The headline in The Sentinel May 18-19 (“Proposed utility-scale arrays in region would dwarf state’s current solar capacity”) was very misleading. The giveaway is the word “capacity” which appears twice on the front page. It is more clearly defined further down on the front page “can produce up to 140 kilowatts.” If I read this right, that means “140 Kw, but only at noon on a bright sunny day.” These panels would generate no solar energy at night or on cloudy days (or right after a snowstorm). To quote Prof. Michael Mooiman: “On average, Chinook’s (Nextera’s solar project in Fitzwilliam) actual output would be about 20 percent of its rated capacity.” Every capacity number in the article needs to be reduced by a factor of five to reflect the actual output.

A solar array that “can produce up to 140 kilowatts” will only produce 20 percent, about a fifth, of that 140 kilowatts on average, or about 30 kilowatts of useful energy. To put that in perspective, a “utility-scale” power plant like Seabrook generates an average of 1 million Kw (1,000 Mw). Even a large wind turbine, just one turbine, generates between 1,000–3,000 Kw (1-3 Mw).

Another way of looking at these issues is to use the numbers from the last section of the article: “The proposed 50 Mw (50,000 Kw) solar array would be built on approximately 245 acres of private land.” The 50 Mw figure is apparently its capability at noon in bright sunshine, meaning it will generate only 10 Mw of useful power overall. Compare this again to a second (1,000 Mw) reactor at Seabrook, generating 100 times that 10 Mw. If it takes 245 acres of solar panels to generate 10 Mw, then it would take 100 times that acreage to match a “utility-scale” plant like Seabrook. 24,500 acres equals about 40 square miles!

Similarly, the statement “(the) 5-acre solar farm (in Peterborough is) capable of generating close to 1,000 Kw (1 Mw)”: This, when divided by the 20 percent inefficiency, equates to only 1 Mw per 25 acres of real output. To match Seabrook’s 1,000 Mw would require 25,000 acres, again about 40 square miles of solar panels.

So to put the highlighted comment from Prof. Mooiman of Franklin Pierce University in perspective, “utility-scale solar development” will let us see not “big changes”, but huge changes, tens of square miles of blue panels, instead of local agriculture; 40 square miles of blue panels that generate no power 80 percent of the time.


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