Comment by beaviskhan | Hacker News Reader

Comment by beaviskhan | Hacker News Reader

This article is all over the place, but the principle is pretty simple - rather than adding more generation for peak usage times, batteries store energy generated off peak and smooth out the macro usage trends.

Our local utility in NC has a program where they'll pay you ~$50/battery/month to enroll in their virtual power plant program. In exchange, they can take control of your battery up to 36 times per year for a period of a couple hours. Summer events are typically early evening during peak air conditioning times. Winter events are typically early morning during peak heating times.

In practice this means one of two things:

* They make your battery charge to full capacity in advance of the event, and then you run your home off the battery and don't take any power from the grid during that time * Sometimes you'll also return power to the grid beyond that used by your house - they pay you the contracted rate for the power you deliver

We've paired our batteries with solar panels, so generally we have a full charge going into the summer VPP events. We have gas heat, but I expect we'll pay for at least some grid energy to charge batteries during the winter events. Regardless, it's been a good program for us - even without solar, we would not pay for any more power than we used, and the monthly rebate from the utility makes the economics of the system a lot more favorable, especially here in the land of relatively cheap coal power.

Ideally for people with a battery they would take charge to manage your battery between 50%-80% full, paying you for anything you send to the grid. 36x a year means major peak events only (one assumes with a limit of 36 they will try to be under that just in case the last day of the year has a problem). However a 50-80% policy is nice to batteries and means they can use it for even tiny local peak events. Ideally there would be enough home batteries that between all the renewables (Parts of NC are part of the TVA with plenty of hydro) they go months between using a fossil fuel plant.

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

What happens if you have a local power outage but they have drained your battery down?

Batteries don’t replace a generator.

They can, depending on storage and outage duration you plan on mitigating. For example, a friend in ComEd's Northern Illinois service territory has quite a bit of rooftop solar. They subscribed to Base Power [1], who came and installed battery storage on site. Base Power became their power provider, which is a few cents/kwh cheaper than ComEd, because they charge the batteries at night when demand is low and Constellation Energy's nuclear fleet is still pumping out power (Illinois has the largest merchant nuclear fleet in the US [2]). Their daily solar generation is sufficient that if utility power fails, daily solar generation is sufficient (with batteries for coupling to enable continued solar production when utility sync is lost) to not need a fossil generator; the battery will carry them from sunset to sunrise until the solar panels are producing again during daylight hours. "What is your risk model?"

If you cannot install residential solar, don't have enough solar, or have to defend against outages lasting for days or weeks, having the infra available to support an exterior fossil generator is certainly something to consider (main load center transfer switch, receptacle on structure exterior for genset supply to the load center or a subpanel of critical loads).

[1] https://www.basepowercompany.com/ (no affiliation, I just like batteries!)

[2] https://nuclearbarbarian.github.io/IL-NLIC/index.html

What is a generator if not a battery that charges with fossil fuels? As long as the battery has enough energy to cover the outage the end result is the same.

Combine it with rooftop solar to get the equivalent of free fuel for your generator every time the sun shines.

> As long as the battery has enough energy to cover the outage the end result is the same.

That is the key—having enough battery to cover an extended outage is very expensive.

My generator can run on natural gas, which is piped to our house and only had one outage in the fourteen years we've lived there (when the gas company replaced lines as part of preventative maintenance). So effectively, we have a redundant electricity source coming into the house. If that was also down, I could also run it on propane or gasoline.

That being said, if I had to pick batteries _or_ a generator, I'd prioritize batteries. We have both, and the batteries cover the majority of outages, while also providing other benefits.

A battery will replace your generator and you are too late to stop it.

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

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.

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.

> They make your battery charge to full capacity in advance of the event..

> We've paired our batteries with solar panels..

Does this imply that the scheme will charge your battery from the grid, and that you don't technically even need solar?

I've never considered that one might get a battery without solar, but I guess you might have some power needs that would make it worthwhile to draw on during cheap periods and drain at peak?

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.

Reading this is the first time in a long while that I've thought, "Man, I love this. Living in the future is awesome."

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.

Does GMP have a community solar program or something similar where you can group buy solar?

https://solarunitedneighbors.org/co-ops/ is a resource in this context, https://www.brightsaver.org/ for balcony solar (Balcony solar is legal in Vermont via https://legislature.vermont.gov/bill/status/2026/S.202).

(seems like it would make sense for GMP to deploy batteries everywhere commercially logical first wave, and then follow with distributed solar generation across their service territory: https://greenmountainpower.com/map/service-area/)

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.

Reply on news.ycombinator.com