Downwind: Off-grid system turns to windpower when solar is not enough

Off-grid industrial devices and substations powered with solar panels have speckled the countryside for years. Solar, after all, is more cost-effective than running power lines at up to $100,000 per mile. But what about the weather? Snow can cover photovoltaic cells, which lets batteries run dry, and that may take critical equipment offline.

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Maintaining continuous, reliable power at remote, off-grid substations is a critical concern in industries ranging from oil and gas to telecom, and mining to railroad. Hybrid systems that incorporate both solar panels and wind turbines are quickly becoming the solution.

In the energy industry, for example, the failure of a solar-powered monitoring station can have serious consequences. “Without continuous remote data, safety requirements might call for energy producers to shut down production,” says Tony Kaspari, an electrical engineer who works with industrial companies. “An unplanned outage can cost tens of thousands of dollars.”

Hybrid systems that incorporate solar and windpower are a way to reduce the risk of power failure. Many off-grid industrial substations are being retrofitted with small wind turbines to enhance power reliability and build in redundancy.

While solar works well in the daytime, windpower compliments it by also working through the night. Also, while solar works better during long summer days, windpower thrives through the blustery winter. On stormy days, windpower is the only option. Another benefit of adding wind power to a solar-only system is that it lengthens battery life by reducing the depth and frequency of discharge.

One small wind turbine manufacturer, Primus Wind Power, produces several models for areas with different wind speeds and climates. Primus’ turbines generate power at wind speeds as low as 6 mph, and can generate as much as 40 to 80 kWh a month per turbine. Each turbine rotor measures about 4 ft. in diameter, while the whole unit weighs about 13 lbs. and costs about $1,000.

“If your paycheck depends on having reliable remote power, then you need to look into adding a wind turbine to your existing solar-only system, or integrate it from the beginning,” says Brent Busenlehner, president of ReadyFlo Systems, a Texas-based integrator of remote power devices. “The combination extends system capacity and makes the worst case scenario, a power outage, unlikely.” WPE

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