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KEZW Goes Green with Solar

KEZW Goes Green with Solar

Feb 1, 2013 10:45 AM, By Chriss Scherer, editor

KEZW-AM, a 10kW non-directional day, 5kW directional night, has served the Denver area on 1430 since 1954. The transmitter was moved to its current location in the 1960s where the five-tower inline array stands today. Entercom has owned the station since 2002.

What sets KEZW apart from many AM stations is the attention Entercom has given to updating the station’s efficiency. This fits with Entercom’s overall view of promoting sustainability with an eye toward being green. For example, a few years ago, the station’s incandescent tower lighting was replaced with LEDs. The incandescent lamps on the five towers consumed more power than the 5kW night-time transmitter output. This alone saved the station on its utility bills, which covered the initial capital expense in a short time. The added benefit of longer lamp life requiring fewer tower climbings to replace them also helps the bottom line.

So about 2.5 years ago, the idea of using solar power at a station was being considered. Entercom President and CEO David Field was interested in the concept and behind seeing if it could be done. KEZW was a candidate. The first items to consider were the location and of course the costs. Part of the cost discussion included various tax incentives that some areas offer.

All posts are connected to the system ground.

It took a year to go through all the paperwork of pulling permits, applying for the financial incentives and submitting environmental filings. Entercom says Douglas County, the county where KEZW’s transmitter is located, was positive about the project. Everything looked good on paper.

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KEZW Goes Green with Solar

Feb 1, 2013 10:45 AM, By Chriss Scherer, editor

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.

On site

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

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KEZW Goes Green with Solar

Feb 1, 2013 10:45 AM, By Chriss Scherer, editor

Overall site plan, courtesy of REC Solar. Click to enlarge.

Ordinances limit the amount of power a home or business can produce on its own. Installations are typically limited to producing 120 percent of the typical consumption. Surplus power created by the array is sold back to the power company, albeit at a lower rate than what the power company will sell power to the user. The generating limitation is designed to keep individuals from becoming stand-alone power utilities. KEZW’s overall system can produce nearly 100kW of electrical power. A typical home system would generate about 5kW.

Because the system can generate a surplus of power, there are two electrical power meters at the site. One shows the power consumed from the power company. The other shows the surplus solar power returned to the electrical grid.

While only a few months of data have been collected, Ken Beck, VP of technical operations and NTS programming for Entercom, says the electrical cost savings over the summer was about 67 percent. He is awaiting a full year’s use data to get an annual savings. In the end, the solar array has eliminated 1,963,812 pounds of carbon from being added to the atmosphere from burning fossil fuels.

Side view of table, courtesy of REC Solar. Click to enlarge.

While the solar array can’t completely eliminate the station’s need for commercial power — solar panels aren’t very effective by moonlight — it has obviously helped KEZW’s bottom line. Some of the capital costs have been offset by state and federal incentives. An exact break-even point of having the system pay for itself isn’t known yet. Once a full year of data is collected, it may be possible to determine that. But much of this effort wasn’t made simply for the bottom line, Entercom’s interest in sustainability and a reduced carbon footprint is just as important.

February 2013

KEZW goes green with solar power, safety in the workplace, audio editing software, World Radio Day and the UN, and the MXL BCC-1….

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