ERCOT Battery Storage


Mark Witte
 

The projected growth of battery storage in ERCOT over the next couple of years is stunning. 


Eric Johnson
 

The graph is impressive, but 5000 MegaWatt Hours of energy will not keep the lights on in Dallas for very long!


On Fri, Dec 17, 2021 at 8:22 AM Mark Witte <witte.m@...> wrote:
The projected growth of battery storage in ERCOT over the next couple of years is stunning. 


Dan Lepinski, P.E.
 

4,500 megawatt-hours of battery storage is impressive to many people, especially when compared to "typical" residential requirements. As Eric correctly stated, it's actually quite small in terms of utility-scale systems.

To put 4,500 megawatt-hours into perspective .. it's sufficient for approximately 440 homes in north Texas for one night, at which point the battery would be completely discharged (not a good practice). To be sensible about battery usage, and limit the use to 30% discharge every night, 4,500 megawatt hours is enough for 132 homes.

Many generalities are incorporated into the above comments, such as seasonal variation in sunlight and energy use, among others.

Dan

On 12/17/21 8:52 AM, Eric Johnson wrote:
The graph is impressive, but 5000 MegaWatt Hours of energy will not keep the lights on in Dallas for very long!

On Fri, Dec 17, 2021 at 8:22 AM Mark Witte <witte.m@att.net <mailto:witte.m@att.net>> wrote:

The projected growth of battery storage in ERCOT over the next couple of years is stunning. 


Eric Pratt
 

The chart Mark forwarded is for MW (power) not MWh (energy).  While the typical grid battery installation has had a one hour capability at rated load to this point, some are being installed with a four hour capability.  It is still not a lot of energy for grid scale needs, but it is a start.

I haven't found anything on the ERCOT website that indicates a storage system's MWh capacity.  Am I missing a report that shows it?

Eric Pratt

------------------------------------------------------------------------------------------------------

On 12/17/2021 10:15 AM, Dan Lepinski, P.E. wrote:
4,500 megawatt-hours of battery storage is impressive to many people, especially when compared to "typical" residential requirements.  As Eric correctly stated, it's actually quite small in terms of utility-scale systems.

To put 4,500 megawatt-hours into perspective .. it's sufficient for approximately 440 homes in north Texas for one night, at which point the battery would be completely discharged (not a good practice).  To be sensible about battery usage, and limit the use to 30% discharge every night, 4,500 megawatt hours is enough for 132 homes.

Many generalities are incorporated into the above comments, such as seasonal variation in sunlight and energy use, among others.

Dan


On 12/17/21 8:52 AM, Eric Johnson wrote:
The graph is impressive, but 5000 MegaWatt Hours of energy will not keep the lights on in Dallas for very long!

On Fri, Dec 17, 2021 at 8:22 AM Mark Witte <witte.m@... <mailto:witte.m@...>> wrote:

    The projected growth of battery storage in ERCOT over the next couple of years is stunning. 






Eric Johnson
 

What concerns me the most is how a battery will be implemented into operation of the statewide electric grid, in such a way, that it contributes value in routine daily usage.  That has to be done, so that there is some mechanism to pay for the cost of installation, maintenance, and the eventual replacement of the battery.  If the battery and the associated inverter sit unused for many months, or many years, until an actual emergency takes place, then the question of who pays, and how much, becomes an issue.

On Fri, Dec 17, 2021 at 2:08 PM Eric Pratt <ewpratt@...> wrote:

The chart Mark forwarded is for MW (power) not MWh (energy).  While the typical grid battery installation has had a one hour capability at rated load to this point, some are being installed with a four hour capability.  It is still not a lot of energy for grid scale needs, but it is a start.

I haven't found anything on the ERCOT website that indicates a storage system's MWh capacity.  Am I missing a report that shows it?

