Silver Spring Networks has raised $81 million in its initial public offering, after the smart grid networking startup boosted the number of shares on offer on the eve of its debut on the New York Stock Exchange.

Silver Spring sold 4.75 million shares at the midpoint of its previously announced price range, according to lead underwriter Goldman Sachs. That’s more than the 3.7 million shares the company had been planning to sell as of last week, at a midpoint price of about $63 million.

But it’s also far from the $150 million the Redwood City, Calif.-based startup hoped to raise when it first announced plans to go public in July 2011. Still, given the declining appetite amongst public investors for green technology IPOs that we’ve seen since then, news that Silver Spring was able to sell more shares than expected appears to augur well for institutional investors’ interest in the company’s offering.

Silver Spring will also raise $12 million in a private placement to its biggest shareholder, Foundation Capital, in a move akin to SolarCity backers Elon Musk, DFJ and DBL Investors pledging to buy up a big share of the company's stock the day before its December IPO.

Silver Spring will also extend to underwriters a 30-day option to buy up to 712,500 additional shares of common stock. That list of underwriters no longer includes Morgan Stanley, which dropped out as lead underwriter, but does include Goldman Sachs, Credit Suisse, Piper Jaffray, Stifel, Baird, Canaccord Genuity, Evercore Partners and Pacific Crest Securities.

We will be filing updates to Silver Spring’s opening day under the ticker symbol SSNI through the coming hours, so stay tuned for more.

Here’s our previous coverage of the company that would seek to break the IPO barrier in the smart grid industry:

We’ve covered Silver Spring’s IPO plans from the pre-inception phase to the official S-1 filing in July 2011, through the company’s continuing list of project wins, technology developments and strategic investments since then, culminating with the the company’s decision late last month to price its IPO at $16 to $18 per share.

Silver Spring has has raised just under $300 million to date, with big investors including Foundation Capital, with 27.7 percent of the company after the IPO and private placement, and Kleiner Perkins Caufield & Byers with 12.8 percent. Other investors include Northgate Capital Partners, Google, EMC and Hitachi.

As for its financials, Silver Spring reported 2012 revenue of $196.7 million, down from $237.1 million in 2011, and a 2012 net loss of $89.7 million, which represents a slight improvement over 2011’s loss of $92.4 million. The company hasn’t stated when it expects to achieve profitability, though it has offered some non-GAAP metrics for its billing and payment cycles, which run on utility (i.e., slow) timescales.

In the meantime, the company is facing a slowdown in the U.S. smart metering market, which is more a consequence of the one-time jolt of billions of dollars of federal smart grid stimulus money passing through the system. That puts pressure on Silver Spring, as well as competitors (and sometime partners) such as Itron, Sensus, Elster, Toshiba’s Landis+Gyr, Aclara, Echelon, Trilliant and General Electric to expand to international markets.

In the week and a half since it named its IPO target price, Silver Spring did announce one new project with CPS Energy, San Antonio, Texas’s municipal electric and gas utility. The two said they’re working on “increased energy efficiency, automating energy distribution, and improving grid reliability,” all terms that describe some of the distribution automation (DA) services that Silver Spring is trying to grow as a way to make money on its existing networks, as well as new ones.

The project, part of San Antonio’s “New Energy Economy” initiative, is also aimed at laying the “groundwork to implement smart energy and Smart City technology across CPS Energy’s service territory,” with possible projects including smart streetlighting, environmental sensors, traffic signals, electric vehicles and parking meters – a pretty long list of functions that Silver Spring is working on with various partners.

Diversification of its revenue streams will be vital for Silver Spring to meet its profitability goals. The company currently relies on several large-scale projects with big U.S. customers such as Pacific Gas & Electric, FPL, Oklahoma Gas & Electric, Baltimore Gas & Electric, Commonwealth Edison and Progress Energy for the majority of its revenue. While Silver Spring has also networked smart meters in Australia and is working with partners in Brazil, the U.K. and Singapore, international business accounted for only 8 percent of revenue in the first nine months of 2012, up from 5 percent in the same period in 2011.

Silver Spring’s share of revenues from services such as demand response, distribution automation and others it has built on top of its core networking and software platforms will also be a critical measure of the company’s prospects. Silver Spring hopes to expand recurring revenues from those services, both for customers that have already networked millions of meters with the company’s technology and for future customers such as CPS.

Silver Spring’s S-1 notes that “the majority of our utility customers are already leveraging the networking platform for advanced metering to support at least one other solution,” such as OG&E’s using the company’s smart meters for its large-scale residential demand response program, or Sacramento Municipal Utility District buying its distribution automation services. Other customers, such as FPL, have extended Silver Spring’s managed services contracts for longer periods.

Even so, revenue from the company’s demand response and DA solutions only represented 11 percent of the company’s revenues for the first nine months of 2012. That’s up from only 1 percent in the same time period in 2011, which indicates that the company is finding few new customers interested in those services. Whether or not Silver Spring can continue to grow the share of revenues that are coming from these recurring service contracts, and thus avoid being caught in the overall smart metering slowdown, may play a key role in its future financial prospects.