The state Public Utilities Commission does not review or approve the credit, and Xcel pays it to customers at its own discretion. So far, Xcel has paid out more than $40 million in such credits to customers.
The utility says it will be a wash for customers who still will be able to recover half their cost of solar installations through a rebate, a bigger federal tax credit and the lower renewable energy credit.
"It will not be a wash for customers, and we are going to talk to Xcel about that," countered Ritter, speaking on the sidelines of the National Renewable Energy Laboratory's Industry Growth Forum.
"There are a lot of policy questions we can ask... the Public Utilities Commission and legislature can ask so we are not stepping back on our renewable energy goals."
Ritter said the federal tax credit, contained in the recently approved $700 billion bailout package, won't be available to solar customers until April 15, 2010 - increasing the upfront cost of solar installations for customers.
Solar industry executives also criticized Xcel's move, saying lower credits would dissuade customers from installing solar panels on rooftops and stunt the growing solar industry.
Xcel spokesman Joe Fuentes said the purpose of the renewable energy credits was to "kick-start" the solar industry in Colorado. Under state laws, Xcel needs to get 20 percent of its electricity from solar, wind or other renewable resources by 2020.
To encourage more customers to use solar, Xcel launched a program two years ago that offered customers a $2.50-per-watt renewable energy credit and a $2-per-watt rebate for residential solar systems.
The credit comes from Xcel's operating costs, while the rebate is funded by a surcharge that Xcel collects from all customers.
The intention was to help cover half the cost of solar installations for customers, Fuentes said.
But the bailout package approved by Congress offers a 30 percent investment tax credit to residential solar customers.
That bigger federal tax credit, combined with Xcel's credit and the rebate would have covered 60 percent of installation costs - more than Xcel's plan to cover only half the cost, Fuentes said.
"By changing the credit to $1.50 per watt from $2.50 a watt, we are effectively going back to our goal of covering only 50 percent of the cost," he said. "We will take those dollars and re-allocate to other renewable energy projects like wind or bigger solar... we are not making any money. We are being reasonable stewards of money."