Acciona’s Portuguese PV plant may be big, but one of the numbers just doesn’t add up

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Tom Cheyney

Tom Cheyney is former senior editor of PV-Tech / Photovoltaics International magazine. A veteran technology journalist / editor / blogger, he covered the semiconductor, microelectronics and solar sectors for many years - since fax machines were state of the art. His PV-Tech blog has become a must-read for industry insiders and observers. He was also chief editor of "The Rise of Thin-Film Solar Technology" book published in early 2010.

The newly activated photovoltaic power plant run by Acciona Energy in Portugal, with its 46 MWp capacity, sets the bar higher than ever for ground-based solar farms. With more than 262,000 crystalline-silicon-based modules deployed on some 2500 tracker arrays spread out over 250 hectares (that's alot of soccer pitches), the installation is physically very impressive--a heady holiday gift for the entire renewables community.

But one of the numbers cited in the company's press release strains credulity, because it's flat-out wrong. Unfortunately, most of the media reports about the project just picked up the erroneous info without blinking.

The number in question is Acciona's statement that "Amareleja is capable of producing 93 million KW/hr a year―equivalent to the electrical consumption of over 30 million Portuguese households (emphasis added)."

Aside from the fact that there aren't 30 million households to consume said energy in Portugal, a smallish albeit sunny country of about 10.6 million people, the solar-energy conversion math just doesn't add up.

A standard calculation, at least the one used for California homes, holds that an installed megawatt can power about 750 households. Multiplying that number by the 46 MW installed at the Portuguese site, we get enough energy for about 34,500 homes.

Since 34,500 is only three extra zeroes from being in the same numerical ballpark as 30 million, one gets a sense that the glaring mistake in Acciona's PR is likely one of a typographic not hyperbolic variety.

But the asleep-at-the-wheel acceptance of that bogus figure by just about every media outlet that's reported on the story--from the trades (who should know better) to the mainstream (who are oft clueless on such matters)--is an error of a much more disturbing nature.

As we ring out the old--and troubling--year none too soon and greet double-naught nine with a raised glass, we in the media covering the solar PV space have an obvious resolution for the new year--to not regurgitate every piece of press release fodder as fact and to strive for greater accuracy in our reporting.