What is ESS(Energy storage system) and why it is used in microgrid system(ESS +PV)?

[zohaib]

Hello,

I want to know whats the purpose of using ESS system in Pv system and the components involve in this like PCS,Static switch panel and Lib panel what are role in this system.
And what is the purpose of Islanding concepts in this case?

Kindly share your experience in this regard.

Thanx

[inetdog]

The fundamental role of an energy storage system in conjunction with PV is to provide power when the sun is not shining. It is that simple.

If you only need power within a several hour window around solar noon or if you are using PV to supplement other energy sources like hydro or generators, then ESS might be helpful but is not a necessity.

[zohaib]

ESS system

The fundamental role of an energy storage system in conjunction with PV is to provide power when the sun is not shining. It is that simple.

If you only need power within a several hour window around solar noon or if you are using PV to supplement other energy sources like hydro or generators, then ESS might be helpful but is not a necessity.

Thnax for your help. It will be very helpful if you tell me or share any helpful link about the role of components involve in a ESS system and how it work with PV system.

[jflorey2]

I want to know whats the purpose of using ESS system in Pv system and the components involve in this like PCS,Static switch panel and Lib panel what are role in this system.
And what is the purpose of Islanding concepts in this case?

Kindly share your experience in this regard.

ESS is just what it sounds like - energy storage systems. They store energy (which is different than power) for many reasons. In the case of residential solar, it is generally for three reasons:
1) Protection against loss of service during blackouts
2) Grid arbitrage - buying power when it's cheap and selling when it's expensive. This is a common goal for battery storage systems, but it is nearly impossible to break even (much less make any money) doing this.
3) Use reduction. In areas where grid tie is not legal, batteries provide a method to offset more of a user's electric bill than daytime solar alone.

Islanding is what happens when a small system "separates" from the grid and powers itself. This was, for a while, used to identify a dangerous condition where a grid subsection (say, your neighborhood) was powered by someone's poorly-connected generator; this posed a risk to utility workers trying to repair damaged distribution lines, because lines they expected to be unpowered would be powered. Modern grid-tie and hybrid inverters prevent this via anti-islanding algorithms.

The modern usage tends more towards grid segments that are _designed_ to be able to disconnect and run independently if the need arises. In that case, the appropriate switchgear and procedures are in place to minimize risk to utility workers.

[zohaib]

ESS is just what it sounds like - energy storage systems. They store energy (which is different than power) for many reasons. In the case of residential solar, it is generally for three reasons:
1) Protection against loss of service during blackouts
2) Grid arbitrage - buying power when it's cheap and selling when it's expensive. This is a common goal for battery storage systems, but it is nearly impossible to break even (much less make any money) doing this.
3) Use reduction. In areas where grid tie is not legal, batteries provide a method to offset more of a user's electric bill than daytime solar alone.

Islanding is what happens when a small system "separates" from the grid and powers itself. This was, for a while, used to identify a dangerous condition where a grid subsection (say, your neighborhood) was powered by someone's poorly-connected generator; this posed a risk to utility workers trying to repair damaged distribution lines, because lines they expected to be unpowered would be powered. Modern grid-tie and hybrid inverters prevent this via anti-islanding algorithms.

The modern usage tends more towards grid segments that are _designed_ to be able to disconnect and run independently if the need arises. In that case, the appropriate switchgear and procedures are in place to minimize risk to utility workers.

Thanx my friend for your help and explanation.

[zohaib]

Figures Explanation

Hi,


I have gone through some figure related to ESS concept i am sharing these but there is no explanation in this i need your help to explain how these system will work as shown in the diagrams.
Capture 2 figure shows the off grid system and capture 3 figure show the islanding mode.
Wait for your useful suggestions in this regard.

Zohaib

Capture3.JPGCapture2.JPGCapture1.JPGCapture.JPG

[jflorey2]

I have gone through some figure related to ESS concept i am sharing these but there is no explanation in this i need your help to explain how these system will work as shown in the diagrams.
Capture 2 figure shows the off grid system and capture 3 figure show the islanding mode.
Wait for your useful suggestions in this regard.

They show a pretty standard AC-coupled system. (One shows a conventional panels-to-batteries arrangement as well.) What specific suggestions do you want? For small scale systems I'd go with a conventional hybrid system over an AC-coupled systems; AC-coupled systems are still a bit "sporty" to configure and install.

[zohaib]

Figures Details

They show a pretty standard AC-coupled system. (One shows a conventional panels-to-batteries arrangement as well.) What specific suggestions do you want? For small scale systems I'd go with a conventional hybrid system over an AC-coupled systems; AC-coupled systems are still a bit "sporty" to configure and install.

