SAN FRANCISCO (MarketWatch) — Google Inc. on Wednesday said it has teamed up with SunPower Corp. for a big push to make solar power more accessible to households.

Google and SunPower SPWR, +2.22% are creating a $250 million fund for buying residential rooftop solar systems, aimed to “make it easier for thousands of households across the U.S. to go solar,” Google said in a company blog post.

The news sent SunPower’s stock rallying 8%. Google’s Class A GOOGL, -2.41% and Class C shares GOOG, -2.37% were each down nearly 1%, joining a broader tech sector retreat.

Google will invest $100 million, while SunPower will invest $150 million in the plan.

“Essentially, this is how it works: Using the fund, we buy the solar panel systems,” Google said in a blog post. “Then we lease them to homeowners at a cost that’s typically lower than their normal electricity bill. So by participating in this program, you don’t just help the environment—you can also save money.”

The company said the SunPower deal is Google’s 16th renewable energy investment and the third geared toward residential solar power systems. The technology giant has invested more than $1 billion in renewable projects throughout the world.

Google unveiled the SunPower deal at a time when some analysts are raising questions about the company’s expenses. Google has also been investing in major projects that could yield long-term benefits but involve huge capital allocations, such as its evolving superfast Internet system, Google Fiber.

In a note to clients, Bernstein Research analyst Carlos Kirjner said, “We believe the lack of clarity about the causes of the elevated capex levels and the potential for increased capex due to a large Google Fiber expansion are increasing the risks of owning Google stock.”

But IDC analyst Crawford Del Prete also argued that “Google is committed to disrupting categories.”

“Energy is one of them,” he told MarketWatch. “I think in the context of overall investments, this is pretty small. It’s also a way to Google to invest in moving a category forward, which is more of a market development spend as opposed to cap ex.”

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