CWE Visits Solar Power Plant

Mark Meshulam — Wed, 16 Sep 2009 03:24:43 +0000

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Your Chicago Window Expert recently had an opportunity to visit a real, working solar power plant in Richmond, California. The Richmond site, a wastewater treatment plant, now obtains one-third of its electrical energy needs from solar power.

Aside from the great story-value of a municipal agency (The West County Wastewater District, or WCWD) creating its own energy on its own land, there are interesting backstories, too.

2-axis tracker at West County Wastewater Treatment Plant

For instance, the WCWD site is the largest solar power plant in the US that uses 2-axis trackers to aim the PV panels toward the sun at all times. “2 axis” means that the panels not only move East to West (the azimuth direction), as the sun crosses the sky every day, but also North-South, as the sun’s position varies over seasonal cycles.

The manufacturer of the solar trackers, as these aiming devices are called, is ET Solar. They generously arranged this tour.

Another story worthy of mention is the financial structure of the deal. WCWD entered into a contract with a “solar developer” Solar Power Partners, Inc. to furnish and install the entire installation. They, in turn, contracted with a “solar contractor”, Premier Power Renewable Energy, Inc. for the performance of the work.

A crane is used to place the assembled array onto the tracker base

The solar developer retained ownership of, and responsibility for the maintenance of, the entire installation. WCWD agreed to buy the electrical output of the plant at a predetermined rate for 20 years in a PPA – a Power Purchase Agreement.

At the end of the 20 year term, WCWD may purchase the power plant from the solar developer at market rate.

Another interesting story: the use of trackers, whether 1 or 2 axis, will be an increasingly familiar part of the PV landscape because of its ability to increase power output by 20-40%.

Land usage was also of interest. The land was somewhat unstable and prone to flooding. The trackers used a ballasted base that required little excavation, yet provided stability for the trackers up to 110 mph.

The 1.1 megawatt plant uses about 5 acres of land.

Each tracker measures approximately 22-by-36 feet each and carries 56 panels with a total peak power of about 11.24 kilowatts (kW) each. The system is designed to produce approximately 1.97 million kilowatt-hours (kWh) of electricity annually. That annual output would be enough to meet the annual needs of 3,654 California homes.

Detail and dimensions of solar tracker

Now you can tread among the trackers. See our video now…

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My phone: 847-945-9200 ext 229
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CWE Visits Solar Power Plant