DRAFT: Safety of Alternatives to Onsite Diesel: Things to Consider - Solar PV
Date Posted: 3 March 2023
The drive to reduce carbon and other airborne emissions from onsite diesel requires alternative sources of energy onsite. In the context of safety, a series of 'Things to Consider' guides are being produced for various alternatives. These are currently drafts, for industry input. This draft covers onsite use of site solar PV.
The following information is currently a draft for industry consultation* – the initial deadline for comments (to email@example.com) is 1 September 2023.
Solar photovoltaic (PV)
Solar PV may be deployed onsite to provide temporary off-grid or supplementary power for:
- Lighting, fans and ventilation
- Other small onsite power, including communications/wireless
- Equipment that needs external power to start
- Various rechargeable small equipment batteries
Systems can supply usable onsite energy and utility can be enhanced with onsite battery storage, load shifting (e.g. supplementary EV charging) or available grid supplies. The two main types of site solar energy systems are:
- site installed PV - requiring installation activity onsite; and
- self-contained unit - delivered to site, requiring less site set-up (may include generator emergency backup).
In addition to the PV modules (panels), essential system components include DC connectors, isolators, inverters, power optimizers, combiners and junction boxes.
- Electric shock
- Electrical fire
- WAH/fragile surfaces
- Manual handling and other injury
- Extreme weather
Example causes of electrical failure to danger can range from poor equipment configuration/connections to water ingress, lack of inverter cooling and damage to equipment.
PV modules generate DC electricity in sunlight and when modules are connected in series the voltage hazard increases. Situations including water ingress and poor connections can lead to DC or AC shock.
Overall, electrical fire due to voltage overload or other system stress is very rare, but poor design and/or installation can increase the risk. In the event of an electric arc, fire may spread to surrounding site materials.
The PV system and its components require competent design for the required onsite electrical load; competent installation (including connection, sealing, isolation); and monitoring.
Onsite, it is particularly important to protect all DC and AC cabling from potential damage.
Water ingress into electrical components and equipment can lead to failure and electrical danger.
Weatherproofing such as IP65 enclosure must not be compromised.
Ensure safe isolation, including lock off, and that information to enable safe isolation is readily available to competent persons and emergency services. Isolation does not stop a PV module from producing DC, but it can prevent AC elsewhere in the system.
To help protect workers:
- assume all PV contacts and wires are live/energised until testing confirms otherwise;
- ensure effective isolation; and
- use insulated gloves and tools.
- IP68 ‘MC4’-type DC connectors are now commonly used on UK PV installations - both halves of the connector are ‘touch-proof’, improving installation and maintenance safety.
Although PV systems are not prone to fire, causes can include:
- poor installation practice, including compromised waterproofing (e.g. via top-mounted cable entries to an isolator)
- other damage, including corrosion
Incorrectly specified or designated DC isolators are a prevalent cause of failure.
Certain PV components, if incorrectly specified/manufactured or poorly installed, may generate an arc. To help prevent arcing, do not disconnect PV module connectors (even MC4 connectors) or cables when the module is under load.
Work at height/fragile surfaces
For all activity at height (e.g. on a container, cabin top) and/or fragile surfaces, even if short duration:
- ensure effective safety precautions (safe system of work);
- ensure a competent person has confirmed the supporting surface can safely take the weight of the required workers and equipment;
- signpost, cordon and sufficiently cover any hazards in and around supporting surfaces, as necessary
- use a non-conductive ladder if working near power sources.
- Ensure the PV system is working before removing any required elevated access.
Panels can be heavy, bulky and fragile. They may also become hot to the touch.
Poor or unprotected manual handling can lead to:
- hand injury (sharp edges, hot surfaces)
- chronic or acute musculoskeletal injury
- dropping the panels - a damaged module (which may include internal damage) can lead not only to operational failure but also electrical danger.
Remembering that PV modules produce DC when in sunlight – take all necessary precautions to avoid touching module terminals.
Take site conditions and site/WAH access fully into account when moving PV equipment.
Use mechanical handling for site unloading, movement, lifting access and installation, wherever possible. If manual handling of larger panels is required, any manual lifting/movement should be shared.
Ensure the PV system:
- is from a reputable manufacturer/supplier who can offer any necessary technical support
- meets the necessary product Standards and is installed, operated and monitored according to product and manufacturer specifications
- is designed to meet the energy and other requirements of the site
- is manufactured to the appropriate British Standard or industry accepted equivalent
- holds UKCA/CE markings
Before bringing PV onto site, consider onsite factors such as:
- sufficient and safe access for delivery, installation and maintenance.
- a stable base to site the system on
- site PV and its electrical cabling away from hazards such as moving vehicles and equipment, flammables. and excessive dirt/dust;
- the safety and integrity of electrical cabling.
- BS 7671 Wiring Regulations and s. 704 (Construction and Demolition Site Installation)
- any need for access and work at height is considered/communicated in advance of delivery.
- the PV system meets any site insurance requirements.
Although PV is naturally intended to operate outdoors, ensure the supporting structure and entire electrical system is able to withstand rain and high winds.
An emergency fire-fighting plan should include electrical isolation (e.g. inverter/isolator switches), suitable fire-fighting equipment, site cordoning/personnel exclusion zones, and effective communication with emergency services.
Competency, training and information
Anyone working on the installation and maintenance of solar PV must be competent to carry out their role. This is particularly important for anyone connecting, isolating, fault finding and monitoring the PV system, in addition to anyone involved in equipment handling and work at height. A competent electrician should test and commission an installed system.
- Information should be readily available on how to safely isolate the system, along with a system diagram that includes the inverter location.
- Warning signs should show:
- key points of DC and AC electrical hazard
- any access hazards.
PV modules generate DC electricity as soon as they receive solar energy, leading to electrical danger at the terminals.
- keep panels packed as long as possible – where possible, open in the shade and cover the panel with opaque material until ready to install
- do not touch the terminals when modules are exposed to sunlight
- keep operational panels as clean as possible.
- PV panels are protected from damage at all times.
- a system of continual system monitoring and testing, by a competent person, to include:
- visual inspection of the system for corrosion and damage
- system AC and DC monitoring - including continuity, voltage and current test, and fault identification.
Protective equipment (PPE)
Insulating gloves should be worn during electrical work, or in emergency.
To protect from handling injury, workers should wear suitable gloves, clothing and safety footwear.
Only trained and competent personnel should engage in PV system firefighting. Fire fighters must understand and prevent the risk of:
- electric shock from the system/cables
- injury due to any weakened supporting surfaces
Fire extinguishing materials may include carbon dioxide and dry powder (avoid water near any energized electrical system).
References/sources of further information
(to develop - examples below, which should include links).
- IET CoP Grid connected Solar PV systems 2nd edition
- FPA/RISCAuthority RC 62: Recommendations for fire safety with PV installation v2.
- Solar OEM guide Solar Energy UK
- BS 7671 IET Wiring regulations.
- IET Code of Practice for Grid-connected Solar Photovoltaic Solutions
- Electricity at Work Regulations
- MCS MUS3002 Solar PV Standard
- BS7671 (latest Wiring Regulations)
- HSE guide to fragile surfaces
To follow at end of consultation.
© ECA 2023 CONIAC: *draft - not for reproduction or adaptation without written permission. This content is solely to highlight various safety issues for consideration. None of this content constitutes official/industry guidance or in any way seeks to replace or supersede existing official/industry guidance.