Solar power companies around the U.S. are getting a boost in sales from people who fear the impact of the Y2K problem. Some speculate that the millennium bug will cause massive failures in the nation’s power grid, though electric companies claim they have the situation under control. In another Y2K-related development, the French Institute of Nuclear Safety acknowledged this week that between 45 and 80 percent of internal nuclear power systems in France could experience malfunctions related to Y2K and create safety problems.