Year 2: Solar Tracking and Energy Use for 2017

Last year, I’d been very pleased with the house’s first year performance, but after analyzing the numbers, I’d thought there was still room for improvement.

With a few tweaks and utilizing our wood stove a bit more, I was looking forward to seeing how we did for 2017 compared to our first year. Let’s find out!

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For completeness sake, below are some key stats from my previous 2016 blog post about our energy modelling and actual use:

HOT2000 Predictions:

Annual Space Heating Energy Consumption: 7159 kWh

Annual Domestic Hot Water (DHW) Energy Consumption: 3409 kWh

Annual Appliance Energy Consumption: 8760 kWh

TOTAL = 19,328 kWh/year

PHPP Predictions:

Annual Space Heating Energy Consumption: 7584 kWh

Annual DHW Energy Consumption: 3974 kWh

Annual Appliance Energy Consumption: 11,310 kWh

TOTAL = 22,868 kWh/year

PV Array Predictions (6.2 KW)

PHPP Estimation: 7321 kWh/year

Solar Installer’s Estimation: 9300 kWh/year

Also:

For interest, according to Stats Canada website’s most recent 2011 home energy use data, a Saskatchewan home consumes an average of 30,555 kWh/year (110 GJ), of which electricity for appliance use is 8889 kWh/year (32 GJ).

2016 ACTUAL TOTALS:

Actual Solar PV Generated = 8189 kWh

Actual Household Energy Consumed = 19,000 kWh

Actual Total Energy Used (consumption – PV) = 10,811 kWh

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We did pretty darn good in 2016, actually coming in under the estimated values with the exception of the higher end of the solar production (though that is the manufacturer’s estimates so probably these are the “best case scenario” numbers anyway).

So how did we do for 2017?

2017 ACTUAL ENERGY CONSUMPTION AND PV GENERATION:

January: Solar generated = 250 kWh vs. Energy Use = 2979 kWh

• A dramatic difference no doubt. But I was not surprised given I had 2016 to compare, it’s January in Saskatchewan after all. Still our energy use was less than the previous year (by almost 400 kWh) so we were off to a good start.

February: Solar generated = 378 kWh vs. Energy Use = 1258 kWh

• This is when I did my experiment. We kept the boiler set at 65°F and tried to burn wood as much as possible. There was a more than 50% drop in energy use (electric) from 2016.

March: Solar generated = 695 kWh vs. Energy Use = 1652 kWh

• Pretty much the same as 2016. We kept the boiler set a bit high at 68°F (65°F is too cool first thing in the morning!). But it was starting to get warmer this month. Note that we used over 400 kWh more this month then February – due to less wood heat, even though the outdoor temperatures were rising.

April: Solar generated = 736 kWh vs. Energy Use = 1125 kWh

• April kind of sucked. It was cloudy and not very Spring-like at all. Many days were around the freezing temperature still.

May: Solar generated = 1143 kWh vs. Energy Use = 840 kWh

• Hot month and hit the net positive energy production one month early as a result.

June: Solar generated = 1092 kWh vs. Energy Use = 708 kWh

• It was a hot and dry month and I watered the garden nearly every day which uses a fair bit of electricity to run the water pump at the river.

July: Solar generated = 1112 kWh vs. Energy Use = 575 kWh

• It was really hot again in July. Only 2 or 3 days of rain all month.

August: Solar generated = 982 kWh vs. Energy Use = 643 kWh

• Almost completely opposite weather to 2016, which was extremely rainy. This month was HOT and DRY.

September: Solar generated = 744 kWh vs. Energy Use = 662 kWh

• Finally started to become seasonal temperatures in September. But still remained Net Positive for energy use.

October: Solar generated = 555 kWh vs. Energy Use = 771 kWh

• Last October (2016) was terrible – snowing on October 4th. This October was more normal and as such, our energy use was 50% less than 2016 (1478 kWh). I did turn the boiler on for the basement heat, but not on the main level.

