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Comment by toomuchtodo | Hacker News Reader

LFP stationary battery storage appears to be at ~$52/kWh in China [1] (compare to $181 in 2018 per Our World in Data). California buys a lot of stationary storage from Tesla though, which is preparing to start production at the new Sparks, NV LFP cell production facility [2]. Ford is building their own facility in Michigan [3], with 35 GWh of capacity.

[1] https://reneweconomy.com.au/watershed-moment-big-battery-sto...

[2] https://electrek.co/2025/07/01/tesla-unveils-lfp-battery-fac...

[3] https://electrek.co/2025/06/25/ford-stands-by-controversial-...

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That $52/kWh price isn't for raw battery modules, it's for a fully packaged bulk storage system. Which means the raw battery module price is significantly less than $52/kWh. Wowsers.

Its 35 for cells.

For comparison a project in NZ recently finished cost 550 usd / kwh (which also includes site, etc)

I just bought an ecoflow for around $350 for 1 kWh. It uses LFP, I guess there's a lot of room for it to fall in price.

I wonder if there will be a tipping point where people start defecting from the grid, making it more expensive for people still on the grid, giving them a bigger incentive to defect.

Your $350/kWh for the EcoFlow is actually pretty good - that's lower to mid-range for consumer LFP power stations right now [0]. The best consumer units are still hitting around $300/kWh, but there's a long tail of more expensive options. Still a huge gap from utility-scale ($52/kWh), but the trajectory is steep.

The "death spiral" scenario you mention is interesting - we're probably still a few years out from consumer storage being cheap enough to cause mass grid defection, but the economics are getting compelling fast. The portability premium and all the inverter/BMS/housing costs still add up compared to raw cells, but even those are dropping quickly.

[0] https://gearscouts.com/power-stations

From your first link:

They will also pull forward the economic tipping points for longer duration 8 hour to 10 hour systems needed to shore up ‘Round The Clock’ renewables use cases, which disproportionately stand to benefit.

I never understood the difference between standard systems that deliver the power over a 4 hour interval versus longer duration systems of 8 hours or more. The amount of energy delivered is the same, it is just delivered more slowly. What is the factor that makes delivering over 4 hours more cost effective than 8 hours?

Yeah I’ve never understood this for lithium ion systems. Maybe some parallel or series the cells differently to get different total max power outputs? But I don’t expect that would affect cost either way.

With flow batteries there are definitely differences since the power and energy components of the system can each be scaled independently from each other. Ie need more total energy then just expand the amount of liquid electrolyte storage you have.

X hour batteries is mostly because battery people think in MWh and grid people talk in MW (and confusingly both call that capacity.)

The hours designation is the MWh / MW i.e. how fast you can empty the battery into the grid at full throttle.

The economics comes in because batteries are expensive and you want to target the highest and lowest prices during the day, charging and discharging totally to maximize revenue via price abitrage. A 1 hour battery is going to be shaving the very peak prices of each day soaking up solar at noon and displacing expensive gas peaker plants in the evening.

As the battery MWh gets bigger, but not the ability to put it all on the grid, that implies you'll be charging and discharging for 4 or 8 hours each day which means you'll be paying and getting paid closer to the average prices in both directions.

It only works economically if the battery is itself cheaper (and/or there's more renewables pushing down prices for longer periods of the day)

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