How Long Does Solar Installation Take? UK Timeline Guide

The most common question homeowners ask before going solar is not “how much does it cost?” — it is “how long will my house be disrupted?” The honest answer is that the physical installation takes just one or two days, but from accepting a quote to generating your first kilowatt-hour, the total timeline is typically four to twelve weeks. That range reflects installer backlogs, scaffolding availability, and — crucially — whether your system needs prior approval from your Distribution Network Operator (DNO). Here is a stage-by-stage breakdown of everything that happens between signing on the dotted line and watching the monitoring app climb.

Stage 1 — Pre-installation survey (week 1–4)

What happens. After you accept a quote, your MCS-certified installer books a physical site survey. An engineer visits your home — usually for around one hour — to assess roof condition and orientation, structural integrity, shading from trees or neighbouring buildings, and your consumer unit’s capacity. The survey feeds the final system design and confirms the panel layout, inverter spec, and expected yield.

Timing. Most installers schedule the survey within one to three weeks of your deposit. The design sign-off and ordering of equipment typically adds another few days. For a 4–6 kWp system on a standard semi-detached, there are rarely surprises at this stage — but if your roof needs repairs or your fuse board is outdated, factor in extra time.

Stage 2 — DNO notification or approval (days to 9+ weeks)

This is the stage that most affects your total wait. Before your system can be commissioned, it must be registered with your local DNO under one of two Engineering Recommendations set by the Energy Networks Association.

G98 — notify after installation

Systems up to 3.68 kW on a single-phase supply (16 A per phase) fall under Engineering Recommendation G98. Your installer can proceed with the installation and simply notify the DNO within 28 days of commissioning. There is no waiting period — the system can go live immediately. Most standard domestic arrays of three to eight panels qualify.

G99 — prior approval required

Systems above 3.68 kW single-phase — which includes the majority of modern 4–6 kWp residential systems — require Engineering Recommendation G99 approval before installation begins. The DNO has up to 45 working days (approximately nine weeks) to assess the application. A fast-track route exists for straightforward “Small Generation Installations” and can shorten this to around two weeks, but it is not available in all network areas or for all configurations. If your system includes a battery, G99 is almost always required regardless of solar-only capacity.

The practical upshot: if your installer submits the G99 application before booking the scaffold and crew, the DNO clock runs in parallel with your wait for an install slot. Good installers manage this automatically — ask them to confirm the G99 was submitted when you sign the contract, not the week before install.

Stage 3 — Scaffolding erection (half a day, 1–2 days before install)

What happens. A scaffolding contractor erects access towers and edge protection around the relevant roof slope. For a typical two-storey semi-detached this takes around half a day. The scaffold usually goes up one to two days before the installation crew arrives, and stays in place for a total of around one week — stripped within a day or two of the panels being fitted.

Seasonal note. Scaffolders are frequently fully booked from March through August when demand peaks. If you are planning a spring or summer installation, your installer may need to book the scaffolding contractor several weeks ahead. This is one of the main reasons the total timeline stretches during the busy season. Booking in autumn or winter often means shorter waits and occasionally more competitive quotes.

Stage 4 — Installation day (1–2 days)

What actually happens on the day. For a standard 4–6 kWp system on a pitched roof, the installation crew typically completes everything in one day; larger or more complex systems may run to two days. The sequence is roughly:

1. Mounting rail and fixings — brackets are fixed through the roof tiles into the rafters; mounting rails are bolted on.
2. Panel installation — monocrystalline panels are clipped onto the rails and DC cabling is run down through the roof void.
3. Inverter fitting — usually in the loft or on an internal wall near the consumer unit; converts DC output to 230 V AC.
4. AC cabling and consumer unit connection — a dedicated solar circuit is added to your distribution board. Expect a power outage of one to two hours while the electrician works on the consumer unit — plan around this if you work from home.
5. Smart meter / CT clamp — a clamp-type sensor is fitted around the incoming supply cable to measure import and export, feeding your monitoring app.
6. Commissioning and handover — the system is switched on, output is verified, and you are walked through the monitoring app. On a good day, you will see generation figures within minutes of the inverter going live.

All MCS-certified installers must test to BS 7671 standards and issue an Electrical Installation Certificate alongside the MCS certificate. Check that you receive both before the crew leaves. Understanding whether your system uses string inverters, microinverters, or optimisers is worth doing before install day — it affects where cabling runs and how granular your monitoring will be.

Stage 5 — Scaffolding removal and final paperwork (days 2–5 post-install)

What happens. The scaffolding contractor returns to strip the access towers — usually within two to three days of the installation completing. Your installer should also submit the G98 or confirm the G99 is closed, register the system with the MCS database, and apply for your Smart Export Guarantee (SEG) tariff if you want to be paid for surplus electricity exported to the grid. The SEG application is separate and handled directly with an energy supplier; approval typically takes a few working days to a few weeks depending on the supplier.

If you want to compare current export rates before your install, see our SEG rate comparison to pick the best tariff from day one.

Full timeline summary

Putting it all together, here is what a typical residential installation looks like:

The lower end (four to six weeks) applies to G98-eligible systems booked in autumn or winter with a prompt installer. The upper end (ten to twelve weeks) applies to G99 systems booked during the spring/summer peak, where DNO and scaffolding queues stack up.

What can cause delays?

Beyond the DNO wait, a handful of factors regularly extend timelines. Roof repairs — replacing a few broken tiles is the most common — must be completed before the scaffold goes up. Listed-building or conservation-area properties may need permitted-development confirmation. Supply chain delays on specific inverter or panel models can add a week or two; a good installer will flag this early and offer alternatives. Finally, adverse weather can push scaffold erection or the install itself by a day or two, though the crew will work on most “British weather” days.