China is reducing the amount of money it pays to newly completed solar and wind power generators for their electricity, in order to reflect declines in construction costs, the country’s price regulator and economic planner said Monday. The nation will cut tariffs paid to solar farms by as much as 19 percent in 2017 from this year’s levels, and by as much as 15 percent for wind mills in 2018 from current prices, according to a statement posted on the National Development and Reform Commission’s website.