The News Behind Today's Move In Solar

Vivint Solar Inc VSLR is more than 1.3 percent lower following an announcement that Yingli Green Energy Hold. Co. Ltd. YGE would become a preferred supplier.

Shares of Yingli initially spiked 2 percent on the news, though the price settled up 1 percent - at $1.05 - an hour into trading. Yingli shares have been troubled this year, falling more than 55 percent. Shares hit a high near $40 in late 2007 before plummeting. More recently, shares hit a high above $8 in late 2013.

On Monday, Benzinga reported on the recent spike in the short interest at certain solar names - notably Vivint Solar, as well as Solaredge Technologies Inc SEDG and SunPower Corporation SPWR.

For Vivint, the number of shares sold short increased 25 percent to more than 22 percent of float. During this time, however, shares have handily outperformed the S&P 500, gaining nearly 51 percent year-to-date versus gains of 2.5 percent for the index. Solaredge and SunPower have also outperformed the market, gaining 96 percent and 18 percent year to date, respectively.