Archive for October, 2012

September performance

performance chart september

Fall weather arrived last month. More rain and clouds with cooler nights. We generated 883 kWh in September, down 15% from last month, but still about 37 kWh better than predicted. We generated on average 29.4 kWh per day.

We used 292 kWh, our lowest month yet. That’s down 7% from the previous month. We used the air conditioning only 2 days and heating for 1 day. We used 9.5 kWh for cooling / dehumidification, and 5.9 kWh for heating. Together that’s 5% of our month’s total usage. We generated a 591 kWh surplus this month, our 7th surplus month in a row.

I changed the format of the table a bit. Months now run down the table instead of across.

Month Solar PV Usage Net usage or (surplus) Avg. daily usage HDD3,4
Jan1 369 873 504 28.2 1,2125
Feb2 597 666 69 23.0 1,045
Mar6 860 515 (345) 16.6 704
Apr7 925 378 (538) 12.9 617
May 867 309 (558) 10.0 298
Jun 939 325 (614) 10.8 144
Jul 970 319 (651) 10.3 34
Aug 1,018 315 (703) 10.2 56
Sep 883 292 (591) 9.7 188
All values in kWh (except HDD).
1 January values based on meter reads.
2 February values based on TED data.
3 Heating Degree Days, a measure of how many outside degrees in a day it is below a base target inside temperature, 68F.
4 Calculated from our HOBO outdoor weather monitor hourly data, unless otherwise noted.
5 January HDD data downloaded from degreedays.net, Station ID: KALB (Albany International Airport).
6 March values based on meter reads. (TED died March 1st, eMonitor installed March 16, 2012)
7 Values starting in April are based on eMonitor data.

Again I was surprised that our usage for the month was lower than last month. The big energy saver this month was less need for cooling and dehumidification. Most of the canning was finished last month. We added a freezer in the basement last month. So far it has not appeared to impact our daily usage by a noticeable amount.

The number of hours we experienced temperature values below 68F increased to 188 HDD, right on average for September in our area. Our water usage is also back down to a more normal non-summer range of 43.8 gallons per day.

You can see heat maps and detailed charts of temperature and electrical usage at netplusdesign.com. View solar, usage, net usage, temperatures and HDD for all of February and circuit-level data for 16 days in March and the full months of April through September.


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