The state Division of Rate Counsel estimates that the law will save ratepayers about $1.1 billion over the next 15 years.
After the bill-signing ceremony at the Statehouse, Christie said the law also would "help maintain New Jersey's position as a national leader in the solar industry."
He said the industry has created thousands of jobs in the state and "helped businesses thrive and grow" while generating more than 800 megawatts of clean energy.
In recent years, New Jersey has built more solar projects than any state except California. But the plethora of projects contributed to a glut of solar-subsidy credits, driving down prices.
The market also grew stagnant when utility companies started producing more of their own solar energy, sharply dropping the value of the credits, a major source of revenue for independent solar developers.
Environmental groups, who have been at odds with the governor over some key issues, praised the new law and its goals, but said more needed to be done.
"The recent boom in solar development demonstrates our state's potential is much greater than previously anticipated," said Matt Elliott, clean-energy advocate for Environment New Jersey.
"Moving forward, longer-term state policy must keep up with that potential," he said. "We should be increasing the state's overall clean-energy requirements and ensuring more of our clean-energy goals are carved out for solar specifically.
"In the short term, however, this bill," Elliott said, "will ensure that New Jersey continues to be a solar leader."