel costs in Bedfordshire.
The real number comes from the survey of your actual roof and usage, which is why we do not publish one; for an early indication of the saving side, the savings calculator is there.
The grid-connection step: G98 or G99
Every grid-connected system is registered with the distribution network operator — the company that owns the local cables, not your supplier. Under G98, type-tested generation of up to and including 16 A per phase, which is 3.68 kW, is simply notified: before commissioning, or no later than 28 days after it, counting the day of commissioning itself. We do the notification, and it does not hold the work up.
Anything above 16 A per phase takes the G99 route: an application the network operator has to approve before the work starts. The line sits lower than people expect — a 4 kW inverter is 17.39 A, just over it — so the inverter chosen at the design stage decides which side you fall on. Network operators run a fast-track route for small generation; SSEN, for example, says it aims to respond within 10 working days. That wait comes before the scaffolding can be booked, which is why a G99 job runs to weeks and why we lodge the application as soon as the design is agreed.
Scaffolding
Panels cannot be fitted safely from a ladder, so scaffolding goes up a day or two before installation day. It is booked around the install date and stays until the roof work is finished and checked, usually coming down within the following week. For you that means a short period of restricted access to one side of the house — and the scaffolding, not the installation, is the first thing you will see happen.
Installation day, in order
The sequence is the same for nearly every pitched roof.
- Roof hooks and rails. Tiles are lifted, brackets are screwed to the rafters, the tiles go back, and the mounting rails are fixed to the brackets. The panels end up anchored to the structure of the roof, not its covering.
- Panels. Clamped to the rails, wired together in strings, with the DC cabling run through to the loft.
- Inverter. Mounted in the loft, garage or a utility space, where it turns DC from the panels into mains AC.
- Cabling and the consumer unit. The AC cable runs from the inverter to the consumer unit, where it gets its own circuit and protective devices.
- A brief power-off. The supply is isolated to make that final connection — usually under an hour, and we will tell you when.
- Commissioning. Tests on the DC and AC sides, the inverter switched on, generation checked, monitoring set up, and a walk-through of the display.
From that point the panels are generating.
The paperwork afterwards, and why the MCS certificate matters
Once the installation is registered — which we do after commissioning — the MCS certificate and the electrical certification follow. A G98 notification is completed inside its 28-day window. Warranties are handed over at the same time: panels are designed to last 25 to 30 years, and inverters typically carry shorter warranties than panels.
The MCS certificate is the document to keep safe. The Smart Export Guarantee — the Ofgem scheme under which suppliers with 150,000 or more domestic customers must offer an export tariff — requires the installation and the installer to be MCS-certified (or an accredited equivalent) and a meter capable of half-hourly export readings. Without it, you cannot be paid for what you export. Rates are set by each supplier, must be above zero, and change on short notice, so we never quote one; compare them once the certificate is in your hand. We are NAPIT member 73495 and a HIES Consumer Code member (HCE/A/1392), with MCS certification for solar PV via NAPIT, so the certificate follows every installation we register.
What slows a job down
Four things, each with its own clock.
- G99 approval. Above 16 A per phase, the work cannot start until the network operator says yes.
- Roof repairs first. If the survey finds a covering that needs repair before it can carry panels for their design life, that work comes first.
- Listed building consent. Permitted development does not apply to listed buildings or buildings in their curtilage; consent is a separate application with its own timetable. How that plays out with one set of councils is in our planning permission guide for Bedfordshire.
- A flat roof on protected land. Most pitched-roof installations on houses are permitted development — panels must not protrude more than 0.2 m from the roof slope — but a flat-roof array on article 2(3) land (conservation areas, National Landscapes, National Parks, the Broads, World Heritage Sites) needs the council to determine whether prior approval of its appearance is required, before work starts.
An Article 4 direction on a particular street can also remove roof rights; we read the direction before we design.
The 0% VAT window, and why the timeline should not drift
Residential installations of solar panels and batteries are zero-rated for VAT in Great Britain until 31 March 2027; from 1 April 2027 the rate reverts to the reduced 5%. If a G99 approval or a listed building consent is in your chain, start it now rather than let the quote sit. The same logic applies to battery storage: fitting it alongside the panels costs less than a separate visit later, and keeps both inside the window.
The specifics — your roof, your consumer unit, your network operator — are what the survey is for, and that is where our solar panel installation service begins.
Sources: Energy Saving Trust, “Solar panels: costs, savings and benefits explained” (updated 27 August 2026) and “Battery storage” (updated 19 August 2026); ENA Engineering Recommendation G98 Issue 2 (10 March 2025), with SSEN’s published fast-track response time; Ofgem’s Smart Export Guarantee guidance; HMRC VAT Notice 708/6; the Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2 Part 14 Class A, as amended by S.I. 2026/896 (in force 27 August 2026). On-site durations, the scaffolding sequence and the installation-day order are standard installation practice, not published statistics.