When Susan and Michael Graham decided, more than 30 years ago, to live off the grid on Maui’s north shore, Laf Young, their neighbor and “energy guru,” helped them configure an integrated energy system, borrowing from marine and mobile-home technology.
Sustainable technology has come a long way since then, says Young, whose background is engineering. “In the early days, we tried to do as much as possible with stored DC [direct current] energy; some appliances and lights were available as DC even then. As the industry matured, we started using inverters, which convert DC into AC [alternating current], just like what you get from Maui Electric Company. Battery capacity is measured in amp hours; the Grahams have a 1,400-amp-hour, 12-volt storage battery with a 120-volt AC inverter.”
That energy came primarily from a series of photovoltaic panels, which differ from those used in solar water-heating systems. “Solar water-heating systems capture infrared energy, which is diffuse and available even on a cloudy day. Photovoltaic panels are semi-conductors; they don’t work on heat, but on light converted to DC energy,” says Young. “Photovoltaics only operate under blue-sky conditions, so in a rainy environment like Huelo, if you just have photovoltaics, you need a backup generator.”
The Grahams have both a backup propane generator and a wind turbine. “Their turbine charges the batteries 24/7, it’s so windy here,” says Young. “They can blaze lights and use up the battery and have energy the next morning. Without the turbine, they’d have to wait till the end of the day.
“But Maui’s marine environment is hard on turbines. The trade winds are laden with salt, which interacts with the various metals in the turbine to create electrolysis—that corrosive green stuff you have to clean off your car battery’s posts. Most people don’t want the maintenance, or they don’t have the real estate for it—wind turbines are only permitted in agricultural zones.”
Young expects to help the Grahams upgrade their system in the next couple of years, and says he’ll suggest increasing to 48 DC volts, making it easier for the electronics to convert to 120 AC volts. Surprisingly, he’d rather see the Grahams go back on the grid the way he has. Young’s own house has 18 huge photovoltaic panels, and no storage batteries. If the panels generate more energy than the family needs, those extra kilowatts get fed back to Maui Electric. If the family uses more energy than their photovoltaics provide, the kilowatts flow the other way. “We pay Maui Electric $7 or $8 a month, and have the reliability of being on the grid; I can run air compressors . . . anything.”
The Grahams’ reluctance to follow Young’s lead is mostly a matter of aesthetics; Susan doesn’t want power poles leading onto her property. And there’s a practical drawback to partnering with the power company: “If the grid goes down,” says Young, “I go down like everyone else. This is a battery-free system. So I do have generators.”
Want to learn more? Young recommends Home Power Digest—maybe the only magazine you’ll ever need, besides Maui No Ka Oi.