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Comment by r00fus | Hacker News Reader

An EV inverter for $200 can allow your car to power your refrigerator + router/phone/laptops for many hours (days for a LR Tesla).

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A powerwall has what, 12ish KW usable (less in reality) which a single one can power a house for for up to a day if you're careful about what you're using. If you scale that up to the 75KW+ batteries being put into EVs today buying an inverter could be a good investment if you live in an area with frequent power outages (or a cabin or whatnot).

There was also some talk about Teslas being able to send power back to the house with the new HPWC - not sure if that ever happened.

My two person household uses maybe two kWh per day.

I find that very unlikely if you have any appliances at all. Multiple it by ten and I might start to believe you. For reference, right now we, granted in a four person household and electric heating in the coldest winter month, are using around 100 kWh per day. Even when the house is unoccupied in the summer the consumption is around 3.5 kWh per day. That is probably mostly just a fridge and two freezers.

From May 2019 to January 2020 we used 706kWh. I have a fridge but no other appliances that constantly draw power. I don't heat electrically, but I cook using electricity. I run the washing machine about once a week or so and hang-dry the clothes.

I guess I've used a bit more electricity during the last year because I worked from home more, but I doubt it's a factor 10. 100kWh per day would cost more than I pay for rent...

Do you heat water with electricity? That’s a big part of our consumption. Just by looking at what hour we use electricity I realise that just the kids bath every evening is around 2kWh.

And with two small kids the laundry machine runs at least once per day and the dishwasher at least twice when we both grownups work from home.

No, no heating or hot water with electricity.

With a household of 4 and doing everything electrical (cooking, heating, hot water but no electric car) we use on average about 9-10 kWh per day. A bit more in the winter, a bit less in summer. This is a well-insulated, relatively recent house in western Europe. 100kWh seems excessive to me.

This is a 45 year old house with crappy isolation. Compared with similar households in the area our consumption is about 20% higher than average.

And here I thought my ~5 year old house was efficient at 25-30kw per day. Granted I do charge my ev. But my heating and water, water and oven are gas.

Wow, that's really impressive! I'm jealous!

I live in a just ok, older, 65m^2 (700sq ft) apartment in the midwest US with one other person. Everything is electric except the water heater.

We average about 30kWh/day in winter and summer, and about 15-20kWh/day in the fall and spring.

100 kWh per day??? You're burning it like there's no tomorrow. Or somebody is stealing your electricity. My experience from 2-5 person households is that 20 kWh per day is a _very heavy_ consumption. I couldn't even imagine for what is 100 kWh per day needed.

Is that including hot water and heating? Because those are where most our electricity go. We burn no gas or oil.

Hot water yes, heating no. Luckily both countries in which I lived have central heating.

I agree that a lot of kWh are needed for heating. But I hope it's, in your case, for less than 6 months a year? Did you notice a difference in consumption in summer and winter months?

Oh yes, in the summer we use something like 20-25 kWh per day, and it is clear that the bulk of those are used either when we cook or when someone is using hot water.

AFAIK there are other makers that are also ready for this. I seem to remember that the Leaf is.

What I think will be the hard part of including cars into the grid is the warranty issues. I.e. if a battery gets so much usage from the grid that it somehow gets broken or worn out, who should take that cost/ risk?

IIRC, it was added in one of the charging standards, I want to say it was CCS. In theory every car that supports that charging standard should be capable of it, but in practice that will likely be a different matter. As few people need it, few people are likely testing that it works.

I've heard the hard part right now is more regulatory in nature. Especially in the US where energy regulations vary not just from state to state, but also sometimes regionally within states based on power utility provider for a region.

Nissan LEAFs (since the first generation I think) have had the tech built into the car to support this, but so far the corresponding hardware to connect it to the grid hasn't been available outside Japan. In the UK trials are starting for it now:

https://youtu.be/kl9_cWF7fXo

The Roadster was able to do it, but Elon said that it wasn't used enough, and probably it's not worth it because of the battery degradation.

Why would you want to stress a very expensive and hard to replace car component - reducing its life.

Just put some solar panels on your roof

Night during an outage?

A good generator cost 5k or more. I have a 75 kWh battery sitting in my garage. Bummer the tech isn’t right to reverse the flow. My understanding is Tesla don’t have the right part to reverse the AC flow.

This use case is for a 1-2x /yr event, not an every day thing. Also, solar panels do nothing for you if there is a power outage when there's no sun...

So Tesla makes a lot of changes for a facility that a tiny number of people will use once or twice a year.

Refurbishing old car batteries into a Powerwall type of device might make more sense though for a domestic use a fuel cell make more sense.

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