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Solar Power Systems Risk Assessment: Electrical, Fire, Design and Site Risks

A worked example of how an installer finds, scores and controls the risks in a rooftop solar project, from electrical shock, falls and fire to design faults, maintenance, suppliers and legal duties.

Updated November 2026 8 hazards assessed Review every 6 months Highest risk: Critical to Medium
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Executive summary

This assessment shows how a small solar installer can find, rate and control the risks that matter most on a rooftop project. Eight risks were chosen because they are plausible in design, installation, commissioning and service. Electric shock, falls from height and fire carry the highest severity because they can kill or injure people. Design faults and maintenance gaps are more likely but cost output and money. Each risk is scored before controls and again after existing and added controls. Most risks fall to Medium or Low once added controls are in place, while electrical and height risks stay at Medium because the harm could still be severe. The first actions are an isolation and test procedure, edge protection, connector checks and a permit checklist. The installer is a teaching example, so every score illustrates method, not a real company.

Focus area
Solar power systems
Setting
Small company installing and servicing rooftop solar systems on commercial buildings
Method
Five by five likelihood and impact risk register

Scope

This assessment covers the design, installation, commissioning and service of a rooftop solar system on a commercial building. It looks at risks to people, equipment, output, contracts and the environment. It does not cover large ground-mounted plants or the market price of electricity. Location, system size and equipment are assumptions made for teaching.

Context

The installer has a design engineer, an electrical supervisor, a site supervisor, a small crew and a procurement lead. A typical job fits panels, mounting, cables, an inverter and monitoring to a flat or pitched roof and connects to the building supply. Work moves from survey and design to purchase, installation, commissioning and service visits. Each risk is scored before controls to show its natural level, then again after existing controls and the controls that should be added.

Objectives, assets and stakeholders

The objective is to install a safe and reliable solar system that meets its design output, protect everyone who works on or near it, and meet the legal duties that apply. The assets in scope are the people on site, the building, the modules, inverter and cabling, the monitoring data, the installer reputation and the owner investment. Stakeholders include the crew, the supervisors and engineers, the building owner and occupants, the grid operator, suppliers, inspectors and emergency responders. Clear roles matter: every risk has one owner role, and the electrical supervisor keeps the register current and reports to the company director.

Risk matrix: before and after controls

Each cell shows hazard numbers placed by likelihood and impact. Compare the two grids to see how controls move each hazard.

Before controls

Inherent risk

Risk before controls: rows are likelihood from almost certain to rare, columns are impact from insignificant to catastrophic. Cells list hazard numbers.
1
Insignificant		 2
Minor		 3
Moderate		 4
Major		 5
Catastrophic
5 Almost certain
4 Likely Likelihood 4, impact 3, score 12, high: H05 Likelihood 4, impact 5, score 20, critical: H01
3 Possible Likelihood 3, impact 3, score 9, medium: H06 Likelihood 3, impact 4, score 12, high: H04 H07 H08 Likelihood 3, impact 5, score 15, high: H02 H03
2 Unlikely
1 Rare

After controls

Residual risk

Risk after controls: rows are likelihood from almost certain to rare, columns are impact from insignificant to catastrophic. Cells list hazard numbers.
1
Insignificant		 2
Minor		 3
Moderate		 4
Major		 5
Catastrophic
5 Almost certain
4 Likely
3 Possible
2 Unlikely Likelihood 2, impact 2, score 4, low: H05 H06 Likelihood 2, impact 3, score 6, medium: H04 H07 H08 Likelihood 2, impact 4, score 8, medium: H01 H02 H03
1 Rare
  • Low 1 to 4
  • Medium 5 to 9
  • High 10 to 16
  • Critical 17 to 25

Hazard register

A summary first, then the detail for each hazard.

