Powerwall - Numbers don't add up (for me at least)

[SabrToothSqrl]

Even one for me at $6500 would buy a sweet generator... I already have a 500 gallon underground propane tank...

I'll look into the roof thing when mine wears out in 20 years... :-/

 

[JeffreyY]

The reason powerwall were pushed hard in Australia is our power prices. My averaged cost is 19.5c per kWh! Peak is around 48c!! A bit different to the single digit prices you have in the USA.

Closer to Hawaii 32c/ Kwh

 

[SabrToothSqrl]

You guys have it rough. Here I'm about $0.11/kWh.

 

[dckiwi]

Even one for me at $6500 would buy a sweet generator... I already have a 500 gallon underground propane tank...

I'll look into the roof thing when mine wears out in 20 years... :-/

Hrm, you're right. I really hadn't even looked at generators. Here's one that could power my entire house - on natural gas - for about the price of a Powerwall. And because it's hooked up to natural gas it could run 'forever':

Generac Power Systems | Home Standby Generators | Guardian Series | Generac Power Systems

 

[miimura]

When I looked into Generac natural gas generators I was surprised at how expensive they are to run. 1/2 load on the 20kW Guardian is 301 ft^3/hr @ 9kW. Doing a little math, that's 33.4 ft^3/kWh. In Therms, the billing unit of my utility, it's 0.334 Therm/kWh. We pay $2.00/Therm over baseline, which you certainly would be if the generator was running all the time to power your house. That's $0.667/kWh. Sure, if there's a natural disaster it's probably worth it, but I was still surprised at the figure relative to utility power from natural gas.

 

[Skipdd]

What winfield100 listed did drive us to get a generator. Not whole house, would have needed a 30kw one which was crazy expensive. We are all electric and heater uses 20kw when it kicks on at very cold temps. Wanted backup to last a couple of days and power electronics (we work from home a lot, have fios and VoIP vs CO powered line), so best thing I could find was Honda EU6500IS. Runs up to 14 hrs on 4.7 gal of gas, has inverter to protect electronics, and is very quiet. I couldn't see how to use the PW and still don't. Maybe by the time we retire and relocate..

 

[winfield100]

Wow, you're bringing back some bad memories! The worst was actually number 3 (the derecho). We lost power for 3 days in early July, with temps in the high 90s. Maybe a couple of Powerwalls would be worth it. That'd only power my home for ~12 hours, but that's with us using everything as we normally do. I'm pretty sure we could scale down fast if needed, maybe getting to 24 hours or so of power.

driving in the Derecho was "enlightening" branches flying/floating horizontally past me, trees bending over to kiss my vehicle,
from calm to insanity in 30 seconds. like a100 mile wide, but 1 mile deep tornado
If you have a PV array to recharge the Powerwalls every day, it will work for a longer time

 

[SageBrush]

My annual electricity consumption is 3800 kWh, my 4-person house is about 300 m^2 (but not using electricity for heating nor for transportation).

Pools can be a huge drain
If OP buys a PW for back-up he should size it for an outage scenario use case -- or expect to buy a small mountain of batteries.

Our home is similar in size and electric uses and usually consumes ~ 150 kWh a month on average.

 

[electracity]

In the U.S the powerwall is positioned for the end of new net metering users. California will have to switch to another incentive approach for new solar buyers by the end of the decade. The only residential solution appears to be batteries.

The typical smaller solar user in Germany and Australia perhaps can't fully charge a 14kWh powerwall. In those market they probably intend powerwall 2 to go into bigger than average houses.

Tesla is exploiting their lower cell cost advantage and moving upscale. Many upscale buyers will not be primarily focused on ROI.

 

[dennis]

Pools can be a huge drain.

My single speed pool pump drew 2kWh. My new variable speed pump draws 400Wh, saving ~11kWh per 8 hour day or 330 kWh per month. That is a 15% savings on your summer usage. My new pump cost $2000, so at your low electricity rates the payback period would be about 7 years. In California it was less than 2 years.

 

[Olle]

My very first observation was why so low on the PV? I'm about 4K sq-ft and did 10 KW-Dc which still does not cover my whole bill. I'm looking for a way to do 3KW more......

Hard to make a case for the PW as long as my utility continues to be my battery for free (net-metering).

True, but since inverter is included, someone starting from scratch could get PV for $5500 instead of inverter for $4000 for let's say a 10kW system. Now they have a $1500 back up generator. not a bad price...

 

[Olle]

True, but since inverter is included, someone starting from scratch could get PV for $5500 instead of inverter for $4000 for let's say a 10kW system. Now they have a $1500 back up generator. not a bad price...

I meant PW as in powerwall, not PV

 

[SageBrush]

My single speed pool pump drew 2kWh.

I presume you mean a 2 kW draw, for 8 hours a day. That works out to almost 500 kWh a month on average.

Another huge drain can be from jacuzzi thingies.

 

[JamesPolk]

You need to tackle the efficiency of your home. I'm in 3800sqft plus basement 1970's home with four children under 8 years old who seem to only know how to switch a light in one direction (on) and love to cuddle up in electric blankets every morning in their underwear. We are at 309kwh for this month in Michigan and I still have a lot of work to do in terms of insulation. I have never seen the type of consumption you have in any home I have lived in. It seems you must be oblivious to your energy consumption or just don't care. Maybe find a more efficient way to run the pool. Hopefully you have already eliminated every incandescent bulb in the house. We love our LEDs. Shut off the breaker to your HVAC condensers (outdoor units) during non-cooling seasons. I found my newer Carrier unit uses 30-40w in standby. That's ~22kw++ per unit/month. Small change for you but 7% of my energy consumption for nothing in return. If you have older fridge, replace it. Many utilities will pay you for it to recycle. Only use one fridge/freezer. Buy bigger energy star unit if your family requires more space. Air seal then insulate according to your area. FLIR camera is awesome for finding heat loss around the home. If you have a basement, make sure rim joists are insulated. Use rigid foam cut loosely to fit and seal around edge with Great stuff.

