Archive for the 'Solar' Category

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.

We’re net positive again in 2015!

We used 7,141 kWh and generated 8,694 kWh for a net of 1,552 kWh for the year. This is our second highest net energy year after 2012. Here’s our progress for the first 4 years in the house.

Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 28,056 34,473 (6,417) 19.1 26,530
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
All values in kWh (except HDD which is base 65°F).

Q4 2015 summary: 18% warmer, 24% less usage and 42% more sun as compared to Q4 2014.

In Q4 our total usage was 1,802 kWh, an 8% decrease from our 1,957 kWh in 2014. We also generated 497 kWh more this quarter than last.

Overall, here’s how this quarter and the year compare to 2014.

Charts comparing Q4 and YOY usage, solar and HDD

2015 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 1,367 1,683 (315) 14.9 1,810
Oct
377 710 (192) 12.2 488
Nov
399 648 (81) 13.3 597
Dec
591 325 653 19.1 725
2014 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 1,802 1,186 616 19.6 2,213
Oct
413 538 (125) 13.3 373
Nov
570 400 170 19.0 807
Dec
819 248 571 26.7 1,033
All values in kWh (except HDD which is base 65°F).

Year-over-year comparison

Year over year usage comparison

Our biggest energy months continue to be in Spring when we’re hatching and brooding chickens and turkeys. This is our second year to raise a year’s worth of chicken and turkeys. It is worth noting that I’ve been spending a lot more time outside the home office and the energy usage reflects this. Running a few computers, radio, etc every day adds up over a year. I think it’s interesting which months are very close (January-February), fairly close (October-November) and very divergent (April-June). 

Pie chart - circuit breakdown

There’s not a lot of notable changes in usage by circuit (above). 2015 was both colder and hotter than prior years (see temperature ranges below). Because of the increased cold, the ASHP and water heater used a larger percentage of the total. Vampire loads increased this year because I forgot to flip the circuit breaker for the ASHP during the summer. The induction cooktop & stove and solar inverter both used about the same vampire loads as last year. In total these 3 appliances used 145 kWh in 2015 to do no useful work for us except be ready to leap into action at a moment’s notice. 

Net zero moment

Our ‘net zero moment’ this year occured in early July. This was earlier than last year but much later than 2013. Our solar curve remains fairly constant. Our usage changes the most from year to year, manly due to weather.

Charts showing mix of solar and grid supplied elect.

All that solar is awesome, but I’d really like to use more of it. Currently we only use 22% of the solar power we generate directly. The other 78% goes back to the grid so other people use it. That 22% represents 27% of our energy mix. 73% of the electricity we use is from the grid.

There are two ways to use more of our solar. 1) Only use power when the sun is shining. 2) Use a battery. Something like the Tesla PowerWall would do nicely.

Chart of ASHP usage values Oct-Dec, 2012-2015

This was the warmest fourth quarter since we moved into the house. As a result, we used a lot less heating energy than the last two years. Every year I try a slightly different strategy with the thermostat. This year I programmed it at 65 during weekdays from 8am-4pm and 9pm-4am, and 68 at all other times. We generally get enough sun during the day that the daytime setback is not really noticeable. If we see a cold snap coming up I’ll reset it to stay at 68. I’m also trying to be more diligent and clean the filters every month. I think this may have played a part in our prior years increased usage, adjusted for weather.

Chart of ASHP usage values Jan-Apr, 2013-2015

I also added a plot (above) of our heat energy usage in the January through April timeframe. It’s interesting because 2015 was colder than 2014 (4,541 vs. 4,274 HDD) but the heat energy was not that much greater (1366 kWh in 2014 vs. 1,665 kWh in 2015).

Chart showing kWh used by ASHP in 10 degree bucketsThe plot above shows the amount of hours and energy we used for each 10 degree drop in temperature. 2014 had a larger number of hours in the 20-30 and 30-40 degree buckets. 2015 had less in these areas and more in the lower temperature bands. Most of the ASHP usage has consistently occurred in the 20-40 degree range.

Chart comparing water usage 2012-2015

We seem to be fairly consistent in our hot water usage. Over the year we averaged 17.5 gallons/day, down from 18.4 last year. That hot water requires 263 watts/gallon to heat. We used 39.1 gallons of cold water per day, down from 43.5 last year. The difference is almost completely attributable to how much we water the garden. We used a total of 20,684 gallons of water in 2015, down from 22,575 last year. It took 52 kWh to pump that water out of the ground. 

Chart comparing temperature ranges 2014-2015

We experienced our largest temperature range this year out of the last 4 years, 110.721°. Our coldest temperature was -16.112° on February 16 at 7am. Our high was 94.609° on July 29 at 3pm. Our highest recorded temperature in the last four years was 95.135°, set on July 19, 2013 at 3pm.

The average temperature for 2013 was 48.5°. 2014 was 47.5° and 2015 was 48.9°. I’m missing January temperature data for 2012. At the end of this January I will be able to calculate the average for the last 4 years of our collected data.

Happy 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 2015 performance

Q3 2015 summary: 38% warmer, 22% less usage and 3% more sun as compared to Q3 2014.

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

Traditionally, 3rd quarters are pretty boring in the home performance category. No heating. Generally no air conditioning. No ventilator because the windows are open. At this time of year, the main job of the house is to keep the rain out, and we didn’t get much of that this quarter.

Our most exciting finding this quarter was that we had a 1+ megawatt month. In August we produced 1.003 MW. This is only the second time we’ve produced more than a megawatt in a single month. The first was August 2012 when we produced 1.018 MW.

Sometime in early August we became net positive for the year. We now have a surplus of 1,239 kWh heading into the final months of 2015.

Overall, here’s how this quarter compared to 2014.

Charts comparing Q3 usage, solar and HDD

2014 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 1,263 2,780 (1,517) 13.7 280
Jul 432 950 (518) 13.9 37
Aug 440 919 (479) 14.2 64
Sep 391 911 (520) 13.0 179
2015 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 991 2,866 (1,874) 10.8 175
Jul 342 949 (607) 11.0 39
Aug 332 1,003 (671) 10.7 34
Sep 317 914 (596) 10.6 102
All values in kWh (except HDD which is base 65°F).

 

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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