The system that we are putting in is 4.94 KW and is supposed to supply about 60% of our electrical needs, or about 6,000 KWh a year. This should drop us out of Tiers 4 & 5 (34 cents a KWh), and make a dent in Tier 3 (30 cents a KWh). Our bills average somewhere around 700 to 1000 KWh a month. What's funny is that since I've gotten the PiP, the overall monthly bill has gone down. Even month to month (April versus May) or year to year (April '11 versus April '12). Of course some of that may be due to different usage during the day (no longer have roommates at home during the day).