KRUU has been powered by solar electricity since September 9th, 2009 at 9am CST. The solar electric system consists of:
-24 Photocomm solar panels each rated at 65 Watts for a total rated capacity of 1.6kW.
-2 arrays, each holding 12 solar panels, that can be adjusted to the sun at different times of the year thus getting better electricity out of the panels. This also allows a proper angle during the winter so the snow quickly slides off the panels.
-1 Trace 4kW inverter.
-10 Interstate GR12-140 12-volt gel cell batteries with a total rated capacity of 700 amp hours, are installed in a 24-volt configuration. If there is no sunshine, the batteries are kept fully charged by the regular electric grid.
We also have a gasoline-powered backup generator that can be used to charge the batteries. On a daily basis, the batteries are first charged by the sun and when that is done the energy goes into running the studio and the transmitter. The transmitter is the only load wired to one electric circuit and the most essential equipment in the broadcast studio ("Mission Control") are the only loads wired to another circuit.
In the event of a power outage, KRUU continues to broadcast. The 2 electric circuits servicing both the transmitter and the most essential equipment in the broadcast studio will then be powered by the solar energy stored in the batteries. As far as we know, KRUU-FM is the only radio station in the whole USA able to do this. We currently know of 16 radio stations in the US which have varying degrees of solar electricity availble.
Community-wide Solar Collective
The solar panels and the inverter were a gift from the Alan and Martha Kreglow family. Most of the equipment, batteries and the installation was donated by companies, professionals and individuals.
Corporate donors include: Sustainable Living Coalition, Alliant Energy, Ideal Ready Mix, Interstate Power Care, Clipper Wind, LISCO, Kelly Supply Company, Phocos, Vintage Power Wagon, The Walker Group, 1-Stop Rental, and Everybody's.
KRUU received a partial grant from The Greater Jefferson County Foundation. Frank Cicela and Lonnie Gamble of The Sustainable Living Coalition secured the donation of the batteries, wire and charge controllers.
Other major contributors include John Freeberg, Roy Tonnessen, Brian Robbins, Robert Reeder, electricians Paul Rabalais, Rick Belmer and Greg Derise, installers Nelson LaFrancis and Dylan Katz, Tim Freeberg-Renwick, and Roland Wells.
Photovoltaic (PV) cells are silicone wafers that convert sunlight into direct current (DC) electricity. A solar electric panel, often called a PV panel is basically a set of e.g. 32 silicone wafers hooked up together. The rated capacity of individual solar electric panels is steadily increasing, now available with more than a 300 Watts rated capacity.
A solar array is a number of solar panels installed together, and connected to create e.g. 12, 24, 48 volts.
An inverter converts the (e.g. 24 volt) DC to (e.g. 110 volt) Alternating Current (AC) electricity.
Alternating Current is the electricity we are familiar with in our houses in the US. Batteries can be used to store the solar energy. During a power outage the stored electricity can be sent through an inverter--to the building and equipment--and be used to keep a radio station on the air.
Grid = the national/regional/local electric transmission grid.
Off the grid = not connected to the electric transmission grid.