A fight over whether licensed electricians are required for installing larger solar energy systems prevented California lawmakers from passing a bill to expand their net metering program.

The bill, AB 560, would have raised the cap for the net metering program to 5 percent from the existing 2.5 percent.

The net metering program allows utility customers who own solar or wind energy systems to get credits on their electricity bills for feeding the power they don't use back to the grid. In the current program, each utility would stop accepting net metering customers when the overall generation capacity of existing net metering customers' systems reach 2.5 percent of the load.

An amendment pushed by the International Brotherhood of Electrical Workers sparked some contention that couldn't be resolved before legislators ended their 2009 legislation session last Friday, said Adam Browning, executive director of Vote Solar Initiative, a San Francisco-based advocacy group.

"We were all pretty surprised and incredibly disappointed with the turn of the event," Browning said. "The bill got stuck in a vortex and it never came out."

The amendment would require someone with the C-10, electrician license to carry out installations of systems that are larger than 250 kilowatts, Browning said.

Currently, someone with a solar-specific license, C-46, could do the installations.

"It's fine to talk about licensing, but that's a separate question that should be dealt with in a separate, licensing conversation," Browning said.

Net metering has been particularly popular among solar energy system owners partly because the state also offers incentives that help pay for solar installations at homes and businesses.

Lawmakers began to consider raising the cap when it became apparent that the San Francisco-based Pacific Gas and Electric Co. could hit the limit next year if not earlier.

Legislators initially considered raising the cap to 10 percent, but ditched the ditch the idea after facing lots of opposition from utilities.

Lawmakers trimmed the proposed to limit to 5 percent and then 3.5 percent, the last of which was carried out in the Senate's appropriations committee only a few weeks ago (see Cal Lawmakers Propose Smaller Increase for Net Metering). The bill then went through another change that increase the proposed cap to 5 percent again.

The sticking issue has been a big debate over the costs of the program to ratepayers throughout the state. Utilities such as the San Diego Gas & Electric, for example, have questioned whether the program is benefiting a small group of people at the expense of those who choose not to or can't afford to install solar energy systems.

Utilities typically recoup the cost of the programs it runs by seeking rate hikes that apply to its overall customer base.

Also, lawmakers have expressed concerns that some net metering customers are not paying their fair share of the costs of maintaining the electric grid.

Utilities can't tag on the maintenance fee on bills that show no amount is due, which could happen to those solar energy customers who consistently feed their excessive electricity to the grid. Yet these customers still rely on the utilities for power at night, when their solar energy systems aren't working.

Most of the time, customers do owe utilities money when they reconcile the credits with their energy use at the end of the year, however. In fact, 78 percent of the time, PG&E customers have no credits left at the end of the year, said PG&E spokeswoman Katie Romans via email.

As of early August, PG&E had 32,350 net metering customers, Romans said.

The California Public Utilities Commission is due to issue a report analyzing the costs and benefits of the net metering program in January next year. Lawmakers may consider increasing the cap higher after seeing the report.

Although legislators didn't pass AB 560 to send it to the governor's desk, they could choose to work on in a special legislative session later this year.