O.K. That's different. February is always a significant loss for us. March is the first month with gains.
It was a VERY unusual February, and our first in this house. I don't expect this to repeat, or much less be the norm.
That said, we have installed our panels at a steeper angle. It gives us better efficiency in the winter, and helps snow to sluff off.
RegGuheert wrote:That's very good! I suppose that is the beauty of a ground-source heat pump versus a air-source heat pump like we have. Your house is WAY better insulated than ours, though your outdoor temperatures are also lower. Below about 10F, the resistive heaters come on in our air handler. I don't know their exact power rating, but I expect the entire system likely draws about 15 kW when they are on.
Yeh, the groundsource is definitely the way to go, if you can. For some renovations or builds it just doesn't make sense.
Resistance heat will definitely chew up the energy. We have one two as our backup to the backup. So far, it hasn't kicked off at all.
We had a string of sub zero days (one of the days the high temp was -2(f)). Our system wasn't working properly, and we didn't notice for 3 days
RegGuheert wrote:OTOH, it appears you have an 18.6 kW PV array on your home. Certainly in the springtime your production must approach that level. The inverter needs to be sized for the maximum power flow in either direction if you intend to keep all electricity in-house. I would think that your house may have as much as 14 kWh flowing out during some hours of the year. Peak is probably sometime in April, but you must also have fairly-high production hours in the middle of the wintertime.
In February we are peaking just under 18kW at any one moment. I expect that to peak this month due to the steeper angle. In the summer we don't have use for all the power, so the less than optimal angle works just fine.
If I had unlimited storage, I'd shoot for the more optimal summertime angle as it would give us more power for the entire year. But this way we get more power when we need it and less when we don't.
RegGuheert wrote:That's extremely good! If only more homes were built the way yours is...
Thank you! They are out there, and many more are being built. However it is still a small percentage of all houses and needs to expand. I have been to a couple of Net Zero renovations which amazed me. I would have never thought you could take a 100+ year old house and turn it net zero (with only a small solar array).
RegGuheert wrote:I will note that I see single-day consumption numbers in the middle of December of about 3X what occurred on your graph December 5. (That would match my worst day, which was December 16, 2016.) I also see three-day drops in both the middle of December and around the 10th of January that appear to be 200 kWh total drops. The middle day in each of those drops appears to be a drop of over 80 kWh. Of course that data includes your cars, but all my data includes my LEAF, as well.
Clouds are a wonderful thing, or not
Those three days in the middle of December were three very cloudy, and cold days.
So our HVAC went up, and on the 17th alone we used 62kWh to charge the vehicles. I don't recall if I was planning for a trip or just had both needing to charge on the same day.
In January there was a day when we used 71kWh to charge our cars, sending the total power use just over 101kWh.
However, I don't need to plan for that as it would never happen if I didn't have the grid.
If I were off grid, we would charge on a much more even schedule than no charging for two or three days and a full charge the next.
With the battery backup, I would never charge the cars while the power is out.
With an off grid setup, I would only charge at home on sunny days, or at public chargers.
RegGuheert wrote:It seems to me that you will come in WAY below the 22 MWh/year that you mention on your website, even while fueling two EVs. Let's say the EVs use about 5 MWh/year total. That would mean the rest of the house consumes 17 MWh. Do you have an updated estimate where you will come in for the year?
Our original model was for the cars and house to each use about 11 MWh/year.
We are WAY ahead of that on the cars so far. However, I expect we will be putting more miles on as the summer arrives and we start having more EV and Net Zero events to travel to.
I still expect to come in well below the 11MWh estimate, probably closer to 7. If I am lucky though, perhaps I will get closer to your 5MWh number
Zythryn wrote:And of course, this winter wasn't the coldest we have ever had.
No, in fact it was one of the warmest here. But it followed a warm summer in which we used much more electricity for air conditioning than normal. The result was that are total electricity usage was very close to normal.
Interesting, does your AC take as much energy as your heating?
We moved in September, so we haven't yet seen how the house performs in the Summer. We have had a couple of cold snaps this winter, but I suspect it is one of the top five warmest winters for us as well.
As for those that don't have to deal with winter, net zero gets much easier!https://www.youtube.com/watch?v=fkQBVoS9lAo