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I would assume they do not use every enrolled home's 36 allotment on the same 36 days.

Not the OP, but I'm on the same program in NC. You can set a minimum level to keep your battery that will cover at least short power outages (mine is set to 20%). You can also decline to participate with a limited number of VPP events a year.

My utility doesn't have a program quite like this, but they do have a peak power rate that incentivizes similar behavior. I have our system configured to charge up to 90% at 12pm, and then consume no grid power until 7pm (peak rate is 1-7pm), or if the battery gets down to 35%.

I also have it configured to charge to 100% if there are any weather watches or warnings. That overrides the time-of-use configuration.

We do also have a generator that I can hook up if the batteries get too low. We have enough battery to get us through the night, but we don't have enough solar to keep up in an outage during the darker months, or if we want to run the A/C.

How 'bout accepting their $50/battery/month deal for only some of your batteries?

Batteries don’t replace a generator.

We're in the GMP program from TFA. We don't have solar (it's on the list of longer-term projects). GMP is using the batteries solely to time-shift the load by charging from the grid during periods of low demand and drawing during periods of high demand. It decreases their (and indirectly their customers') costs because peak-rate power is expensive to buy or generate.

Solar is very popular in Australia, to the point that we have too much surplus during the day. So now we often have effectively free energy late morning to early afternoon. So while not common, some people here do get batteries despite having no solar, to store the excess from the grid for when it’s more expensive later.

Correct, solar not needed. Depending on your battery capacity and usage patterns you could enroll in one of the plans that lets you pay cheaper rates off-peak to charge your batteries from the grid, and then power your house off the batteries during peak times. Some places this makes a lot of sense - the spread here (between off-peak, flat rate, and peak) is not favorable enough to make it interesting though, as far as I can tell.

Amber is my retailer, and it’s their SmartShift VPP system that controls the battery to minimize grid consumption and maximize export revenue. The battery/inverter system is SigEnergy.

This is the case for us, too. The reason is that whenever there is more supply than consumption on the grid the excess must be shed, and that costs the utility. Hence negative export prices to discourage supply to the grid.

Our battery/inverter system automatically curtails solar generation when our battery is full and export prices are negative, so this isn’t anything we need to think about. (Exception: I’ll charge the car to drain the battery overnight if I expect curtailment the next day. No point letting all that free sunshine go to waste!)

The negative price can either be from subsidized renewables that are passing some of that subsidy onto people who use the power (a good thing!) or remaining coal plants that can't flex fast enough and would rather pay than incur extra costs from flexing (which is good in that they are being effectively fined for lack of flexibility but bad in that they are inflexible and still generating dirty power while more flexible renewables curtail).

If clean energy is being curtailed increasing usage is a better response which negative prices also incentivize but in many jurisdictions they refuse to pass those price signals onto users because they'd rather waste clean energy so they can sell them dirty energy later.

In Australia it's not uncommon on moderate temperature sunny days for the wholesale price to enter the negatives. Lots of solar production, with minimal heating and cooling demands.

Many plans offer a 3 hour period where electricity is free to encourage shifting your load to that time. Which is amazing if you're able to charge an electric vehicle in that time, a standard single phase charger could provide 21kw/h in that 3 window all for free.

Maybe I’m not picturing it correctly but wouldn’t a negative price mean more money in your wallet? Or are you saying that the set price is less than it costs to produce the energy on your side?

https://www.latimes.com/world/la-xpm-2011-jun-14-la-na-adv-w...

> Lately though, electricity, not recreation, has become the big-ticket wind client in the Columbia Gorge. Wind turbines have sprung up all over the blustery hilltops in eastern Washington and Oregon, an area soon to become home to the largest wind farm in the world, developed for customers of Southern California Edison. Indeed, half the massive new wind power generated in the Pacific Northwest goes down the grid to California.

> For the last three weeks, however, many of the wind farms have been ordered to shut down their generation for several hours a day — victims of an unusual surplus of hydroelectric power that has confounded regional electricity operators and infuriated renewable energy advocates who have worked so hard to develop the region’s wind bonanza.

> The problem is an unexpected collision between two of the Northwest’s most treasured environmental assets, wind power and endangered salmon. Spring flows on the Columbia are so high that power system operators say they cannot dial back hydroelectric generators without harming the small juvenile fish now making their way down the river in their spring migration to the sea. With the turbines generating so much electricity, there is much less room on the grid for wind power.

