Silver Spring Networks, the San Mateo, Calif. company that offers wireless utility metering technology, has raised $39.9 million in a third round of funding, according to a Securities and Exchange Commission filing cited by VentureWire (sub required).

It is just the latest funding in a sector that has become hot lately, as utilities invest more in making their grids more intelligent and efficient, and as Silicon Valley investors such as Foundation seek to bring Internet technologies to bear in the sector. Silver Spring, for example, uses Internet Protocol for its grid management technology.

VentureWire offered few details, noting only that existing investors Foundation Capital and JVB Properties returned to participate in the funding.

Coincidentally, VentureBeat had scheduled a talk with chief technology officer Raj Vaswani today, so we hope to have more details shortly.

Earlier this year, Foundation and JVB committed $10.5 million in debt and warrant financing to Silver Spring Networks.

Silver Spring Networks and Florida Power & Light Co. recently signed an agreement to deploy the company’s technology in Juno Beach, Fla.