The Sierra Club is asking a state court to invalidate new state Department of Taxation rules that change renewable energy tax credits for solar panel installations.

An Earthjustice attorney filed a lawsuit on behalf of the Sierra Club in circuit court in Honolulu today. The complaint asks the court to reinstate the department’s earlier interpretation of the tax credits.

The department issued new rules last month, saying it wanted to provide clarity to taxpayers.

But the Sierra Club says the new rules will increase the cost of installing solar panels and fewer panels will be installed.

The new rules calculate tax credit eligibility by total output capacity. The old rules based eligibility on the number of independent connections to the project’s electrical system.