Underwriters are zeroing in on inverter fire risk across Australian and New Zealand solar projects and brokers who arrive at renewal without a documented mitigation story are watching deductibles rise - with sub-limits and coverage restrictions the next step.
That is the warning from Melbourne based John Rae (pictured), renewable energy leader for the Pacific at Willis following the release of the broker's latest Renewable Energy Market Review. The review describes an Australian renewable energy insurance market that is supportive but highly selective: Well-structured, high-quality projects are achieving favourable outcomes, while complex or poorly presented risks face pricing pressure and tighter terms.
Inverters - the equipment that converts a solar farm's direct current output into grid-ready alternating current - have become a particular pressure point. Some are showing up more frequently than other solar project risks in the Willis global data from the last 18 months on its clients’ insurer claims.
"I've had a few underwriters come to me and say they've had an issue with certain inverters," Rae told Insurance Business.
Regulators have noticed too. In February 2025, a fire at the Raywood solar farm and battery site north of Melbourne - which trade publication pv magazine Australia reported began in an inverter - originated in electrical equipment and spread to vegetation, sending smoke over the town, according to Energy Safe Victoria (ESV). Within days, ESV directed five Victorian solar farms owned by subsidiaries of Sungrow Power Australia, including Raywood, to stop generating until vegetation and fire-break management met official guidance. It followed the January 2024 fire at the Mannum 2 solar farm in South Australia, where an inverter in a shipping container burst into flames during commissioning, injuring a subcontractor.
For the insurers watching this uptick in inverter losses their response follows a predictable escalation and Rae is blunt about where it starts.
"If the responses from the insureds are not adequate in relation to mitigations from these types of losses, the insurers first response will be to increase deductibles and at worst they will look to put sub limits or restrictions on coverage," he said.
The difference between a project that renews on standard terms and one that absorbs a restricted program, Rae argued, is rarely the hardware alone, it is the quality of the risk story the broker can tell. That is where claims data becomes a broking tool rather than an underwriting weapon.
"We can look at how many inverter fires that we've seen in our solar projects globally through our renewable energy loss database and advise that to our clients," Rae said.
Armed with that benchmarking, the conversation with a client can shift from defensive to practical: Does the operator know that fires have originated in inverters using a certain technology and what are they doing about it? Increased maintenance schedules, critical spares held on site and engineering fixes within the technology itself all count. In one case Rae has worked on, the mitigation ran all the way back to the manufacturer, which reformulated a sealant that had been weakening in humid conditions - exactly the kind of documented fix that gives an underwriter a reason to hold terms.
"There's always a solution to these types of situations," Rae said.
The scrutiny matters on both sides of the Tasman. New Zealand's grid-connected solar fleet stood at 247 megawatts (MW) in early 2026 but the Electricity Authority expects 783 MW of new grid-connected solar to come to market in 2026/27 - quadrupling capacity to just over 1,000 MW. That means most of the country's utility-scale solar is in construction or commissioning, the phase in which both Raywood and Mannum burned. The 168 MWp Kōwhai Park solar farm at Christchurch Airport, developed by Contact Energy and Lightsource bp, is expected to be operational in 2026 and will be among the country's largest.
For larger Australian and New Zealand projects, underwriting judgement is often made in London. Rae's advice is to brokers is to go there in person and make the trip count.
"You've got to go there and talk to underwriters and get their comfort around your experience of risk and mitigations and allows them to go under the bonnet which creates a closer connection to the underwriters/insurance market," he said.
The Willis review also found that capacity and competition are driving premium reductions of 20% to 30% for top-tier renewable accounts globally, with underwriters prioritising engineering standards, maintenance regimes and data insight when deciding who gets the best of the softening. In Australia, renewables supplied approximately 36% of national electricity generation in 2025, according to the Department of Climate Change, Energy, the Environment and Water. Every new project adds inverters to an underwriter's watch list.
For brokers, the takeaway is simple: the client who shrugs that "that's what insurance is for" is heading for a higher deductible. The one with a mitigation file keeps their cover intact.