November: Solar generated = 234 kWh vs. Energy Use = 1569 kWh

• It snowed on November 1st and stayed snowy and cold until the last week of the month when it got above freezing and melted a lot of the snow off.

December: Solar generated = 291 kWh vs. Energy Use = 2229 kWh

• December was extremely cold again with several days of -40°F. Good fun. But still used way less energy then 2016 (almost 600 kWh less!) despite it being a similar month weather-wise.

ACTUAL TOTALS:

Actual Solar PV Generated = 8212 kWh (Comparison 2016 = 8189 kWh)

Actual Household Energy Consumed = 15,011 kWh (Comparison 2016 = 19,000 kWh)

Actual Total Energy Used (consumption – PV) = 6799 kWh (Comparison 2016 = 10,811 kWh)

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Shheeeet! That’s good! I was pleased about 2016, but 2017 was awesome. That’s a 4012 kWh reduction of our electrical energy use from the previous year. And at $0.12/kWh that works out to a $481 saving for the year.

Granted we burned more wood this year than last. I’d estimate we burned around 3/4 cord of wood in 2017 compared to about 1/3-1/2 cord in 2016. But at $250 per 1 cord that’s still a good savings. My February experiment had the biggest single month change with mostly burning wood. I have no idea how to factor in the equivalent energy. Obviously it’s not zero. Maybe another post if I find some information on it.

Even so, almost every month we improved from the prior year. I think part of that was us getting used to the functioning of the house and getting our house thermostat temperatures dialled in better at least in the winter. As for why it was still less energy use in the summer months, well, I’m not sure?

Our solar generation was almost identical to the 2016 which was good to see.

My favourite comparison though is to the Canadian home average of 30,555 kWh/year. At 15,011 kWh, our house used 50% as much energy, while factoring in solar use, it’s at 78% less energy use then the average house. High fives!

Also we were again, way under the predictions of both the HOT2000 (19,328 kWh/year) and the PHPP (22,868 kWh/year), which is pretty sweet. Again, I have to wonder how close we would have come to meeting the Passive House standards had we made sure to reach the 0.60 ACH airtightness benchmark…

Speaking of airtightness, in January (2018) we made a few changes to our doors to try and get a better seal.

I wrote in the “everything is perfect” article how we’d had issues with bowing of two of our three doors from Duxton. I’ve been really happy with the service of Duxton and they’ve been out to our house a few times now to tweak and make some changes to help optimize our house’s performance this past year. But the doors had been a problem since the beginning with not getting a great seal on top and bottom corners. In an apparent airtight house, leaky doors is not something you want. Due to the bowing of the door frames, Duxton offered to replace the doors at no charge. Still, we had some issues with getting a really tight seal even after replacement.

Duxton now offers multi-point locking doors which, like it sounds, have multiple latches that create an extra tight closure. Unfortunately, I didn’t know they were available at the time or they actually weren’t available yet when we ordered our original doors, either way a deadbolt with one single 1″ contact in the middle of 6.5′ tall door, inherently doesn’t create an optimal closure. So what were our options? We did chat with Duxton briefly about pulling out the doors and retrofitting them with their multi-point doors, but the labour and extent of work to do so was going to be terribly extensive. Instead, we went with a simpler option: cam locks.

We had them install two of these low profile cam locks on each of the doors: one at the top and one at the bottom. Immediately we’ve noticed a difference. The house felt… snugger. We’ve also noticed a significant improvement in the heat retention of the house overnight. It does not cool off nearly as quickly at night, even on the -40°F/C nights. It’s tempting to have another blower door test done as I’m certain there has been a fairly dramatic improvement with this simple fix. I wonder how much under 0.72 ACH we’d be now…

It’ll be interesting to compare the above numbers with 2018. I’m not expecting as dramatic a change from this past year as I’m not going to burn as much wood – just what is comfortable for us. But I think the change in airtightness will have really positive effect. We will see.