Solar farms around the world are under threat due to costly hailstorm-related claims, according to renewable energy underwriter GCube Insurance.

Hail was the costliest category for insurance claims by the renewables industry in the last five years, averaging around $58.4 million per incident, the underwriter said in a Wednesday report. Even though hail makes up only about 1.4 percent of total claims, more than half of total solar loss claims are due to hail.

“The consequences of hail damage risk undermining the security of solar power as a prominent clean-energy solution,” GCube Chief Executive Officer Fraser McLachlan said in a statement.

Extreme weather fueled by climate change is making renewable projects vulnerable to natural disasters, potentially leading to delays in the global push to adopt cleaner energy sources and reduce carbon dioxide emissions.

Insurers are beginning to reduce coverage for solar businesses due to the rising severity of hailstorms according to GCube, which insures more than 100 gigawatts of projects in 40 countries. That has also brought uncertainty to future solar projects, due in part to rising premiums and higher deductibles, the firm said.