Summary of hazards with scores before and after controls
No.HazardBeforeAfterOwner
H01 Electric shock and DC arc during installation and service 20 Critical 8 Medium Electrical supervisor
H02 Falls from roofs, ladders and access routes 15 High 8 Medium Site supervisor
H03 Fire from connection faults, hot spots and stored energy 15 High 8 Medium Commissioning engineer
H04 Design or component failure 12 High 6 Medium Design engineer
H05 Maintenance gaps and declining reliability 12 High 4 Low Operations manager
H06 Supplier and site dependencies 9 Medium 4 Low Procurement lead
H07 Standards, permits and legal duties 12 High 6 Medium Compliance lead
H08 Weather, wind, lightning and environmental exposure 12 High 6 Medium Design engineer
H01

Electric shock and DC arc during installation and service

Safety Before 20 After 8

Solar modules produce direct current whenever light falls on them, so an installer who opens a connection or touches a live conductor can suffer shock, burns or an arc that is hard to extinguish.

Who or what is affected: Installers, electricians and service technicians

Causes

Panels that stay live in daylight, rushed work and connectors that are mismatched or damaged.

Consequences

Serious burns, shock, a stopped job and a possible investigation.

Existing controls

  • Insulated tools and gloves are issued to the crew.
  • A qualified electrician signs off the electrical work.

Control gaps

Test-before-touch is taught but not checked on site, so it depends on habit.

Additional controls

  • Prevent: Use a written isolation and test-before-touch procedure for every DC and AC connection.
  • Detect: Check rapid shutdown and isolation devices at commissioning and record the result.
Likelihood 4 x impact 5 before; 2 x 4 after Owner: Electrical supervisor Target: Within 30 days Early warning: A crew member who works on a string without a recorded isolation and test.
H02

Falls from roofs, ladders and access routes

Safety Before 15 After 8

Roof work exposes crews to edges, fragile surfaces, wet or hot modules and awkward lifting of panels, and a fall can cause serious injury or death.

Who or what is affected: Installers, laborers and site visitors

Causes

Pressure to finish before weather changes, missing edge protection and panels carried by hand.

Consequences

Fatal or life changing injury, a stopped site and legal action.

Existing controls

  • Ladders are inspected before use.
  • Crews wear harnesses on steep roofs.

Control gaps

Harness use is expected but anchor points are not always checked or planned.

Additional controls

  • Prevent: Install edge protection or guardrails before panel work and plan safe routes for lifting panels.
  • Respond: Prepare a rescue plan for a worker suspended in a harness and rehearse it.
Likelihood 3 x impact 5 before; 2 x 4 after Owner: Site supervisor Target: Within 30 days Early warning: Roof work started without a checked anchor point or edge protection.
H03

Fire from connection faults, hot spots and stored energy

Safety Before 15 After 8

Loose connectors, damaged cables, shaded cells and faulty inverters or batteries can overheat, and a fire on a roof is difficult to reach and may involve live equipment.

Who or what is affected: Building occupants, firefighters and owners

Causes

Poor crimping, mixed connector brands, cables rubbed by roof edges and blocked ventilation.

Consequences

Building fire, injury, loss of the system and an insurance dispute.

Existing controls

  • Connectors are of the type the module maker specifies.
  • Smoke alarms are installed in the building.

Control gaps

Thermal imaging is done at handover only, not after the first season of operation.

Additional controls

  • Prevent: Torque and inspect every connector and use thermal imaging after commissioning.
  • Respond: Label isolation points clearly and give emergency responders a site plan.
Likelihood 3 x impact 5 before; 2 x 4 after Owner: Commissioning engineer Target: Within 45 days Early warning: A thermal image that shows a connector or cell much hotter than its neighbors.
H04

Design or component failure

Operational Before 12 After 6

Wrong string sizing, an inverter that does not suit the array, undersized cables or defective modules cause low output, repeated trips or early failure.

Who or what is affected: Owners, installers and the grid operator

Causes

Rushed designs, unfamiliar equipment and shortcuts in cable sizing to reduce cost.

Consequences

Low energy yield, warranty disputes, rework and loss of customer trust.

Existing controls

  • A design check is made against the module and inverter data sheets.
  • Components come with maker warranties.

Control gaps

The second review is optional on small jobs, where mistakes are just as likely.

Additional controls

  • Prevent: Have a second engineer review string design, voltage limits and cable sizing before purchase.
  • Detect: Compare measured output with the design estimate at commissioning and after the first month.
Likelihood 3 x impact 4 before; 2 x 3 after Owner: Design engineer Target: Within 45 days Early warning: Output in the first month that falls well below the design estimate.
H05

Maintenance gaps and declining reliability

Operational Before 12 After 4

Dust, bird droppings, loose fixings, failed fans and unnoticed faults lower output over time, and a fault can stay hidden until a bill or a failure reveals it.

