Tesla Powerwall: Crunching the Numbers for Australia | Hacker News Reader

Tesla Powerwall: Crunching the Numbers for Australia

lifehacker.com.au

64 pointsqzervaas41 comments

Interesting to see the different power usage and electricity rates for a different part of the globe. Here in the Houston, TX area we used 848 kWh in a 30 day winter period for a mid-sized home, which is as much as the article states the household used in a 95 day period. During the summer, when my old AC unit is running like crazy, we'll use ~1800 kWh, and our rate is an average of $0.102 USD, which is around 60% of the top rate from the article.

A Powerwall unit still wouldn't make sense for us, but this is rev 1, and so in a couple of generations we could be looking at something that actually could be impactful.

848 kWh sounds a lot. For a 4 person house in germany you have a yearly usage ~1800kWh. You have the same amount in a 1/3 year. That's a shitload.

Currently I'm single and use 848 kWh for a whole year.

That sounds so little. Just having two 50W lightbulbs shining 24x7 would be slightly more than that in a year.

Currently I'm below average something like 200kWh below.

However currently I'm only at home on Sundays, all other days I'm only be here to sleep and eat, however I barely cook, so a toaster and breed doesn't use so much energy and I have LED's everywhere so I use max. 7W per room (2 rooms total + 1 bath) however I turn off the light's after leaving a room. I have no dishwasher and my watching machine is really really good when it comes to energy. I barely watch TV and I use my MacBook for surfing which gets loaded at my company (I use it there, too). So I only need a light with 7W for like 4 Hours, have a router running 24/7 which consumes nearly nothing. I'm a single. So no problem there. (Btw. my invoice for food is definitely higher than most ;))

oh and btw. in germany energy isn't as cheap as in the usa. also if you use solar energy in germany you could only use 30% since the rest goes to the public (and you get nearly nothing for that).

Houston, TX is both very hot and very humid. It can exceed 30C for 4-5 months out of the year and it will be dreadfully humid for much of that time. A/C is virtually required to do anything productive.

I guess if he's in Houston, TX then a chunk of that goes on air con

The 848kWh is for winter, summer is 1800.

I'm guessing it's a ton of heating because houses are very badly insulated, both for historical reasons and because otherwise everything rots in hot and humid summers (and nothing ever dries completely).

Japan has the same issue (insulation is quite terrible throughout, central heating is also rare), I'm guessing Houston is even worse because people keep to western habits (light-ish indoor garments and heating the whole house).

Is electric heating so common in the US?

In the northern states you'll often find furnaces, at least in older homes. In the southern states, it's pretty much all electric heating if it's recent (< 30 year old) construction.

Maybe in apartments, but in recently built single family homes throughout the south, a gas furnace is very common. I haven't known anyone that has anything else in the several southern states I have lived in, other than those people who tried to get away with heat pumps. Electric heating is significantly more expensive than gas.

I've lived in numerous houses and apartments in Georgia built in the 50s, 60s, 80s, and 00s. Every single one used a gas furnace. Every heat pump system I've seen had a propane or natural gas backup furnace. The only times I've ever seen electric were in water heaters and stoves.

Having lived in SC, NC, GA my whole life I can't remember a being in a home that didn't use a gas furnace.

I'm replying to you, but really you're all saying the same thing. I've lived half my life in GA and NC, and I've seen the opposite. Guess it's very dependent on the cities.

There are graphs at http://www.eia.gov/todayinenergy/detail.cfm?id=18131 showing the primary heating fuel choice, based on a US survey from about 6 years ago. Among other things:

> Everywhere but Northeast, fewer homes choose natural gas as heating fuel

> EIA data show that homes built since 1970 use electricity and natural gas as their main heating fuel in roughly equal proportions.

> The South is the only Census region where electricity is the main space heating fuel in the majority of homes.

The survey data is at http://www.eia.gov/consumption/residential/data/2009/ .

That's not true. I've lived in the south all my life and I've never even seen electric heating. The predominant systems I've seen are all gas powered. Water heaters seem to be split 50/50 between gas and electric as are stoves.

As a counter-example, I grew up in Miami. We had neither A/C nor a furnace, only electric space heaters for when it got to the 40s and upper 30s. (Our house was built in the 1950s, before A/C, so built in the older style with high ceilings, many windows, a crawl space for even more cooling, and no insulation. When it was 40 outside, it was 40 inside.)

We did have a neighbor who contracted with a propane company to fill a residential tank, which was used for heat and cooking. But that wasn't common in the neighborhood.