---

In some areas, hydro is coupled with environmental regulations. You can either use the water for power (doesn't mix with the air when doing so), or have it go over the spillway (substantial mix with the air).

The hydro plants, during periods of time when fish are swimming upstream are regulated on how much they can have go over the spillway - and so are forced to generate power... and potentially more power than the demand calls for, and so you've got negative rates.

More on this:

https://www.windpowermonthly.com/article/1133689/stoppage-co...

> BPA insists it can dump only a limited amount of water over the dams because excess spillage creates dangerous levels of nitrogen that are harmful to salmon and other fish. The curtailments may defy an order from the Federal Energy Regulatory Commission (Ferc), which ruled in December that BPA, as operator of 31 federal dams and much of the regional grid, cannot discriminate against wind power by forcing unilateral shutdowns. Several factors have changed since last year, but wind generators still stand to lose millions of dollars.

Another aspect of this is timing. Solar and wind have peak power at different times (and different times in relationship to demand).

https://www.forbes.com/sites/jamesconca/2014/01/18/wind-ener...

> But notice that the thermal generation (nuclear, gas and coal) does not vary much at all. It is the hydro component that has to constantly cycle up and down to adjust to the demand and to wind’s intermittent supply. This competition between two renewable sources means that the relatively carbon-free accruable hydro energy must be shed to take on the wind supply, with no net benefit in carbon emissions or energy cost.

> But constant cycling between 2,000 and 4,000 MW produces significant wear on the hydroelectric turbine gates.

> The following graph compares wind energy production and total demand (or load) for the first half of January 2014. Wind is weakly, but negatively, correlated with demand, meaning wind energy generally comes onto the grid when it’s not needed. Thus the constant need to ramp down hydro production to accommodate.

Demand curve is also known as the duck curve, because it kind of looks like a duck. https://en.wikipedia.org/wiki/Duck_curve

From 2017 Confronting the Duck Curve: How to Address Over-Generation of Solar Energy https://www.energy.gov/cmei/solar/articles/confronting-duck-...

... which brings us back to the article:

> Solar coupled with storage technologies could alleviate, and possibly eliminate, the risk of over-generation. Curtailment isn’t necessary when excess energy can be stored for use during peak electricity demand. SETO launched several projects in 2016 that pair researchers with utilities to examine how storage could make it easier for utilities to rely on solar energy to meet customer needs around the clock. This research will enable even more solar energy to be integrated into the grid, while tackling the obstacles utilities face when incorporating solar.

Though this will be something to look at for in the winter with "how does the house get heated?" https://www.maps.com/home-heating-fuels/ - This likely won't impact New England too much as that's primarily oil, but it's something to watch for. The "batteries with solar backup" would have more difficulty if there was increased demand for electric heating and reduced solar production.

Absolutely. It’s amazing here how government incentives to install batteries have led to stabilization of the grid. Power outages are pretty much a thing of the past now.

Here in Belgium, there's "a bit" of asymmetry: the price per kWh I pay from the grid is roughly 3 times of what I get when I inject. I also have a fixed cost per year to have the right to inject. I knew this before I installed solar and have a home battery, so it only happens during summer.

Distribution charges are per kwh and vary by the hour (more expensive in high-demand morning and evenings, lower during the day and at night). The spot price has to be high enough to exceed the distribution charges for net income on export.

Most of the time, distribution charges are higher than the spot wholesale prices for import and export.

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.

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.

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.

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/...

>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...

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.

> 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.

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

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

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.

> it was a genuine win/win even before getting into softer factors like reducing usage of fossil fuel peaker plants that a lot of us do really care about. In an ideal world neutralizing that carbon pollution would all just be built into pricing so the market could better sort it out, but as it stands I don't feel bad about supporting a shift to some extent too.

We should be doing this as a society (or as a state or as a utility company) instead of relying on individual do-gooders to pay for it. 70-80% of the cost sounds very good, but if you're not getting any latitude on how the things are used, that 20-30% is still unfair. If they belong to the utility, the utility makes all decisions regarding it, and you are giving up your space for it, if anything you should be getting paid, not paying.

They could at least let you actively decide if you want to allow it to be drawn down and to what extent; some sort of latitude. As it is, for them it's money for nothing.

