Archive for the 'Performance' Category

Third quarter 2017 performance

Q3 2017 summary: 33% cooler, 9% more usage and 7% less sun as compared to Q3 2016.

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

Nothing exciting to report, which is normal for 3rd quarters.

At 1pm on July 17th we became net positive for the year. As of the end of September, we have a surplus of 1,326 kWh heading into the final months of 2017. That’s about 574 less kWhs than last year at this time. Overall for the year, our solar production is down about 13%.

Overall, here’s how this quarter compared to 2016.
Chart showing usage, solar, net and hdd

2016 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 957 2,857 (1,900) 10.4 191
Jul 300 955 (655) 9.7 32
Aug 330 934 (604) 10.6 27
Sep 328 968 (641) 10.9 133
2017 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 1,045 2,657 (1,611) 11.4 254
Jul 322 848 (527) 10.4 39
Aug 377 944 (567) 12.2 73
Sep 347 864 (517) 11.6 143
All values in kWh (except HDD which is base 65°F).

Water usage was down 6%. Hot water usage up 30%. I think that’s attributable to the chillier mornings this summer.

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

Second quarter 2017 performance

Q2 2017 summary: 15% warmer, 1% less usage and 15% less sun (412 kWh) as compared to Q2 2016.

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

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

Chart showing usage, solar, net and hdd

2016 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 1,439 2,668 (1,229) 15.8 994
Apr 575 893 (317) 19.2 615
May 551 834 (283) 17.8 279
Jun 313 942 (629) 10.4 100
2017 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 1,421 2,258 (837) 15.6 846
Apr 531 758 (227) 17.7 420
May 514 692 (178) 16.6 315
Jun 375 807 (432) 12.5 110
All values in kWh (except HDD which is base 65°F).

Most noticeable is the lower solar generation, 15% down this quarter and 17% down for the combined first and second quarters. I think we’ll still easily remain net positive for the year, but this might be the lowest solar generation year for us since we got the panels.

The last day we used heat was April 11 for a total of 69.3 kWh this quarter. Last year we turned the heat off on April 17th and used 117.2 kWh that quarter.

Here’s our breakdown on energy use and cost for the last four winter seasons.

Winter season Heat kWh Est. Cost
2012-13 957 $144
2013-14 1,804 $271
2014-15 2,200 $330
2015-16 1,305 $196
2016-17 1,804 $271
Est. cost based on $0.15 kWh.

We would have spent about $1,212 (if we paid for electricity) in the last five winters. That’s still a lot less than many of our neighbors would spend in one winter.

We haven’t netted out energy-wise yet. Last year we netted out on May 31 after 8am. In 2015 we were 637 kWh short of netting out for the year. In 2014 we netted out around mid-July. In years prior we were net positive by May or June.

Our overall water usage is down 34% from Q2 2016. This has been a very rainy an cloudy season as evidenced by the lower solar generation numbers. Out hot water usage was up 17%.

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

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 netplusdesign.com

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)
Avg.
daily usage
HDD
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)
Avg.
daily usage
HDD
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 netplusdesign.com. View hourly, daily and monthly values for solar, usage, net usage, circuit-level usage, temperatures and HDD.

We’re net positive again in 2016!

We used 6,837 kWh and generated 8,910 kWh for a net of 2,073 kWh for the year.

This is our second highest net energy surplus year after 2012 and our highest solar generation year.

Q4 2016 summary: 24% colder, 38% more usage and 17% less sun as compared to Q4 2015.

In Q4 our total usage was 1,890 kWh, a 38% increase from our 1,368 kWh in 2015. We also generated 281 kWh less solar.

Overall, here’s how this quarter and the year compare.

Charts comparing Q4 and YOY usage, solar and HDD

2015 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 1,368 1,683 (315) 14.9 1,810
Oct 377 710 (333) 12.2 488
Nov 399 648 (248) 13.3 597
Dec 591 325 266 19.1 725
2016 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 1,890 1,402 488 20.5 2,243
Oct 412 607 (195) 13.3 420
Nov 567 451 115 18.9 722
Dec 911 343 568 29.4 1,102
All values in kWh (except HDD which is base 65°F).

Year-over-year comparison

Here’s our progress for the first 5 years in the house.

Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 34,892 43,382 (8,490) 19.1 32,910
2012 5,601 8,856 (3,256) 15.3 5,885
2013 7,206 8,575 (1,368) 19.7 6,810
2014 8,108 8,348 (240) 22.2 7,063
2015 7,141 8,694 (1,552) 19.6 6,772
2016 6,837 8,910 (2,073) 18.7 6,380
All values in kWh (except HDD which is base 65°F).

Year over year usage comparison

Circuit-by-circuit 

Pie chart - circuit breakdown

I broke out a few additional circuits worthy of note, the refrigerator (4%) and chest freezer (7%), removing them from the ‘everything else’ category. 2016 was our second warmest year in the house, although we continue to see wide extremes in temperature ranges (see temperature ranges below). As a result, the ASHP used a smaller percentage of the total. Vampire loads increased this year. Seems to be the nature of vampires, they such you dry without vigilant attention. We appear to have cooked less in 2016 as the induction cooktop & stove vampire loads increased in comparison to use. The combined vampire load for the stove, ASHP and solar inverter was 145 kWh in 2016 (same as 2015).

Net-zero moment

Our ‘net zero moment’ this year occurred on May 31 at 7am. This was our second earliest time since 2012. Our solar curve remains fairly constant. Our usage changes the most from year to year, manly due to weather.

Chart showing net-zero moment

Where did all that solar go?
Charts showing mix of solar and grid supplied elect.

28% of our power needs were supplied by our own solar generation directly. The other 72% was supplied from the grid. Of the 8.910 kWh we generated in 2016, we only used used 21% directly. The other 79% we sold back to the grid (at a greatly reduced price) so other people use it (if there was demand for it).

This make 5 full years not having to pay for electricity. We still pay the monthly connection fee, minus any rebate from the utility for excess electricity generated. This year we earned $73.62, or 0.355 cents per kWh. We won’t be quoting our day jobs any time soon.

National Grid does not tell us how much electricity would cost if we bought it from them. They only do that if you actually use more electricity than you generate. So I have to go to the NYSEDA website to find the state averages. Using their data, we would have paid about $6,500 over the past 5 years for the 34,892 kWh we’ve used if we didn’t have solar. Our solar cost $14,320 in 2011. In very simple terms that puts us at about 45% payback.

Air-source Heat Pump performance

Chart of ASHP usage values Oct-Arpril, 2012-2016

This was the second coldest fourth quarter since we moved into the house. As a result, we used a more heating energy than the last two years. We’re currently on course with the coldest season 2014 as seen in the chart above. Overall, heating season 2015-2016 worked out to be our second highest energy use in the last 5 years. We used just over 1,297 kWh for heat. At $0.17/kWh that would be about $220.

My thermostat strategy this year is to mostly just leave it at 68 degrees F. As the charts show below, leaving it at 68 every day incurred more vampire losses, but overall the energy use is not greater. Cleaning the filters every month also has a noticeable impact.

Chart showing kWh used by ASHP in 10 degree buckets

Chart of temperature buckets year-over-year

Something that is quite different than previous years, the temperature bucket for 30-40 degrees F was off the chart this year. Literally, I had to change the range in the chart! Our last highest number of hours in this range was 935 hours in 2014. This year we had 1,484 hours in this temperature range, almost double the average. Although 2016 saw the ASHP working the largest number of hours, it’s total usage was only the second largest since we started tracking circuit-level data.

The lesson I’m learning from this data is that I should just leave the thermostat at 68. Set and forget. Fiddling with the thermostat settings does not appear to decrease our energy usage.

Water


Chart comparing water usage 2012-2016

We have been fairly consistent in our hot water usage. Over the year we averaged 17.5 gallons/day, same as last year. That hot water requires 251 watts/gallon to heat. But our cold water usage is a different story. As you can see from the chart above, we used a rather large amount of water in June. At first I thought perhaps we left the water on overnight. But no, it appears we watered the garden a lot in June. We used a total 26,735 gallons of water in 2016, 73 gal/day, as compared to 20,684 gallons in 2015, up 6,051 gallons, a 29% increase. It took 69 kWh to pump that water out of the ground.

Temperature
Chart comparing temperature ranges 2014-2016

Chart of average temperate, year-over-year

We experienced our largest temperature range this year out of the last 5 years, 111°. Our coldest temperature was -17.3° on February 14 at 7am. Our high was 93.7° on July 7 at 12pm. Our highest recorded temperature in the last four years was 95.135°, set on July 19, 2013 at 3pm.

The average temperature for 2016 was 50.1°, 1.2° up from 48.9° in 2015.

