Biwatt unveils new residential sodium-ion batteries | Hacker News Reader

Biwatt unveils new residential sodium-ion batteries

pv-magazine.com

28 pointsdanboarder14 comments

Not mentioned for some reason is the energy stored - which is 75*48 = 3.6kWh. That seems to be about half of a similar sized lithium-iron-phosphate (LiFePO4) battery.

What is a good resource to check potential cost of solar panels installation in southern part of USA?

I had a few quotes and the prices were all over the place. Prices seem to be going up rather than down. Tesla quote was about $55k, Sunrun quoted me at $96k for slightly lower capacity and same power wall batteries. And I thought that Tesla was going to be the mark for top price. Feels like I’m doing this wrong.

I’m waiting a year. There is some new tech that sound come on the market Q4 this year. Can’t recall the exact name of it but the efficiency they are touting in real applications is worth the wait to me. I feel like buying panels now is like buying the latest iPhone on September 1.

This is a significant step for affordable energy storage. However, a lifetime of 3000 cycles seems low for such a big investment. Does anyone have an idea how this compares with other solutions and how it would perform in under expected load?

3,000 is more than the 2,000 of lithium iron phosphate, which is more than the 300–500 cycles of lithium ion.

That is what they say the lifespan is, but it could just mean diminished capacity after that many cycles. Durability is important, because if you double the durability, you cut the cost in half over time.

Depth of discharge is curiously missing from their cycle count

Sodium Ion is a new chemistry that a lot of places are starting to sell. This is just one company.

Cycles at 80% depth of discharge[a] Hundreds to thousands

https://en.wikipedia.org/wiki/Sodium-ion_battery

The depth of discharge affects the amount of cycles that can be achieved without a significant capacity drop (e.g., down to 80%). Measuring with a shallow depth of discharge can artificially inflate the cycle count.

I'm not sure what you are trying to say here, there is more information out there, I just copied from the wikipedia page.

https://en.wikipedia.org/wiki/Sodium-ion_battery#Commerciali...

80% depth of discharge means to 20% capacity, not 80% capacity. You can see on that section that the lowest number is for 100% depth of discharge, which wouldn't make any sense if depth of discharge and capacity were the same thing.

with good rate performance till 3C and cycle lives of 300 (100% depth of discharge) to over 1,000 cycles (80% depth of discharge).

Another section says 5000+ cycles at 80% capacity

https://en.wikipedia.org/wiki/Sodium-ion_battery#TIAMAT

It's fair to say that between battery manufacturers cycle counts will vary. Like you said, sodium ion is a nascent technology with many new players, and improvements to battery technology could improve cycle count, but cycle measurement in absence of the DoD it was tested at makes it hard to know how durable the battery is under real-world usage.

Li-ion and LiFePo can have insane cycle counts if you never go below 80%. To illustrate here's a diagram I found on the first Google result (though from 2017, batteries were worse then)

https://www.researchgate.net/figure/Depth-of-discharge-versu...

I'm still not sure what you are trying to say. The wikipedia page compared various cycle depths. By that information sodium ion is more durable than lithium iron phosphate.

> big investment

Sorry, what? The _cells_ are ~$100/kwh on aliexpress. You are looking at residential batteries around the cost of an iPhone. Shipping + installation costs more. Sure Tesla still sells theirs for like $10k, but that won't last.

Most interest question, how much will cost per KWh. I hear, sodium-ion are better than Lithium on this, but exactly numbers still undisclosed.

"Its smart home energy management platform integrates a cloud-based battery management system..."

Yeah... no thanks.

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