That being said, the article says that they're starting to install them for free. Thanks for sharing your experience.

> First, the batteries took the place of a generator,

The generator would have been yours, and only used for your needs. It wouldn't have involved any data collection, the uncompensated use of your bandwidth, or exposed you to so much liability.

> Part of the program is that in case of storm warnings or other risk it actually switches out from the VPP for the duration to protect you instead.

They may do this, but by their own terms they aren't obligated to. The good news is that in the event where a cable is cut/down and they lose the ability to siphon power from your battery you will be sure to get the benefit of whatever power it has stored. It's also nice that they compensate you for the power that they draw, but again, all of that energy is already theirs by right.

The state contracts them to provide the people with reliable power and you pay them for that service. They should be expected to reasonably deliver that in exchange. Installing their equipment inside people's homes can be part of how they manage that responsibility, but it's still their responsibility and they should compensate you for that and not expect you to pay them even more for the privilege of paying their costs and accepting liability.

> it was a genuine win/win even before getting into softer factors like reducing usage of fossil fuel peaker plants that a lot of us do really care about.

It's honestly not a bad idea conceptually. It seems like it can have real benefits, but the terms are exploitative. At a minimum they should be obligated to prioritize your power needs above others when it comes to energy stored in the battery on your premises, and they should be obligated to compensate you for power taken, as well as for providing them storage, access, security and bandwidth for their equipment, and they should also assume responsibility for any damage/harm their equipment causes to your property and anyone one on your property as long as it wasn't caused by tampering or improper use. Ideally, you'd also be able to opt out of all personal data collection (not related directly to the use/monitoring of their hardware), and any loss/theft/damage would be covered by their insurance (provided their equipment was reasonably secured), otherwise they'd have to pay you enough to get additional insurance coverage of your own.

I'm glad it worked out for you when you had it, but unless the terms were very different from what they are today you were absolutely cheated and being taken advantage of, even if you didn't feel that way.

It's more economically optimal to convince wealthy Vermonters to house the batteries by branding it as subsidized resilience than it is to buy and maintain substations?

If home owners are paying then it might be less efficient for the overall economy but better for the utility company. It is often easier to find a million people willing to spend a thousand dollars than finding one person willing to spend a billion.

There’s probably a significant element of consumer batteries being so good, so easy to setup, and so cheap to buy. That it actually ends up being more economical to take this approach, than build dedicated utility scale battery storage.

With consumer units, you can reasonably expect that they’ll operate with zero maintenance and zero direct supervision for a decade plus. If the cost of those units is low enough, that reduced operational burden starts looking very attractive, especially if you want to scale up your battery capacity across your network very quickly.

> That seems like the economically optimal middle ground.

It is not when we are talking about government subsidies intended to redistribute wealth from the poor to the middle class.

Home batteries provide backup power in emergencies to the home without a substation being involved.

It's a 10 year lease agreement. You pay them, and when the 10 years is up you have to return the batteries. At no point does the customer own the batteries.

It's like leasing a car, except with a car lease you have the option to pay extra to buy it out at the end and take ownership; with this lease agreement you don't.

Linked from that link: https://greenmountainpower.com/wp-content/uploads/2026/04/ES...

There is no local "base load" generation to begin with. 73% of power in VT is imports from out of state/country. Primarily from Hydro-Quebec.

- There are no coal plants left in New England at all.

- Most of VT doesn't have access to Natural Gas (the Burlington metro does, via a pipeline that is only served from Quebec, it is not connected to the US pipeline grid). There are no Natural Gas plants in the state.

- The nuclear plant closed over a decade ago.

- Actual in-state generation on a normal basis is a few biomass plants, some modest hydro on the rivers, and some scattered wind/solar.

- The power plants being "replaced" here, or at risk of being replaced, are some small and rarely used oil-fired peakers that run a few hours a year currently and have nameplate capacity in total of <200MW even if they shut down all of them.

- Transfer capacity to stressed regions (NY-ISO, PJM) is low so they can't really draw that much off the region's grid (ISO-NE).

- Power prices are always some of the highest in the country, the region in general is known for regulation and disliking development - and VT even more so. Making it unlikely you see some sort of AI data center boom here or the like.

- The most realistic source of significant new demand in the state is probably electrification (heating, cooling, vehicles).

