Soaking up the sun

Tag: voltage controller

If there is any upside to day after day of hot, dry weather for area ranchers, it’s that many of them are taking advantage of the blazing sun to power water pumps in their pasture wells for a fraction of the cost it would take to run utility lines to the area.

Randy Hauck, member service manager for Verendrye Electric Cooperative, said the company has been exploring alternatives to building power lines to remote sites since 1980.

“And the reason behind that was, even at that time, the cost of a line extension was quite high versus the return (because) the amount of kilowatt hours you sell through that meter would be quite low on a low-usage account,” Hauck said. “So we started exploring options, and one of them that floated to the top in our area, because we do serve a lot of ranchers in this area, was trying to figure out how to do something different with pasture wells.”

Pasture wells use a small amount of power to intermittently pump water into a holding tank for cattle to drink from. Since the power drawn by such systems is minimal and running utility lines out to a remote site isn’t very cost efficient, Verendrye started installing solar-powered pasture well systems for its members in 1991.

The ranchers pay for the well, pump and water tank, while Verendrye provides the solar system to power the pump and installs it. Although the cost to lease the system varies with how much water needs to be pumped, Hauck says the most common system used by ranchers costs $15 a month to lease.

Compared to running power lines out to the pasture wells, these solar-powered systems are a bargain. Hauck said that running lines to a well that is one mile away costs around $20,000. While Verendrye offers a $2,500 credit toward the cost of the extension, the member must foot the rest of the bill. Added to that is the $26 monthly charge just to have power going to the pump, plus the cost of whatever electricity is used. The solar systems cost around $3,000 or $4,000 to install, providing a huge cost savings.

“And the other way to look at it ... is the rancher benefits with fresh water versus stale water in a dugout,” Hauck said. “There’s a big benefit there.”

The system itself is relatively simple. A number of solar panels, usually two, generate electricity using sunlight and are aided by a solar tracker. The tracker constantly moves the position of the panels from east to west throughout the day so they are always pointed directly at the sun.

At a two-panel system just west of Velva, Tom Jespersen, energy advisor for Verendrye, demonstrated how critical the positioning of the panels is to their efficiency. After starting the pump and letting the water flow from a pasture well into a water tank, he stood in front of one of the solar panels to cast his shadow on it and water flow decreased noticeably.

There are no batteries in the systems because they introduce unnecessary inefficiency and complexity. To make sure cattle have enough water during cloudy days and at night, the system is designed to provide a three-day supply. This means if the animals need 1,000 gallons per day, 3,000 gallons will be stored in the tank.

The solar array generates a DC power current that goes to a voltage controller, which then sends the power to a submersible pump in the well.

“And that controller’s also connected to a float, so if the float falls down, the pump kicks on and fills up the tank,” Hauck said.