It isn’t always easy to estimate how much power renewable energy installations create or save, so Fat Spaniel is building a business around doing so.

Among its over six hundred clients are companies like Staples and Wal-Mart. The software and hardware Fat Spaniel offers can help discover exact cost savings and secure renewable energy credits from the government.

We reported in October 2006 that the company had raised a total of $7 million for its first round of funding, from DFJ Element and Chrysalix Energy.

Now it has raised a further $3 million bridge round, and is seeking a total of $20 million for its second round, according to VentureWire (subscription required).

VentureWire goes on to note that some investors have decided to avoid the company, as it “will face stiff competition as traditional information technology and networking companies warm to the market potential of so-called smart-grid applications for energy management.”