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- Hacker News
- >thirty-two people contribute €50 each.
I guess Europeans have more friends than Americans -- I can't think of 32 people I'd invite to a birthday party, and certainly not 32 people that I'd expect to give me a €50 gift. I haven't received a real birthday present from friends (beyond a cheap gag-gift) in decades.
by Johnny555 - How long do such batteries last?
I remember having to replace the lead acid battery in my UPS every 2-3 years, which seemed like a waste of money considering my country's power grid is fairly stable apart from the occasional blackout from lightning strikes.
by ValentineC - > €1,600 for 5 kWh
Those prices are high. You can get 2.56kWh for 270€ on Aliexpress, delivered locally from Germany.
by Tepix - Most of these are illegal to install in Belgium though. Anything connected there needs national grid type approval.by markvdb
- 2.56kWh for 270€ on Aliexpress
What could possibly go wrong? The things that people do.
Personally, I'd like the company to be in the EU so that I can at least sue them if it burns down the house.
by microtonal - How does 12 years required for this scheme to pay for itself stack up against the typical house battery's lifetime?by or_am_i
- Sounds like that's roughly the average usable lifetime for the battery, so you will break even on average.by strbean
- Also, as more batteries get added to the grid, the difference between the "cheap" and "expensive" energy prices ought to reduce.by Retr0id
- > 2. Confirm that their home, meter, and electricity contract are compatible.
This seems like the hardest step. The costs of "just a battery" are much lower by comparison.
by jerlam - You don't necessarily need to export power, especially for a small battery like tihs. Charge it up when power is cheap, and then configure it to discharge when power is expensive but only to match your current usage. You will need a CT on your main feed for it to balance against, but it can be done.by jandrese
- People don't tend to buy people large furniture because it's rude to assume that theyll want to keep something large and relatively permanent, much less something that requires an electrician to install.
- Strange article, even though the idea is nice. $200 birthday presents might be a thing in America in some circles, but for German standards that is ludicrous (even 50 bucks is quite a lot, and then you need 32 people).
I also don't get his example calculation. He mentions that average price in Germany is 38c/kWh, but in the table it's suddenly 4c min vs 13c max (or 40 vs 133?). That doesn't compute.
by hobo123 - At my mother's workplace, there was a group of coworkers who each donated an amount of money per paycheck. Each paycheck, one coworker would get the lump sum that was collected for that paycheck. Similar concept to the one described here. They called it "susu" or something to that effect. If I remember correctly, it got messy when people would leave the workplace or when, occasionally, someone would get robbed on the way home.by scaredreally
- I read the book Poor Economics[0] around when it came out, and it described something similar.
For people who don't have access to banks, they form "savings clubs" where there will be, say, 12 people who put in $100 per month, and one person takes the pot every month. The idea is that if you keep the money yourself, then you're socially pressured to spend it when there are holidays or guests, but if it's locked up in the savings club, you can't spend it, and then you get a big lump sum to spend on a large purchase that would be otherwise hard to save for.
by mtlynch - There are two issues with the articles calculations, that end up making the already bad payback time even worse, before considering opportunity costs. Numbers are for Germany since that's the more favorable case:
1 - degradation: assuming the 15 years battery life / 10.000 cycles number from the datasheet is accurate, and that the manufacturer considers 70% capacity end-of-life, this pushes the payback time from 11.1 to 12.7 years.
2 - The article calculates the savings with:
> daily saving = 4.5 × expensive price − 5 × cheap price
but this is wrong because it assumes that grid charges fully cancel out. The article generally does a poor job at explaining this, but essentially it proposes you overbuy electricity when it's cheap and use it when it's expensive. The difference of those two, €0.133/kWh - €0.041/kWh is much smaller then the average electricity price of €0.3869/kWh because the latter also includes taxes and grid charges. So with 90% efficiency they end up with the formula above, but completely ignore the fact that from the grid's point of view, the total electricity consumption increased. On the flipside, it's also taking EPEX prices directly, pre-VAT, so you actually save 19% more then the difference 0.133 - 0.041 = 0.092. So the actual formula should be:
> daily saving = 1.19 × (5×0.9 × expensive price − 5 × cheap price) − 5 × (1−0.9) × grid charges
At a average rate of 21 cents/kWh for total grid costs (including VAT) that comes out to a payback time of 13.71 years.
So yeah, buying batteries alone doesn't make sense. You need solar or wind to charge them, so you actually avoid the grid charges. So that instead of saving 10 cents you save 40.
by Tharre - 11-13yr payback on something that is going to degrade ~3-4%/yr for 10 years (and limited terminal value) doesn't seem like the greatest investment unless you think the arb is going to widen a ton.by balderdash
- Let's assume the calculation is correct and you actually earn back in 11-13 years. You are better off investing the money in something like the S&P 500 where you'd double your investment in about a decade without the hassle.
Things will start to get interesting where €1600 don't buy you 5kWh but double or triple the amount.
I can imagine most people are better off either investing like I said or in insulation.
by mosselman - Add in that my freezer probably contains over $500 of food (and the fridge has less, but not none.)
Usually you can buy ice, but when I had a ~36 hour outage a couple years ago, I couldn't. Most stuff was fine for that long, but 2-3 days would've meant tossing pretty much the entire contents.
