A state program that provides rebates for the installation of solar systems will soon end after funds allocated for the incentive were gobbled by California energy customers.

The California Public Utilities Commission (CPUC) reported Monday that the allotment of residential rebates in PG and E and SDG and E territories under the statewide California Solar Initiative (CSI) rebate program have been fulfilled.

Solar advocates say that the end of the program is a sign of success, noting that the completion of this major $2.2 billion state incentive program marks a new phase of solar market maturity, with low and middle income households now driving solar energy's growth in California.

"This is a major milestone for solar," says Susannah Churchill, Policy Advocate at Vote Solar. "The California Solar Initiative was designed to do something remarkable: achieve scale and lower costs to make rooftop solar a real and growing part of the state's energy landscape. Supported by smart policy, the solar industry has given Californians a cost-effective alternative to buying power from the grid."

Churchill says lower prices are the driving force behind a record number of installations and predicts that California energy consumers will continue to invest in solar without the rebates because it makes economic sense.

"Now that our state has successfully built this new energy industry, it's increasingly important that we make sure energy consumers can continue to choose solar without unnecessary red tape or utility barriers," says Churchill. "All Californians benefit from more rooftop solar."

Launched in 2007, the CSI provides incentives for solar system installations to customers of the state's three major utilities: Pacific Gas and Electric Company (PG and E), Southern California Edison (SCE) and San Diego Gas and Electric (SDG and E).

The program was designed to automatically reduce the incentive level in ten "steps" based on target amounts of solar capacity in each utility service territory. As the solar market grew and achieved new economies of scale, the incentive levels dropped predictably down these steps, from $2.50 per watt to $0.20.

PG and E has completed the tenth and final step for both residential and commercial rebates, although some continued funding is expected to be made available to replace program dropouts. SDG and E has completed the final step of its residential program and is in the eighth step of its commercial program. And SCE is close behind in the ninth step for residential and the eighth step for its commercial program.

The California Solar Initiative is the country's largest solar program, with a $2.2 billion budget and a goal of 1,940 megawatts (MW) of solar capacity by the end of 2016. It has helped make California the nation's solar leader.

California Solar Initiative success by the numbers:?

Market growth: California energy consumers have installed more than 140,000 solar energy systems amounting to nearly 1,500 MW to date, more than seven times the total amount of solar installed when the CSI launched in 2007.

Cost reductions: The average pre-incentive price of going solar through the CSI decreased more than 35% from $9.48 per watt at its most expensive to $6.10 per watt today.

Job and economic benefits: California's solar industry has created more than 43,000 high-wage jobs and spurred more than $10 billion in private investment in the local economy during the past decade. The CSI has been a major driver of this growth.

Taxpayer benefits: Public agencies that go solar through CSI will save a total of $2.5 billion in electricity costs over the next 30 years. Schools alone will save $1.5 billion, valuable resources that can be directed to core educational programs and teacher salaries. Ratepayer benefits: CSI installations can generate approximately as much electricity as three conventional power plants. These solar energy systems help reduce the need for expensive and polluting conventional peak power generation by producing electricity when and where it's needed most on California's grid.