HONG KONG — The military authorization law signed by President Obama on Friday contains a little-noticed “Buy American” provision for the Defense Department purchases of solar panels — a provision that is likely to dismay Chinese officials as President Hu Jintao prepares to visit the United States next week.

Although there are many big issues to discuss, including concerns about North Korea, trade and economic matters are certain to be high on the agenda. And while both sides are aiming to keep the discussion positive — the United States is the world’s largest importer and China the largest exporter of goods — simmering resentments over trade in green-energy technologies could be a distraction.

China has emerged as the world’s dominant producer of solar panels in the last two years. It accounted for at least half the world’s production last year, and its market share is rising rapidly. The United States accounts for $1.6 billion of the world’s $29 billion market for solar panels; market analyses typically have not broken out military sales separately.

The perception that Beijing unfairly subsidizes the Chinese solar industry to the detriment of American companies and other foreign competitors has drawn concern in Congress. The issue of clean-energy subsidies is also at the heart of a trade investigation under way by the Obama administration, which plans to bring a case against China before the World Trade Organization.