Eric Pratt

------------------------------------------------------------------------------------------------------

On 12/17/2021 10:15 AM, Dan Lepinski, P.E. wrote:
4,500 megawatt-hours of battery storage is impressive to many people, especially when compared to "typical" residential requirements.  As Eric correctly stated, it's actually quite small in terms of utility-scale systems.

To put 4,500 megawatt-hours into perspective .. it's sufficient for approximately 440 homes in north Texas for one night, at which point the battery would be completely discharged (not a good practice).  To be sensible about battery usage, and limit the use to 30% discharge every night, 4,500 megawatt hours is enough for 132 homes.

Many generalities are incorporated into the above comments, such as seasonal variation in sunlight and energy use, among others.

Dan


On 12/17/21 8:52 AM, Eric Johnson wrote:
The graph is impressive, but 5000 MegaWatt Hours of energy will not keep the lights on in Dallas for very long!

On Fri, Dec 17, 2021 at 8:22 AM Mark Witte <witte.m@... <mailto:witte.m@...>> wrote:

    The projected growth of battery storage in ERCOT over the next couple of years is stunning. 



Dan Lepinski, P.E.
 

Batteries in utility-scale systems don't sit idle. Ever. They serve several purposes:

1. They're an energy reservoir. When clouds move overhead and output power from solar panels decreases, the batteries make up the difference. This allows the solar energy equipment power output to remain steady. In longer-term overcast, the output power can decrease gradually, using batteries to keep the output constant, which in turn gives the "rotating reserves" (what we call "power plants") to make up for the reduction in power from the PV system. This gradual reduction in solar output power can happen over a period of minutes to hours, depending on the extent of the cloud cover. For the "period of minutes", once the clouds have passed and full sun is restored, the batteries get recharged by the PV system.

System #1 (above) is a "generator-assist" configuration, where solar energy provides some of the required electrical energy during the day. This in turn means the power plants don't work as hard, thus burn less fuel. On a partly cloudy day, output from a large utility-scale system is constantly changing. This isn't good for grid "stability". Grid voltage and frequency would vary as a result. The batteries are to a utility-scale system what a large flywheel is to an internal combustion engine.


2. Provide power overnight (if that's how the system is designed).

System #2 is akin to a totally off-grid system. Batteries and PV must be sized to handle the loads overnight, with sufficient PV to power all of the loads during the day, while having sufficient excess to fully recharge the batteries in approximately 6 hours of sunlight. Thus the PV array for system #1 might be 125% of the load power requirement (after all adjustments are applied for PV output), and up to 300% or more of the load requirement to generate enough power for all of the loads, plus enough to recharge the batteries in a few hours.

With proper design of either system, the latest battery technology has a 20-25 year life expectancy. Even then, the batteries don't just quit. "Worn out" is defined as the point where the batteries won't hold more than 80% of the energy value when they were new. Subsequently, even "worn out" batteries can continue to be used, although with less capacity. They can then be replaced without any panic, but should be done at or even slightly above 80%. 80% is the benchmark for "worn out" because as batteries approach 75% and lower of "new" capacity, the rate of degradation increases rather rapidly.


Dan

On 12/17/21 3:24 PM, Eric Johnson wrote:
What concerns me the most is how a battery will be implemented into operation of the statewide electric grid, in such a way, that it contributes value in routine daily usage.  That has to be done, so that there is some mechanism to pay for the cost of installation, maintenance, and the eventual replacement of the battery.  If the battery and the associated inverter sit unused for many months, or many years, until an actual emergency takes place, then the question of who pays, and how much, becomes an issue.

On Fri, Dec 17, 2021 at 2:08 PM Eric Pratt <ewpratt@mindspring.com <mailto:ewpratt@mindspring.com>> wrote:

The chart Mark forwarded is for MW (power) not MWh (energy).  While the typical grid battery installation has had a one hour capability at rated load to this point, some are being installed with a four hour capability.  It is still not a lot of energy for grid scale needs, but it is a start.

I haven't found anything on the ERCOT website that indicates a storage system's MWh capacity.  Am I missing a report that shows it?