Who or what is affected: Owners, operators and service technicians

Causes

No set schedule, remote sites and no one watching the output data.

Consequences

Lost output, hidden faults, shorter equipment life and warranty claims refused.

Existing controls

  • Panels are cleaned when the owner notices a drop.
  • The installer offers a service visit on request.

Control gaps

Monitoring is available but alerts are not assigned to a person.

Additional controls

  • Prevent: Set a scheduled maintenance plan with inspection, cleaning and torque checks.
  • Detect: Use monitoring alerts for low output and inverter errors and check them each week.
Likelihood 4 x impact 3 before; 2 x 2 after Owner: Operations manager Target: Within 60 days Early warning: An inverter fault code or output drop that stays open for more than a week.
H06

Supplier and site dependencies

Supplier Before 9 After 4

Late deliveries, wrong parts, substandard components and unready sites delay the project, and a single supplier or access problem can stop all work.

Who or what is affected: Project manager, installers and the client

Causes

One supplier for key parts, long lead times and site access that is not confirmed.

Consequences

Idle crews, penalties, rushed substitutions and poor quality equipment.

Existing controls

  • Orders are placed early for main equipment.
  • The site is visited before work is quoted.

Control gaps

Certificates are filed but not checked against the items that arrive.

Additional controls

  • Prevent: Qualify suppliers, check certificates on delivery and keep a second source for key items.
  • Detect: Track delivery dates against the plan and flag any delay on the critical path.
Likelihood 3 x impact 3 before; 2 x 2 after Owner: Procurement lead Target: Within 60 days Early warning: A key delivery that is late with no confirmed new date.
H07

Standards, permits and legal duties

Legal and compliance Before 12 After 6

Work proceeds without the permits, grid connection approvals, electrical certification or safety planning that apply, and later fails an inspection or is refused connection.

Who or what is affected: Owners, installers and the grid operator

Causes

Rules that differ by place, assumptions made from earlier jobs and approvals that arrive late.

Consequences

Refused connection, fines, rework and unsafe installations.

Existing controls

  • The installer checks the main local requirements before the job.
  • Electrical work is certified by a qualified person.

Control gaps

The checklist is built from past jobs, and may not match the rules now in force.

Additional controls

  • Prevent: Keep a permit and standards checklist for each jurisdiction and confirm approvals before ordering equipment.
  • Detect: Have a qualified reviewer inspect the finished work against the checklist before handover.
Likelihood 3 x impact 4 before; 2 x 3 after Owner: Compliance lead Target: Within 30 days Early warning: A job that reaches installation with any required approval still pending.
H08

Weather, wind, lightning and environmental exposure

Environmental Before 12 After 6

Strong wind, snow load, hail, heat, lightning and corrosion can damage mountings and modules, while removed panels and batteries create waste that must be handled correctly.

Who or what is affected: Owners, nearby people and the environment

Causes

Local weather data that is not checked, corrosion in coastal sites and unplanned disposal.

Consequences

Damaged panels, injury from falling parts, environmental harm and costly repair.

Existing controls

  • Mountings are chosen for the roof type.
  • Earthing is installed with the system.

Control gaps

End of life handling is left to the owner and not covered in the contract.

Additional controls

  • Prevent: Check mounting loads against local wind and snow data and fit surge protection and bonding.
  • Respond: Keep a storm inspection routine and a plan for the safe disposal and recycling of old equipment.
Likelihood 3 x impact 4 before; 2 x 3 after Owner: Design engineer Target: Within 60 days Early warning: Visible corrosion, loose fixings or storm damage found at inspection.

Rating method and evaluation

Each risk is rated on two five-point scales. Likelihood runs from Rare to Almost certain, and impact runs from Insignificant to Catastrophic. Multiplying the two gives a score from 1 to 25, which falls into one of four bands: Low from 1 to 4, Medium from 5 to 9, High from 10 to 16 and Critical from 17 to 25. The score is a guide for ordering work, not a measurement. Inherent risk is the score before any controls. Residual risk is the score after the existing and added controls. Impact is judged on injury first, then on damage, output loss, cost and legal effect, so a risk to life is never traded off against a cost saving. Anything still High needs senior attention and a dated plan, anything Medium needs routine controls with a named owner, and anything Low is accepted and watched. The people who do the work should challenge the ratings, and they are reviewed whenever an indicator reaches its threshold.

