Health, safety and regulatory requirements for small scale solar PV
The DC side changes the rules
A PV array is a current-limited source that is live whenever there is daylight. There is no functional switch at the module, so the only way to make the DC side safe for work is to isolate, lock off, prove dead and cover or otherwise control the array. A DC arc has no natural zero crossing, so it does not self-extinguish the way an AC arc does - this is why DC-rated switchgear, correct polarity and tight, correctly crimped connectors matter so much. Work at height, roof access and manual handling fall under the Work at Height Regulations, CDM (for larger projects) and the Electricity at Work Regulations.
The regulatory map a candidate must know
- BS 7671 - Section 712 (PV power supply systems) plus Section 551 (low voltage generating sets).
- Building Regulations Part P - a new PV circuit in a dwelling is notifiable work.
- Parts A and L - structural loading of the roof, and the SAP/energy calculation for new dwellings.
- DNO connection - G98 covers single-phase installations up to 16 A per phase and is a notify after commissioning process (within 28 days); G99 covers larger schemes and needs approval before connection.
- MCS 001 / MCS 012 - certification of the contractor and the installation standard. Not statute, but needed for the Smart Export Guarantee and most grant schemes.
- IET Code of Practice for Grid Connected Solar PV Systems - design and installation guidance.
- WEEE / PV Cycle - disposal routes for inverters and modules.
Traps
MCS being described as a legal requirement (it is not); assuming Part P notification also notifies the DNO (it does not); believing a DC isolator makes the array dead; forgetting that a roof with modules is a both-sides-live installation for a firefighter or a later electrician.
Rule of thumb
If it can see the sky, treat it as live. Prove dead at the point of work, not at the isolator handle.