Eric Pratt

------------------------------------------------------------------------------------------------------

On 12/17/2021 10:15 AM, Dan Lepinski, P.E. wrote:
4,500 megawatt-hours of battery storage is impressive to many people, especially when compared to "typical" residential requirements. As Eric correctly stated, it's actually quite small in terms of utility-scale systems.

To put 4,500 megawatt-hours into perspective .. it's sufficient for approximately 440 homes in north Texas for one night, at which point the battery would be completely discharged (not a good practice). To be sensible about battery usage, and limit the use to 30% discharge every night, 4,500 megawatt hours is enough for 132 homes.

Many generalities are incorporated into the above comments, such as seasonal variation in sunlight and energy use, among others.

Dan


On 12/17/21 8:52 AM, Eric Johnson wrote:
The graph is impressive, but 5000 MegaWatt Hours of energy will not keep the lights on in Dallas for very long!

On Fri, Dec 17, 2021 at 8:22 AM Mark Witte <witte.m@att.net <mailto:witte.m@att.net> <mailto:witte.m@att.net> <mailto:witte.m@att.net>> wrote:

The projected growth of battery storage in ERCOT over the next couple of years is stunning. 


Lissa
 

I seriously doubt battery installers are applying such conventional thinking to such new and versatile technology.  In any case we need to stop holding renewables and batteries to higher standards than we have required of traditional energy sources.  For years it was (and still is) an accepted part of the grid for natural gas peaker plants to kick on in times of high electricity demand.  Peaker plants are typically less efficient, cause more pollution, and are Expensive.  They sit unused for weeks or months until they are needed, but no one worries about "who pays, and how much" - their high costs are built into the system and are accepted as business as usual.   Who pays?  consumers, of course!  And that's okay.  It's just that consumers should have more of a say in how clean energy production should be and which technologies are adopted with the dollars they spend. 

Regards,

Lissa


On Friday, December 17, 2021, 3:24:58 PM CST, Eric Johnson <vaxaugustifolium@...> wrote:


What concerns me the most is how a battery will be implemented into operation of the statewide electric grid, in such a way, that it contributes value in routine daily usage.  That has to be done, so that there is some mechanism to pay for the cost of installation, maintenance, and the eventual replacement of the battery.  If the battery and the associated inverter sit unused for many months, or many years, until an actual emergency takes place, then the question of who pays, and how much, becomes an issue.

On Fri, Dec 17, 2021 at 2:08 PM Eric Pratt <ewpratt@...> wrote:

The chart Mark forwarded is for MW (power) not MWh (energy).  While the typical grid battery installation has had a one hour capability at rated load to this point, some are being installed with a four hour capability.  It is still not a lot of energy for grid scale needs, but it is a start.

I haven't found anything on the ERCOT website that indicates a storage system's MWh capacity.  Am I missing a report that shows it?

Eric Pratt

------------------------------------------------------------------------------------------------------

On 12/17/2021 10:15 AM, Dan Lepinski, P.E. wrote:
4,500 megawatt-hours of battery storage is impressive to many people, especially when compared to "typical" residential requirements.  As Eric correctly stated, it's actually quite small in terms of utility-scale systems.

To put 4,500 megawatt-hours into perspective .. it's sufficient for approximately 440 homes in north Texas for one night, at which point the battery would be completely discharged (not a good practice).  To be sensible about battery usage, and limit the use to 30% discharge every night, 4,500 megawatt hours is enough for 132 homes.

Many generalities are incorporated into the above comments, such as seasonal variation in sunlight and energy use, among others.

Dan


On 12/17/21 8:52 AM, Eric Johnson wrote:
The graph is impressive, but 5000 MegaWatt Hours of energy will not keep the lights on in Dallas for very long!

On Fri, Dec 17, 2021 at 8:22 AM Mark Witte <witte.m@... <mailto:witte.m@...>> wrote:

    The projected growth of battery storage in ERCOT over the next couple of years is stunning. 


