kWh Consumption and Production

The Metroplex, a 1922 up-down duplex, has two Xcel energy accounts, that is two power lines in, two meters. For a variety of reasons, we're going to tie into the upper unit's feed, but are internally combining the billing since we share in the consumption in both units.

The lower unit uses more electricity because as a whole household we have three compressors running (freezer, fridge, and basement dehumidifier), and often a heater in the chicken coop. The upper unit has only one compressor on its circuits. We have no air conditioning.

We have windows in every room so for a lot of the year our lighting needs are met by the sun. For example, right now, in our unit we have a computer running (this one) and not a whole lot more. It's sunny out and we really don't need additional light anywhere. Upstairs we've been working on eliminating "phantom-load" and have been reluctant to purchase electronic equipment or appliances that rely on standby power.

For the upper unit our last year consumption in kWh was this:
10/24/10 - 169 kWh
9/23/10 - 208 kWh
8/24/10 - 162 kWh
7/26/10 - 160 kWh
6/24/10 - 162 kWh
5/25/10 - 147 kWh
4/26/10 - 136 kWh
3/28/10 - 209 kWh
2/25/10 - 369 kWh
1/27/10 - 479 kWh
12/28/09 - 275 kWh
11/23/09 - 192 kWh

Average: 222 kWh

Lower unit:
10/24/10 - 270 kWh
9/23/10 - 343 kWh
8/24/10 - 547 kWh
7/26/10 - 625 kWh
6/24/10 - 379 kWh
5/25/10 - 427 kWh
4/26/10 - 356 kWh
3/28/10 - 350 kWh
2/25/10 - 310 kWh
1/27/10 - 661 kWh
12/28/09 - 428 kWh
11/23/09 - 317 kWh

 Average: 418 kWh

Total metroplex monthly consumption: 640kWh.

Our system will be 3.24 kW composed of 18 Silicon Energy 180 watt modules with 9 modules flush mounted on house roof and 9 mounted on pergola in yard.

By the estimates from the National Renewable Energy Laboratory (NREL)

Month	Solar Radiation (kWh/m2/day)	AC Energy (kWh)	Energy Value ($)
1	3.85	325	25.68
2	4.72	348	27.49
3	4.97	393	31.05
4	4.90	353	27.89
5	5.73	410	32.39
6	5.91	398	31.44
7	5.88	409	32.31
8	5.64	393	31.05
9	5.21	362	28.60
10	4.28	320	25.28
11	2.95	220	17.38
12	2.85	234	18.49
Year	4.74	4165	329.04

On a monthly average, our system hopefully will produce ~345kWh. Or approximately 54% of our use.

The fanatic in me wonders, so what else can we reduce? I'd love to see the dial spin backwards and have Xcel pay us.