Burbank solar company eSolar Inc. has raised $12.8 million in a funding round, according to a filing with the Securities and Exchange Commission.

The money was raised as part of a registered $30 million equity offering. The company, founded in 2007, makes products that convert heat from the sun into electricity, unlike solar panels, which convert sunlight into power.

In 2009, eSolar built Sierra SunTower, a 5-megawatt project in Lancaster. It also has an agreement with a company in India that is licensed to build utility-scale projects using eSolar’s technology.

The company has not commented on the most recent funding, but has raised approximately $170 million since it was founded. Google Inc. and General Electric Co. were early backers.