As per Procedure Safety procedures for working on solar plant high-tension (HT) panels, converters, and transformers require strict adherence to safety protocols, primarily de-energization and lockout/tagout (LOTO) procedures, and the use of appropriate Personal Protective Equipment (PPE).

 Shri SKB Vali sir instructions SAFETY ALWAYS FIRST 

Safety procedures for working on solar plant high-tension (HT) panels, converters, and transformers require strict adherence to safety protocols, primarily de-energization and lockout/tagout (LOTO) procedures, and the use of appropriate Personal Protective Equipment (PPE). 

General Safety Requirements

Qualified Personnel: All tasks must be performed by trained, authorized, and qualified personnel only.

Permit-to-Work (PTW) System: Implement a formal PTW system for all maintenance activities to ensure proper coordination and safety checks.

Emergency Preparedness: Have emergency response plans, including clear evacuation routes, first-aid kits (especially for electrical burns), and emergency contact lists, readily available.

Site Safety: Barricade the work area, use caution signs, maintain a clean workspace to prevent slips/trips, and ensure adequate illumination. 

Step-by-Step Isolation and Safety Procedures

The primary safety measure before any work is to ensure an electrically safe work condition by following LOTO procedures. 

Notify Personnel: Inform all affected personnel and control room operators about the impending maintenance work and system shutdown.

Shut Down the System: Follow the prescribed shutdown sequence provided by the manufacturer. This typically involves:

Opening the AC side breaker connecting the inverter to the transformer/grid.

Switching off the DC disconnect switches in the string combiner boxes (SCB) and at the inverter input.

Note that solar panels generate hazardous voltage when exposed to sunlight, even when disconnected from the system; they cannot be completely de-energized unless covered with an opaque material.

Isolate Energy Sources: Disconnect all potential energy sources (AC grid, DC from panels, battery storage) using switches and circuit breakers.

Apply LOTO Devices: Apply approved lockout devices and warning tags to all disconnection points. Each worker must use their personal lock and tag.

Verify Absence of Voltage: Use a properly rated, calibrated voltage tester to confirm that all circuits are de-energized and there is an absence of voltage. Test before you touch.

Ground the Equipment: If necessary, apply temporary grounding to discharge any stored energy in the circuit, as per site-specific procedures.

Allow Discharge Time: For converters/inverters with capacitors, wait for at least 5 minutes (or as specified by the manufacturer) for internal parts to discharge completely before maintenance.

Perform Work: Once the equipment is confirmed to be in an electrically safe work condition, proceed with the task using insulated tools. 

Required Personal Protective Equipment (PPE)

Select PPE based on a hazard/arc flash risk assessment and the specific voltage levels involved. 

Head Protection: Non-conductive hard hat (Class E rated).

Eye and Face Protection: Safety glasses or goggles (with side shields) and an arc-rated face shield or hood to protect from arc flashes and debris.

Hand Protection: Insulated gloves (rubber insulating gloves with leather protectors) rated for the specific voltage level.

Body Protection: Flame-resistant (FR) and arc-rated clothing (long-sleeve shirts, pants, or coveralls). Non-melting natural fiber undergarments must be worn underneath.

Foot Protection: Non-conductive safety boots with electrical hazard (EH) ratings.

Hearing Protection: Hearing protectors are required when working within the arc flash boundary due to the potential for high sound pressure levels. 

Specific Precautions for Equipment

Transformers: Ensure proper grounding to prevent static buildup. Keep the area around transformers dry and well-ventilated. Immediately shut down and analyze any malfunctions.

HT Panels/Converters: Restrict access to authorized personnel only. Use appropriate test leads and probes that are rated for the high voltage levels present in solar systems (e.g., CAT III 1500V). Ensure proper ventilation to prevent overheating.

"Recharging": If the activity is the initial "charging" (energization) of a new system, ensure all pre-commissioning checks, continuity tests, and insulation resistance tests are complete and documented.