In Tallahassee, the places I rented didn't have gas, only electricity. Eg, pulling up rental housing in Tallahassee, https://www.rentrange.com/tallahassee-fl/o-3316-calumet-nice... says it has "Electric heating". Searching for Atlanta, I found http://www.cbs46.com/story/21444870/atlanta-fallen-tree-leav... which says "'Fallen tree leaves Atlanta residents without lights and heat' ... "My house used electric heat so it's cold".

Rather than be anecdotal about it, I found "Space Heating in U.S. Homes, by Climate Region, 2009" from http://www.eia.gov/consumption/residential/data/2009/#sh . Of the 19.1 million homes in the "Hot-Humid climate region", 12.4M use electricity, 4.6M use natural gas, 1.4M have no heat, 0.5M use propane, and the others (fuel oil, wood, etc.) are too small to be meaningfully reported.

There is an apparent conflict between your observations and this survey (and with my own observations from living in Florida).

Oh! There's also a breakdown by state, including "Table HC6.10 Space Heating in U.S. Homes in South Region, Divisions, and States, 2009".

GA has 1.7M homes heated with gas, and 1.7M heated with electricity, out of 3.5M. That has the highest percent of homes heated by gas.

In FL, and in line with my observations, has only 0.4M heated with gas, and a whopping 5.7M out of 7M heated with electricity. That's the lowest percentage, which is reasonable for a place with little need for winter heating.

Overall in the South, some 13.3M homes are heated with gas, 24.2M with electricity, 0.6M with fuel oil, 1.9M with propane, 0.8M with wood, 0.2M with kerosene, and 1.0M have no heat.

There are several forms of insulation that work well in high humidity environments ex: foil. The real issue is they take more skill to install and home builders can save money on insulation without making an obvious lemon.

IMO, we need to start designing the equivalent of energy star ratings for new construction as there is a lot of low hanging fruit out there.

There is LEED.

http://www.usgbc.org/leed

Meh. If you are really looking for savings, I'm much more in favor of PassiveHaus [1].

To me, minimizing temperature variance is a much more useful goal than say "hey solar!"

[1] http://www.passivhaus.org.uk

LEED has a really wide scope.

People care about $ so they care about energy costs. If you just show them people will make informed decisions where now it's all up in the air.

EX: Heating and cooling costs for the average 3 bedroom hose in this area is X to Y$ per year, this house is estimated at: z$.

Another advantage of this approach is most savings shows up at the low end of the scale. Where LEED and other green certifications focuses on the high end of the scale which has diminishing returns. EX: Over 100,000 miles 10 vs. 11MPG saves 909 gallons, where 40 vs. 60 MPG only saves 833 gallons.

> and so in a couple of generations we could be looking at something that actually could be impactful.

But battery technology in itself isn't new; you could make a similar package out of car batteries if need be. I think that if it was economically viable, it would've been done ages ago.

Then again I'm probably wrong.

Battery technology has changed a lot over the past couple of decades. A good chunk of the cost here is in the controller electronics (you need a hefty inverter to allow the battery to power your AC household circuits) and that has, of course, changed enormously.

All of this changes the costs and the space requirements, and that in turn changes whether or not it's economically viable.

Kinda sad situation with the alternative energy source.

I did a similar back of the envelope calculation for my dad when he considered putting solar panels onto his house roof when the Australian Govn't was subsidizing it. It would have taken him 17 years to breakeven from the initial installation. This did not even consider the maintenance and insurance cost. We weren't even sure if my parents would have stayed in that house for that long. So we skipped it.

The initial costs is just too high for average Joe.

Its as if people have forgotten about infrastructure or something.

https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta...

Spend a few billion on a 3 Gigawatt plant (roughly 30-Gigawatt hours of energy storage). Large-scale infrastructure projects are going to be cheaper and more efficient than most direct-to-home solutions.

The economies of scale, and the innovative designs that exist at the large level (CAES: Compressed Air Energy Storage. Redox-Flow Batteries, Pumped Hydro, Flywheel Energy Storage) are superior to the designs that exist at a micro-level (Li-Ion Batteries)

The new infrastructure projects are occurring all over the place in the US.

* http://www.energy.ca.gov/tour/helms/ * https://www.greentechmedia.com/articles/read/texas-calls-for...

Etc. etc. These infrastructure projects are the future (and past). They're proven, reliable, and there are tons of engineers with decades of experience on these sorts of projects.

--------

Tesla needs to try to make a Utility-scale 500 MW plant.

Those infrastructure projects don't sell Tesla batteries at scale, making future Tesla battery packs cheaper, making future Tesla cars cheaper.

