Solar Farm Electrical Safety: Managing Arc Flash, Isolation and Electrical Risk

Solar farms play an increasingly important role in the UK’s energy infrastructure. However, the electrical systems that generate, convert, and distribute power across these sites pose risks that must be understood and managed throughout the installation’s life.

From photovoltaic (PV) panels and DC cabling to inverters, transformers, switchgear, and high-voltage distribution networks, solar farms comprise a combination of electrical equipment that requires appropriate safety management, maintenance, and working procedures.

One of the key challenges is that solar PV panels can continue generating electricity as long as they are illuminated. Switching off an inverter or isolating one part of the installation does not necessarily mean every conductor is safe to touch.

Arc Flash, electric shock, inadequate isolation, equipment deterioration, and gaps in electrical safety management can all expose workers to serious harm if not properly controlled.

At Electrical Safety UK (ESUK), we have supported organisations in assessing electrical safety arrangements across large solar farm installations. Our experience has highlighted the importance of looking beyond individual pieces of equipment and considering how the entire electrical installation is managed.

So, what should operators, owners, and those responsible for electrical safety consider?

Why is electrical safety important on solar farms?

Solar farms have characteristics that distinguish them from many conventional industrial electrical installations.

Their modular design can make some aspects of inspection, assessment and maintenance more straightforward. However, large sites may contain hundreds or thousands of similar PV strings, multiple inverter stations, transformers, DC and AC distribution equipment, and connections to a wider electrical network.

A consistent equipment design does not automatically mean that every item presents the same risk. Fault levels, protection arrangements, cable routes, operating conditions and maintenance history can vary across the installation.

Solar farm operators should consider several key areas of electrical risk:

• Arc Flash: an electrical fault can release intense heat and energy, potentially causing severe burns, blast injuries and equipment damage.
• Electric shock: contact with live conductors, including DC circuits, can result in serious injury or fatality.
• Isolation: PV modules and associated circuits can remain energised even when other parts of the system have been disconnected.
• Equipment condition: damaged insulation, loose connections, contamination, moisture ingress or deteriorating enclosures can increase risk.
• Competence and authorisation: personnel need appropriate knowledge, experience, supervision and authorisation for the work they undertake.
• Electrical safety management: procedures, maintenance arrangements and risk assessments must reflect the actual installation and its operating conditions.

These risks should be considered as part of a structured electrical safety management system, rather than being addressed only when maintenance or repair work is required.

Solar PV isolation: why switching off is not enough

One of the most important electrical safety considerations on a solar farm is the behaviour of photovoltaic equipment during isolation.

PV modules generate DC electricity when exposed to light. Depending on the installation, this can mean that cables and equipment on the module side of an isolation point remain energised even when an inverter has been shut down.

The precise isolation requirements depend on the system design, the location of the work and the equipment involved.

Before work begins, those responsible must identify the equipment to be worked on, understand all relevant sources of electrical energy and establish a safe system of work.

This may involve considering:

• PV strings and DC cabling.
• DC isolators and inverter inputs.
• AC supplies and transformer connections.
• Auxiliary and control supplies.
• Backfeeds from other parts of the installation.
• Stored electrical energy, including energy retained in capacitors.
• Automatic or remote switching arrangements.
• Other generation or energy storage systems connected to the site.

An isolation procedure must account for the actual electrical arrangement, not simply the operation of a single switch.

Where equipment is to be worked on dead, suitable precautions must be taken to secure the isolation, prevent inadvertent re-energisation and verify that the relevant conductors are not live.

The Electricity at Work Regulations 1989 are particularly relevant here. Regulation 12 addresses the means of cutting off the supply and isolation, while Regulation 13 covers precautions to prevent equipment made dead from becoming electrically charged during work.

The practical arrangements must be appropriate to the equipment, the work activity and the risk involved.

Proving dead and selecting the correct test equipment

Safe isolation depends on more than identifying and operating an isolator.

Personnel must follow the appropriate procedure to establish that the equipment they intend to work on is safe. This includes using appropriate test equipment and verifying that no voltage is present at the point of work.

Voltage indicators should be suitable for the circuit and the conditions in which they are being used. They should be checked using an appropriate proving unit immediately before and after testing, in accordance with the relevant procedure and equipment manufacturer’s instructions.

The test method must also account for the characteristics of the system. DC and AC circuits may require different equipment or testing arrangements, and the test instrument must be suitable for the voltage and measurement category involved.

Solar farms can contain long cable runs, multiple isolation points and circuits that remain energised from the PV array. These factors make it particularly important to ensure that the correct conductors have been identified and that the test is performed at the intended point of work.

A procedure that works for one part of a solar farm may not be sufficient for another.

Switching equipment off is not the same as proving it is dead.

