The solar PV industry is an integral part of the renewable energy sector in the UK. With around 1.3 million solar panel residential and small commercial installations in the UK according to MCS Installations Database (MID), the market is considerable.
The MID data speaks for itself, with a noticeable jump from 61,165 solar PV installations in the UK during 2021, to 136,298 installations in 2022. Clearly, both the domestic and commercial solar markets are strengthening.
With this increase in installations, solar PV safety experts, including myself, are invested in ensuring that safety and the adherence to secure technologies is adopted across the sector to reduce instances of fire and related damaging events.
There’s no doubt that solar PV panels are safe, as long as the most suitable technology is in place to support their use and longevity. We need to make sure we can construct safe situations for PV installers, people in their homes, for firefighters and other responders.
The way a solar PV panel operates is to convert day light into direct current (DC) electricity. An inverter is then used to convert DC to Alternating Current (AC) for connection to the grid and use at the property.
It’s important to understand solar PV panels will always generate electricity during daylight hours and all parts of the DC circuit up to the input of the inverter will be live. This presents operational issues for those using, maintaining and working on the roof, as well as for firefighters, as the inability to isolate the DC sections of the solar PV system increases the risk of fire.
As mentioned, every solar PV system requires conversion from DC to AC. With systems utilising ‘string inverters’, the DC cabling interconnects solar PV panels into a ‘string’ and in UK residential systems often runs into the loft space to connect to the string inverter.
A means of disconnection is required on both the DC and AC side of the string inverter, but even after their being fully isolated from the AC installation, the DC circuits will still be live up to the DC switchdisconnector before the string inverter.
While there are no true AC solar PV panels, by using microinverters integrated into the DC connections, a means of full isolation of the cabling system of the solar PV systems is provided. Microinverters are placed at the rear of each solar PV panel in the system and provide immediate conversion of the electricity from DC to AC. The system then includes AC cabling to interconnect the microinverters and provide connection into the electrical system in the property.
This approach increases safety from an isolation and operational process reducing contact with a DC system, which users would be unfamiliar with, and provides firefighters with a safe system to carry out normal firefighting procedures.
Enphase IQ7+ Microinverter
Efficiency, safety and durability lie at the heart of a successful solar PV system design, manufacture and operation. Component functionality is also important when it comes to ensuring a solar system can undergo years of service and still maintain safe operational capabilities.
The design of solar PV systems should minimise the risk of product failure over their lifecycle and factor in the impact of weather variations. Transformers and thermal duty cycles need to be carefully considered in the system design process and manufacturing. It’s expected that a PV system should last around 30 years.
It’s true to say that the microinverter has transformed solar PV systems and has enabled the solar sector to develop and enhance existing technology with additional safety facilities integrated within the product. Fig 1 illustrates an example of a microinverter.
The benefits of microinverters in solar panel installations are substantial. Each panel has its own microinverter so panels can operate individually. More sophisticated microinverters usually have integrated insulation monitoring that ensures a responsive analysis of the continual workings of each microinverter, as shown in Fig 2 in the Enphase MyEnlighten App
These microinverters are very sensitive and can instantly detect a single fault. The beauty of microinverters is that if one stops working only that one panel will be out of action while the rest of the array will continue to operate as normal.
Put simply, with a microinverter, if a break in the DC circuit forms, a spark is observed rather than an arc. Energy in the spark is well below 100 Joules and has a duration of a few milliseconds. UL 1699B certifies arc energy at less than 750 Joules and the arc must be extinguished in less than two seconds. UL is an accredited standards developer in the US and Canada.
Once there is a gap in the conductor, the microinverter will shut down, improving safety standards and reducing risk. This is a game changer for solar safety and the development of the next iteration of solar systems.
Due to the very nature of the DC architecture, the system can never be truly isolated as the solar PV panels will continue to generate throughout the DC equipment and cabling.
With a resulting increase in temperature, there may be some heat impact on surrounding materials to increase the risk of fire.
I’m a committed advocate for renewable energies and, with 30 years in the American fire services, I understand the opportunities and risks that solar energy can bring to both domestic and commercial settings.
The Enphase Enlighten app with solar PV information
With my organisation, Solar And Fire Education (S.A.F.E.), we provide free training to firefighters across the world. The S.A.F.E. programme trains professionals to alleviate structure fires involving solar PV (photovoltaic) systems and ESS (energy storage systems).
In addition, I support communities across the globe with access to renewables in their drive towards building resilience in the face of power cuts and grid failures.
Our advice at S.A.F.E for any domestic or commercial setting looking into solar PV system safety is to check the architecture then try to choose AC systems over DC to minimise the risk of potential incidents from occurring within the system.
Another key component is to install products that use integrated microinverters. Microinverters have been proven to reduce risk and improve the safety of solar PV systems because they are AC single source manufactured components. In addition, microinverters do not rely on an installer having access to specialised tools to combine multiple components from different manufacturers.
In the Government’s Powering Up Britain March 2023 report, the Department for Energy Security and Net Zero (DESNZ) stated its ambitions for a five-fold increase in solar energy by 2035, which could power about 20 million homes. There’s a need to maximise deployment of both ground and rooftop solar to achieve this target.
In the light of this Government policy, it’s more important than ever to maximise the potential of microinverters in solar systems. Microinverters are the gold standard for public and firefighter safety, incident stabilisation and property conservation. They are available, affordable and are effective in practice.
Being proactive instead of reactive will help support the renewable energy industry to thrive.