New App

screenshot of new home performance app

I recently rewrote the data viewing app to make it easier to drill down from years, to months, days and hours, and back up again. It’s now easier to switch between years, circuits and temperature locations. Check it out at Netplusdesign.

Another new app

Every winter I pick a new tool or technology to learn. This year it was Electron. I built a desktop app to help publish my quarterly data. If you’re into code, you can check that out on Github.

May your 2017 be better than 2016!

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

Third quarter 2016 performance

Q3 2016 summary: 10% cooler, 3% less usage and about the same amount of sun as compared to Q3 2015.

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

Nothing exciting to report, which is normal for 3rd quarters.

At 7am on May 31st we became net positive for the year. As of the end of September, we have a surplus of 1,900 kWh heading into the final months of 2016.

Overall, here’s how this quarter compared to 2015.
Chart showing usage, solar, net and hdd

2015 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 991 2,866 (1,875) 10.8 175
Jul 342 949 (607) 11.0 39
Aug 332 1003 (671) 10.7 34
Sep 317 914 (597) 10.6 102
2016 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 958 2,857 (1,900) 10.4 192
Jul 300 955 (655) 9.7 32
Aug 330 934 (604) 10.6 27
Sep 328 968 (641) 10.9 133
All values in kWh (except HDD which is base 65°F).

Water usage was up 22%. Water for the garden plus we installed a water softener and flushed the hot water tank this summer.

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

Second quarter 2016 performance

Q2 2016 summary: 23% cooler, 8% less usage and 11kWh more sun as compared to Q2 2015.

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

Overall, here’s how this quarter compared to 2015.

Chart showing usage, solar, net and hdd

2015 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 1,568 2,658 (1,090) 17.3 810
Apr 594 796 (202) 19.8 566
May 417 998 (581) 13.4 145
Jun 557 864 (307) 18.6 100
2016 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 1,439 2,669 (1,230) 15.8 994
Apr 575 893 (318) 19.2 615
May 551 834 (283) 17.8 279
Jun 313 942 (629) 10.4 100
All values in kWh (except HDD which is base 65°F).

The last day we used heat was April 17 for a total of 120.4 kWh this quarter. Last year we turned the heat off on April 28th and used 150.3 kWh that quarter.

Here’s our breakdown on energy use and cost for the last four winter seasons.

Winter season Heat kWh Est. Cost
2012-13 957 $144
2013-14 1,804 $271
2014-15 2,200 $330
2015-16 1,305 $176
Est. cost based on $0.15 kWh.

We would have spent about $921 (if we paid for electricity) in the last four winters. That’s still a lot less than many of our neighbors would spend in one winter.

We netted out energy-wise on May 31 after 8am. Last year we were 637 kWh short of netting out for the year. In 2014 we netted out around mid-July. In years prior we were net positive by May or June.

Our water usage is up 66% from Q2 2015. June was very dry this year and we were determined not to let the garden die. Our reward is lots of tomatoes and other veggies.

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

First quarter 2016 performance

Q1 2016 summary: 26% warmer, 21% less usage and 33% more sun as compared to Q1 2015.

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

Although it seemed a lot warmer this winter, 1,023 less heating degree days than Q1 2015, it was still 9% cooler than first quarter 2012 which is the warmest winter since we began recording temperature data.

Despite it being warmer this winter, we recorded a low of -17.3°F, 1.2 degrees colder than last year’s low. Our high was 78.5°F which was considerably warmer than last year’s high of 52.8, but lower than 2012 when we recorded a high of 82.4°F.

Overall, here’s how this quarter compared to 2015.

Chart showing usage, solar, net and hdd for Q1 2016

2015 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 3,214 1,488 1,726 35.7 3,975
Jan 1,163 400 763 37.5 1,419
Feb 1,096 300 796 35.4 1,449
Mar 955 788 167 30.8 1,107
2016 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
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
All values in kWh (except HDD which is base 65°F).

Our heat pump used 1,529 kWh last year and 955 kWh this year. 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 lower energy use was directly correlated to warmer temperatures. Plus there was less snow to hide the solar panels and it was less cloudy, so we generated more energy too.

The grass was just starting to green up. We had a few plants budding out and a few trees looked like they were ready to pop. We even had two new baby goats born last week. Then we got about 4 inches of snow Monday. Thankfully it’s mostly gone after temps in the upper 30’s and lots of sun today. We’re ready for Spring!

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


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