If you read their FAQ page, it's a capacitor. It won't change your bill at all since residential homes have Kwh meters, not Kvah meters (well, at least most are). The POCO, however, should love them.
[This message has been edited by WFO (edited 03-10-2006).]
Power factor correction is nothing new. As Rodalco pointed out, it's generally motors that have power factor issues, and not lights or heaters. In other words, you're fixing a problem you don't have.
Come to think of it, if the thing is hardwired on all the time, it will overcorrect the PF when the AC isn't running. Wonder if a leading PF is cheaper than a lagging PF?
Put a kWh meter on a test bench, run it at UPF then 0.5 PF. Same test current. Meter runs at half speed at 0.5 PF. Bear in mind that extra losses appear in wiring if you run your house at 0.5 PF.
The product of rotation, excitation and flux produces electricty.