it is entirely possible to issue a basic Permit to Work (PTW) for solar plant module cleaning, including for a short-term duration like one week

  it is entirely possible to issue a basic Permit to Work (PTW) for solar plant module cleaning, including for a short-term duration like one week. Such permits are standard practice in solar operations and maintenance (O&M) to ensure safety, as module cleaning involves risks such as working near high-voltage DC electricity, water-electricity interaction, and potential working at heights. 

Key Aspects of a Weekly Cleaning Permit

Purpose: To formally authorize the cleaning team, confirm they have received safety briefings, and ensure all risks are managed, such as ensuring proper water pressure and, if required, temporary shutdown or isolation of inverters.

Validity: While a PTW can be issued for a week, it often requires daily check-ins or re-validation by a site supervisor to confirm safe conditions (e.g., no adverse weather, no changes to equipment).

Components: The permit will include a Method Statement (how to clean) and a Risk Assessment (identification of hazards like shock or falls).

Requirements: Personnel must be trained in safe cleaning practices, such as not standing on panels and using authorized, low-TDS water to prevent panel damage. 

Key Procedures for Authorization

Issuer & Receiver: The Permit Issuer (Site Safety Officer) must inspect the site, while the Permit Receiver (Cleaning Team Supervisor) must understand all safety rules.

Pre-checks: Isolation of DC sides (if required) and checking Personal Protective Equipment (PPE).

Completion: The permit is closed only after the site supervisor verifies the area is safe upon completion. 

Operational Context

Periodic cleaning is generally required every 2 to 4 weeks, or as per site conditions. A short-term, weekly permit is suitable for intensive cleaning, such as cleaning a specific section of a large plant or addressing heavy soiling.