As of early 2025, according to Solar Power Portal, the UK’s total installed solar capacity was around 18–18.1 GW across approximately 1.78 million installations.
According to EcoAim, there are over 200,000 commercial and industrial solar panel installations in the UK.
Installing commercial solar panels is not as simple as plugging in a new coffee machine. It’s a process of assessments, permits, equipment delivery, and professional installers climbing over your roof. But here’s the good news: with the right strategy and execution, the process can be smoother than you think. In this guide, we will understand what to expect, how long the procedure is to install, and a few tips that can get your solar panels up and running faster without complications.
What is the Average Timeline for Commercial Solar Panel Installation?
The time to install commercial solar panels differs according to the size of the system, building type, and local regulations. Generally, a full commercial solar panel installation takes approximately 2 to 12 weeks from start to finish. Let’s understand the key steps in more detail.
1. Site Assessment and Feasibility Study (1–2 Weeks)
An installer will take a thorough assessment of your commercial property before placing an order for panels. The assessment involves going through roof or ground space, analysing structural integrity, shading issues, and energy requirements. Moreover, the installer will have a look at your current energy consumption to strategise a system that fits your needs perfectly.
2. Design and Engineering (1–2 Weeks)
Once the installer thoroughly checks the site, the design team will create a customised layout for solar array. This involves panel placement, wiring routes, and inverter positions. For huge complex projects, this stage may include structural calculations and detailed engineering plans for safety purpose and compliance with building regulations.
3. Permitting and Approvals (1–6 Weeks)
Getting approvals for planning and electrical work can vary depending on your local council and how complex the system is. Some councils process applications quickly, whereas others might take upto several weeks. Preparing early and providing proper documentation can essentially reduce delays at this stage.
4. Equipment Procurement (1–3 Weeks)
Once the permissions are approved, the required solar panels, inverters, mounting systems, other materials are ordered. Lead times can fluctuate depending on supplier availability especially for larger commercial orders or specialised equipment.
5. Physical Installation (2–7 Days for Small, 1–3 Weeks for Large Systems)
The main process of installation involves mounting panels, connecting wiring, installing inverters, and integrating the system with your building’s electrical setup. A small system setup on the roofs approximately takes under a week, while complicated or large installation may take several weeks.
6. Inspection and Grid Connection (1–2 Weeks)
Once installed, the system must be inspected to ensure compliance with safety standards and building regulations. Following approval, the system is connected to the national grid, tested, and commissioned. Only after this stage can your solar panels begin generating electricity officially.
Total Average Duration:
- Small to Medium Installations: 2–4 weeks
- Large or Complex Installations: 6–12 weeks
By understanding each phase, businesses can plan operations effectively, avoid unnecessary downtime, and ensure a smooth transition to solar energy.
What To Consider Before Installing Commercial Solar Panels?
Before speaking to a professional installer there are a few key points your business can consider to assess the suitability of a commercial solar installation.
Structural Considerations
A roof-mounted commercial solar panel installation adds a weight of 10–25 kg/m² for 25+ years so it is essential to ensure your building can safely support this load. Before proceeding with a commercial solar installation it is important to consider the following factors that may make the installation more challenging:
- Asbestos sheet roofs – These often need to be replaced if this area is to be used for mounting commercial solar panels.
- Roofing in poor condition – Deteriorating roof spaces may not be able to support mounting systems securely.
- Timber-frame roofs – Timber-framed roofs, common in older buildings, may have a lower load capacity.
- Limited access – Roofs without ladders or access hatches can make it difficult for installers to work safely, increasing the need (and cost) of scaffolding.
On-Site Power Usage Profile
An investment in a commercial solar panel installation is likely to be most effective where:
- Peak daytime consumption – A large proportion of electricity is consumed during daylight hours, when solar panels generate the most power.
- Consistent consumption – The more stable your power usage profile, the more efficiently solar panels can reduce your electricity bills.
