AllEarth Renewables Solar Farm, 20 Sept 2011

After class this morning, we drove two cars of ILEAD students to South Burlington VT, in partly cloudy and rainy weather -- then muddy shoes.

Our host was Andrew Savage, Director of Communications and Public Affairs, who led us through the newly constructed, muddy field of 382 5.5 kW trackers, which had just recently come on line. Here he is holding a control circuit module manufactured in the Burlington area.

Each of the large panels rotates on a vertical axis and a horizontal axis. This lets the panel point directly to the sun. This increases incident energy about 40% compared to a fixed solar panel such as might be on a homeowner's roof. The anemometer at the top of each panel senses wind speed. If it exceeds 30 mph the controller flatens the panel to a horizontal position to avoid wind damage.

A hydraulic cylinder provides motive force to move the panel skyward. The position is adjusted every few minutes; not all the panels move at once. The panels are programmed to follow the sun's path through the sky. There is a similar actuator to rotate the panel about the vertical shaft. On the left is the DC to AC power converter for this panel.

With the demise of US PV solar panel manufacturers such as Evergreen Solar in Massachusetts, AllEarth now obtains the PV panels from China. The cost is dropping from about $1.75 per watt of peak capacity. These represent about 30% of the costs of the solar farm, with most additional value added coming from the US, especially from the Burlington VT area.

Because we visited on a cloudy day, the day's production of 4359 kWh of electric energy was only about a quarter of what can be achieved on a sunny day. You can see up-to-date production reports on-line, at

The solar farm was a $12 million investment. It made good economic sense because of a 30% federal tax credit and a 30% Vermont state tax credit. Vermont established a feed-in-tariff for photovoltaic solar power, guaranteeing that electric utilities will buy the energy at $0.30 per kWh. That's about four times the average power cost, but it is spread over the cost of all energy provided by the utility to its customers. Since then the Vermont tax credit has expired and the feed-in-tariff rate has dropped to $0.24.

Generators of solar power also receive renewable energy credits (RECs) that can be retained or sold in a nascent marketplace.

Sept 20, 2011

AllEarth Renewables Solar Farm
350 Dubois Drive
South Burlington VT
At end of Dubois Drive off of Rt 116; park before the roundabout.
94 Harvest Lane # 101
Williston VT 05495
Host: Andrew Savage, Director of Communications and Public Affairs

Background reading

Visit here to learn about AllEarth Renewables solar power.

David Blittersdorf and his company are featured in Wentworth Institute of Technology's alumni magazine, here, and a Blittersdorf presentation is here.

Valley News' Chris Fleisher wrote about the home solar market, here.

John McLaughry's Ethan Allen Institute newsletter is critical of the subsidies that make solar power economic.

Gov. Shumlin also made an enthusiastic visit last week to the $12 million solar electricity farm in South Burlington promoted by his pal, the noted subsidy farmer David Blittersdorf.

Blittersdorf and a partner formed Chittenden County Solar Partners, which owns the $12 million solar farm. The partners have a 25-year power purchase contract with the state of Vermont to sell power to the utilities at a fixed price of 30 cents per kilowatt hour, under a state law pushed through by Senator Shumlin in 2009.

Blittersdorf said since the inception of his project, the PSB has reduced the subsidy price to 24 cents per kilowatt hour. At that price, he said, he would not have been able to build the solar farm.

Robert Hargraves,
Sep 15, 2011, 2:22 PM