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Just as several new plug-in electric vehicles are headed to showrooms, the government is letting expire a tax credit for installing home and commercial charging equipment.

A tax credit for chargers ends Saturday, even as proponents press Congress to reinstate it, perhaps retroactively, in January.

“The timing of this couldn’t be more unfortunate,” coming just as more electric cars are on the way, says Genevieve Cullen, vice president of the Electric Drive Transportation Association, a trade group for the electric-vehicle industry.

The credit “created a growth opportunity for a new industry” and competition, says Tom Saxton of advocacy group Plug In America.

The credit allows taxpayers to deduct 30% of the cost of chargers installed in their garages up to $1,000. On commercial units, the tax break is up to $30,000, according to the IRS.

That’s down from 2010, when the tax credit was 50% as part of the government’s stimulus package.

The credit was another subsidy for adoption of electric vehicles, seen as a way to cut carbon dioxide emissions and use of foreign oil. The $7,500 tax credit for buying new electric vehicles remains in place.

Prices of electric chargers and installation vary widely. General Motors says the charger for its Chevrolet Volt, a plug-in that has a backup gas engine, runs $490, and installation can cost $500 to $1,500.

Loss of the tax credit will have a “minimal impact on Volt sales” because about 40% of buyers recharge from their home 110-volt sockets, rather than a special 220-volt charger, GM spokesman Rob Peterson says. Nissan, which makes the all-electric Leaf sedan, declined to comment. A 220-volt home charger can cut the time it takes to juice up an electric-vehicle battery by about half to about four hours or less.

Ford, Toyota and Honda are major makers planning new plug-in cars in 2012. Start-ups Tesla, Fisker and Coda have new cars coming, too.

Tax credits spurred interest in electric vehicles, says Don Karner, president of ECOtality North America, a charger installer, but the charger credit “runs out about the time it could stimulate things.”

Even if consumers wanted to try to get one installed before Sunday, they may be thwarted by the local permit process, Karner says.

Sears, which is just entering the charger business, says the credit “makes a difference to help customers make that decision” to install a home charger, says Duncan McCulloch, director of strategy for home improvements at Sears.

The Energy Department says it wants to try to cut the cost of home chargers in half in the next three years. It announced $7 million in grants last week to four companies to develop a lower-cost charger.

Copyright 2011 USA TODAY, a division of Gannett Co. Inc.