Do-It-Yourself PV for Burning Man
Over the summer I was invited to join a camp at Burning Man, the counterculture arts festival held annually on the Black Rock Desert in northern Nevada. The guiding principles at Burning Man include “radical self-reliance” and “radical sustainability,” so it seemed fitting to take a decent-sized photovoltaic (PV) system for independent power.
On Craigslist I’d found a 1976 Ford Econoline motorhome, cheap. It needed work — several coats of white paint on the interior, some bright new slipcovers sewn by my daughter, and a lot of minor plumbing and electrical fixes.
On the roof I put two 140-watt Kyocera modules, on a homemade racking system. I used aluminum L-angle stock to bolt a couple of 6-foot pressure-treated 2×6 planks to the roof, to serve as exterior “rafters.” The modules attach to the rafters using short sections of L-angle, fastened with clevis pins to allow pivoting. By releasing the pins on the left side of the truck, I can tilt the modules up toward the sun, pivoting on the starboard pins. A set of four legs, of the same L-angle stock, props the system and proved solid in 40-knot winds. It takes about five minutes to deploy or stow the modules, but you have to climb onto the roof to do it. Of course, the modules produce power whenever the sun shines, whether tilted up or locked down flat.
The modules feed a pair of Trojan T-105-RE 6-volt batteries via a Morningstar ProStar-15 charge controller, providing around 220 amp-hours of storage — plenty to run AC electric fans all day in the desert heat, with 12-volt LED lights and music all night. A Samlex SA 1000-112 pure sinewave inverter provides reliable AC.
By plugging the motorhome’s AC system into the inverter, we keep the truck’s own dual-battery 12-volt system fully charged while running the small refrigerator and the water pump.
For summer use, with the sun high, the modules are best left flat through the day. The tilt-up feature is meant for winter and spring use, in ski resort parking lots.
At Burning Man, the array cranked out 9 amps at midday, tapering to 3 amps at dawn and dusk. That kept the battery bank near 14 volts most of the time, and battery temperature rarely reached 30°C (86°F). Total cost was about $1,700 ($6 per watt, including storage), plus about six hours of my own labor. — SETH MASIA
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