    


Philip Timmons
 

Well, if they are about the money (they are) . . . . .

They will be used to take cheap surplus Coal and Nuke power from the night and sell into the profitable day.

Keeping us with Coal and Nuke power longer.   




On Friday, December 17, 2021, 04:07:47 PM CST, Dan Lepinski, P.E. <dan@...> wrote:


Batteries in utility-scale systems don't sit idle.  Ever.  They serve several purposes:

1. They're an energy reservoir.  When clouds move overhead and output power from solar panels decreases, the batteries make up the difference.  This allows the solar energy equipment power output to remain steady.  In longer-term overcast, the output power can decrease gradually, using batteries to keep the output constant, which in turn gives the "rotating reserves" (what we call "power plants") to make up for the reduction in power from the PV system.  This gradual reduction in solar output power can happen over a period of minutes to hours, depending on the extent of the cloud cover.  For the "period of minutes", once the clouds have passed and full sun is restored, the batteries get recharged by the PV system.

System #1 (above) is a "generator-assist" configuration, where solar energy provides some of the required electrical energy during the day.  This in turn means the power plants don't work as hard, thus burn less fuel.  On a partly cloudy day, output from a large utility-scale system is constantly changing.  This isn't good for grid "stability".  Grid voltage and frequency would vary as a result.  The batteries are to a utility-scale system what a large flywheel is to an internal combustion engine.


2. Provide power overnight (if that's how the system is designed).

System #2 is akin to a totally off-grid system.  Batteries and PV must be sized to handle the loads overnight, with sufficient PV to power all of the loads during the day, while having sufficient excess to fully recharge the batteries in approximately 6 hours of sunlight.  Thus the PV array for system #1 might be 125% of the load power requirement (after all adjustments are applied for PV output), and up to 300% or more of the load requirement to generate enough power for all of the loads, plus enough to recharge the batteries in a few hours.

With proper design of either system, the latest battery technology has a 20-25 year life expectancy.  Even then, the batteries don't just quit.  "Worn out" is defined as the point where the batteries won't hold more than 80% of the energy value when they were new.  Subsequently, even "worn out" batteries can continue to be used, although with less capacity.  They can then be replaced without any panic, but should be done at or even slightly above 80%.  80% is the benchmark for "worn out" because as batteries approach 75% and lower of "new" capacity, the rate of degradation increases rather rapidly.


Dan


On 12/17/21 3:24 PM, Eric Johnson wrote:
> What concerns me the most is how a battery will be implemented into operation of the statewide electric grid, in such a way, that it contributes value in routine daily usage.  That has to be done, so that there is some mechanism to pay for the cost of installation, maintenance, and the eventual replacement of the battery.  If the battery and the associated inverter sit unused for many months, or many years, until an actual emergency takes place, then the question of who pays, and how much, becomes an issue.
>
> On Fri, Dec 17, 2021 at 2:08 PM Eric Pratt <ewpratt@... <mailto:ewpratt@...>> wrote:
>
>    The chart Mark forwarded is for MW (power) not MWh (energy).  While the typical grid battery installation has had a one hour capability at rated load to this point, some are being installed with a four hour capability.  It is still not a lot of energy for grid scale needs, but it is a start.
>
>    I haven't found anything on the ERCOT website that indicates a storage system's MWh capacity.  Am I missing a report that shows it?
>
>    Eric Pratt
>
>    ------------------------------------------------------------------------------------------------------
>
>    On 12/17/2021 10:15 AM, Dan Lepinski, P.E. wrote:
>>    4,500 megawatt-hours of battery storage is impressive to many people, especially when compared to "typical" residential requirements.  As Eric correctly stated, it's actually quite small in terms of utility-scale systems.
>>
>>    To put 4,500 megawatt-hours into perspective .. it's sufficient for approximately 440 homes in north Texas for one night, at which point the battery would be completely discharged (not a good practice).  To be sensible about battery usage, and limit the use to 30% discharge every night, 4,500 megawatt hours is enough for 132 homes.
>>
>>    Many generalities are incorporated into the above comments, such as seasonal variation in sunlight and energy use, among others.
>>
>>    Dan
>>
>>
>>    On 12/17/21 8:52 AM, Eric Johnson wrote:
>>>    The graph is impressive, but 5000 MegaWatt Hours of energy will not keep the lights on in Dallas for very long!
>>>
>>>    On Fri, Dec 17, 2021 at 8:22 AM Mark Witte <witte.m@... <mailto:witte.m@...> <mailto:witte.m@...> <mailto:witte.m@...>> wrote:
>>>
>>>        The projected growth of battery storage in ERCOT over the next couple of years is stunning. 
>>>






