Powerwall 2 and Integrated Solar

It's really going to depend on the location in the US.

When I was living in the southwest, my energy bill per month was ~$500 for a 4 bedroom house. A/C eats a lot of power. After moving to the northwest, my bill is around $80/mo.

For those who are looking for something similar but (being the kind of people who read HN) would like something more configurable and hackable, you might check out the products of Victron Energy[0]. They've also have an optional remote management portal[1] which allows you to set up and monitor everything remotely for years now, and most the software running locally on the devices is open source and fully modifiable (such setups are even supported!).

Full disclosure: I'm one of the developers of the mentioned Remote Management portal.

[0]: https://www.victronenergy.com/ [1]: https://vrm.victronenergy.com/

I heard great things about heat pumps efficiency-wise, but that their downside were noise. However, that information is dated because I haven't looked into it in a long time.

Has that improved? I'd expect the market in Scandinavia to be much more developed than in my country.

Over the past 12 months, 12000 kWh, in the Pacific Northwest [1]. I expect that to be lower this year, because I just had my house insulation improved. My house was originally a two bedroom house of approximately 1000 sq ft (92 m^2) built in 1964, and an additional bedroom was added in 1984, bringing it up to approximately 1400 sq ft (130 m^2). There was no insulation under the floor in the original house, and just a small layer of some kind of shredded paper-like material in the attic. The added room had decent insulation under the floor, and some real insulation in the attic, although not up to current recommendations for attics in this area. I now have a properly insulated floor, and the whole attic has been brought up to R49.

Here's a month-by-month breakdown, giving kWh for the month and average temperature.

  2015-11:  730 kWh, 54 F (12 C)
  2015-12: 1780 kWh, 42 F ( 6 C)
  2016-01: 2100 kWh, 40 F ( 4 C)
  2016-02: 1600 kWh, 43 F ( 6 C)
  2016-03: 1420 kWh, 46 F ( 8 C)
  2016-04: 1130 kWh, 48 F ( 9 C)
  2016-05:  580 kWh, 57 F (14 C)
  2016-06:  460 kWh, 59 F (15 C)
  2016-07:  490 kWh, 62 F (17 C)
  2016-08:  460 kWh, 66 F (19 C)
  2016-09:  530 kWh, 67 F (19 C)
  2016-10:  560 kWh, 59 F (15 C)

(Note: dates are the dates on the bills, which come about a week into the month, so the actual period covered is mostly in the prior month)

Rates here are $0.09/kWh for the first 600 kWh per month, and $0.11/kWh for whatever is over 600 kWh.

I don't see how you can use so little power. 2550 kWh/year is under 7 kWh/day.

During the summer months I turn my heat pump off, doing climate control by opening windows and using a couple of box fans to ensure air flow through the house. I typically have two fans running at opposite sides of the house. Figure 50 watts each, running whenever I'm home (weekends, plus one day a week working at home, plus 2/3 of the day on days I work at the office), and that comes to about 2 kWh/day average.

I usually have my entertainment system on when I'm home. If I'm using the TV, it's a total of about 100 watts. If the TV is off because I'm just listening to the streaming radio services my cable provider provides, it's about 60 watts. Call it 75 watts on average, and rounding to the nearest kWh, that's another 2 kWh/day.

My desktop computer uses 150 watts when used casually, such as reading and posting on HN, or browsing the web. Figure 4 hours a day on the computer on work days, and double that on my work at home day and weekends), and that's another kWh.

I'm up to 5 kWh/day now, just for fans, TV/stereo, and one desktop. Then there is my refrigerator, the pump for my well, my water heater, a washer and dryer, cooking appliances (stove, oven, microwave, electric griddle), and lights. Some of those use quite a bit of power. For instance, cooking baked french fries in the over (preheat to 450 F (230 C), then bake for 35 minutes) uses 3 to 4 kWh. I only do that maybe once a week, though, so it maybe contributes 0.5 kWh/day. Lights (all LED) are probably about 0.25 kWh/day (mainly two 14 watt (100 watt equivalent) Cree bulbs running 8 hours a day). All in all, these other things are going to probably average 2 to 3 kWh/day combined...and that puts me at or above your usage.

So, best case I should be able to maybe get down to your usage, during times of year when I can turn off the HVAC system and rely entirely on a couple of fans for climate control. And the best I've actually achieved is twice that...which means I've got something drawing more power than I accounted for above. My first guess is the refrigerator, as it is quite old. Time to stick the Kill A Watt meter on it and see what it is going on. The only other things I can think of that I left off are battery chargers for phone, tablet, handheld ham radio, and rechargeable batteries.

During months when I have to use the heat pump, I don't see any way I could get down to anywhere near your usage. How do you keep your house warm in winter?

I have noticed that if it is sunny out, then if I open blinds and drapes to let the sunlight in, I can reasonably heat the house that way even if the outside air temperature is low. I did that today, and got the house up to 68 F (20 C), and the insulation was good enough to keep it warm enough to keep the heat pump off for most of the night. It's now 4 AM and 43 F (6 C) outside, but the heat pump has not come on yet. Unfortunately, it is usually overcast during most of the winter around here so most days that won't work.

[1] West across Puget Sound from Seattle. Here's monthly temperature data for this general area: http://www.usclimatedata.com/climate/bremerton/washington/un...