Clear isolation procedures, accurate electrical drawings, competent personnel and effective supervision all help ensure that the process is carried out consistently.

Arc Flash risk on solar farms

Arc Flash is a serious electrical hazard that should be considered wherever the electrical system and working activity could expose personnel to an arc event.

An Arc Flash can occur when electrical current flows through an unintended path, releasing intense heat and potentially producing pressure effects, molten material and damaging projectiles.

The consequences can include severe burns, permanent injury, equipment destruction, fire and significant operational disruption.

On a solar farm, Arc Flash risk may need to be assessed across equipment such as:

• AC switchboards and distribution panels.
• Inverter output equipment.
• Transformers and associated switchgear.
• Main distribution boards and auxiliary supplies.
• DC equipment where the relevant fault conditions and working activities create an Arc Flash hazard.
• Collector systems and site substations.
• Grid connection equipment.

The risk depends on factors including the electrical system configuration, available fault current, protective device performance, fault-clearing time, equipment design and the task being undertaken.

It should not be assumed that all equipment on a solar farm presents the same level of risk. Equally, a relatively small item of equipment should not automatically be considered safe because of its size or location.

A suitable assessment needs to consider the installation and the circumstances in which people may interact with it.

Why an Arc Flash study matters

An Arc Flash study can help an organisation understand the potential Arc Flash hazard associated with equipment within the assessment’s defined scope.

Depending on the agreed scope, the work may include collecting and verifying electrical system data, developing a network model, calculating prospective fault currents, reviewing protective device performance and determining incident energy and Arc Flash boundary information.

The findings can help identify where further assessment or risk reduction measures may be appropriate.

For solar farms, a modular design may enable modelling of representative sections of the installation and applying the findings to other equipment where the relevant design and electrical conditions are demonstrably equivalent.

However, this approach must be validated. Differences in cable lengths, protective devices, transformer arrangements, fault contributions and network configuration can affect the results. The scope and cost of a study will therefore depend on the quality of available data, the complexity of the installation and the level of analysis required.

An Arc Flash study should not be treated as a one-off exercise that remains valid regardless of subsequent changes. Significant alterations to equipment, protection settings or the electrical network may require the assessment to be reviewed.

Electrical enclosures and electric shock protection

Inverters and other electrical enclosures are distributed throughout a solar farm. Their condition and the protection they provide are important considerations during inspection, maintenance and fault-finding activities.

The original design may incorporate barriers, shrouds or enclosure protection to reduce the risk of accidental contact with hazardous live parts. However, protection can be compromised by damaged covers, missing fixings, incomplete reassembly or modifications made during maintenance.

Where protection equivalent to IP2X is part of the required design or risk controls, it should be maintained and verified as appropriate. The suitability of the enclosure and protection measures must be assessed against the equipment, the environment and the work being carried out.

Operators should consider whether:

• Enclosure doors, covers and barriers are intact.
• Shrouds and internal protective barriers have been correctly reinstated after maintenance.
• Cable entries and seals remain in suitable condition.
• Equipment is protected against foreseeable environmental exposure.
• Defects are recorded and corrected through a controlled process.
• Workers understand the limitations of the protection provided.

These checks should form part of a planned inspection and maintenance programme, rather than relying solely on visual checks when equipment is opened for work.

Electrical safety management: the wider picture

Technical controls are essential, but they are only one part of effective electrical safety management.

Solar farms may be owned by one organisation, designed and installed by another, and operated or maintained by a third-party contractor. Responsibilities must be clearly defined so that electrical risks do not fall between organisational boundaries.

The organisation responsible for the installation should ensure that appropriate arrangements are in place for its safe operation and maintenance. This includes identifying who has authority over electrical work, how contractors are managed and how the condition of the electrical system is monitored.

A comprehensive Electrical Safety Management System (ESMS) should address the arrangements relevant to the site, including:

• Electrical safety policy and responsibilities.
• Electrical safety rules and authorisation.
• Competence, training and supervision.
• Risk assessment and safe systems of work.
• Isolation, switching and earthing procedures where applicable.
• Tools, test equipment and test leads.
• Asset integrity, inspection and maintenance.
• Arc Flash and electric shock risk management.
• Management of contractors and changes to the installation.
• Incident reporting, investigation and learning.
• Electrical drawings, records and technical documentation.
• Periodic audits and corrective action tracking.

The arrangements should be proportionate to the installation and the risks involved. Generic procedures are unlikely to be sufficient if they do not reflect the equipment, site layout and work activities.

An independent audit can help identify gaps between documented arrangements and what actually happens on site. It can also provide a structured basis for prioritising improvements.

UK electrical safety legislation and guidance

Solar farm owners, operators, employers and contractors need to understand the legal duties relevant to their activities.