The initial consultation phase will review the on-site power usage profile of your business to determine the feasibility of on-site solar generation.
Financial Viability
Commercial solar panel installations require a significant upfront investment but should produce a positive return on investment over the lifetime of commercial solar equipment. For your business to benefit from this investment it will need to continue occupying the property in the long term.
Factors That Affect Installation Time
| Factor | How It Affects Installation Time |
| System size and capacity | Larger systems need more panels, wiring, and labour, thus increasing installation time |
| Roof type and condition | Complex, flat, or ageing roofs may need extra mounting or repairs |
| Structural assessments | Engineering checks and reinforcements can delay the start of work |
| Planning permission | Approval processes may add weeks to the project timeline |
| Grid connection approval | DNO approvals or grid upgrades can cause significant delays |
| Existing electrical infrastructure | Upgrades to switchgear or metering increase installation duration |
| Weather conditions | Poor weather can halt or slow installation for safety reasons |
| Site access and logistics | Limited access or working-hour restrictions slow progress |
| Installer experience | Skilled teams complete installations more efficiently |
| Health and safety requirements | Safety planning and equipment add preparation time |
| Equipment availability | Delays in panel or inverter supply affect schedules |
| Project management | Poor coordination can lead to avoidable delays |
Tips to Speed Up Your Commercial Solar Project
- Carry out early site, roof, and electrical assessments
- Engage with planning authorities at an early stage
- Secure DNO grid connection approval in advance
- Choose an experienced commercial solar installer like Arc Renewables
- Finalise system design before installation begins
- Order equipment early to avoid supply delays
- Prepare the site and access routes in advance
- Plan installation around business operations
- Appoint a dedicated project manager
- Monitor progress regularly to address issues quickly
Conclusion
The installation of commercial solar panels is a complex and dynamic process that includes careful planning, detailed design, and precise execution. While the actual installation process of panels takes only a few days but the entire process from planning to final operation can take up to several months. Getting to know each phase and prepare accordingly can help ensure a smooth and successful transition to solar energy, ultimately leading to a long-term savings and sustainability benefits.
Worried about choosing the right solar panel installer? The team at Arc Renewables is very professional in installing solar panels. The provide support at each phase of installation and tailor services that cater to your needs. If you planning a new project where you want to install commercial solar panels, Arc Renewables will help you install with expert guidance.
Frequently Asked Questions
Is planning permission required for commercial solar panels?
In most cases, commercial solar panels are allowed under Permitted Development Rights and therefore do not require planning permission. However, you may need permission if:
- The building is listed or located in a conservation area.
- Panels will project significantly from the roof.
- The installation is ground-mounted.
What’s the lifespan of a commercial solar system?
Commercial solar systems are designed to last between 25 and 30 years, with the panels typically covered by a performance warranty of 25 years. Inverters require more frequent replacement, usually lasting between 10 and 15 years.
How much roof space do I need?
A standard commercial solar panel requires approximately 2 square metres (21.5 square feet) of space. The number of panels needed depends on the electricity consumption of your commercial property. A single panel will produce, on average, 1.5 to 2 kWh per day in Britain.
Can I install solar on a leased building?
Yes, but only with the landlord’s written permission. You may also need to amend your lease to cover:
- Roof access rights.
- System ownership and maintenance.
- Removal terms at the end of the lease.
How long does a commercial solar installation take?
The full commercial solar installation process typically takes 2 to 4 months from contract to commissioning, broken down into the following stages:
- Design, approvals, and DNO consent: 4–12 weeks
- Equipment ordering and preparation: 2–3 weeks
- On-site installation: 1–3 weeks
Larger or more complex projects may take longer, particularly if grid upgrades or planning permission are required.
Will the installation disrupt business operations?
Most of the physical work for a commercial solar installation takes place on the roof, so it is unlikely to disrupt day-to-day operations. A temporary power outage will be required to connect the system to the mains distribution board, but in larger buildings, this is usually isolated to specific areas.