Eric Pratt
 

They can also be used to take surplus wind power in West Texas as we have had recently.  The price per MWh per the ERCOT app has been single digit dollars to negative for much of the day the last few weeks for the West Texas region.

I'm happy for now if batteries can extend the time to use wind and solar generated energy and replace peaker plants.  The rising cost of coal, the declining price of batteries and the magic of the market (greed) should get rid of coal fired plants.

Eric Pratt

----------------------------------------------------------------------------------------------------------------------------------

On 12/17/2021 10:47 PM, Philip Timmons via groups.io wrote:
Well, if they are about the money (they are) . . . . .

They will be used to take cheap surplus Coal and Nuke power from the night and sell into the profitable day.

Keeping us with Coal and Nuke power longer.   




On Friday, December 17, 2021, 04:07:47 PM CST, Dan Lepinski, P.E. <dan@...> wrote:


Batteries in utility-scale systems don't sit idle.  Ever.  They serve several purposes:

1. They're an energy reservoir.  When clouds move overhead and output power from solar panels decreases, the batteries make up the difference.  This allows the solar energy equipment power output to remain steady.  In longer-term overcast, the output power can decrease gradually, using batteries to keep the output constant, which in turn gives the "rotating reserves" (what we call "power plants") to make up for the reduction in power from the PV system.  This gradual reduction in solar output power can happen over a period of minutes to hours, depending on the extent of the cloud cover.  For the "period of minutes", once the clouds have passed and full sun is restored, the batteries get recharged by the PV system.

System #1 (above) is a "generator-assist" configuration, where solar energy provides some of the required electrical energy during the day.  This in turn means the power plants don't work as hard, thus burn less fuel.  On a partly cloudy day, output from a large utility-scale system is constantly changing.  This isn't good for grid "stability".  Grid voltage and frequency would vary as a result.  The batteries are to a utility-scale system what a large flywheel is to an internal combustion engine.


2. Provide power overnight (if that's how the system is designed).

System #2 is akin to a totally off-grid system.  Batteries and PV must be sized to handle the loads overnight, with sufficient PV to power all of the loads during the day, while having sufficient excess to fully recharge the batteries in approximately 6 hours of sunlight.  Thus the PV array for system #1 might be 125% of the load power requirement (after all adjustments are applied for PV output), and up to 300% or more of the load requirement to generate enough power for all of the loads, plus enough to recharge the batteries in a few hours.

With proper design of either system, the latest battery technology has a 20-25 year life expectancy.  Even then, the batteries don't just quit.  "Worn out" is defined as the point where the batteries won't hold more than 80% of the energy value when they were new.  Subsequently, even "worn out" batteries can continue to be used, although with less capacity.  They can then be replaced without any panic, but should be done at or even slightly above 80%.  80% is the benchmark for "worn out" because as batteries approach 75% and lower of "new" capacity, the rate of degradation increases rather rapidly.


