Solar Installations and CDM 2015: What the Business Must Do as Client
Updated 10 November 2026 · SEO Dons Editorial
Is the business the client on a solar project?
Usually, yes. HSE defines a commercial client as any individual or organisation that carries out a construction project as part of a business, and says client duties apply in full to commercial clients whatever the project size. CDM 2015 defines construction work to include the installation, commissioning, maintenance, repair or removal of electrical services normally fixed within or to a structure, a description that fits a rooftop array fixed to a building.
The client is the party the project is carried out for, so on a leased building or under a power purchase agreement more than one party may qualify. Where there is more than one client, they may agree in writing that one is treated as the only client, although each still owes duties to cooperate and to pass on information it holds. Settle that early, in writing, with the landlord or funder. HSE guidance (L153) and a solicitor can help on a given arrangement.
What must the client do before work starts?
HSE summarises the commercial client's duties on every project as follows:
- make suitable arrangements for managing the project, including allocating enough time and other resources;
- appoint contractors and designers who have the skills, knowledge, experience and organisational capability for the work;
- provide pre-construction information to every designer and contractor bidding or appointed;
- make sure suitable welfare facilities are provided for the duration of the work;
- make sure the contractor, or principal contractor, prepares a construction phase plan before work begins;
- make sure a health and safety file is prepared, kept up to date and available for later work.
The practical difficulty on a solar job is the second and third points. For competence, the installer vetting checklist shows the evidence to ask for. For information, regulation 2 defines pre-construction information as information in the client's possession, or reasonably obtainable by or for the client, that is relevant to the work, covering the project, its planning and management, and health and safety hazards, plus any existing health and safety file.
| Pre-construction information | Why it matters on a rooftop PV job |
|---|---|
| Asbestos register and survey reports | Fixings, cable routes and plant openings disturb the roof and fabric; HSE says asbestos information should reach contractors early, for example when requesting a quote |
| Roof drawings, structure and loadings | Set the array layout and the lifting and edge arrangements |
| Roof covering, fragile areas and rooflights | The main fall hazard, and often hidden by paint or poor light |
| Electrical intake, switchgear and isolation points | Live services the work will connect to or pass near |
| Site operations: traffic, hours, work going on below the roof | The plan must account for the industrial activities taking place on the site |
| Any existing health and safety file | Part of the defined pre-construction information |
The feasibility study guide lists how to gather these.
When are a principal designer and principal contractor needed?
Only when more than one contractor is, or is reasonably foreseeable to be, working on the project at any time. Then the client must appoint, in writing, a designer with control over the pre-construction phase as principal designer and a contractor as principal contractor, as soon as practicable and before the construction phase begins. If the client fails to appoint, the client must fulfil their duties. HSE's notification page adds that on a notifiable project with only one contractor the client does not need to appoint either. The Building Regulations add their own dutyholder duties for the client, and the building regulations guide explains how they sit alongside CDM 2015 on a rooftop project.
A rooftop project often reaches the threshold even when one firm leads it. For example, an installer who brings in a scaffolding firm, a crane or telehandler hire company and an electrical subcontractor has several contractors on the same site. A sole-contractor project means the single contractor prepares the construction phase plan. HSE also notes that one organisation can hold more than one dutyholder role if it has the skills, knowledge, experience and organisational capability for each, so the installer may be proposed as both designer and principal contractor. Put the roles in the contract. The installation guide shows where appointments fall in the programme.
What should the construction phase plan cover on a roof?
Under regulation 12 the plan must set out health and safety arrangements and site rules, taking account of the industrial activities on the site, and include specific measures for work involving particular risks. Schedule 3 lists work that puts workers at risk of falling from a height where the risk is particularly aggravated by the nature of the work or the environment. For solar the plan should address four things.
- Fragile surfaces. HSE says to treat all roofs as fragile until a competent person confirms otherwise, and that falls through fragile surfaces, particularly fibre-cement roofs and rooflights, account for 22% of all fall from height fatal injuries in construction. Expect rooflight covers or barriers and a stated route for people and materials.
- Edges. HSE says flat roof edges can be protected by a secure double guardrail and toeboard, and sloping roofs need scaffolding to prevent falls from the edge.
- Lifting. The Lifting Operations and Lifting Equipment Regulations 1998 require every lifting operation to be properly planned by a competent person and appropriately supervised, so pallets of modules need a lift plan, not an improvised hoist.
- Live DC. An IET article says DC-side equipment should be considered energised even when the inverter is disconnected from the DC or AC sides. Regulation 14 of the Electricity at Work Regulations 1989 restricts working on or near live conductors where danger may arise, so ask how strings will be isolated and made safe.
HSE adds that on business premises contractors should work closely with the client and agree arrangements. The client's operations continue below the roof, so ask to see the plan before work begins; CDM requires the client to ensure it exists first.
Does the project have to be notified to HSE?
Only if the work is scheduled to last longer than 30 working days with more than 20 workers at once at any point, or to exceed 500 person days; a commercial client then notifies HSE through its online notification form. A small crew over a few weeks, for example, would sit below both limits.
What stays with the client after commissioning?
The health and safety file stays available for later work, and if the client disposes of its interest in the structure it must pass the file to the new owner and make them aware of its purpose. HSE says a commercial client's responsibility for health and safety issues arising from maintenance and use of the building continues until it disposes of its interest. Later inverter replacement or repair falls within the same definition of construction work, so the arrangements apply again; the commissioning guide covers what belongs in the handover file.
Sources
- Health and Safety Executive: Managing health and safety in construction (L153); Commercial clients; Are you a commercial client?; Principal designers; Are you a principal contractor?; Summary of duties; Notification of construction project; Roof work; Fragile surfaces; Asbestos: provide information, checked 22 October 2026.
- legislation.gov.uk: CDM Regulations 2015, regulation 2; regulation 4; regulation 5; regulation 6; regulation 12; Schedule 3; LOLER 1998, regulation 8; Electricity at Work Regulations 1989, regulation 14, checked 22 October 2026.
- IET: Wiring Matters, March 2025: unearthed DC solar PV systems, checked 22 October 2026.
Common questions
Does CDM apply to a small rooftop installation?
Yes. CDM 2015 applies to construction projects of every size, and HSE says client duties apply in full to commercial clients whatever the project size. What scales with the project is the effort: HSE says planning should be proportionate to the complexity and the risks.
Who is the client if a funder owns the system under a PPA?
It depends on who the project is carried out for, and more than one party can qualify. CDM lets multiple clients agree in writing that one is treated as the only client, while each still owes duties to cooperate and share information. Agree this in the contract and take advice on the arrangement.
Can the installer act as principal designer?
Possibly. HSE says an organisation can carry out more than one dutyholder role if it has the skills, knowledge, experience and organisational capability for each. The client remains responsible for appointing in writing and for checking that capability.
What happens if the client appoints no principal designer or principal contractor?
Where more than one contractor is involved, regulation 5 makes the client fulfil the principal designer or principal contractor duties itself if it fails to appoint. That is why most clients appoint, and write the roles into the contract.