Hazard Knowledge

At any incident involving photovoltaic (solar) systems, there is a potential electrical hazard from energy produced by these units. Panels or tiles may be mounted onto building roofs or walls and may not be easily identifiable. Panels can also be located at ground level, for example in solar farms. Even when isolated at the consumer unit or inverter, the system may remain live between the panels and the isolation point.

For more information see Fires in Buildings Building Research Establishment supplementary information Microgeneration renewable energy

The potential for the system to continually produce electricity presents a hazard for fire and rescue service personnel. The generation of electricity will not only happen in direct sunlight but also in cloudy conditions. Moonlight will generate negligible current. However, artificial scene lighting may be sufficiently bright to generate electricity.

Damaged photovoltaic panels can cause arcing and subsequent fire, with the potential for firespread via molten glass dropping underneath the panels.

The security of the panels may be compromised by fire or building collapse, with the potential for them to fall from the roof.

It may be necessary to isolate power at the inverter, however it may be difficult to locate the isolation switches, or there may be restricted access to the isolation switches.

Other methods have been used to deactivate photovoltaic systems, for example, in the United States they have investigated covering the panels with a light-blocking material, such as certain types of tarpaulin. However, this is a difficult tactic to implement because many tarpaulins are not completely light-blocking and the panels are often too large for this to be successfully achieved. Additionally, wind, fire or other external influences may make it difficult to maintain coverage.

With the growth of photovoltaic systems, emerging technology is looking at ways to deactivate production of DC power from photovoltaic systems.

For further information, refer to the BRE knowledge sheet: Photovoltaic (PV) systems and the supplementary information for solar panel (photovoltaic) systems.

Battery storage for domestic and commercial solar photovoltaic (PV) systems

With advancements in solar-powered domestic and commercial photovoltaic systems, battery storage is becoming an economically viable option for some households and businesses. 

The two types of batteries most commonly offered for solar photovoltaic storage in the home are lithium-ion and lead-acid batteries. These units will usually be located near the system’s inverter and often found in a utility room, garage or similar location. 

There are two main ways of linking a battery storage system into a PV system:  

• DC coupled: the batteries are installed on the same side of the solar inverter as the PV panels, they charge from the panels, and their DC is only converted to AC when it is used 
• AC coupled: the batteries are installed on the grid side, where the DC from the PV panels has already been converted to AC. A separate inverter converts the AC back to DC for storing in the battery. When the battery discharges, the same separate inverter converts the DC back to AC. 

For illustrations of, and further information about, battery storage, refer to BRE and RECC (2016) Batteries and Solar Power: Guidance for domestic and small commercial consumers. 

Also refer to the Utilities and fuel supplementary information, Solar panels (photovoltaic) systems.