Shareholders for SolarCity and Tesla voted Thursday to approve merging the two companies.

"Tesla's shareholders have overwhelmingly approved our acquisition of SolarCity," said a statement from Tesla sent to CNBC. "Excluding the votes of Elon and other affiliated shareholders, more than 85% of shares voted were cast in favor of the acquisition. With SolarCity's shareholders also having approved the acquisition, the transaction will be completed in the coming days."

Tesla will pay $2.6 billion to acquire SolarCity, which has struggled financially despite revenue growth.

In a question and answer session following the announcements, Tesla chairman and CEO Elon Musk, who also chairs SolarCity, said the company plans to begin volume production of its recently announced solar roof sometime in summer of 2017. The company will roll out the different varieties in three month intervals, starting with the one that appears to be most popular.

Costs will vary according to the size of the house and the difficulty of the installation, Musk said.

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