In a solar power plant, a Permit to Work (PTW) system is crucial for cleaning activities to manage risks like electrical shock, falls, and module damage.

 In a solar power plant, a Permit to Work (PTW) system is crucial for cleaning activities to manage risks like electrical shock, falls, and module damage. Module cleaning is generally considered a low-to-medium risk activity but requires formal authorization to ensure safety and prevent equipment damage. 

Here is a brief module on the basic permit, roles of the issuer/receiver, and cleaning procedures.

1. Basic Permit to Work (PTW) Structure

Purpose: To formally authorize cleaning, ensuring that proper precautions (e.g., inverters off, safe water pressure) are in place.

Validity: Often valid for only one shift (e.g., 8–16 hours).

Key Components:

Method Statement: Detailed cleaning procedures.

Risk Assessment: Hazards (water/electricity mix, working at height, sharp frames).

Location: Specific array/table to be cleaned.

Pre-checks: Isolation of DC side (if necessary), PPE check. 

2. Permit Roles: Issuer and Receiver

The PTW process requires two key, trained individuals to communicate and ensure safety. 

Permit Issuer (Authorized Site Representative/Safety Officer)

Authority: Has the sole authority to issue the permit.

Duties:

Inspects the site beforehand to ensure safe conditions.

Verifies that electrical hazards are controlled (e.g., LOTO - Lockout/Tagout).

Confirms the cleaning team is trained and wearing proper PPE.

Closes the permit after verifying the area is clean and safe upon completion. 

Permit Receiver (Contractor/Team Supervisor)

Authority: Person in charge of the work crew.

Duties:

Understands all permit conditions and hazards.

Briefs the cleaning crew on the scope and safety rules.

Ensures the team follows the agreed method (e.g., no standing on panels).

Stops work if conditions change (e.g., sudden rain/wind).

Signs off to return the permit to the issuer.

3. Brief Module Cleaning Procedures (SOP)

Timing: Early morning or late evening when the sun is low to avoid thermal shock and reduced power output.

Water Quality: Use demineralized or RO water to avoid mineral deposits (TDS < 30 mg/L).

Tools: Soft brushes, sponges, squeegees, or specialized microfiber mops. Abrasive materials or harsh detergents are prohibited.

Pressure: Water pressure must be low, typically below 35 bar, to prevent damaging the glass or frames.

Safety Restriction: Do not walk or stand on the PV modules.

Technique: Clean from the top down, removing bird droppings or heavy dirt first.

Inspection: A final visual check for scratches or cracked glass is mandatory

Summary Workflow

Request: Receiver requests permit.

Safety Check: Issuer & Receiver review site.

Authorization: Permit signed and issued.

Cleaning: Execution of cleaning (early morning).

Closure: Site inspection and signing off.