Dan


On 12/17/21 3:24 PM, Eric Johnson wrote:
> What concerns me the most is how a battery will be implemented into operation of the statewide electric grid, in such a way, that it contributes value in routine daily usage.  That has to be done, so that there is some mechanism to pay for the cost of installation, maintenance, and the eventual replacement of the battery.  If the battery and the associated inverter sit unused for many months, or many years, until an actual emergency takes place, then the question of who pays, and how much, becomes an issue.
>
> On Fri, Dec 17, 2021 at 2:08 PM Eric Pratt <ewpratt@... <mailto:ewpratt@...>> wrote:
>
>    The chart Mark forwarded is for MW (power) not MWh (energy).  While the typical grid battery installation has had a one hour capability at rated load to this point, some are being installed with a four hour capability.  It is still not a lot of energy for grid scale needs, but it is a start.
>
>    I haven't found anything on the ERCOT website that indicates a storage system's MWh capacity.  Am I missing a report that shows it?
>
>    Eric Pratt
>
>    ------------------------------------------------------------------------------------------------------
>
>    On 12/17/2021 10:15 AM, Dan Lepinski, P.E. wrote:
>>    4,500 megawatt-hours of battery storage is impressive to many people, especially when compared to "typical" residential requirements.  As Eric correctly stated, it's actually quite small in terms of utility-scale systems.
>>
>>    To put 4,500 megawatt-hours into perspective .. it's sufficient for approximately 440 homes in north Texas for one night, at which point the battery would be completely discharged (not a good practice).  To be sensible about battery usage, and limit the use to 30% discharge every night, 4,500 megawatt hours is enough for 132 homes.
>>
>>    Many generalities are incorporated into the above comments, such as seasonal variation in sunlight and energy use, among others.
>>
>>    Dan
>>
>>
>>    On 12/17/21 8:52 AM, Eric Johnson wrote:
>>>    The graph is impressive, but 5000 MegaWatt Hours of energy will not keep the lights on in Dallas for very long!
>>>
>>>    On Fri, Dec 17, 2021 at 8:22 AM Mark Witte <witte.m@... <mailto:witte.m@...> <mailto:witte.m@...> <mailto:witte.m@...>> wrote:
>>>
>>>        The projected growth of battery storage in ERCOT over the next couple of years is stunning. 
>>>






Mellen West
 

This conversation is interesting but appears to be preaching to the saved  and a bit technology driven   Government elected or otherwise need more voices.  Better add a FEW BUCKS with your note if you want their attention. Sad but true..

Mellen

 

From: main@NTREG.groups.io <main@NTREG.groups.io> On Behalf Of Eric Pratt
Sent: Saturday, 18 December, 2021 5:45 PM
To: main@NTREG.groups.io
Subject: Re: [NTREG] ERCOT Battery Storage

 

They can also be used to take surplus wind power in West Texas as we have had recently.  The price per MWh per the ERCOT app has been single digit dollars to negative for much of the day the last few weeks for the West Texas region.

I'm happy for now if batteries can extend the time to use wind and solar generated energy and replace peaker plants.  The rising cost of coal, the declining price of batteries and the magic of the market (greed) should get rid of coal fired plants.

Eric Pratt

----------------------------------------------------------------------------------------------------------------------------------

On 12/17/2021 10:47 PM, Philip Timmons via groups.io wrote:

Well, if they are about the money (they are) . . . . .

 

They will be used to take cheap surplus Coal and Nuke power from the night and sell into the profitable day.

 

Keeping us with Coal and Nuke power longer.   

 

 

 

 

On Friday, December 17, 2021, 04:07:47 PM CST, Dan Lepinski, P.E. <dan@...> wrote:

 

 

Batteries in utility-scale systems don't sit idle.  Ever.  They serve several purposes:

1. They're an energy reservoir.  When clouds move overhead and output power from solar panels decreases, the batteries make up the difference.  This allows the solar energy equipment power output to remain steady.  In longer-term overcast, the output power can decrease gradually, using batteries to keep the output constant, which in turn gives the "rotating reserves" (what we call "power plants") to make up for the reduction in power from the PV system.  This gradual reduction in solar output power can happen over a period of minutes to hours, depending on the extent of the cloud cover.  For the "period of minutes", once the clouds have passed and full sun is restored, the batteries get recharged by the PV system.

