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Apr 3, 2014  | Tom Cheyney  | 0 Comments

Solar March Madness

Lightsource plugs in prodigious amounts of UK solar in a month, super-cheap Austin PV project moves forward, Sandia gets the drop on solar power plant variability

You could call it Solar March Madness, British style. UK-based Solar Power Portal has an exclusive video interview with Lightsource Renewable Energy CEO Nick Boyle, in which he provides details on his company’s ridiculous levels of interconnection activity last month. The herculean effort was carried out to get the projects completed under the wire before the “renewable obligation rate” decreased as of April 1. He says that over the course of those 31 days, his teams managed to connect 26 commercial and utility projects across the United Kingdom, with a total installed capacity of 227MW. During one weekend alone, 16 systems were hooked up.

One does wonder though, how did those engineers traverse so much territory in such a short period of time? Apparently he hired several helicopters to transport the technical side hither and yon. Which then raises ye olde carbon footprint question: how much clean energy generation will be needed from all those Blighty solar megawatts to offset the accumulated fossil fuel use and attendant exhaust release resulting from all that choppering about?

A landmark effort of a different sort is taking shape down in the heart of Texas. A solar deal based on a 25-year PPA contract touted to have the lowest rates ever seen in the United States has moved closer to fruition. The 5-cents-per-kilowatt-hour deal in question, SunEdison’s $525 million contract with Austin Energy to sell power to the utility from 150MW of PV projects, was duly covered and analyzed a couple of weeks ago on Greentech Media. The Austin Business Journal reported April 1 that the contract “slipped quietly through City Council on the consent agenda last week.” But the deal is not quite done, according to the paper, as the council “has authorized the negotiation and execution of the agreement, which means the utility may be finalizing some details.” (Thanks to Yann at Solar Wakeup for pointing me to the story.)

Something that the operators of those UK PV farms, SunEdison’s future Austin installations, and pretty much any other solar power plants have in common is a crying need for more accuracy in weather modeling prediction and power output variations, especially the impact of cloud events on said output and the resultant variability in electricity supplied to the grid. Ongoing SunShot-supported research at Sandia National Labs has recently come to light on the topic, and a fresh post at Solar Novus provides a nice companion piece to the original press release.

Using a unique modeling approach based on a clever solar irradiance point sensor placement scheme and plant output data from a 48MW utility-scale farm and a 2MW project distributed over several rooftops, the Sandia team “directly compared the point sensor irradiance variability with the PV plant power output variability,” according to SolarNovus. “One key finding was that the more geographically dispersed PV modules are within the plant, the stronger the smoothing effect. Hence, developers of a new solar plant may want to spread out their PV modules more and take maximal advantage of the site’s geographic diversity.”

Sandia’s Matt Lave summed up the importance of his team’s work in the well-written PR from the lab. “It is important to accurately scale solar variability to ensure accurate grid integration studies and PV plant evaluations. Having a solid understanding of the effect of PV plant variability will encourage PV installations while helping to maintain a safe electric grid.”


Sources: Solar Power Portal UK, Lightsource Renewable, Greentech Media, Solar Wakeup, Austin Business Journal, SolarNovus, Sandia National Labs

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