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.
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] <a href="https://www.basepowercompany.com/" rel="nofollow">https://www.basepowercompany.com/ (no affiliation, I just like batteries!)
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.
>having enough battery to cover an extended outage is very expensive
It sure used to be, but I think battery backups that cover a whole house for 24h is cheaper than a diesel generator that can do the same now. Depending on your situation you can make it back in savings even without solar panels. (Charge when electricity is cheap, use when expensive).
Piped gas generators is a thing I had no idea existed until now! Edit: Curious to learn if they are a common thing?
Look at the page at <a href="https://epicelectrical.com/what-is-base-power/" rel="nofollow">https://epicelectrical.com/what-is-base-power/
25 kWh covers maybe 1-2 hours in a worst-case scenario, and that’s with only a peak eleven-kilowatt output. You’d need ~24 kilowatts peak to cover a full 100-amp old-style mains feed for a house. This is just basic math — 100 amps times 240VAC == 24 kilowatts.
Most houses here in Texas are now built with 200-amp mains feeds. So, you’d need ~50 kilowatts peak. And if you really can get two hours of runtime for 25 kWh, then you would need 300 kWh to get 24 hours of runtime.
Check the prices for batteries and inverters. 50 kilowatts peak and 300 kWh runtime is a lot more expensive than you realize.
Maybe one day, when batteries get much, much, much cheaper than they are today, you will be able to afford that kind of system. But today, a 24 kilowatt natural gas generator is a lot cheaper.
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.
beaviskhan · · focus · HN ↗
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.
izend · · focus · HN ↗
voakbasda · · focus · HN ↗
toomuchtodo · · focus · HN ↗
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] <a href="https://www.basepowercompany.com/" rel="nofollow">https://www.basepowercompany.com/ (no affiliation, I just like batteries!)
[2] <a href="https://nuclearbarbarian.github.io/IL-NLIC/index.html" rel="nofollow">https://nuclearbarbarian.github.io/IL-NLIC/index.html
Kon5ole · · focus · HN ↗
Combine it with rooftop solar to get the equivalent of free fuel for your generator every time the sun shines.
organsnyder · · focus · HN ↗
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.
Kon5ole · · focus · HN ↗
It sure used to be, but I think battery backups that cover a whole house for 24h is cheaper than a diesel generator that can do the same now. Depending on your situation you can make it back in savings even without solar panels. (Charge when electricity is cheap, use when expensive).
Piped gas generators is a thing I had no idea existed until now! Edit: Curious to learn if they are a common thing?
bradknowles · · focus · HN ↗
25 kWh covers maybe 1-2 hours in a worst-case scenario, and that’s with only a peak eleven-kilowatt output. You’d need ~24 kilowatts peak to cover a full 100-amp old-style mains feed for a house. This is just basic math — 100 amps times 240VAC == 24 kilowatts.
Most houses here in Texas are now built with 200-amp mains feeds. So, you’d need ~50 kilowatts peak. And if you really can get two hours of runtime for 25 kWh, then you would need 300 kWh to get 24 hours of runtime.
Check the prices for batteries and inverters. 50 kilowatts peak and 300 kWh runtime is a lot more expensive than you realize.
Maybe one day, when batteries get much, much, much cheaper than they are today, you will be able to afford that kind of system. But today, a 24 kilowatt natural gas generator is a lot cheaper.
mbgerring · · focus · HN ↗
bell-cot · · focus · HN ↗
organsnyder · · focus · HN ↗
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.
pacman128 · · focus · HN ↗