The quick answer
A standard 4 kW solar system is installed in 1–2 days — but from accepting a quote to generating your first kilowatt-hour, allow 4–12 weeks. The gap is made up of installer backlogs, scaffolding availability, and — for systems over 3.68 kW — the DNO approval that can take up to 45 working days.
The key insight: the roof work is the fast part. The waiting is in the survey, the DNO paperwork and the install slot. Understanding this upfront stops you being surprised.
Step-by-step process
Step 1 — Survey and quote (week 1–3)
An MCS-certified installer assesses your roof (condition, orientation, shading), your consumer unit, and your usage. The survey takes about an hour and feeds the final system design. You'll get a written quote within a few days.
Step 2 — DNO application (days to 9+ weeks)
Your system must be registered with your Distribution Network Operator. Systems up to 3.68 kW use G98 (fit-and-notify, no waiting). Systems above that use G99 (prior approval, up to 45 working days). A good installer submits this when you sign, so the clock runs while you wait for an install slot.
Step 3 — Scaffolding (half a day)
Scaffolding goes up 1–2 days before install, usually costing £400–£700 (included in most quotes). It stays up for about a week total.
Step 4 — Installation day (1–2 days)
Roof rails and fixings first, then panels, then the inverter (usually in the loft or near the consumer unit), then cabling and a generation meter. Most 4 kW systems finish in a single day.
Step 5 — Commissioning, MCS and SEG
After testing, you get your MCS certificate (essential for SEG), wiring certificates, warranties and the monitoring app. Then you register for SEG payments with your chosen supplier.
G98 vs G99: the DNO step
This is the step most people don't know about — and it's the biggest variable in your timeline:
| G98 | G99 | |
|---|---|---|
| System size | Up to 3.68 kW (single-phase) | Above 3.68 kW |
| Process | Install, then notify (within 28 days) | Prior approval required |
| Waiting | None — go live immediately | Up to 45 working days |
| Typical for | 3–8 panels | Most 4–6 kW systems, any battery |
If your system includes a battery, G99 is almost always required regardless of the solar-only capacity — so factor the DNO approval into your timeline.
Realistic timeline
| Stage | Time |
|---|---|
| Survey + design + quote | 1–3 weeks |
| DNO (G98: no wait / G99: 45 working days) | 0–9 weeks |
| Scaffolding + install slot | 1–4 weeks |
| Physical install | 1–2 days |
| Commissioning + MCS + SEG | a few days |
Busy season (March–August) stretches the install slot; autumn/winter often means shorter waits and sometimes better quotes.
Planning permission
In England, roof-mounted solar is usually permitted development — no planning permission needed, provided panels don't protrude more than 200 mm from the roof plane. Exceptions: listed buildings and conservation areas may need consent.
Why MCS matters
MCS (Microgeneration Certification Scheme) certification is the non-negotiable. It's required for:
- Qualifying for SEG payments (export income)
- Most grid-connection agreements
- Keeping your warranties valid
Always use an MCS-certified installer. A cheap non-MCS install locks you out of SEG permanently — costing you far more than you saved.
Common pitfalls
- Paying 100% upfront — a deposit of 10–25% is normal; never the full amount.
- Not checking the G99 was submitted — ask your installer to confirm the DNO application went in when you sign, not the week before install.
- Comparing quotes that aren't like-for-like — check panel brand, wattage, inverter, and whether scaffolding/DNO/MCS are included.
- Skipping MCS — it's the gateway to SEG and warranties.
Size your system first
Know how many panels you need before you start getting quotes.
Calculate panels →FAQ
Will the install disrupt my home?
Minimally. The roof work is external, and the inverter is usually fitted in the loft or garage. Most homeowners are home during the install but not disrupted — it's one day of roof work, not a renovation.
Can I install in winter?
Yes — installers work year-round. You'll see lower output for the first few months, then a rapid climb in spring. Winter installs can mean shorter waits and the 0% VAT (to March 2027) applies regardless of season.
How long until I start getting paid for export?
After handover you register for SEG with your chosen supplier, which takes 2–4 weeks. Your MCS certificate and an export-capable smart meter are the two requirements.
Sources: MCS standards, Energy Networks Association (G98/G99), installer timelines (2026). Figures verified August 2026. Timelines vary by installer, region and season.
Disclaimer: this guide is for general information only. Planning rules and DNO requirements vary by location — confirm with your installer and local authority.