System #1 (above) is a "generator-assist" configuration, where solar energy provides some of the required electrical energy during the day.  This in turn means the power plants don't work as hard, thus burn less fuel.  On a partly cloudy day, output from a large utility-scale system is constantly changing.  This isn't good for grid "stability".  Grid voltage and frequency would vary as a result.  The batteries are to a utility-scale system what a large flywheel is to an internal combustion engine.


2. Provide power overnight (if that's how the system is designed).

System #2 is akin to a totally off-grid system.  Batteries and PV must be sized to handle the loads overnight, with sufficient PV to power all of the loads during the day, while having sufficient excess to fully recharge the batteries in approximately 6 hours of sunlight.  Thus the PV array for system #1 might be 125% of the load power requirement (after all adjustments are applied for PV output), and up to 300% or more of the load requirement to generate enough power for all of the loads, plus enough to recharge the batteries in a few hours.

With proper design of either system, the latest battery technology has a 20-25 year life expectancy.  Even then, the batteries don't just quit.  "Worn out" is defined as the point where the batteries won't hold more than 80% of the energy value when they were new.  Subsequently, even "worn out" batteries can continue to be used, although with less capacity.  They can then be replaced without any panic, but should be done at or even slightly above 80%.  80% is the benchmark for "worn out" because as batteries approach 75% and lower of "new" capacity, the rate of degradation increases rather rapidly.


Dan


On 12/17/21 3:24 PM, Eric Johnson wrote:
> What concerns me the most is how a battery will be implemented into operation of the statewide electric grid, in such a way, that it contributes value in routine daily usage.  That has to be done, so that there is some mechanism to pay for the cost of installation, maintenance, and the eventual replacement of the battery.  If the battery and the associated inverter sit unused for many months, or many years, until an actual emergency takes place, then the question of who pays, and how much, becomes an issue.
>
> On Fri, Dec 17, 2021 at 2:08 PM Eric Pratt <ewpratt@... <mailto:ewpratt@...>> wrote:
>
>    The chart Mark forwarded is for MW (power) not MWh (energy).  While the typical grid battery installation has had a one hour capability at rated load to this point, some are being installed with a four hour capability.  It is still not a lot of energy for grid scale needs, but it is a start.
>
>    I haven't found anything on the ERCOT website that indicates a storage system's MWh capacity.  Am I missing a report that shows it?
>
>    Eric Pratt
>
>    ------------------------------------------------------------------------------------------------------
>
>    On 12/17/2021 10:15 AM, Dan Lepinski, P.E. wrote:
>>    4,500 megawatt-hours of battery storage is impressive to many people, especially when compared to "typical" residential requirements.  As Eric correctly stated, it's actually quite small in terms of utility-scale systems.
>>
>>    To put 4,500 megawatt-hours into perspective .. it's sufficient for approximately 440 homes in north Texas for one night, at which point the battery would be completely discharged (not a good practice).  To be sensible about battery usage, and limit the use to 30% discharge every night, 4,500 megawatt hours is enough for 132 homes.
>>
>>    Many generalities are incorporated into the above comments, such as seasonal variation in sunlight and energy use, among others.
>>
>>    Dan
>>
>>
>>    On 12/17/21 8:52 AM, Eric Johnson wrote:
>>>    The graph is impressive, but 5000 MegaWatt Hours of energy will not keep the lights on in Dallas for very long!
>>>
>>>    On Fri, Dec 17, 2021 at 8:22 AM Mark Witte <witte.m@... <mailto:witte.m@...> <mailto:witte.m@...> <mailto:witte.m@...>> wrote:
>>>
>>>        The projected growth of battery storage in ERCOT over the next couple of years is stunning. 
>>>