A team of Americans and Israelis launched an experimental solar technology plant Thursday in Israel's Negev Desert, a prototype designed to drastically cut the cost of energy produced from the sun. Israeli company Luz II, Ltd. and its American parent, Brightsource Energy, Inc., plan to use the Israeli solar array to test new technology for the three new solar plants they are building for California utility Pacific Gas and Electric Company. Arnold Goldman, founder of the Oakland, California-based company, called the array "the highest performance, lowest cost thermal solar system in the world." His previous company built the first commercial solar plants in the 1980s. The new technology uses fields of computer-guided flat mirrors called heliostats to track the sun and focus its rays on a boiler at the top of a 200-foot tower. Water inside the boiler turns to steam, which powers a turbine and produces electricity. The steam is then captured and cooled naturally so the water, scarce in the desert, can be reused. The concept is in the final testing stage. Results from the experimental facility, a fraction of the size of the commercial plants, are expected by the end of the summer. The plan is to complete full-sized facilities in California's Mojave desert by 2011. The test plant does not have a turbine to create electricity, but engineers can measure the pressure and temperature of the steam to estimate how much energy the towers would produce. As fossil fuels become more expensive, solar power is sought-after as a clean, renewable source of electricity. But harnessing the sun's rays has proved expensive and often inefficient. BrightSource CEO John Woolard estimated that the new technology could cut the costs associated with solar energy by 30 to 50 percent. Although the tower technology is not a new idea, "No one's ever put it together in the right way before," he said. The flat mirrors and sun-tracking technology improve on previous designs, he said. Creators employed simpler cost-cutting strategies as well, such as using many small mirrors that can be mass-produced, instead of special-ordering a few large ones. BrightSource says its deal, delivering at least 500 megawatts of solar energy to Pacific Gas and Electric, is the largest solar energy agreement ever signed.