Citing a significant drop in the cost of solar power, Sonoma Clean Power says it will cut its electric rates for residential customers in March about 10 percent.

“Solar is beginning to drive the electric market in California,” said Sonoma Clean Power CEO Geof Syphers.

The price for solar power “has been dropping remarkably,” Syphers said. Solar electricity now costs less per kilowatt hour than that produced from coal, and he said it drawing “darn close” to the cost of electricity produced by natural gas.

Sonoma Clean Power provides electric power to 88 percent of Sonoma County households, plus a large number of businesses.

The independent agency is run by the county and eight participating cities.

It will start serving homes and businesses in Mendocino County in June.

State law allows such agencies under a program known as community choice aggregation.

Sonoma Clean Power’s board approved the rate decrease last week, Syphers said.

Rates are just one component of the monthly electric bill. Residential and business customers of Sonoma Clean Power also must pay Pacific Gas and Electric for the transmission and distribution of the power they use.

PG&E, one of the largest combined natural gas and electric companies in the U.S., this month raised its average customer’s electric bill 1.4 percent to $99.13, spokesman Donald Cutler said.

PG&E customers are “still well below” the national average electric bill of $114.86, he said.

Solar power is having an increasing impact on California’s electricity market, Cutler said.

A quarter of all the solar power generated in the U.S. is transmitted over PG&E’s power grid.

“It has resulted in much more energy on the grid when the sun is up,” he said.