A home improvement business that had nothing to do with solar until a couple investors bought it in 2008 is now the no. 1 solar installer in California, the hottest solar market in the country.

Verengo Solar installed more residential solar than any other business, according to a report this week from the California Solar Initiative. The company added 44 jobs in January, 40 in February and 400 in 2011. It’s opened offices in Central and Northern California and in New Jersey.

“Our plan was always to move it to solar,” said CEO and co-founder Randy Bishop.

Verengo did mostly handyman work, installing new windows and doors and insulation. Bishop and his long-time friend bought the business with plans to slowly transition into solar in 2008.

“We felt the existing sales and support staff could make the transition,” he said.

But then the economy bottomed out in 2008, and no one was putting in new windows anymore.

“Solar became the rock we were trying to jump to from a sinking ship,” Bishop said.

People were still interested in investing in solar even in the throws of the worst economy since the Great Depression. Solar would protect them from rising energy costs. It made people feel safer and more secure in an uncertain time.

Verengo also found creative ways of financing solar projects so they would be affordable to homeowners. The company offers leasing options with no or little upfront cost.

Bishop credits the company’s niche with its rapid expansion as well.

“We have a laser focus on residential,” he said. “It’s all we do. We just focus on residential. You’ll see most of our competitors also do commercial and other things.”

That focus has enabled the company to target a specific audience and manage its marketing materials and message and its team for success.

Bishop said that because the company has that focus, his team is able to interview new employees for friendliness and ability to communicate with customers and make them feel comfortable about having Verengo at their homes.

The company assigns a specific representative to every customer, and the customer will always be able to reach that rep for information and questions. The company also has a reputation for getting solar installations done quickly and making the process as easy as possible, Bishop said.

For those reasons, he said he’s prepared to hire another 400 people this year. The company started with 60 employees in Southern California. It had no presence in the central or northern parts of the state and certainly not on the East Coast. Now it has 600 employees and saw 133 percent growth in 2011. Bishop said the company’s January and February business is already double what it was in 2011.