At the world 's largest solar power plant near Barstow , an explosion occurred just as third and fourth natural gas - fired oil heaters were being brought on line . One of the heaters , used to back up the solar power system , exploded as a result of equipment malfunction and set fire to a second , which also exploded . Two plant workers suffered minor breathing problems . Fire and plant officials disagreed on whether smoke from the burning oil was carcinogenic . Cause of the fire was unknown, but fire officials ruled out arson and said it probably resulted from an equipment malfunction. The Harper Lake plant is operated by Solar International , which operates 8 such plants in the California area and had a fire at another solar plant two years ago .
At the world 's largest solar power plant near Barstow , an explosion occurred just as third and fourth natural gas - fired oil heaters were being brought on line . One of the heaters , used to back up the solar power system , exploded as a result of equipment malfunction and set fire to a second , which also exploded . Two plant workers suffered minor breathing problems . Fire and plant officials disagreed on whether smoke from the burning oil was carcinogenic . The Harper Lake plant is operated by Solar International , which operates 8 such plants in the California area and had a fire at another solar plant two years ago .