Likelihood, impact and rating bands

Likelihood

  • 5 Almost certain: Expected to happen in most circumstances.
  • 4 Likely: Will probably happen in many circumstances.
  • 3 Possible: Could happen at some time.
  • 2 Unlikely: Not expected, but it could happen.
  • 1 Rare: Only in exceptional circumstances.

Impact

  • 1 Insignificant: No lasting effect. Handled within routine work.
  • 2 Minor: Small effect that is quickly corrected.
  • 3 Moderate: Noticeable effect that needs managed effort to correct.
  • 4 Major: Serious effect on people, delivery or reputation.
  • 5 Catastrophic: Severe or lasting effect that threatens the whole activity.

Bands (likelihood x impact)

  • Low (1 to 4): Accept and monitor.
  • Medium (5 to 9): Manage with routine controls.
  • High (10 to 16): Senior attention and a treatment plan.
  • Critical (17 to 25): Act first. Do not proceed until reduced.

Monitoring, escalation and review

Review this assessment every 6 months, and sooner when an indicator below reaches its threshold.

Early-warning indicators and escalation thresholds
Indicator to watchEscalate when
Jobs where isolation and test steps were recorded before work on live parts.Escalate to the electrical supervisor when any record is missing, and stop the task until it is complete.
Roof jobs started with checked anchor points and edge protection.Escalate to the site supervisor at once if work starts without them, and to the director if it repeats.
Thermal image findings and connector inspection results after commissioning.Escalate to the commissioning engineer when any hot spot is found, and shut down the string until cleared.
Measured output compared with the design estimate in the first month.Escalate to the design engineer when output is well below the estimate, and review the design.
Open approvals and late deliveries on each project.Escalate to the compliance lead or procurement lead when an item is late, and to the director if it threatens the start date.

Contingency arrangements

If a serious event occurs, such as an electric shock, a fall or a fire, the first duty is to make the area safe, call emergency services and give first aid. The site supervisor stops work, isolates power where it is safe to do so and keeps people away from the roof. The electrical supervisor secures the system and records what happened. The director informs insurers and any authority that must be told under local rules, which are not assumed here. The client is told early and plainly, and work resumes only after the cause is understood.

Prioritized action plan

  1. Adopt a written isolation and test-before-touch procedure and check it on site, owner electrical supervisor, within 30 days.
  2. Fit edge protection and plan anchor points before any roof work, owner site supervisor, within 30 days.
  3. Torque and inspect every connector and add thermal imaging after the first season, owner commissioning engineer, within 45 days.
  4. Build a permit and standards checklist for the local jurisdiction, owner compliance lead, within 30 days.
  5. Start a maintenance plan with weekly alert checks, owner operations manager, within 60 days.

Conclusion

A solar project is safe and productive when a few controls are checked every time: isolate and test before touching, protect edges, inspect connectors, review designs and confirm approvals. The highest scores sit with electrical contact, falls and fire, and each has actions that bring the residual score down as far as the work allows. Treat the register as a living record, review it on the stated cycle, and use a qualified person for any real installation or legal decision.

Assumptions and limitations

Assumptions

  • The building supply is alternating current and the system is connected to the grid.
  • Crews are trained and a qualified electrician certifies the electrical work.
  • Local law applies but is not named, so duties are described in general terms.

Limitations

  • The scores are examples for learning and do not describe any real project.
  • Electrical, building and grid rules differ by place and need specialist review.
  • This is educational content and does not replace a site-specific assessment by a qualified person.

Related frameworks to study

  • Hierarchy of controls
  • Lockout and tagout principles
  • Risk register with likelihood and severity scoring

Technical Risk Assessment

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For Learning Reference Only: This assessment demonstrates how risk assessment principles are applied in a practical setting, providing a useful reference for learning and understanding. Actual assessments may be adapted to suit specific site conditions and circumstances.

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