Sungevity, the solar sales and service platform, has just entered a new partnership with energy retailer Viridian.

A retail energy services company founded in 2009, Viridian already has hundreds of thousands of household energy customers buying electricity in varying shades of green, as well as natural gas. Viridian calls itself "a socially responsible energy company providing clean energy choices at competitive prices."

So in addition to selling green energy, Viridian's sales channel can now offer solar installation and financing. Which it has already been doing since 2013 in its partnership with SolarCity.

But Viridian is now switching to the Sungevity platform. Executives at Viridian and Sungevity referred to it as a better match in "culture." Viridian CEO Michael Fallquist said the co-branding aspect of the Sungevity platform allowed his company to maintain a 20-year relationship with the customer. He also praised Sungevity's technology and tools.

Viridian employs a network marketing method to reach the customer through friends and family, with what it calls a "20,000-contractor network." Viridian offers service in 16 markets and will be working with Sungevity in eight states initially: Arizona, California, Connecticut, Delaware, Maryland, Massachusetts, New Jersey and New York. Viridian will continue to work with SolarCity in markets that Sungevity doesn't currently service.

Fallquist said, "What makes our model so powerful is that it's a warm sale." He said it's about "education and awareness" in the residential market. The company has already sold 6,000 solar systems for a total of 48 megawatts, according to the CEO.

Sungevity believes that its partnership model drives its success. Viridian, a Crius Energy company, now joins Sungevity partners such as Lowe's, Sierra Club, UC Berkeley and European utility E.ON.

A SolarCity spokesperson noted, "Viridian was a good partner but the cost of acquisition was too high to justify continuing the relationship. Others may be willing to pay the higher cost, but as we look forward to 2017 -- it’s not sustainable."

Dave Dunlap, Sungevity's chief development officer, stressed that Sungevity has a different model. "It's not vertical integration," said Dunlap, adding, "It's a platform model" focused on strategic growth through partnerships.

Fallquist spoke of the potential to "own the home" and offer more customer packages and products further down the line.