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How Battery Energy Storage Systems Support Renewable Energy Integration
Solar and wind power can produce electricity without burning fuel, but their output changes with weather conditions and time of day. Solar generation falls when sunlight decreases, while wind generation can vary as wind conditions change. Electricity demand, meanwhile, does not always follow the same pattern.
A battery energy storage system (BESS) can help manage this mismatch by storing electricity when renewable generation exceeds immediate demand and releasing it when generation falls or demand increases. This allows renewable electricity to be used at a different time from when it was generated.
By combining renewable generation with battery storage, energy systems can gain greater flexibility in how they use available electricity. BESS can also help manage renewable energy curtailment and support grid operations where additional flexibility is needed.
Why Does Renewable Energy Need Energy Storage?
Solar and wind generation do not always produce electricity when people need it. Solar power typically reaches its highest output during daylight hours, while electricity demand can remain high after the sun sets. Wind generation can also rise and fall as weather conditions change.
This difference between when renewable electricity is generated and when it is needed can create challenges for energy systems. When renewable generation exceeds immediate demand or available grid capacity, operators may need to reduce some of that generation.
Energy storage provides a way to manage this mismatch. A battery energy storage system can absorb surplus electricity and store it for later use. When renewable output falls or demand increases, the BESS can discharge the stored energy.
Storage therefore adds flexibility to renewable energy systems. It does not make solar or wind generation constant, but it can help shift available electricity to a more useful time and support a better balance between generation and demand.
How Does a BESS Support Renewable Energy Integration?
A BESS can store electricity from renewable sources when generation exceeds immediate demand and release that energy when renewable output falls or demand increases. This allows the system to shift some renewable electricity from one period to another rather than using it only when it is generated.
The process typically follows four stages:
Renewable generation: Solar panels or wind turbines produce electricity.
Battery charging: When generation exceeds immediate demand, the BESS can direct surplus electricity into the battery.
Energy storage: The battery holds the stored energy until the system needs it.
Battery discharge: The BESS releases stored electricity to the site or grid when renewable generation is lower or demand increases.
An Energy Management System (EMS) can coordinate these energy flows based on factors such as renewable generation, electricity demand, battery state of charge, and grid conditions. The Battery Management System (BMS) monitors the battery and manages its operating conditions.
For projects that use batteries specifically to store and shift renewable generation, Renewable Energy Storage can form an important part of the overall system design.
The amount of renewable energy a BESS can store and later deliver depends on its energy capacity, power rating, storage duration, efficiency, and operating limits.
How Does Battery Storage Work With Solar Power?
Solar generation changes throughout the day, which can make it difficult to match solar output with electricity demand at every moment. A BESS can store part of the solar electricity produced during periods of high generation and make that energy available later.
For example, a solar system may produce more electricity around midday than a business needs at that time. Instead of using only the electricity immediately, the BESS can charge with some of the surplus. Later, when solar generation decreases, the battery can discharge stored energy to help meet the site's electricity demand.
T
his creates a simple cycle:
Solar generation → surplus electricity → battery charging → stored energy → battery discharge → electricity demand
The amount of solar energy a BESS can shift depends on the system's energy capacity, power rating, storage duration, and operating strategy. A properly sized system can therefore help a site make greater use of its available solar generation without requiring the battery to supply every electrical load at all times.
How Does Battery Storage Support Wind Power?
Wind generation can change as wind conditions change, making its output less predictable than a constant power source. A BESS can help manage these changes by storing electricity when wind generation is available and releasing stored energy when output falls.
For example, when wind turbines produce more electricity than the site or grid can immediately use, the BESS can charge with some of the surplus. When wind generation decreases, the battery can discharge to provide additional electricity, subject to its available capacity and power rating.
The BESS can therefore help shift some wind-generated electricity to a different period and give the energy system more flexibility in managing variable generation.
How much support the battery can provide depends on factors such as the wind generation profile, battery energy capacity, power rating, storage duration, and operating strategy. A system designed for short periods of fluctuation will have different requirements from one intended to shift large amounts of wind energy over several hours.
