May performance

May was a warm and rainy month. (52% less heating degree days than April, 7% less sun). This partially resulted in 20% lower energy usage in May. We only used 4.8 kWh for space heating. Our daily average usage was down 23% from April. We generated a 558 kWh surplus this month, our third surplus month in a row.

All values in kWh (except HDD)	Jan 20121	Feb 20122	Mar 20126	Apr 20127	May 20127
Solar PV generation	369	597	860	925	867
Usage	873	666	515	378	309
Net usage or (generation)	504	69	(345)	(538)	(558)
Average daily usage	28	23	17	13	10
HDD (base temp 68F)3,4	1,2125	1,045	704	617	298

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 target inside temperature)
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 based on eMonitor data.

May was our second full month of circuit level data monitoring. The largest percentage of our energy still goes toward producing hot water (151 kWh). The second largest load was all the unmonitored circuits including the refrigerator, coffee maker, ventilator and all lights and plug loads (108 kWh). The water pump, clothes washer, and dishwasher as a group tied with the Dryer and Range for 3rd place (ranging from 14 to 16 kWh). Now that we have our clothes line, our dryer energy usage has gone down. The heat pump came in last.

All the data is available at netplusdesign.com. You can now 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 and May.

April performance

April saw the return of weather normalcy. (12% less heating degree days than March but only 8% less than the 10 year average, 7% more sun). This partially resulted in 25% lower energy usage in April. We used 49 kWh just for space heating. We also installed a clothes line outside and used the clothes dryer less this month. Our daily average usage was down 22% from March. We generated a 538 kWh surplus in April, our second surplus month in a row.

All values in kWh (except HDD)	Jan 20121	Feb 20122	Mar 20126	Apr 20127
Solar PV generation	369	597	860	925
Usage	873	666	515	378
Net usage or (generation)	504	69	(345)	(538)
Average daily usage	28	23	17	13
HDD (base temp 68F)3,4	1,2125	1,045	704	617

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 target inside temperature)
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 April values based on eMonitor data.

April marked our first full month of circuit level data monitoring. As the circuit usage chart above shows, the largest percentage of our energy goes toward producing hot water (152 kWh). The second largest load was all the unmonitored circuits including the refrigerator, coffee maker, ventilator and all lights and plug loads (123 kWh). The air-source heat pump came in 3rd (49 kWh). The clothes dryer and range almost tied (26 and 25 kWh respectively). We did  lot of cooking around Easter. Now that we have our clothes line, our dryer energy usage should continue to go down.

All the data is available at netplusdesign.com. You can now view solar, usage, net usage, temperatures and HDD for all of February and circuit-level data for 16 days in March and the full month of April.

March performance

Actual vs. Projected for 2012

March madness, the weather that is. March was freakishly warm and much sunnier than February (33% less heating degree days, 31% more sun). This partially resulted in 23% lower energy usage in March. Our daily average usage was down 28% from February. We generated a 345 kWh surplus in March, the first since we moved in Jan 1st.

All values in kWh (except HDD)	Jan 20121	Feb 20122	Mar 20126	Apr 2012
Solar PV generation	369	597	860	–
Usage	873	666	515	–
Net usage or (generation)	504	69	(345)	–
Average daily usage	28	23	17	–
HDD (base temp 68F)3	1,2124	1,0455	7045	–

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 target inside temperature)
⁴ Downloaded from degreedays.net, Station ID: KALB (Albany International Airport).
⁵ Calculated from my HOBO outdoor weather monitor hourly data.
⁶ March values based on meter reads. (TED died March 1st, eMonitor installed March 16)

The chart at the top of the page illustrates our actual performance for the first three months of the year, and our projected performance for the rest of the year based on estimated output of our array and historical heating degree days for the last 10 years. The usage numbers are a complete guestimate, but based on these numbers we could be net positive at the end of the year by 242 kWh. In any case, it will be interesting to track actual values against the projected values.