Tesla is making utility-scale stuff. Their "Powerpack" product starts at 100kWh and can be chained together to scale as large as you want, and is intended for industrial and utility use.

The home version is basically a byproduct of that, for people who want a whole-house UPS, or really want to go off-grid, or whose utilities are slow to get with it.

> Kinda sad situation with the alternative energy source.

I find it kind of sad that the only way people will consider alternative energy sources is if it's significantly cheaper than the existing, embedded, kill the planet options.

I find it sad, but I'm not surprised. People in general don't actually give a shit about anything around them.

You should cheer up. Rational people (like gp) only care about what's around them. Why should he waste money on solar instead of sending it to charity, etc?

The Rational Man is a economic construct which is dubious as an abstract concept for building economic models, and irrelevant as a justification for individual behaviour. If the limit of morality is the law and the market, we might all just as well give up now.

Apologies for this comment. I dashed off about 30% of my thoughts (the shittiest 30%) and this isn't really what I was trying to express. I'll leave it here to remind myself to think more. -----

If the most convincing case you can make for your morals is "you should because I say so" then you can't be too surprised when it's not 100% convincing to people.

> If the most convincing case you can make for your morals is "you should because I say so" then you can't be too surprised when it's not 100% convincing to people.

Yeah, there are all sorts of questions you can discuss about how your values inform the way you spend money above and beyond what's necessary, whether it's about luxury, convenience, status, or how you would want to spend charitable money.

What annoyed me was the raising up of an observation ('people don't care about anything beyond their surroundings') into something which is glibly justified because it is Rational. I would say that's a "you should because I say so", or at best a "you should because it is" argument for morality.

Edit: Ah, I see your edit, consider the above part of the fossilized argument then!

Relevant SMBC: http://www.smbc-comics.com/index.php?db=comics&id=2095

What I find sad is that we allow dirty, polluting energy sources to remain artificially cheap by not requiring them to pay the costs of their pollution.

If the cost of coal-fired electricity included all the costs from the pollution it emits, alternative energy would look a lot more attractive, and rational economic actors would start switching over a lot faster.

who would build their own coal/oil/gas power system at home?

I would not mind seeing more solar but why is the onus put on the individual home owner? the loss of efficiency alone by having so many individual and separate setups let alone the maintenance nightmare makes me wonder, who thought this was a good idea? It might become one when the systems become plug and play, something you can go down to your local big box construction store and buy.

just as with wind, coal, and other forms of power generation, solar is far more suited to where it can be deployed in large configurations. The maintenance savings alone make it sensible. The ease of integrating back into the grid make it more sensible.

but solar as an individual home owner with its current roi and complexity? I guess if you need a visual feel good statement.

Everything has maintenance costs, solar is likely to be lower than most. I have a 4.8kWh PV system on my roof, and though it's only been up there 2.5yr, it has required no maintenance whatsoever (I bought my home with it, so the upfront costs were rolled into total). It provides far more power than I need to heat and cool, run all my appliances, water heater, etc. - and that's in the cool and cloudy Pacific NW. Now, I am in a certified Passivhaus...

I've done some sums too. A 4kw system without storage has a payback time of 10 years for me. I can't see storage making an economic difference at this stage.

The price for solar is not accurate in this article.

My parents just installed a 5KW system, with an inverter and smart meter in Warrnambool, Victoria. They paid $10k AUD, then the government refunded them $5k, so total out of pocket expense for them was only $5k

The whole notion of the powerwall is based on the assumption that either utilities or consumers are irrational. If buying a powerwall was at all economical, utilities would buy them in bulk, charge them on wholesale power, alter their pricing structure, and make a larger margin than you ever could. If powerwalls aren't economical, the only reason they make sense is to capitalize on consumers who are willing to buy the thing because its cool, or because they like living "off the grid".

Utilities also have access to utility-scale energy storage -- pumped hydro, thermal, etc -- which is far cheaper than consumer focused powerwalls.

Not to mention, if people actually used these in large enough numbers--or utilities building a battery reserve--the off peak power and peak power difference will be smaller. Because you have increased demand for off peak due to charging. And decreased peak usage.

That smoothing out of the daily demand curve might actually lead to significant capital savings on the part of utility companies as less need for short term high power reserve. Also the resilience of the system to problems would increase. UK is providing a degree of subsidy to reduce peak demand already. Smart meters may help in future.

http://www2.nationalgrid.com/uk/Industry-information/Electri...

http://www.eunomia.co.uk/eunomia-supports-uks-first-electric...

http://www.carbonbrief.org/how-national-grid-keeps-the-light...

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