Up on the roof
Since early last year, the San Rafael, Calif., Fire Department has been operating a solar-powered fire engine created by two of its firefighters. The invention has worked so well that the department plans to outfit all of its rigs and ambulances with solar panels.
A common difficulty with fire trucks is maintaining a battery charge when a rig is away from an electricity source, says San Rafael Chief Christopher Gray. Often the trucks are left running to charge the batteries when they are on the scene of a fire. Rigs typically carry six batteries, which cost about $100 each and can last between three to five years.
Firefighters Dave Holland and Steve Rutkowski decided to install a solar panel on the roof of an engine company rig and connect it to one of the rig’s batteries to charge it. The firefighters used a thin, 50’×24′ Teflon solar panel in an aluminum frame, which was then mounted to the apparatus roof. The department’s staff completed the installation and wired the panels to the battery. In the end, the cost for materials and installation was less than $250.
One solar panel can deliver about 64 watts and four amps to the battery. The equipment requires about six amps to keep running without affecting the batteries, so the department has since installed a second panel on the truck. The solar panels will augment either the alternator while the rig is running or the AC power if it is plugged in at the fire station. Gray anticipates a two-year payback period based on previous battery life and costs. The city’s fleet administrator estimates that shutting off diesel-powered public works vehicles when they are not in use will save thousands of gallons of fuel and reduce the noise at the scene.