But Jeff Garrett, KEZW director of engineering, had practical concerns. The potential cost savings and benefit to the environment are good reasons, but would a solar power array work in the strong RF field of a 10kW AM radio station? Garrett needed to know before the heavy work began.
REC Solar was chosen to install the system. A test rig of one solar panel and inverter was set up to evaluate the system. Fortunately, everything worked. The system successfully collected and converted sunlight into electricity with no significant interference from the transmitter. The only interference issue relates to a weather monitor that is used to check sunlight, temperature, wind and other conditions. In the RF field, the anemometer reported a constant, heavy wind of 100MPH or more. It's not that windy. That was the only interference issue.
The transmitter site is located on a slight slope of land. Most of the land has been leveled, and there is a raised area on the west side of the property. This was an ideal spot for the solar panel array, and it only needed a slight amount of grading. The electrical power feed, telco feed and ground radials were all marked and the footers for the arrays were set in place. The panel footers and the underground lines for the most part lined up just right, but you can see in the overall plan (next page) that two sets of panels are slightly offset. This was done to avoid the underground telco lines.
Solar table disconnect panel
Once the footers were poured and set, assembly began. There are 12 tables with 36 panels on each table. A fence then surrounds the array. All the structural members and supports are tied to the station ground system. Each table's output runs to an inverter mounted on the west outside wall of the transmitter building. With everything grounded, there was minimal effect to the antenna pattern. The slight change was easy to retune.
Electrical service panels
The solar panels are rated for 20 years. The inverters are rated for 10 years. Overall maintenance of the array is minimal. With less than one year in operation, there hasn't been much maintenance. Garrett says it has easily survived a few storms with hail already. And snow tends to just slide off if it accumulates.
The wall of inverters from the solar tables
- continued on page 3