Energy audit couldn't hurt and it's usually free through utility. If you are on electric water heater, make sure pipes near heater are well insulated with pipe wrap and buy low flow showerheads to minimize hot water use. Some of the 1.28-1.5gpm units give a very gratifying shower. Use energy star dishwasher and front load washer for clothes. Clean clothes with cold water cycle.

There must be a ton you can do since with the consumption you have, you must be doing next to nothing.

 

[dckiwi]

Our home is similar in size and electric uses and usually consumes ~ 150 kWh a month on average.

I assume you mean 1500 kWh a month. If you really mean 150 kWh, electric bill or it didn't happen.

EDIT: Although do you need to run AC in the summer where you live in Colorado? If not, kind of apples to oranges comparison.

 

[dckiwi]

You need to tackle the efficiency of your home. I'm in 3800sqft plus basement 1970's home with four children under 8 years old who seem to only know how to switch a light in one direction (on) and love to cuddle up in electric blankets every morning in their underwear. We are at 309kwh for this month in Michigan and I still have a lot of work to do in terms of insulation. I have never seen the type of consumption you have in any home I have lived in. It seems you must be oblivious to your energy consumption or just don't care. Maybe find a more efficient way to run the pool. Hopefully you have already eliminated every incandescent bulb in the house. We love our LEDs. Shut off the breaker to your HVAC condensers (outdoor units) during non-cooling seasons. I found my newer Carrier unit uses 30-40w in standby. That's ~22kw++ per unit/month. Small change for you but 7% of my energy consumption for nothing in return. If you have older fridge, replace it. Many utilities will pay you for it to recycle. Only use one fridge/freezer. Buy bigger energy star unit if your family requires more space. Air seal then insulate according to your area. FLIR camera is awesome for finding heat loss around the home. If you have a basement, make sure rim joists are insulated. Use rigid foam cut loosely to fit and seal around edge with Great stuff.

Energy audit couldn't hurt and it's usually free through utility. If you are on electric water heater, make sure pipes near heater are well insulated with pipe wrap and buy low flow showerheads to minimize hot water use. Some of the 1.28-1.5gpm units give a very gratifying shower. Use energy star dishwasher and front load washer for clothes. Clean clothes with cold water cycle.

There must be a ton you can do since with the consumption you have, you must be doing next to nothing.

Thanks, overall your reply had some helpful ideas and it's good to hear other people's experiences. I will say I am not 'oblivious to my energy consumption' nor am I 'doing next to nothing', or I wouldn't be on a Tesla message board talking about energy usage and how to reduce it. I've switched every lightbulb in our house to LEDs. Our appliances are all new (~5 years), as is our HVAC system (2 years). I have the thermostats programmed based on time of day to reduce energy usage.

I suspect it has to do with insulation issues (that's why I'm getting an energy efficiency check-up) and of course our pool, which we did not run efficiently this past summer. Someone also mentioned a variable speed pump - I wish my pool builder had brought up that option. I only learned about them after the pool was built.

 

[SageBrush]

I assume you mean 1500 kWh a month. If you really mean 150 kWh, electric bill or it didn't happen.

You assume wrong. I really shouldn't be so surprising to you though, many European countries are in the ~ 500 kWh/month range and IIRC Japan is < 400 kWh/month. And by the way, this is a ~ 3800 SF rental home in Colorado. Our previous home in Albuquerque, where we had more control over home infrastructure and appliances usually hovered around 100 kWh a month.

This website is a cornucopia of energy efficiency advice. And if you are curious, a talented engineer in Australia chronicled his energy efficiency adventure on the web, eventually settling at ~ 20 kWh a month. I figured I could hit ~ 50 kWh a month but never reached my goal. I blame my wife and the gluttonous American lifestyle. One unexpected side-effect of my conservation: I ended up too low to bother with home PV. I expect that to change with an EV ;-)

 

[Garlan Garner]

That is amazingly low. I don't think you can make an economic case for a Powerwall. But you can certainly make a "health of the planet" case.

Illinois Power costs are around the same here in Illinois.

 

[Frank99]

I need to look at ours...
We're on a 7PM-Noon demand plan - between noon and 7PM electricity costs us about $0.25 / kwh, between 7PM and noon it's about $0.04. No gas in the neighborhood, so hot water, dryer, etc., are all electric. We've got everything (hot water, pool, etc) on timers, so that roughly 85% of our usage in the summer is off-peak. My wife stays home with the kids, so gotta pay for AC in the summer - and boy do we use AC here in Phoenix.
I looked at Solar last year, but couldn't make it pay, mostly because of the demand charge on peak - Solar generation would be tailing off starting about 5 in the summer or 4 in Sept, but the AC would have to run between 5 and 7 eliminating enough of the benefit that it didn't make sense. If I can rely on the PowerWall to make it from 5 to 7, I've got a chance.

 

[nativewolf]

I assume you mean 1500 kWh a month. If you really mean 150 kWh, electric bill or it didn't happen.

EDIT: Although do you need to run AC in the summer where you live in Colorado? If not, kind of apples to oranges comparison.

Doesn't even matter it is still apples/oranges. CO has no humidity, nightime temps drop quickly reducing radiant energy trapped in the building structure, etc. The actual cooling degrees is just a fraction (about 1/3 give or take quite a bit depending upon where in CO) of what you see in the DC area. Then you factor humidity which means the DC air is just loaded with heat, maybe 20-30% more energy needed just due to heat.