Archive for April, 2017

First quarter 2017 performance

Q1 2017 summary: 3% colder, 6% more usage and 20% less sun as compared to Q1 2016.

This is part of our quarterly home performance reporting. All data is posted at

I’ll say it, it was a whacky winter. Lots of cold days, but also lots of warm days. It would be warm for a week or two, the ground would thaw, then we’d get snow.

We recorded a low of 3.3, quite a bit warmer than the -17.3°F  last year’s low. Our high was 73.6, less than the 78.5°F last year. In 2012  we recorded a high of 82.4°F in the same period.

Overall, here’s how this quarter compared to 2016.

Q1 Comparison

2016 Usage Solar PV Net usage
or (surplus)
daily usage
Total 2,550 1,982 568 28.0 2,952
Jan 1,055 499 556 34.0 1,192
Feb 846 586 260 29.2 1,009
Mar 649 897 (248) 20.9 751
2017 Usage Solar PV Net usage
or (surplus)
daily usage
Total 2,709 1,586 1,122 30.1 3,054
Jan 1,035 357 678 33.4 1,085
Feb 783 478 305 28.0 890
Mar 891 752 140 28.8 1,079
All values in kWh (except HDD which is base 65°F).

Our heat pump used 955 kWh last year and 1,195 kWh this year. Thats about $180 in electricity. We’re getting a fairly consistent correlation between energy use and heating degree days using a base temperature of 65°F. 

ASHP regression analysis correlating HDD to kWh

The higher energy use was directly correlated to colder temperatures. Plus there was more snow to hide the solar panels and it was more cloudy, so we generated less energy as well.

Last year the grass was just starting to green up and we had a few plants budding out. A few trees looked like they were ready to pop. Not this year. April 1 we got about an inch of ice/snow and it still looks like Winter out there. As always about this time of year, we are most definitely ready for Spring!

You can see heat maps and detailed charts of temperature and electrical usage at View hourly, daily and monthly values for solar, usage, net usage, circuit-level usage, temperatures and HDD.

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