(Plus, I don't have cell service where I live, so being able to power my router is pretty useful.)
This is probably a bad move if you live in a city. It makes more sense in rural areas.
by lkbm - And any arbitrage is also trivially exploited by the electricity company, who has a much greater financial incentive and scale, so there's really no reason to think that it's going to widen in the future either.
- Alternative systems are closer to 5 years payback if you have access to off peak energy. 3-4%/year degradation is very high, battery packs available in the UK from Fogstar are rated at 8,000 cycles with a 95% depth of discharge.
FWIW my high voltage battery pack has almost 365 cycles and is still at 100% state of health.
by homebessguy - > You are also safer during a power outage. The STREAM 5000 provides up to 3 kW of off-grid output. Keep essential devices on its backup output and reserve some battery capacity, and your refrigerator, lights, router, and laptop can keep running when the grid goes down. An ordinary grid connection does not back up the whole house automatically; the backup output must be configured correctly.
Being able to cut over your entire house from grid power to a battery requires an invasive, expensive change to most connections. I wish people would stop breathlessly promoting batteries (which are good! we need decentralized storage!) because "you can use them to run your fridge, router, etc". Yes you can, but for almost all consumers it's an order of magnitude more effort and cash compared to just buying and plugging in a battery.
by isoprophlex - If a fridge is your only concern, they make UPSes specifically for fridges.
https://duckduckgo.com/?q=Uninterruptible+power+supply+refri...
by fhdkweig - I mean, yes and no. Switching your whole house over automatically? Yeah, ok, that can get invasive and expensive. Running an extension cord from a battery/inverter or generator a multiport plug then to to your fridge, router and a couple of lights? That's about 5-10 minutes of effort.
There's a pretty massive middle ground between "plug in a battery" and "rewire the house.
by apercu - I disagree. During an outage, you need your fridge and a few other essential items. A novice can plug into the back. The device tells you the load and whether you are exceeding. And you can test it at any time. For $600 you can get started without an electrician.
it's the easiest, safest , most affordable and most reliable emergency solution ever available.
by tonymet - The cost/invasiveness of cutover is dropping. There is a relatively new category called "plug in solar" where the inverter/battery is smart enought to detect, sync and use grid power.
The Stream system: Connect the device to the grid to enable it to feed power into the grid or draw power from it when solar energy is insufficient. This can be done via a standard home outlet (if permitted), or through a circuit breaker. [0]
0. https://manuals.ecoflow.com/us/product/stream-ultra?lang=en_...
by adolph - I think you're right -- depending on the country.
It seems australia has very low friction
and US with our power companies, significantly more
- where you going to find an electrician?
- do you need someone to design your grid-tie plan?
- when will the power company approve your connection?
I've had friends wire their house, have to really work to plan the setup, and be stuck with a working system offline while PG&E approves slowly
Another point: People might be better served NOT buying a battery, instead getting an EV and wiring it into their house.
for example: https://www.tesla.com/powershare/
or just "bidirectional charging" for other brands
by m463 - Not necessarily the point. If it provides a normal wall outlet I'm happy to plug essentials around for the one time per 1-2 decades this happens for longer than 4 hours and the fridge/freezer/laptop needs a boostby Aachen
- And the proposed battery solution only works at up to 3kW. My electric range uses more than that, and my water heater, clothes dryer, and aircon each come close.
And, sure: I can get by very well with refrigeration, networking, computing and/or TV, and lights during a power outage. But those loads need to be segregated, or it just doesn't work. That adds more expense.
And since those segregated loads don't even come anywhere near 3kW, it isn't clear to me how I'm to be maximizing my local use of surplus power events.
There are grid-interactive battery solutions from companies like EG4 that can go betwixt the entire house and its grid connection, but this isn't it.
by ssl-3 - > Create a battery birthday club. Buy each friend a battery on their birthday until everyone has one.
At that point, wouldn't it be easier if everyone just bought their own? And then whoever has the latest birthday doesn't have to wait a year to get theirs.
by Retr0id - It is like an energy storage cost cutting rotating potluck. blitzar mentions bulk buying in a comment, which is a great idea to drive down cost. Not sure what the EU version of that looks like, the US versions are:
https://solarunitedneighbors.org/
Europe has quote a bit of renewable generation currently that is curtailing or otherwise going unused, and needs all of the battery energy storage it can get (residential, commercial, utility scale) to convert curtailment into realized clean energy offsetting potential fossil energy usage (gas and coal).
Solar Power Is So Big in Europe That Electricity Is Being Wasted - https://www.bloomberg.com/news/articles/2026-05-13/europe-so... | https://archive.today/nAdiA - May 12th, 2026
> Hundreds of millions of solar panels have been installed in Europe, turning solar into the region's biggest source of power during summer months, but the system around it hasn't kept up. A record amount of electricity is being wasted because grids can't handle the surge in output, with about 40 terawatt-hours of electricity expected to go to waste in the coming months. The glut of solar power is pushing power prices deep below zero during peak solar hours, eroding returns for producers and forcing them to shut down plants, with consumers potentially paying twice for the subsidies and compensation.
by toomuchtodo