Solar sector exchange traded funds are powering up on rising global demand, with Yingli Green Energy Holding (NYSE: YGE) revealing a favorable outlook for emerging market demand and SolarCity Corp. (NasdaqGS: SCTY) cutting costs and increasing supply in the U.S.

The Guggenheim Solar ETF (NYSEArca: TAN) rose 3.2% Tuesday while the Market Vectors Solar Energy ETF (NYSEArca: KWT) gained 1.8%. Year-to-date, TAN is up 21.5% and KWT is 16.4% higher.

Elon Musk’s SolarCity is expanding its manufacturing ability through a $200 million deal with Silevo Inc as the solar panel provider tries to install as much as 1 gigawatt this year, reports Ehren Goossens for Bloomberg.

“If we don’t do this, we thought there was risk of not being able to have the solar panels we need to expand the business,” Musk said in the article.

SCTY shares surged 15.8% Tuesday on Musk’s plans.

Musk is taking control of Silevo’s production capacity in a bid to drive down overall costs. Silevo produces photovoltaic panels that convert 21% of sunlight energy to electricity and could reach efficiency rates of 24%, compared to industry average of 17%.

“The path to ultimately having solar power be way cheaper than coal or fracked-gas power is to combine huge economies of scale with the most advanced technology,” Musk added.

Meanwhile, YGE shares jumped as much as 12% Tuesday, the most in almost four weeks, after diminishing losses and issuing a positive guidance, reports Bloomberg. The company projects it will sell 4 to 4.2 gigawatts this year after a record 3.2 gigawatts last year. [Alternative Energy ETFs for Shifting Global Demand]