The Commerce Department said on Tuesday that it would impose tariffs on solar panels imported from China after concluding that the Chinese government provided illegal export subsidies to manufacturers there.

The tariffs were smaller, at 2.9 to 4.73 percent, than some American industry executives had expected. At that size, their effect on the market could be limited. But additional tariffs could be imposed in May, when the Commerce Department is scheduled to decide whether China is “dumping” solar panels into the United States at prices below their actual cost. A finding of dumping would result in additional tariffs that could be far larger than these.

But whatever the size of the penalties, Tuesday’s ruling is likely to further heighten trade tensions with China, and to have implications for renewable energy policy in this country.

Although the ruling is the result of a quasi-judicial review process by civil servants in the Commerce Department, the imposition of tariffs by an arm of the Obama administration also seems certain to enter the partisan fray.