Thanx for the response again. Actually i am not an expert in this area so i want to learn how these system works. It will be very helpful if you can explain what is given in the attached figures and how these system will work.

Wait for your kind response.

[jflorey2]

Thanx for the response again. Actually i am not an expert in this area so i want to learn how these system works. It will be very helpful if you can explain what is given in the attached figures and how these system will work.

OK then. At a very high level there are two kinds of battery based solar power systems.

1) DC coupled. Sun hits the array, panels turn the sunlight into DC power, and the DC power flows to the batteries. (In almost all cases there also needs to be a charge controller between the panels and the battery to prevent the battery from being overcharged, and to optimize the power transfer.) The energy in the batteries is then available for use. Since most people use AC power, an inverter then converts the power to AC for use. Hybrid inverters allow the inverter to supply power to the user _and_ send some power back to the utility. If a hybrid inverter is used it takes care of the sometimes-complex task of deciding when to connect to and disconnect from the grid, and how to safely send power back to the grid.

2) AC coupled. Sun hits the array, panels turn sunlight into DC power, then an inverter turns that power into AC power. In a normal (non AC coupled) system this is then just fed back to the grid. If the grid goes down the inverter shuts down as well. This can be a single large inverter or many small inverters; some systems have one inverter per panel all feeding back to the grid. In an AC coupled system, the inverters send the power to the AC lines, then a separate hybrid inverter has battery backup. When the grid is up, the solar inverters just send power back to the grid, and the battery inverter doesn't get involved at all. When the grid is down, a switch opens (that's the switch in those diagrams of yours) and your grid (often called a "microgrid") is now separated from the utility grid. This gets complicated; since the solar inverters don't know the state of the battery, there needs to be some way to reduce their power output (or stop it) when there is more solar power available than load. This often requires a second switch to disconnect the solar inverters under some conditions. Those two switches - the isolation switch and the solar-inverter disconnect switch - are two reasons that AC-coupled systems are more complex and harder to 'tune' than regular DC coupled systems.

[zohaib]

OK then. At a very high level there are two kinds of battery based solar power systems.

1) DC coupled. Sun hits the array, panels turn the sunlight into DC power, and the DC power flows to the batteries. (In almost all cases there also needs to be a charge controller between the panels and the battery to prevent the battery from being overcharged, and to optimize the power transfer.) The energy in the batteries is then available for use. Since most people use AC power, an inverter then converts the power to AC for use. Hybrid inverters allow the inverter to supply power to the user _and_ send some power back to the utility. If a hybrid inverter is used it takes care of the sometimes-complex task of deciding when to connect to and disconnect from the grid, and how to safely send power back to the grid.

2) AC coupled. Sun hits the array, panels turn sunlight into DC power, then an inverter turns that power into AC power. In a normal (non AC coupled) system this is then just fed back to the grid. If the grid goes down the inverter shuts down as well. This can be a single large inverter or many small inverters; some systems have one inverter per panel all feeding back to the grid. In an AC coupled system, the inverters send the power to the AC lines, then a separate hybrid inverter has battery backup. When the grid is up, the solar inverters just send power back to the grid, and the battery inverter doesn't get involved at all. When the grid is down, a switch opens (that's the switch in those diagrams of yours) and your grid (often called a "microgrid") is now separated from the utility grid. This gets complicated; since the solar inverters don't know the state of the battery, there needs to be some way to reduce their power output (or stop it) when there is more solar power available than load. This often requires a second switch to disconnect the solar inverters under some conditions. Those two switches - the isolation switch and the solar-inverter disconnect switch - are two reasons that AC-coupled systems are more complex and harder to 'tune' than regular DC coupled systems.

Thanx my friend for your detail explanation. One more thing i want to ask is about ESS system. How power is stored in ESS system and role of components involved in it like PCS panel,Lib panel etc. Actually i have searched it on internet but couldn't find any useful information on this topic. It will be very kind of you if you can explain this or share any useful link with me which would be helpful in understanding this topic.
I have shared two figures kindly if you can explain this.
Wait for your response.

[jflorey2]

Thanx my friend for your detail explanation. One more thing i want to ask is about ESS system. How power is stored in ESS system

Almost all ESS systems use batteries to store energy - lead acid, or lithium phosphate, or even nickel-iron or other unusual chemistries.

and role of components involved in it like PCS panel,Lib panel etc.

I don't know what those terms refer to. Often there are two panels in a hybrid system - the utility panel (the regular one that most people have) and the essentials panel (one that is fed by the battery-backed inverter.) That way you can put your big loads (like A/C or pool pumps) on the utility panel, and then just put the essential loads (lights, outlets, furnace fan etc) on the essentials panel. This greatly reduces the size and cost of the system, since the battery backed inverter doesn't need to run the power-hog devices.