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Comment by hettygreen | Hacker News Reader

Here's a better article:

https://electrek.co/2026/07/28/vermonts-largest-energy-sourc...

Seems like they supply each person with 2 Tesla powerwalls for the $55/month and get a reduction in their bills that depends on how much power they choose to share to the grid during power outages.

They've already closed down 2 peaker power plants because of this, so it doesn't seem to just be about handling power outages, but also handling fluctuating power usage instead of firing up extra power plants.

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>They've already closed down 2 peaker power plants because of this, so it doesn't seem to just be about handling power outages, but also handling fluctuating power usage instead of firing up extra power plants.

Yes, that was a significant early argument I remember around the public benefits. The daily power spikes have always been a major challenge particularly when you don't have much commercial/industrial base. And even in the earliest period of the original 2000 home pilot they were surprised and pretty happy about how much load could be spread and the resulting savings. Note though that regulators were cautious and there was controversy around how well it'd actually work, you can find articles like this 2019 VT Digger one [0] from the era. Fortunately it did indeed work out, but easy to forget it was all pretty new at one point.

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0: https://vtdigger.org/2019/09/05/state-calls-for-investigatio...

We're in the program. The powerwalls don't share to the grid when there's an outage. We don't get a direct reduction in our bill for having them. Everyone on GMP gets better rates because GMP isn't buying power wholesale at peak rates or generating it with peaker plants.

I was thinking exactly about this when reading the article. The article writes about house owner benefits but it's the benefits of reduced peaks that are more likely to make providers wanting to do so. With this in place, power plants can take half an hour to increase their generation and top up the battery, instead of having to have faster plants round that caters to peaks.

Lithium is not the way to go for home batteries. As size/weight are not an issue for a basement or shed install, oldschool lead-acid are much cheaper and can be easily recycled once at end of life.

Those tesla wall packs will be a massive headache when they give up the ghost. Read the contract carefully. Who is responsable for end-of-life disposal? Where/how are they to be disposed of? Lead acids can be taken to any number of recycling centers, some will even pay you for them.

Seems like recycling is picking up for lithium batteries and the metal components are still valuable enough.

I think a bigger question is if sodium batteries starts to take over (seems better for homes, heavier but seemingly safer but also for cheaper cars) and lithium/rare-earth metals prices goes down.

And yet everyone is building with lithium, or occasionally sodium. Which leads me to believe that size/weight aren't irrelevant after all.

The technology with PbS or even NiFe has existed for decades, but only took off with lithium.

Not in homes. Density is a huge issue for commercial installations. The off-grid community also values user-repairabilty and avoiding vendor lock-in. Good luck replacing a dead cell in a tesla pack.

The market for this isn't the off-grid community. It's basically every GMP customer.

You aren't wrong about part of the off-grid community not wanting this. I'm not sure I'd want it if I were doing an off-grid install, but it does stand to grow the off-grid community to include people who are looking for a turnkey solution instead of having to do all the research to put together a more user-maintainable system.

Isn't the Tesla pack just a bunch of 18650 (or some similar cell)?

I wouldn't expect the home owner to repair them. However they should be repairable by someone with training in how to diagnose and replace failed cells. (which mostly means a battery welder and some safety systems)

I was looking into this stuff early this year in India, and found LiFePO₄ more compelling on paper: two or three times the cost, but lasting two or three times as long, allowing deeper discharge so it should be equivalent to slightly higher capacity, and requiring no maintenance. I could easily have overlooked or misunderstood something, and am interested in counterarguments.

The lifespan numbers are lies. I have personal knowledge of deep cycle lead batteries lasting 10+ years, thousands of cycles. Many websites actually cite numbers for sealed batteries as used in cars. "Flooded" batteries last longer than sealed because they can be inspected and maintained. There are also "deep cycle" and "marine" units which are also different than car batteries and can be discharged more.

https://offgridsolarguide.com/lead-acid-battery-brands-for-o...

I’ve seen and heard of a lot of lead-acid battery home inverter and desktop UPS setups in India (extremely common due to grid unreliability). Desktop UPS batteries sound to consistently be completely useless (<10% capacity, typically 0%) in 3–5 years, and the larger home inverter batteries are typically in poor shape by around 5 years.

I haven’t known any Lithium-ion batteries yet, so I have no personal figures on them. But what I’ve heard is generally more like “they said 8–10 years but it’s still fine after 12”.

lead-acid does not like deep discharge. Also a UPS is typically going to have maintenance free batteries which don't last as long. Many UPSes don't have good chargers and will overcharge your batteries.

You can get decades our of a proper lead-acid battery, but only if you correctly account for all those factors. Start with batteries that you add water regularly (I'm not sure if this is monthly or yearly). Then make sure you have more than enough so that even in the worst case power outage they finish at 30% charge (meaning most don't get close to 50% discharge - the 30% an educated guess but needs more research for your conditions since this needs to be a rare event, the more often you get the worst case outage the more charge needs to remain after). Finally make sure you have a good chargers - modern "battery tender" (a brand name - there are others) makes a big difference.

Lead-acid has been used in major large installation and have a long history of lasting for 20 years when treated properly.

Lithium batteries are still new enough that we don't have a history. We have educated guesses, but those guesses tend to be conservative. Maybe they will turn out to last just as long or even longer. Only time will tell if they are as good or not. However we also know you can abuse lithium batteries and get much worse life. (the Nissan Leaf is famous for significantly worse capacity at 8 years)

The whole depth of discharge thing does make it harder to compare them. I said upthread “slightly higher capacity” for LiFePO₄, but I feel like by recommendations I’ve heard it’s more like 20–40% higher, which is really quite a bit.

