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Comment by martythemaniak | Hacker News Reader

Current prices are kinda nutty and are largely determined by the size of your buy. Retail prices for home batteries (a few kWhs) are roughly $1000/kWh. A Model 3 gets you about $700/kWh (with two free motors and an ipad). A Tesla megapack is $290/kWh, but you have to spend $1000000 to get that price. Tesla probably gets cells from the factory at round $80-$90/kWh.

Long-term it seems pretty reasonable that retail prices should be a small multiple of the factory price (which keeps decreasing), so I think $1000 for a 20kWh battery is totally reasonable.

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At $1k for 20kw/h, I'd be very tempted to massively over-panel the roof and front/back yard on pergolas, install 200kwh of battery and never deal with pg&e again

Exactly. This is what Tony Seba is talking about for 10 years already! He talked about this in his 2014 book Clean Disruption of Energy and Transportation.

what's pg&e?

Utility company somewhere in the US.

They are the utility company that covers most of California. They recently raised rates and customers are unhappy. They are a for-profit and their lack of spending on maintenance has caused a number of fires which has killed people, leading them to be unpopular, among other reasons.

They killed people thru giant fires exacerbated by climate change then get sued and pay billions of dollars in restitution and then raise the rates for the regular folks.

A source of very expensive electricity in California.

USD 1,000 per kw/h seems very high to me.

A couple of years ago here in South Africa I paid about ZAR 30,000 (USD 1,650) as a consumer for a 5kw/h battery, and I just checked online now, I can apparently get a similar battery for half that:

https://www.ecohub.co.za/shop/solar-power/lithium-batteries/...

In the UK you can buy a battery at £160/kWh, complete with BMS and thermal management: https://www.fogstar.co.uk/collections/solar-battery-storage/...

For less than £130/kWh if you're willing to build it yourself, you can get a slightly less capable setup: https://www.fogstar.co.uk/collections/solar-battery-storage/...

>Tesla probably gets cells from the factory at round $80-$90/kWh.

Where I live there is a warehouse where you can withdraw new MANYI Lifepo4 cells at around 97€/kwh (a single cell) after contacting the seller on Alibaba, so I'm guessing Telsa is getting them at 80 or even less.

At $6343 [1] for 13.5kwh [2], seems closer to $500/kwh? The federal rebate does help substantially, but most folks should qualify. This # is closer to $400/kwh if you buy with solar, and $300 if you're buying a few instead of just one.

Re: car batteries, the difference between the rear-wheel drive and long range is about 20kwh (60kwh vs 80kwh), for $8K. That's $400/kwh and doesn't even include all the other trim differences like having dual motors instead of single.

So, it looks like reality is closer to $300-$400/kwh, depending. Not close to your ideal of $50/kwh, but still much better than $1000/kwh.

1) https://www.tesla.com/energy/design/overview 2) https://service.tesla.com/docs/Public/Energy/Powerwall/Power...

This is asking the wrong question. The question is what is the cost per kWh of electricity delivered from that battery, which is not the cost per kWh of capacity installed (though it is related).

You have to charge the battery with electricity (which you could sell or have to buy), and then when you discharge it you are either offsetting electricity you would buy, or selling it. Throughout the process you're losing some of it (~8%), and the battery is degrading in capacity towards eventual replacement.

You also have black swan events - i.e. an early battery death due to manufacturing defects.

i.e. my rooftop solar array sells power at 7c / kWh. When I run the numbers on various offset scenarios, the cost per kWh delivered after all expenses and life time costs that I can find tends to be about 7 - 8 c / kWh. Which honestly makes perfect sense to me: the electricity company, at much more massive scale, can install and run batteries more cheaply then I can.

> Retail prices for home batteries (a few kWhs) are roughly $1000/kWh.

Do you mean the installed price? Including inverters and such? $1000/kWh is more than 4x what you can buy LFP batteries for off Amazon.

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