A sunny day swept the clouds away for solar companies on Wall Street today.

As measured by Revere Data, firms working in the sector for solar cells and systems saw their shares jump a collective 5.4%.

SunPower (nasdaq: SPWR – news – people ) finished up 5.4%, or $3.28, to $63.54. JA Solar Holdings (nasdaq: JASO – news – people ) climbed 9.9%, or $2.96, to $32.85. Yingli Green Energy Holding (nyse: YGE – news – people ) increased 6.9%, or 94 cents, to $14.50.

Clean power is in great demand. Over the next 25 years solar is expected to be the fastest-growing alternative source of electric energy. Fresh capital is flowing into the sector from governments and capital markets, creating new opportunities for growth and invention. (See: ” The Sunshine Economy.”)

Al Kaschalk, analyst at Wedbush Morgan Securities, wrote in a client note that solar energy still remains a negligible portion of the U.S. energy consumption portfolio, leaving substantial room for future growth.

He points out that solar energy contributed less than 0.1% of U.S. energy consumption in 2006. Kaschalk doesn’t expect this ratio to change much in the near future unless the government kicks in some subsidies.

Kaschalk told clients that a major hurdle to the rapid adoption of solar cells has been the relatively high price tag at the wholesale and retail level. But, using a combination of models, he said, solar power industry players are aggressively driving down their overall costs to become increasingly cost competitive with electrical utility grid.

What’s a potential favorable site for solar technology? Your office building.

Buildings are responsible for at least 40% of energy use in most countries, Kaschalk wrote. He believes that building energy supply will slowly shift to distributive energy sources where efficiencies are a lot higher.

“Solar energy will be one of the viable solutions, once installed costs reach acceptable levels,” the analyst said.

Read more at: http://www.forbes.com/markets/2007/08/29/solar-power-sun-markets-equity-cx_jl_0829markets38.html