Offgrid garage tested it a couple of videos ago and basically the battery lost capacity due to age and not for cycling. And that battery was made with the first generation of lifepo4 from eve, recent battery are better. Realistically it will die first the BMS than the cells in a couple of decades

Do you have a source for the cost benefit? Any lifecycle assessment I find says that Lithium is cheaper.

There are too many variables to make a simple statement. Lead-acid is a lot cheaper and we know how to recycle it. We also have a long proven history of lead acid lasting for decades in ideal conditions (which a house battery is more likely to hit than in a car).

However lead-acid does not like deep discharge so to get max life you will be using much less than the full discharge cycle 80%-100%, and so the lifecycle costs are very different. In some cases lead-acid can be more cost effective if you manage it well, but I would expect lithium to be cheaper for the typical case.

That is lead acid means your real goal is a cheap home backup, which you have to ride out multi-day power outages, and as a secondary you will sell some power to the grid, but you are not trying to make money doing this. By contrast I would expect lithium to make sense if your primary goal is to make money (or at least pay for your home backup system that can ride out a couple hours of outage but not days). The storage to ride out days could work now, but long term as your neighbors buy the system eventually there isn't the need for that much storage and someone gets limited.

We're in the program. As written, it's a 10 year lease, and there's no option to buy-out the equipment at the end. We'll see if they offer that as an option as the end of the lease approaches in another 7 years. For now though, GMP is on the hook to come and get the equipment.

I would also suggest that size and weight are bigger concerns than you're giving credit to. They aren't assembling packs on-site from individual batteries. They're rolling in whole-ass packs in one swell foop. Getting them into basements isn't a small job[0]. Getting them back out will be even less fun for the crews.

Their total on-site install time was maybe 6 hours, and that included tying everything in to the existing system. Putting the hardware in place took maybe an hour of that time. If you want to go with heavier packs or more/larger packs, you're going to add to that a bit. And their doing this in people's finished homes. This isn't new build where they can have a couple of big dudes wrangling packs around without a care in the world for furniture and finished surfaces. The ergonomics of smaller packs matter.

[0] They used a two-wheel dolly with a hydraulic disc brake (bicycle hardware) to get them down our basement stairs.

Thank you for answering so many detailed questions on this.

If the utility owns the packs, part of me wonders why not build out battery stations around substations the utility already owns, instead of managing many small batteries in individual houses.

Seems like the former would have some development costs but ultimately be cheaper to manage

Long term, with people moving towards charging their cars at home, storing excess solar energy at home might be the more economical option because it decreases the amount of power a substation has to send out at peak times.

I guess Vermont’s relatively low population density makes that more likely; with lower population density each service station will either service fewer homes or require more cabling towards those homes. Either way, more cabling is needed per house. Upgrading that to handle the load of charging a car can be costly.

Doing it that way they couldn't charge a lease to the homeowners. By leasing the batteries to the homeowners they're offsetting some of the cost through that lease, but also the selling point for the homeowner is they (presumably) now have a backup in case of a full outage

Also, you're reducing demand on the grid by having them at people's homes, not just reducing the demand on the power plants. If the batteries were centralized you'd still need to move that massive amount of power over distribution and transmission lines, which is actually just as big a problem as needing to spin up a peaker plant. In many areas the bottleneck is transmission not generation

2-wheel dollies with motorized stair climbers are a thing too. Not super common, but aren't cost prohibitive for a use case like this where they'd see daily use.

That was the case before, but is it still? How do lithium battery costs compare to lead battery costs in late 2026?

> oldschool lead-acid are much cheaper

Source? Last time I checked a few years ago the prices were similar and lithium has dropped significantly since then.

Lithium-ion batteries have higher upfront cost then Lead-acid, but Lithium-ion batteries have longer service life.

https://www.whalebattery.com/blog-detail/lead-acid-vs-lithiu...

Cost per kWh per year:

lead-acid batteries: $100 per kWh per year

LFP batteries: $50 per kWh per year

https://www.justplugsolar.com/blog/lithium-vs-lead-acid-batt...

US is outsourcing recycling of Lead acids to Africa.

https://www.nytimes.com/interactive/2025/11/18/world/africa/...

You also need to buy twice the capacity for lead-acid, as they don't like to be discharged below 50%.

>Lithium is not the way to go for home batteries.

Turns out, they're on top of this.

https://cswd.net/cswd-in-the-news/vermont-expands-battery-re...

Lead-acid batteries are amazing for starting an engine, and terrible at basically anything else. They're slow to charge and very sensitive to over-discharge: it's generally recommended to never go below 50% state-of-charge (so you basically need twice the capacity in the first place), and even one full-discharge event will permanently reduce their overall capacity. The fact that they're almost impossible to over-charge means they're never paired with a proper BMS so they usually aren't protected against this type of damage. Also they need to be fully-charged every few days, so they're a poor choice in an application where they're constantly cycled.

Lithium batteries in contrast only need a ~10% buffer, and don't care about being topped off except for calibrating the BMS in certain variants (the only reason why LFP cars want you to charge to 100% regularly), so you don't have to over-provision as much. End-of-life is being sorted out as we speak, recycling companies are popping up as discarded batteries from cars are becoming common. Some may even pay you for them too.

I've put that link in the toptext. Thanks!

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