California-based independent power producer Calpine Corp has announced its quarterly results, showing a worsening Q2 loss on the back of unplanned outages.

Calpine posted a second-quarter net loss of $298.5 million, compared with a loss of $28.7 million the previous year. Revenue rose to $2.23 billion from $2.22 billion.

Calpine shares fell more than 14% on the news, despite the company’s efforts to dispose of generation assets and reduce its debt profile.

Calpine said mild weather had cut demand for power in April and May, but demand had recovered since June.