> they still need base load generation

nit pick, but this isnt true at all. "Base load generation" refers to fixed capacity generators (coal, nukes) that run at 100%, matched to the lowest point of the demand curve overnight. This is an obsolete concept in a modern grid where batteries, wind, solar etc have destroyed that economic niche.

what you mean is likely "backup capacity". And yes heavily renewable grids will likely need some standin / backup generation for exceptional circumstances, for the foreseeable future. The economics and sizing of this backup is almost entirely unrelated to the economics and sizing of "base load generation". (for eg, there will never be a time when a diversified grid is at zero. The amount of backup needed is a function of how frequent these exceptional events are, the mix of your grid, and how much you're willing to pay backup generators to avoid load shedding in these situation)

Entirely agree. I think that this is fantastic technology and it will do wonders to avoid blackouts and deal with storm outages that people talked about. I just think that we need to have more care when it comes to energy.

Turning off plants is a lot easier than turning them back on. Especially when the rest of the world is building data centres and co-locatrd power and there are skill and equipment shortages.

These technologies bring a promise of clean renewable power which is great, but reality is that we haven't fully figured out how to do it reliably enough. I fear that we will get to a stage when old conventional plants are shut down, and we still haven't fully figured out the replacement. It will be a long period of unreliable and expensive power which will undermine entire economies.

The article does not make a big enough deal of another saving for the utility - it means that when snow takes out lines, they have more time to deal with the problems before customers start complaining. That can be quite significant if the utility can wait 12 hours for storms to pass, then fixing things becomes significantly easier.

That could be true, but I think important to clarify - how big is the solar array and how big is the battery? - what does the consumption look like - is your battery big enough to help navigate through a week of cloud cover in winter? - do you live somewhere with great solar resource

From the article

>More than 5,500 people in Vermont have similar home battery systems.

This is _literally_ a rounding error. It's less than 1% of Vermont.

So it's your comment that's truly baffling, though I'm sure others would appreciate if you posted your own source. There's certainly no power plant getting shut down because 5,500 customers have batteries, but again I'd love to be proven wrong.

Parent was just spreading a lot of fud, half-truths, and "yeah, maybe if you squint and force an exotic framing"... they're trying to convince you to throw the baby out with the bathwater, don't lose sleep about it.

Generators are generally used outside. There are some rated for use inside, but they also have strict regulations on how that is done. (there are also some used inside but they will kill someone soon)

I would be much more nervous about a 13+ kWh battery than a natural gas generator.

The generator is generally only risky when in operation. For natural gas units, a normally-closed solenoid keeps the gas off unless the controller actively commands it. A battery is constantly in a state of non zero fire risk when charged.

Why downvoted?

> Tesla Electric customers report making as much as $150 a day

Only on peak demand days, of which there are only a handful every year.

I have Enphase batteries enrolled in an equivalent program, so I've tracked how much I make. Definitely not enough to make much of a dent in the payoff time for the batteries. But a nice perk nonetheless.

there is something really wrong with the economics of this.

it shouldnt be celebrated.

If a home had a detached garage or a storage shed that would be a better area. Some of the newer model batteries can be outside in winter cold and snow on its own base like a stand-by generator would be.

I like the idea of a backup system or a system to offset high rates by storing power on off-peak times. Even if you don't have solar storing power from the grid at low demand times at night then use power from the battery at high energy cost times during the day.

Whatever way it's installed it's still a good idea to have an emergency plan or at the very least assume the worst and place the device away from the home.

out of the few places ive lived, seattle is the only one that had power outages on a regular basis.

maybe not all of europe is good, but at least many places in the US are bad at it

And with the way that grid costs are coming to dominate electricity costs, these sorts of peak shaving technologies will be huge cost savers in the future.

> how astroturfy hn had become

It feels like politics to me, and HN is definitely not immune to partisan motivated reasoning.

Assuming they set up the house to island, which depends a lot on the install. Otherwise live power from a house in an outage is a big risk to those working on solving the outage.

Easily solved, if addressed!

Just found out about this. Any big draw backs to enrolling in it?

Except they're not replacing power plants at all, they're adding batteries to the grid to store and distribute power. After all, something has to charge the batteries.

Batteries compete with peaker plants for diurnal variance, but they can't replace peaker plants for seasonal variance. It's an interesting dynamic.

