Tom Jespersen

Energy Adviser

Verendrye Electric Service Area

• Serve parts of 6 counties around Minot

• 15,000 meters

• First PV system installed in 1991

• Currently have installed 244 PV systems

• PV Systems are leased by the Membership

Why PV water pumping?

• Rural area has a density of 1 meter per mile of line.

• Overhead line now cost $20,000 per mile.

• Water pumping is a low usage load less than 500 kwhs per year.

• PV pumping systems are relatively inexpensive to install.

Lease of PV Systems

• Lease the power supply only---All above ground equipment

• Customer needs to purchase the pump• Keeps Verendrye in the power supply

business

Water Pumping• Rule #1---Keep it simple for reliability

• Use Module direct to pump system, no batteries

• Use large stock tank for storage, 2-3 day water supply

• Cattle drink less on cloudy days when the system pumps less

• Normally a cow/calf pair will drink 20 gallons per day

Typical PV Pumping System

• Uses 2 solar modules• Voltage/Current

controller• Tracker• Disconnect Switch• Float on/off switch• DC 24 volt pump

Solar Modules• Most are 60 to 100

watt modules.

• Goal is a 20 Year Warranty

• Large J-box for easy connections

• Heavy duty aluminum frame

Pump Controllers• Maximize the daily output of the pump while

providing protection for the motor.• The controller circuitry trades voltage for amperage

to allow the pump to start earlier in the morning or on partial sun days.

• Protects the pump from reverse polarity, surges and limits both amperage and voltage.

• Cost in the $250 range

Passive Trackers• Operates by the moving liquid

between sealed frame members. No drive motors, gears or pistons to wear out.

• Ideal for water pumping systems during long summer days.

• Increases the amount of electricity produced 25-40% during the summer months.

• Cost in the $500 range for a two module system.

Pumps• Most are 24 volt DC diaphragm pumps• Operate on low power output days• Small easy to install• Pump water from 100 feet with

reasonable flow rates• Relatively inexpensive about $750 per

pump• Diaphragm will need to be rebuilt after

10 years of pumping

Misc Equipment• Disconnect switch

• Ground rod

• Float switch

• Pipe

• Rope

• Mounting pole