We’re also happy to report the TED folks accepted our return last month without incident and we’re enjoying our new eMonitor circuit level monitoring. Although we don’t have a full month of data for March, we are able to share the 15 days of data we did collect. It is available at netplusdesign.com. You can now view solar, usage, net usage, temperatures and HDD for all of February and circuit-level data for 15 days in March. We’ve included a few snapshots below.

Heatmap composite including all options

The composite image shows all the high-level data heat maps. You can see very easily that the third week was warmest and sunniest days of the month that we collected data.

Air source heat pump mapping and day chart

The above snapshot shows March 16, the first day we started collecting circuit-level data. It wasn’t a particularly cold day, temps were in the mis 40′s, but there was very little sun as evidenced by the relatively flat solar curve. This required the heat pump to kick in enough to make it the most active out of the recorded days. This is a bit misleading because if you compare March to February, power use that day was quite low. Now that we have multi-month data, we’ll have to find a better way to compare across months.

If you have any questions or spot any math errors drop us a note in the comments.

February performance and fun with charts

February was generally warmer and sunnier than January (14% less heating degree days, 38% more sun), not to mention 2 days shorter. This partially resulted in 24% lower energy usage in February. (I say, ‘partially resulted‘ because we don’t have heating energy values separated out from the total load yet.) If you look at it from a daily usage perspective we’re down 18% from January. That almost got us close to netting out to zero for February.

All values in kWh (except HDD)	Jan 20121	Feb 20122	Mar 2012
Solar PV generation	369	597	–
Usage	873	666	–
Net usage or (generation)	504	69	–
Average daily usage	28	23	–
HDD (base temp 68F)3	1,2124	1,0455	–

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 target inside temperature)
⁴ Downloaded from degreedays.net, Station ID: KALB (Albany International Airport).
⁵ Calculated from my HOBO outdoor weather monitor hourly data.

I put together a few charts to compare a cloudy day where the temperatures are dropping throughout the day (February 2nd), and a relatively sunny day where the temperature is rising (February 3rd). There’s always a spike in the morning, the heat, hot water, water pump, and coffee maker all generally go on around the same time. But you can see in this first chart that the HDD day values are low in the morning, meaning it was fairly warm outside in the upper 30′s. No need for the heat pump to kick in. There’s little green on this chart meaning we were not generating a lot of solar power on this day. It also means the house inside temperatures were not getting much help from the sun. Notice how the HDD is getting bigger as the day progresses. It’s getting colder out, down in the mid 20′s. There is clearly more energy being used in the evening as a result.

Compare with the next day below. It continues to get colder until about 8am when it reaches 18F outside. Notice that the heat pump has popped on a few times in the early morning before the morning rush. Then the sun takes over and the temps start to rise, meaning the HDD values get smaller. Very little energy used after the sun kicks in. Evening power spikes a few times for cooking and cleaning.

There’s no big surprises here, but it is fun to see the correlation in data.

We also generated our 6th megawatt in February. It took roughly 61 days to generate this megawatt.

Megawatt Hour	Date	Days
0	Jun 2 2011
1	Jul 7 2011	35
2	Aug 8 2011	32
3	Sep 13 2011	36
4	Nov 1 2011	49
5	Dec 29 2011	58
6	Feb 28 2012	61

If you have any questions (or spot any errors), let me know in the comments.

Nice curve (cloudless day)

The curve above represents our power generation for February 26, 2012 from 6am to 5pm. It is the first fully cloudless day since I’ve been monitoring our energy usage and solar generation. Note that TED tracks solar generation values negative and usage/load values positive.

It’s nice to see the power generation capability when there are no clouds for an entire day. The two dips in the morning represent two clusters of pine trees low in the morning sky.

Last update of 2011

Lot’s of news this week. We got our Certificate of Occupancy (C.O.) on Wednesday! We can officially occupy our home this weekend.

