The six-year-old company, called Varentec, develops algorithms and smart grid gear that can help utilities swiftly manage electrons at the edges of the power grid. Utilities can use the digital tech to run the power grid more efficiently and better manage new sources of clean energy like solar and wind.

Gates and Khosla have played key roles in developing computing and Internet technologies. So it’s not so surprising that they’d be interested in backing computing tech for the energy industry.

Gates is a limited partner in Khosla’s Khosla Ventures, and it’s not uncommon for the Microsoft (MSFT) founder to invest alongside Khosla in deals.

To watch a debate about Bill Gates investing wisely in clean tech, watch:

Power grid companies and utilities have been looking to add computing technology, software, sensors, and wireless networks to all aspects of power grid infrastructure.

Companies like Opower (OPWR), which was recently bought by Oracle (ORCL), have been applying algorithms and web services to utility customer’s energy bills. GE (GE) has been building software to better control connected energy machines like gas and wind turbines.

Varentec sells devices that control grid voltage and which the company says can react much more quickly than traditional voltage controllers. Utilities, like Hawaiian Electric, are testing out the controllers to help minimize voltage fluctuations as residents and businesses connect new rooftop solar panels to the grid.

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A few years ago, Varentec scored a $5 million grant from the U.S. Department of Energy’s ARPA-E program, which funds high-risk early-stage energy technology.

The funding announced on Wednesday is the second close of an initial $13 million Series C round. The company raised a $7.7 million Series A round, and an $8 million Series B round.

Varentec says it will use the new funds to make and sell more of its devices, which it has been testing out in pilot projects for awhile.