Richly funded smart grid startup Silver Spring Networks is swallowing home energy monitoring startup Greenbox Technology – the latest, but likely not the last, in a series of acquisitions in the smart grid space.

Under the deal announced Tuesday, Redwood City, Calif.-based Silver Spring will integrate Greenbox's web-based energy management platform into its series of deployments.

Silver Spring uses IP-based networks to link wireless mesh radios that are in smart meters being deployed by utilities including Pepco, Pacific Gas & Electric, Florida Power & Light, Commonwealth Edison and the Sacramento Municipal Utility District, as well as in Australia (see stories here, here, here and here).

Greenbox, founded by Flash co-creator Jon Gay and former Macromedia engineering vice president Peter Santangeli, has seen its energy portal tested with Silver Spring in a pilot project with Oklahoma Gas and Electric (see Smart Grid: Test Customers Give Thumbs Up).

Financial terms of the acquisition, announced at the at the GridWeek conference in Washington, D.C., were not disclosed.

Silver Spring is one of the best-funded smart grid startups out there, with about $160 million from investors including Silicon Valley VC powerhouse Kleiner, Perkins Caufield & Byers (see Green Light post).

Silver Spring CEO Scott Lang has made no secrets of his hopes to acquire companies that can help Silver Spring expand its offerings. He's also denied that Silver Spring is in the market to be acquired, though he has said that the company may be looking at an IPO in the next year or two (see Green Light post).

Tuesday's news is just the latest in a series of acquisitions and mergers, with smart grid companies hoping to give utilities a broader set of functionalities under one roof (see Tendril Lands $30M as Growth, Consolidation Loom in Smart Grid, Trilliant Joins SkyPilot for End-to-End Smart Grid Communications and Acquisitions in Smart Grid: Get Used to It).

The closest analogy to the Silver Spring-Greenbox deal is that of GridPoint, the smart grid software startup with about $220 million in venture capital, which in June bought Toronto-based home energy monitor startup Lixar for an undisclosed amount (see GridPoint Buys Home Energy Management Startup Lixar).

After all, with giants like Google, IBM, General Electric, Microsoft, Intel, Cisco Systems, Oracle and SAP entering the smart grid space, startups will need a wide range of solutions to compete, or face being acquired themselves (see Carbon Consolidation Begins With SAP's Latest Buy).

The relationship between startups and IT giants can work both ways. Until this summer, Judy Lin, Silver Spring's chief products officer who commented on the Greenbox acquisition in a prepared statement, was Senior Vice President of Cisco's Ethernet Switching Technology Group (see Green Light post).

Utility and metering company executives have been moving to smart grid startups at an increasing pace, indicating that those startups are seeking insider expertise in landing customers in expanding markets (see Trend Watch: Greenbox Lands Energy Industry Insider as CEO).

Also on Tuesday, Silver Spring said its technology is in about 1.5 million homes and businesses and is growing by about 50,000 devices per week. That would put it well on its way toward a goal of having 2 million devices deployed by year's end (see Green Light post).

While that's a small number compared to incumbent smart meter companies like Itron, Landis+Gyr, Sensus, Elster and GE, the smart meter field is only beginning to enter a more rapid stage of growth (see 8.3M Smart Meters and Counting in U.S.).

Incorporating home energy usage displays is "the next big wave of the smart grid," Eric Dresselhuys, Silver Spring vice president of markets, said in an interview at the GridWeek conference. "As all the systems are rolling out, customers are asking us for portals... to get the consumers engaged."

That consumer engagement is also the business of startups such as Tendril Networks, Control4, EnergyHub, OpenPeak and dozens of others (see Green Light post and stories here, here, here and here.

Microsoft and Google have also launched web-based energy management platforms (see Microsoft Launches Home Energy Site, Sees Devices, Demand Management in Future and Enel Considering Google's PowerMeter for Pilot Project).

Some of those platforms also offer the ability to power down or turn off loads like air conditioners, water heaters and appliances, though that functionality generally carries a higher installation cost than simply showing energy use (see Consert Claims Faster, More Complete Home Energy Network).

Dresselhuys said that Silver Spring is working with various partners, including Tendril and demand response and home energy management company Comverge, on that next step.

But "the business model is still being figured out," he noted. "Is it something the utility owns? Is it something you go to Walmart and pick up off the shelf?" Utilities are of mixed minds when it comes to choices like that, he said (see $48: A Threshold Price for In-Home Energy Management?).

Interact with smart grid industry visionaries from North American utilities, innovative hardware and software vendors and leading industry consortiums at The Networked Grid on November 4 in San Francisco.