Commercial solar panel installation in the UK
A commercial solar installation runs from desktop survey to switch-on in typically 3-6 months, with 1-12 weeks of actual work on site depending on system size. This guide walks through each stage, the timescales to expect, and what your business needs to provide at each step.
The six stages of a commercial solar installation
1. Desktop survey and feasibility
Using 12 months of half-hourly electricity data and bills, we model system size, self-consumption and payback before anyone visits site. This stage decides whether the project stacks up at all.
2. Site and structural survey
A physical survey confirms roof condition, purlin spacing, access, switchroom capacity and cable routes. A structural engineer checks the roof can carry the array; this is non-negotiable on commercial roofs.
3. Design and DNO application
The electrical design is finalised and the grid application submitted. Small systems use the G98 notification route; larger ones need G99 approval, which has a statutory response window of up to 45 working days.
4. Procurement and pre-construction
Panels, inverters and mounting are ordered (lead times of 2-6 weeks are typical), scaffolding and access are planned, and CDM duties are discharged. Most disruption planning happens here, not on the roof.
5. Installation
Mounting, panels, DC and AC cabling, inverters and metering go in. On-site time is typically 1-2 weeks for 50 kWp, 3-4 weeks for 100 kWp and 8-12 weeks for 1 MWp or more. Businesses almost always stay fully operational.
6. Commissioning and handover
Electrical testing, DNO witnessing where required, monitoring setup and a handover pack with warranties, schematics and O&M instructions. A short power-down of a few hours is normally needed for the final grid tie-in.
Typical timescales by system size
Indicative UK ranges from signed order to energisation. The grid application, not the roof work, is usually the critical path.
| System | Typical timescale |
|---|---|
| 50 kWp rooftop | 1-2 weeks on site; 8-12 weeks total |
| 100 kWp rooftop | 3-4 weeks on site; 3-4 months total |
| 250 kWp rooftop | 4-6 weeks on site; 3-5 months total |
| 500 kWp rooftop | 6-8 weeks on site; 4-6 months total |
| 1 MWp and above | 8-12 weeks on site; 5-9 months total |
| DNO G99 approval | Up to 45 working days (statutory) |
Managing disruption during installation
Most commercial installations complete with zero downtime. The measures that make that possible are agreed before work starts, not improvised on the scaffold.
- Access planning. Scaffolding, MEWPs and material lifts are positioned to keep fire escapes, loading bays and car parks working.
- Out-of-hours working. Noisy or intrusive tasks are scheduled for evenings or weekends where the operation requires it.
- One planned power-down. The final grid tie-in needs a short outage, typically 2-4 hours, booked around your production or trading hours.
- CDM compliance. A commercial roof is a construction site. Your installer should discharge CDM duties, produce risk assessments and manage subcontractors without involving your team.
What to read next
Frequently asked questions
How long does commercial solar panel installation take?
On-site work runs 1-2 weeks for a 50 kWp system and 8-12 weeks for 1 MWp or more. The full project from signed order to first generation is typically 3-6 months, with DNO grid approval usually the longest single item.
Can installation happen while the business keeps operating?
Almost always yes. Roof work, scaffolding and cabling are planned around operations, and weekend or out-of-hours working is standard where needed. The only planned interruption is a short power-down, typically 2-4 hours, for the final grid connection.
What does a commercial solar installation cost?
Installed costs are indicatively £650-£1,100 per kWp depending on system size, roof condition and grid works, with the per-kWp figure falling as the array grows. Our cost guide sets out full benchmarks by system size.
What does my business need to provide?
Twelve months of half-hourly electricity data and bills for the feasibility model, roof access for surveys, and a point of contact for facilities. Our supplier-by-supplier guide explains how to get the data from your electricity supplier.
Do I need planning permission for installation?
Most rooftop commercial arrays in England fall under permitted development, but listed buildings, conservation areas and ground-mounted schemes are common exceptions. A site-specific check is quick and worth doing at feasibility stage.
Who handles the grid connection?
Your installer manages the DNO application end to end: G98 notification for small systems, G99 for larger ones, plus any export limitation scheme if the local network is constrained. You should never need to speak to the DNO directly.
Read next
Related guides & sector pages
Choosing a commercial solar installer
12-point checklist for shortlisting installers.
Read GuideHow to get your half-hourly data and bills
Supplier-by-supplier steps for your desktop survey pack.
Read GuideRoof & structural survey
The pre-construction checks that de-risk your project.
Read SectorWarehouses & logistics
Large-roof solar for 3PLs and distribution hubs.
ReadPlan your commercial solar installation
Share your site details and preferred programme. We will assess the likely installation route, grid-connection timetable and how work can be planned around your operation. Prefer to explore numbers yourself first? Run the calculator or contact us directly.
- Indicative project programme
- Likely DNO route identified
- Disruption and access reviewed