Solar Power

PV Modules Replace Generator
on Gold Creek Cattle Operation

Every summer, Jim Tomlinson pastures 20-25 cow/calf pairs or replacement heifers in timber and grassland several miles from the town of Gold Creek, Montana. The area is steep, rugged, and remote. A creek flows along one side of the property but "sinks" beneath the surface and goes dry along the way. To give his cattle a reliable water supply, Tomlinson installed a stock-watering system about 10 years ago. 

The nearest power line was about two miles away, so he decided to use a gasoline-powered generator. He pumps water from a 160-foot-deep well to a 1,350-gallon underground cistern. Water flows from the cistern by gravity into a 700-gallon stock tank. The well and tank are located on a high bench and give the cattle access to forage far from the creek. Tomlinson uses solar-powered electric fencing to control cattle movement, as part of an intensive grazing strategy.

The gasoline-powered pumping system gets the job done but has created some headaches. About every five days, Tomlinson has needed to travel 45 minutes each way from his home just to run the generator and fill the stock tank. While he would normally come up to check on the cows at least once a week anyway, he’s been forced to stick to a rigid schedule for watering. This has presented problems during haying and irrigating seasons. A few years ago, Tomlinson also needed to replace a generator that was stolen.

Working with the National Center for Appropriate Technology, Tomlinson installed a solar-powered pumping system in June 2000. The system, supplied by Sunelco in Hamilton, Montana, uses two 120-watt photovoltaic modules, a passive tracking rack, and a submersible diaphragm pump with a maximum flow rate of just under one gallon per minute. The panels are located about 100 feet from the well to avoid shading from trees. 

Tomlinson increased his storage capacity by installing a second 700-gallon watering tank next to the first one. This will ensure adequate water during cloudy weather, when solar pumping will be reduced. After the cows are moved off the pasture each fall, Tomlinson plans to remove the tracker and panels and store them at the ranch to avoid vandalism during hunting season.

The main advantage of solar pumping is that it should be reliable and nearly maintenance free, keeping Tomlinson’s tanks full all summer long and freeing up his schedule during the busy times of irrigating and haying. An unexpected benefit is that he has been able to continue pumping and watering his cattle as usual last summer (2000), despite the drought in Montana. Because of the severely dry conditions and extreme fire danger, he would not have been allowed to run a gasoline-powered generator in the forest this summer.

NCAT photos