Updated from 1:55 p.m. EDT

Shares of solar energy-related stocks mostly traded lower Tuesday, despite news that SunPower ( SPWRA) and Xcel Energy ( XEL) will build a solar power plant.

The two companies have signed a contract to build a 17-megawatt AC photovoltaic solar-power plant in Alamosa County, Colo.

It is the latest in a series of agreements announced by solar energy manufacturers and utilities as more states adopt standards requiring a percentage of electricity to be produced from renewable resources.

The plant, which the companies expect to complete by the end of 2010, will be the second-largest high-efficiency solar PV power plant in North America and create about 200 jobs during construction, they said in a statement.

Xcel said the plant will use SunPower tracker systems, which tilt toward the sun as it moves across the sky, increasing the amount of energy captured.

San Jose, Calif.-based SunPower's shares were down 6.7% to $22.97.

Among other solar movers Tuesday:

JA Solar ( JASO) finished down 13% to $3.06.

LDK Solar ( LDK) was down 7.4% to $6.78.

First Solar ( FSLR) closed down 3.7% to $133.12.

Canadian Solar ( CSIQ) finished down 8% to $6.45.

Suntech Power ( STP) was down 9% to $12.66.

Yingli Green Energy ( YGE) was lower by 13% to $6.31.
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