December 1, 2009

Top Plants: El Dorado Energy’s Solar Facility, Boulder City, Nevada

Dr. Robert Peltier, PE

Building on Success

After one year of successful operation, and with only minor adjustments required on the plant’s design, Sempra is pushing ahead with collecting the necessary approvals from state agencies and obtaining a power purchase agreement to construct a 50-MW expansion of El Dorado. If the regulatory hurdles are cleared this year, the new plant could be up and running by late 2010.

The El Dorado expansion, tentatively called Copper Mountain Solar, will continue to use the tried-and-true 1-MW PV power block design with almost a million PV panels. When completed, the 60-MW integrated PV project may be the largest of its type in the world. First Solar will also provide the panels and EPC services for the expansion project.

Sempra is also proposing the development of Mesquite Solar, a PV plant that would be located adjacent to its 1,250-MW Mesquite combined-cycle plant located in the desert west of Phoenix (a POWER 2004 Top Plant). When fully developed, that project will produce up to 400 MW of PV power. Mesquite Solar was described by Allman as a project that would be developed at the rate of 50 to 100 MW per year, with construction tentatively scheduled to begin in early 2010. Mesquite Solar would build on the knowledge and experience gleaned from El Dorado, although Sempra is also looking at the possibility of integrating some concentrating solar power into the project.

4.    Weather-challenged. During the winter months, the PV systems have little sunlight with which to make electricity. To the right is one of the plant’s 10 power control stations, which contain the inverters and switchgear for enough PV panels to produce 1 MW—when the sun is shining. In the background is the air condenser for the El Dorado Energy gas-fired combined-cycle plant. Courtesy: Sempra Generation

As at El Dorado, the Mesquite Solar project will use existing transmission infrastructure that is sufficient to absorb the additional solar power produced by the project and ship it to electricity markets in Arizona and/or California. Given that the project will be built on land already owned by Sempra, the land is properly zoned, and the project requires no water to operate, Sempra only requires local development permits, which are faster to obtain than state and federal land-use permits that are now holding up other solar energy projects across the Southwest. Once again, the critical path for the project is the signing of one or more power purchase agreements. Given the pressure on California utilities to meet that state’s 33% renewable portfolio standard by 2020, I suspect that contracts for that power will soon be signed.

First Solar recently announced that by year’s end it would have the capacity to produce more than one gigawatt worth of modules per year. First Solar was also the first company to reduce its solar panel manufacturing costs to less than a dollar per watt — a goal reached for production during the fourth quarter of 2008. At that cost, solar power begins to become increasingly competitive with conventional sources of electricity.