Silver Spring Networks (NYSE: SSNI) is looking like gold in its market debut. A provider of smart grid products and services to utility companies, Silver Spring went public at $17 today – the midpoint of its expected IPO range. The company raised $81 million by selling 4.75 million shares – about 1 million more than expected. Right now, those shares are going like hotcakes. The stock is up 27% in its IPO, rising to $21.60 as of 1:40 p.m. eastern time. The Silver Spring IPO is the third to hit U.S. markets this month, and certainly won’t be the last. No fewer than five more companies are listed in Renaissance Capital’s IPO hopper at the moment. Last week Artisan Partners (NYSE: APAM) , an asset management company, and Professional Diversity Network (NASDAQ: IPDN), an online jobs and networking site for minorities, went public with very mixed results. Artisan Partners popped 29% in its IPO. Professional Diversity Network shares fell 4% in the company’s debut. The average first-day returns among U.S. IPOs so far this year has been 13%. Should Silver Spring’s numbers hold, the stock would more than double that mark.