The principal UK legislation and guidance to consider includes the following.

Electricity at Work Regulations 1989

The Electricity at Work Regulations 1989 establish requirements for electrical systems and work activities to prevent danger, so far as is reasonably practicable.

Relevant provisions include:

• Regulation 4: systems, work activities and protective equipment.
• Regulation 5: the strength and capability of electrical equipment.
• Regulation 6: equipment exposed to adverse or hazardous environments.
• Regulation 12: means of cutting off the supply and isolation.
• Regulation 13: precautions for equipment made dead.
• Regulation 14: work on or near live conductors.
• Regulation 15: working space, access and lighting.
• Regulation 16: competence to prevent danger and injury.

The applicable requirements depend on the circumstances. Compliance cannot be established simply by having a written policy or completing an electrical safety audit.

Management of Health and Safety at Work Regulations 1999

These Regulations are also relevant to the management of electrical risks. They include duties relating to risk assessment, the organisation of preventive and protective measures, information, cooperation and team member capabilities and training.

For solar farm operators, this underscores the need to assess foreseeable risks and establish appropriate arrangements to manage them.

HSE guidance

The Health and Safety Executive’s guidance, The Electricity at Work Regulations 1989: Guidance on Regulations (HSR25), helps dutyholders understand the Regulations’ requirements.

HSE publication HSG85, Electricity at work: Safe working practices, also provides guidance on safe working practices for people working on or near electrical equipment and those managing electrical work.

These sources should be considered alongside the installation’s design information, equipment instructions, applicable technical standards and the organisation’s own electrical safety rules.

There is no single document or certificate that, by itself, demonstrates that every electrical risk on a solar farm is adequately controlled. The arrangements must be suitable for the installation and the activities being undertaken.

Maintaining electrical safety as a solar farm develops

Solar farms can change considerably during their operational life.

Equipment may be replaced, inverter stations upgraded, transformers changed, protection settings adjusted or additional generation and storage connected. Maintenance activities can also reveal defects that require changes to the original design or operating arrangements.

These changes may affect the electrical risk and should be managed through a suitable change-control process.

An organisation should consider reviewing relevant assessments, drawings and procedures when:

• Electrical equipment is added, replaced or modified.
• The network configuration or grid connection changes.
• Protective devices or their settings are altered.
• New battery energy storage or other generation is connected.
• Inspection identifies damage or deterioration.
• An electrical incident or significant near miss occurs.
• Existing procedures no longer reflect the work being undertaken.

The frequency of formal reviews should be determined by the applicable requirements, the risk profile, changes to the installation and the organisation’s management arrangements. A fixed review interval should not be treated as a substitute for reassessment when significant changes occur.

Keeping electrical records accurate and accessible is particularly important where several organisations are involved in operating and maintaining the site.

Questions every solar farm operator should ask

A useful starting point is to review whether the current electrical safety arrangements reflect the real conditions on site.

Ask:

• Are electrical safety responsibilities clearly defined between the asset owner, operator and contractors?
• Are isolation procedures specific to the PV installation and its energy sources?
• Do workers understand which parts of the system may remain energised after switching?
• Is suitable test equipment available, maintained and used correctly?
• Have Arc Flash and electric shock risks been assessed for relevant equipment and tasks?
• Are enclosures, barriers and shrouds inspected and reinstated after maintenance?
• Are electrical drawings, protection settings and equipment records current?
• Are personnel competent and authorised for the activities they undertake?
• Are incidents, defects and near misses investigated and acted upon?
• Is there an effective process for reviewing risk when the installation changes?

If the answers are unclear, a structured electrical safety review can help establish the current position and identify where improvements may be needed.

How ESUK can support solar farm electrical safety

Electrical Safety UK supports organisations in understanding and managing electrical risk across complex installations.

For solar farms, our services can include electrical safety management reviews and audits, Arc Flash studies, electrical system studies, risk management advice and training.

We can help assess existing arrangements, identify gaps, explain technical findings and develop practical recommendations to support safer operation and maintenance.

The aim is not simply to produce another report. It is to help organisations understand their electrical risks, establish appropriate controls and maintain effective arrangements as the installation develops.

Take the next step towards safer solar farm operations.

Are your electrical safety arrangements appropriate for your solar farm? Do your isolation procedures reflect the behaviour of the PV system? Are your Arc Flash assessments and electrical records still representative of the installation?

ESUK can help you review your current arrangements and identify where further work may be beneficial.

Contact our team to arrange a free initial consultation.

Telephone: 0800 652 1124
Email: info@elecsafety.co.uk
Website: https://elecsafety.co.uk/about/contact/

Electrical safety should be built into the way a solar farm is designed, operated and maintained. A clear understanding of the risks is essential to protecting people and supporting reliable operation.