OK, so I got the first electric bill since we got the panels.
Here is the raw data:
Covers Jan-7 to Feb-7, the panels were installed on Jan-13
Total kWh used: 991
Total kWh generated: 67 ( 2.6 per day )
Total sold back to PSE: 14
My usage would have been: 1044 without panels.
kWh used per day: 33.6
The first 11 days of the current billing cycle we have already generated 74 kWh. This is due to the fact that the sun is already significantly higher in the sky and last cycle was below average in sun ( we had 12 straight days of dark grey rainy sky immediately after the panels were installed – I counted ).
The post about next month’s bill will be exciting, we are on track to produce almost 20% of our electricity from the panels and generate about what is used by the car and its still only february!
If we compare this current bill to last years bill for the same time period, we used 1201 kWh and 41.4 kWh per day.
Our usage went down about 19% even though the solar panels contributed very little. Amazingly enough it was 3 degrees colder this year per day than last and we used about 20% more gas to heat the house!
Why? Ever since we got the panels I have been trying to conserve. I have a TED energy meter that tells us how much our whole house uses. Aggressive conservation has meant two things, first I turn stuff off. That’s the big one. Turn stuff off. Second has been to install a bunch of LED bulbs, a lot of the LEDs have replaced CFLs, which I bumped down and replaced incandescents. Most of our highest use rooms have LEDs and CFLs now.
Now that our lighting is very efficient, I believe the largest consumer of electriciy used by our house right now is to run the furnace. My energy meter tells me it uses about 900-1000 watts when running and it runs a lot ( I’ll guess somewhere between 4 and 8 hours per day ). It is a 17 year old 80% efficient model but the biggest loss I believe is from low quality ductwork. We lose a lot of heat through leaky ductwork and thus are wasting money heating the crawlspace. We have a company coming out soon to seal our ductwork and fix some problems with our attic and crawlspace insulation.
I need to come up with a way to log the energy used by the furnace each day and chart that against the ambient temperature – then compare the data before and after to find out how worthwhile the work was.
What about the car?
The car uses 7.5 kWh per day ( not counting charging losses ) I drive it to work. In that month I drove it about 22 days, using 165 kWh or about 16% of our total electricity use. In the coming months I will track this more precisely.