Concentration of CO2 in the Atmosphere

A Solar Story

Late last April, here at Yestermorrow we took a huge step towards our goal of producing renewable energy on campus with the installation of a 28kW photovoltaic array. It wasn’t just a token demonstration project, this was a statement—seven tracking units each measuring 22 feet wide and 17 feet tall right out in front of our main building on Route 100. One year later, we were curious to see how the performance of the PVs matched up with our projections. The AllSun Trackers which we used on the project are designed to change their angle and their orientation throughout the day so they are always directly facing the sun. This means they produce up to 40% more energy than a fixed panel. Each of our trackers is projected to produce 5,640 kilowatt hours per year. Multiply that times seven units, and our anticipated production is 39,480 kWh per year. The next question inevitably is… “so, how much did they really produce??”. Between April 20, 2010 when the trackers went online, and April 20, 2011 they pumped out 37,367 kWh – pretty close to our original projections! (You can check out the production day by day on the AER website at: is enough electricity to supply 74% of the demand for our main building (just over 50,000 kWh last year).

So what’s next? This year we’re hoping for more sunny days 🙂 but we’re also looking hard at what we can do to reduce our electricity loads—remember, conservation always comes before efficiency and renewables. We’re working with folks from Efficiency Vermont and the Mad River Valley Localvolts to install a TED energy monitor so we can track our consumption patterns more closely and identify trends over time. We’re also using a Kill-a-watt meter to identify energy-sucking appliances and tools so we can plan future upgrades. And thanks to great state incentives, we’re also testing out some new LED light bulbs around different parts of the campus and looking into occupancy and day lighting sensors.

GET Aug2011 page  23

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