The Universal Solar Pump Controller (USPC) converts solar energy to electricity for powering pumping devices. | The USPC offers variable speed operation, which maximizes system performance by adjusting pump speed to match the available solar power. This allows the controller to maximize the amount of water delivered to the user. In addition, its peak power tracking capability lets the controller constantly adjust for peak output from a solar array; this is important because the voltage and current set points for maximum power vary throughout the day as solar insolation and temperature change.
Adding to its cost-effectiveness, the USPC has a power conversion efficiency of 97 percent, which is higher than many other stand alone or off-grid photovoltaic inverters. Minimum and maximum speeds are configurable, and the controller's power electronics are programmed to automatically shut down in the case of a dry well, clogged pump, or shorted wiring. The controller also has a remote shutdown switch for filling water tanks and a fault-detection LED display.
An additional feature, especially important in a climate like Uganda's, is the USPC's ability to regulate its maximum operating temperature internally. Instead of shutting off at a specified temperature, the unit gradually reduces its power usage. This prevents overheating so that the controller can continue running in very hot weather.
The USPC is also designed to make installation simple. The technology employs a configurable DIP (dual in-line package) switch feature, which lets the installer easily establish settings in the field without software or other sophisticated devices. This significantly simplifies installation in remote settings. Lastly, as it is designed for use in harsh conditions, the controller is enclosed in a rugged, outdoor-rated NEMA (National Electrical Manufacturers Association) 3R steel case.
Closer to the Grid
The USPC can benefit less-developed nations and remote areas anywhere in the world, but it can also serve areas where an electrical grid is available but remote – including in the United States. For example, Culver City, California-based MAP Productions, an alternative energy company, installed USPCs to help provide water to the Tule Elk herd in Northern California.
"The USPCs operate every day – from sunrise to sunset – and are the best solution I've found for pumping water with a standard well pump," said Michael Parsons, the owner of MAP Productions. "Each pump supplies approximately 30,000 gallons of water per day, which would otherwise cost the state about $15,000 a month."
Parsons adds that this allows California to use the savings to pay for feed instead of electricity – a very important factor in the continued survival of the state's last native breeding herd of Tule Elk, whose offspring have been used to repopulate other areas of the Western United States.
For more information about AeroVironment, go to www.avinc.com.
About the Author:David Bernell is Senior Clean Energy Advisor at Think Energy, Inc., a renewable energy consulting firm in Silver Spring, MD, and Assistant Professor of Political Science at Oregon State University.
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