Power isn't a particularly helpful metric here, energy is. Power doesn't tell you anything about how long the batteries will last, it only tells you how quickly they can drain. Also there's a limit to how much power you can draw through residential lines so regardless of whether or not batteries can deliver power on the same order of magnitude as a coal-fired plant, it's highly dubious that these specific batteries can do that.

>Batteries do indeed compete with power plants, every day of every moment they are on the grid. They are also consumers from power plants, they go both ways.

Hey don't tell me that, tell the BBC. They're the ones who wrote an entire article about "replacing power plants with home batteries".

Yeah, peak shaving is a real thing, and it's actually a no-brainer, I think. I just got a bit annoyed and carried away because the article did not make clear how large a challenge it is to actually disconnect from the grid and stop relying on power plants.

The reason is that I have been dabbling with off-grid gear for fun. Nothing major, just a solar power station and a couple of solar panels. And here in Norway, you really get respect for how hard it is to get energy during the winter when there's no wind and no sun. Even if I had 100 kWh of battery storage and 20 kW of rated solar panel capacity, I would be dead in the water, at least for the entirety of December and January. The only viable solution for going full off-grid in Norway is a backup generator. You could get by with wind, maybe if you live in a predictable windy area and you have a large battery bank.

Since it's so cold and darker during the winter, I have always dreamed of someone making a really good Stirling engine for generating electricity. But there are way too few people living as far north as us, so there's really no demand. You don't have to go further south than Germany, and solar is fully viable on its own, even during the winter. And the entirety of the United States, with the exception of Alaska, is completely self-sustainable per household with just solar. But off-gridding one's own home is suffering the March of Nines problem, whereby it's exponentially more expensive to be grid-independent 99.99% of the time, and so forth.

I'm rambling now. Suffice it to say that I stand by the fact that the article is misleading, though the goal of off-gridding and getting as much solar and in-house storage as possible is something I wholeheartedly agree with. I don't like it when people don't communicate how large a challenge it is.

Wispr Flow is a dangerous tool It seems..... it makes it way too easy to write a lot of text.

> As a consumer, would you want the extra usage on your battery?

I feel like this is likely going to be a non-issue in practice. Because these batteries are rated to last at least 10 years either way. And by that time, the cost of replacement will be dramatically cheaper.

How much would I get paid?

Many do - teslas, ford lightnings, Kia ev9, all the GM Ultium stuff (Silverado etc, hummer ev, Cadillacs), and a bunch of others.

Yes, but last I checked the bidi chargers were proprietary - tied to vehicle manufacturer - which is a huge disincentive. I don't want my home's battery connector locked into a vehicle brand/manufacturer.

Lightnings do (well before they were discontinued)

But given they are NMC chemistry, you probably wouldn't want to cycle them a lot for the grid (or just your home).

Many do (assuming bidirectional charger), but it’s only 3.6kW max, in most cases

I think they mean to use EV batteries would require the EV to be designed for V2G capability, which is currently rare

In a hypothetical future where every single car participated, you probably wouldn't need to dedicate more than a few % capacity to still make an absolutely massive VPP

28% of trips are under a mile, 52% under three, 64% under five, 79% under ten, 93% under twenty-five, and 98% under 50 miles.

Only 0.8% of the trips are over 100 miles!

Okay, well, that’s clever for now. The real arbitrage base is pulling is getting in while there’s capital to be raised for it and money to be extracted from the market, before competitors emerge and the incumbents respond and everyone realizes the play all along was to build an enormous battery plant without the expenses of land and compliance and negotiating with producers and carriers. They’re in the buying low phase now.

They’ll sell high when PE buys the company and pulls a Broadcom on all the existing customers, who will abandon the equipment after ten years go back to installing Tri-fuel generators while Centerpoint deals B2B with serious battery plant operators instead of B2C with annoying consumers

Customers running batteries they don’t own to store energy they can’t use for a company that won’t share profits is not the future.

Vermont’s project might be more viable, they’re a little better able to see beyond a spreadsheet up there. California will regulate it into unsustainable price territory. In the meantime finbros in Texas will make a killing having Claude build badass dashboards to show how much they make off bored suburbanites stuck on a grid built and operated as cheaply as possible to take as much money as they can before the useless state government is run out on a rail or finally eats the last bite of its own ass

Since you ask

Yep. I'd never have a large battery like that in my house. Outside, a safe distance away, maybe.