LOS ANGELES — The solar panels covering a vast warehouse roof in the sun-soaked Inland Empire region east of Los Angeles were only two years into their expected 25-year life span when they began to fail.

Coatings that protect the panels disintegrated while other defects caused two fires that took the system offline for two years, costing hundreds of thousands of dollars in lost revenues.

It was not an isolated incident. Worldwide, testing labs, developers, financiers and insurers are reporting similar problems and say the $77 billion solar industry is facing a quality crisis just as solar panels are on the verge of widespread adoption.

No one is sure how pervasive the problem is. There are no industrywide figures about defective solar panels. And when defects are discovered, confidentiality agreements often keep the manufacturer’s identity secret, making accountability in the industry all the more difficult.