Automakers have long resorted to incentives like zero-percent financing, rewards points and rebates to inspire customer loyalty. Now Honda is offering a different deal: inexpensive home solar power systems for customers.

Through a partnership with SolarCity, a residential and commercial installer, Honda and Acura will offer their customers home solar systems at little or no upfront cost, the companies said on Tuesday. The automaker will also offer its dealers preferential terms to lease or buy systems from SolarCity on a case-by-case basis, executives said.

The deal, in which Honda will provide financing for $65 million worth of installations, will help the automaker promote its environmental aims and earn a modest return, executives said. It could also open the door for more corporate investment in solar leasing companies, which has largely been limited to a small cluster of banks to provide capital for their projects.

And SolarCity, one of the few clean-tech start-ups to find a market for an initial public offering of its stock last year, will potentially gain access to tens of millions of new customers through Honda’s vast lists of current and previous owners.

“When we partner with financial institutions, they aren’t promoting us to their customers, they’re essentially just providing us with capital,” said Lyndon R. Rive, SolarCity’s chief executive. But with Honda, he said, the company is gaining, “access to a broader customer base, and a customer base that is conscious of the environment.”

Whether the marriage will prove successful remains to be seen. “I don’t think that by finding Honda buyers you’ve homed in on the perfect solar customer, but there’s enough overlapping between the demographics that you’re better off than the general population,” said Shayle Kann, vice president at GTM Research, adding that car buyers were more likely to own their homes and have the income and credit history to qualify for solar leasing. While the American solar industry in general has been struggling in the face of declining government subsidies, overcapacity in production and a glut of inexpensive Chinese panels, interest and investment in solar leasing, or third-party ownership, has continued to grow. According to a recent report from GTM Research, a renewable energy consulting firm that is a unit of Greentech Media, third-party ownership accounts for more than 70 percent of all residential installations in developed markets like Arizona, California and Colorado and has generated at least $3.4 billion in private investment since 2008.

SolarCity and a rival, Sunrun, were among pioneers of the approach, but players like Clean Power Finance and Vivint, a home security company owned by the Blackstone Group, are also gaining momentum.

In a typical arrangement, a company provides a system at little or no cost in exchange for a long-term contract in which the customer pays a fixed fee for the electricity generated, set at less than the customer would pay for power from the local utility. The solar price often rises over the life of the agreement, which can last 20 years.

Honda approached SolarCity more than a year ago when it was looking for a partner to provide solar installation services for its hybrid and electric vehicle customers, said Ryan Harty, American Honda’s assistant manager for environmental business development. The company then decided to expand to all its customers — a group it is defining “very, very broadly,” Mr. Harty said, to include not just car owners but also those who have explored its Web sites. The offer will be available in 14 states: Arizona, California, Colorado, Connecticut, Delaware, Hawaii, Maryland, Massachusetts, New York, New Jersey, Oregon, Pennsylvania, Texas and Washington, and the District of Columbia.

The two companies say they hope the joint venture leads to projects that integrate solar power and electric vehicle recharging for its customers.

The program will give Honda and Acura customers an extra $400 discount on top of SolarCity’s normal promotions, which they can use to sweeten the terms of the solar contract, like eliminating the escalation of the monthly payment. Honda projects the fund can finance as many as 3,000 systems on homes and 20 for its dealers. If the program catches on, Honda plans to expand it. Executives said they saw more immediate promise in cutting carbon emissions through solar power than the electric vehicles it would sell.