Elon Musk's Tesla and solar tech development and manufacturing company SolarCity on Friday signed a deal that approves the development of their first joint project. According to the Tesla CEO, the project's solar roof product would be more affordable than traditional shingles.

The Tesla pioneer said: "So the basic proposition will be: Would you like a roof that looks better than a normal roof, lasts twice as long, costs less and-by the way-generates electricity?" Elon Musk further asked. "Why would you get anything else?"

According to Bloomberg, Tesla's tempered glass and the use of the Tesla-Panasonic-SolarCity solar power technology would place a "premium" label for the specially-designed roof shingles. However, the report also indicates that Tesla will drive down manufacturing costs with optimized and streamlined manufacturing methods.

Tesla first unveiled their plans to manufacture a solar roof on Oct. 28 this year. Fortune.com collected a statement from SolarCity CEO Lyndon Rive said their competitively priced roofs can become part of the 5 million new roofing products US residents purchase yearly. Cousins Rive and Musk believe the new roof product can make waves.

They also report that an "overwhelming" number of majority shareholders in Tesla had approved the merger with SolarCity. Despite the relation of Lyndon Rive and Elon Musk as cousins, 85% of the investors had agreed to the merger and to the project.

Investor confidence can be due to the "swinging" effect of "green investments". According to an investor survey by SustainableBrands.com, 70% of investors believe green investments are of high risk but majority also believe physical risk from climate change — its lasting effects — are "very important."

Against the merger were four Delaware lawsuits that focus on Tesla's "breach of fiduciary duty." According to some reports, it could mean the delay of the merger's completion — a claim that did not come true as the two companies had completed the merger the previous week.