We worked like crazy last week and over Christmas to finish all the odds and ends for the final inspections. We finished all the electrical Wednesday, 12/21, and had the final electrical inspection the Friday before Christmas. Our water test results arrived Christmas Eve. We spent the rest of Christmas weekend finishing up the porch railings and temporary stairs for the final inspection on Tuesday, 12/27. Our inspector gave us the thumbs up and faxed us the C.O. on Wednesday.

But wait, there’s more… Our contractor Warren entered the Energy Star program with our house. In order to complete the program and qualify under the 2011 rules, we had to get our final inspection and blower door test before the end of the year. This happened Thursday, two days before the end of the year. Final blower door result was 131 cfm, an improvement of 28 cfm from the shell test we did back in September. We’ll post more information on the Energy Star process next month when things settle down. It’s the only certification we’ve chosen to do for the house.

Our kitchen counter tops also arrived yesterday and were installed. The counters are Cambria Quartz (color: White Cliff.) We chose a manufactured quartz counter because we wanted something durable and low maintenance. And we chose Cambria because it’s the only American company manufacturing quartz counter tops. It looks fantastic.

And we generated our 5th megawatt Thursday. It took us almost 60 days to do it. That’s 5 megawatts for half a year. The system went online June 2nd.

We have a few finish work projects to complete. As we were running short on time, Jill found tile contractor, Chad Greenslet, out of Bennington to finish our shower tile job. He installed the Schluter and tile in 2 days, but ran out of tile. We thought we had ordered extra, but somehow miscalculated. The extra tile arrived today, so that project should get finished up next week. Jill is also working with a local glass supplier to install a frameless shower door.

The site-cut maple intended for our stairs is still drying out in our basement. At some point soon we’re going to have to decide if it will be ready in time, or if we should purchase other material for the stair.

95% of the trim is installed. The holes have to be filled and cracks caulked before it gets painted. Doors have to be painted too. Jill is hoping to get the two bedrooms finished this weekend so we can start moving some stuff into them.

Also, a few pieces of siding trim for the basement entry have been sealed and are awaiting installment.

But that is about it. We’re down to the final punch list. We have to be finished in two weeks for the mortgage appraisal. That is our other task – converting our construction loan over to a mortgage. More on that process soon as well.

Solar Update

We generated our 4th megawatt yesterday. Here’s a running tally of the number of days it’s taken to generate each megawatt.

Megawatt Hour	Date	Days
0	Jun 2
1	Jul 7	35
2	Aug 8	32
3	Sep 13	36
4	Nov 1	49

You can tell by the number of days that late September and October were very cloudy, not to mention the shortening of the day light hours. As the days get cooler we’ve been using more electricity in the form of leaving the lights on to keep the space warm overnight. Since we’ve installed all the insulation, the interior temperatures have not dipped below 58 degrees.

Here’s for hoping there’s a bit more sun and few less clouds for the month of November.

Two MEGAWATT hours

Early this morning we tripped the TWO MEGAWATT HOUR mark (say it in your best Count Dracula voice). It took 36 days to generate our first megawatt hour, but only 31 days for the second.

First MEGAWATT Hour

Today at approximately 11:30 am we produced our first megawatt hour. In 36 days we averaged 27.7 kWh per day.

I had originally thought we might be able to generate our first megawatt by July 4th, but we miss it by a few days. Turns out I did my math wrong. It took us 18 days to generate 500 kWh, so it makes sense that it would take a similar amount of time to generate the second half megawatt.

But hey, who’s counting anyway?

No SRECs in New York yet

I’ve mentioned Solar Renewable Energy Credits in previous posts and comments. It’s a great way to shorten the payback period for solar producers and encourage more solar production. Also encourages power companies to purchase more renewable energy from the little guy.

But it requires each state to pass legislation to authorize an SREC market in the state. Several states around us have SREC markets. New York had a bill that did not get voted on this session. Looks like it will be another year before it comes up for consideration again.

http://www.srectrade.com/blog/srec-markets/ny-srec-market-put-on-hold

Maybe next year.