Consideration under Safe and reliable operation of rooftop solar system

The basis for safe and reliable operation is proper planning and installation of the solar PV system. The system developer and installer should possess in-depth knowledge of the applicable (IEC) standards
For roof-mounted PV installations, all safety precautions for working on rooftops have to be taken to provide a safe workplace.
Due to the simplicity of the systems, the requirements for safe and reliable operation are limited but still relevant, such as issues to be considered for routine system inspections as well as for safe and reliable system cleaning.
Solar PV modules produce voltage when they are exposed to light, and they continue to do so in case of a fault or short circuit. In addition, they are often configured to produce high DC voltages. Thus opening or separating contacts when a solar panel is under load might lead to non-self-extinguishing arcing. It has to be ensured that the circuit breaker at the solar PV system output is disconnected. A wire should never be disconnected before measuring voltages, and, if a wire is disconnected, it should not have an exposed end. Furthermore, wires from one circuit have to be reconnected before disconnecting wires from another circuit.
Prior to system cleaning, especially if water is used, a check has to be made to ensure that the system is free of damage, such as solar PV module delamination and cracks or broken cable coatings. Furthermore, the modules should not be cleaned when they are excessively hot, to mitigate the risk of glass breakage and current leakage.

Fire protection
Most residential fires are not caused by PV installations. However, concerns relate not only to the installation itself, but also to the safety of firefighters if a PV system is installed.
Adequate fire protection can be achieved with suitable equipment, sound design and professional installation of the solar PV system, and communications with stakeholders such as the fire department. Various aspects that result in safe operation and fire protection are described in this section.

Quality of PV system components
Test certificates must be provided for all components, in line with relevant international standards:
Cabling
» single-core cables
» double-insulated to protect against short circuits
» minimum cross-section 2.5 mm² copper
» UV-resistant material for outdoor applications
» solar PV modules with uniform configuration and output power

Design
» grounding protection
» lightning protection
» surge protection
» age and roof condition
» adequate mounting
» DC cable routing outside of the building
» proper inverter sizing

Quality of installation
» system installation compliant with local codes
» compliant with system design
» compliant with local codes for grid connection
» sufficient module and inverter ventilation
» do not use the solar PV module connection cables to carry or transport the solar PV module
» do not use damaged solar PV modules
» do not step on solar PV modules » inverters to be installed outside the building or at its entry point, so that only the AC wiring is in the building
» AC manual disconnection to be accessible on the outside of the building
» inverter not to be directly exposed to sunlight
» proper service including maintenance, especially for batteries, for autonomous installations

Electrical connection
» electrical circuit protection
» proper wiring
» correct polarity
» minimising length of wiring
» batteries not to be exposed to direct sunlight, high temperatures or flammable materials
» batteries to be installed in a housing segregated from other solar PV system components
Communication with the local fire department
» proper labelling of the solar PV system at the main connection box
» general plans for fire fighters are desirable
» DC isolating switch.