MARTINSBURG, W.Va. -- Some taxpayers in the Eastern Panhandle are challenging the state's exclusion of solar energy from an alternative energy tax credit.A 2011 law allows a credit of up to $25,000 for alternative-fuel motor vehicles and more than $300,000 for qualified refueling infrastructure between Jan. 1, 2011 and Dec. 31, 2013.Last October, the West Virginia State Tax Department ruled that solar energy would not be included under the law's credits, said John Christensen with Mountain View Solar in Berkeley Springs."That put us in a tough position, because we have a lot of [clients] that are on the hook for that money," Christensen told The Journal. "They were expecting tax credits, and now the tax department is expecting them to pay up."He said that several people are appealing the decision."Everything that's handled in this office is confidential," said Stephen Lee, director of the Office of Tax Appeal. "I can't acknowledge whether we have a case or not."David Levine with solar analytics company Geostellar said the tax department "has been somewhat arbitrary and capricious in accepting and denying individual claims for the tax credit."Geostellar has engaged a national tax accounting firm to gather information and provide advice on the issue, he said."We've found cases where the tax credit has gone through, we've seen cases in which the people have been asked to pay back taxes," Levine said. "There doesn't seem to be any distinction between the two."An environmental group, Sustainable Shepherdstown, has collected more than 800 signatures on an online petition that asks Gov. Earl Ray Tomblin to instruct the tax department to include solar energy in the law."I'm impressed by how fast this petition has spread across the state," said volunteer Than Hitt. "I think this is just the tip of the iceberg."The petition also seeks corrective legislation to provide a "safe harbor" for those who already applied for the tax credit."That's the most important thing out of all of us, because we were led to believe there was a tax credit coming," Christensen said.The petition also asks that solar energy be included in state tax incentives.Hitt said a tax credit would be a positive step toward increasing West Virginia's solar potential."When you look at the places with the strongest economies, you see that those are the places that provide incentives for people to produce and to use solar power," Hitt said. "I think West Virginia should do the same."