Vergennes Solar Array Underperforms


Alessandria Schumacher

By Alessandria Schumacher

The Vergennes solar project just completed its first year of operation, but energy output results were not as great as its developers had hoped.  In 2012, the city of Vergennes leased land by its wastewater treatment plant to Encore Redevelopment, which installed a solar array in that area with the value of $500,000.  This array began producing energy on Dec. 31, 2013.

As one might expect, Vermont is not the sunniest place around, especially not this time of year.  On average, Vermont has a 51 percent chance of seeing the sunlight during daytime hours.  Not only are solar panels inhibited by the lack of sun, but they are also blocked by several inches of snow that may pile up over the winter.  Despite the lack of ideal weather and climatic conditions, Vermont continues to prioritize the solar power industry. The Vermont government has instituted policies to incentivize solar for individuals, businesses and municipalities.

Throughout the first year of operation, the Vergennes solar array was expected to produce about 200,000 kilowatt hours of electricity.  However, the actual output fell short, producing only 176,502 kilowatt hours, which was 88 percent of what was expected.   The city of Vergennes was estimated to save between $4000 and $5000 annually, but only saved $3960, leaving them just shy of the initial estimate.
This lower-than-expected energy output may be due to uncontrollable variables, such as weather, snowfall or shading from nearby trees.  However, engineers can predict this outcome given their ability to predict energy yield with high levels of certainty.

“Generally, a bad year and an exceptional year do not vary a tremendous amount,” said Nathaniel Vandal, co-founder of GreenPeak Solar, a solar development company out of Waitsfield, VT aimed at reducing the cost of solar energy for customers.

“Typically there is a 90 percent probability that the generation in a given year will meet or exceed the estimate,” Vandal said.  Given this statement on the accuracy of estimates, 88 percent production does not appear to be too far off target.

Ironically, while solar panels are an effort to reduce carbon emissions and slow climate change, the very effects of climate change may actually be stifling the production of solar power in New England.  Climate change models predict that New England will experience more cloud cover and precipitation.