National Grid seeks OK to build four solar panel plants in Mass.

National Grid has submitted plans to state regulators to build four solar panel plants in Massachusetts at company-owned sites, including the iconic gas tank off the Southeast Expressway in Dorchester.

The company picked sites with ample space and at strategic locations on the region’s grid to alleviate electricity congestion points. The plans call for a 1-megawatt solar installation in Dorchester, a 1.5-megawatt solar installation in Revere, a 1.5-megawatt plant in Everett and a 1-megawatt installation in Haverhill. The projects will cost about $38 million, and the panels could cost National Grid customers about 8 cents per month.

The state Legislature earlier this year passed a law that allows utilities to develop and own up to 50 megawatts of solar generating capacity by 2010.