Apple will partner with First Solar to build an $850 million solar energy farm in California, CEO Tim Cook said on Tuesday.

First Solar shares spiked on the news and closed the day about 5 percent higher, while Apple ended about 2 percent higher. Apple's value rose to $710.70 billion as it became the first U.S. company to close with a market cap above $700 billion. The tech giant had touched the $700 billion level before but never managed to settle there.

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Cook touched on the solar project and a wide range of company developments—including Apple Pay, the Apple Watch and the company's partnership with IBM—at the Goldman Sachs Technology and Internet Conference.