How Can BESS Reduce Renewable Energy Curtailment?
Renewable energy curtailment occurs when a solar or wind project has electricity available but cannot use or export all of it. This can happen when local electricity demand is low, the grid has limited capacity, or generation exceeds what the system can accommodate at that time.
A BESS can provide another destination for some of this surplus electricity. Instead of immediately reducing renewable generation, the system can charge the battery when suitable capacity is available and store the energy for later use.
For example, a solar farm may produce more electricity than the grid can accept during a period of strong sunlight. A BESS can absorb part of that excess generation and discharge the stored energy later when grid conditions or electricity demand are more favourable.
However, battery storage cannot eliminate curtailment in every situation. Its ability to reduce curtailment depends on factors such as the battery's available capacity, power rating, state of charge, storage duration, grid connection, and the length of the constraint.
This makes BESS one tool for managing surplus renewable generation, rather than a complete solution to every grid constraint.
How Does BESS Shift Renewable Energy to When It Is Needed?
A BESS can change when renewable electricity is available for use. Instead of using all the electricity generated by solar or wind immediately, the system can store part of the surplus and release it during a later period when renewable generation is lower or electricity demand is higher.
For example, a solar installation may produce significant surplus electricity during the middle of the day, while demand increases in the late afternoon or evening. The BESS can charge during the period of high solar generation and discharge later, shifting some of that renewable energy to a more useful time.
This process is known as energy shifting. The amount of energy a battery can shift depends on its available energy capacity, power rating, storage duration, and operating limits.
Where electricity prices vary throughout the day, the same charging and discharging strategy can also support battery energy arbitrage, although the financial value depends on the applicable electricity prices, tariffs, system efficiency, and operating costs.
How Does BESS Support Grid Flexibility?
As renewable generation increases, electricity systems need to respond to changes in both generation and demand. A BESS can provide flexibility by changing its power output quickly, charging when electricity is available and discharging when additional power is needed.
For example, a battery can respond to short-term changes in electricity supply and demand by increasing or reducing its output. Depending on its configuration and connection to the grid, a BESS can also provide services such as frequency regulation, which helps maintain the balance between electricity generation and consumption.
Battery storage can also work alongside renewable generation to help manage periods when solar or wind output changes. Instead of relying only on renewable generation at the moment it is produced, the system can use stored energy when conditions change.
The level of grid support a BESS can provide depends on its power rating, available energy, response capability, control system, grid connection, and operating strategy. Not every BESS is configured to provide every type of grid service.
What Determines the Right BESS for Renewable Energy Integration?
The right BESS depends on how much renewable electricity the system needs to store, when that energy is available, and when the site or grid needs it. A battery designed for short periods of power support will have different requirements from one intended to shift renewable electricity over several hours.
Key factors include:
Renewable generation profile: The timing and variability of solar or wind generation determine when the BESS can charge and discharge.
Energy capacity: This determines how much renewable electricity the battery can store.
Power rating: This determines how quickly the BESS can absorb or deliver electricity.
Storage duration: Longer-duration applications require enough usable energy capacity to discharge for the required period.
Cycling requirements: Frequent charging and discharging can affect the way the system should be designed and operated.
Site demand: The site's electricity consumption helps determine when stored renewable energy will be most useful.
Grid connection: Available grid capacity and connection limits can influence the required battery size and operating strategy.
Operating strategy: The system may prioritise renewable self-consumption, energy shifting, curtailment reduction, or grid services.
These factors need to work together. A larger battery is not automatically a better battery for renewable integration; the system should match the renewable generation profile and the application's actual requirements.
What Are the Benefits of Combining BESS With Renewable Energy?
Combining battery storage with renewable generation gives an energy system more control over when electricity is used. Instead of relying on solar or wind generation only when it is available, the system can store some of that electricity and use it later.
Key benefits include:
Better use of renewable generation: A BESS can store surplus solar or wind electricity instead of requiring all generation to be used immediately.
Greater flexibility: Stored energy can be released when renewable output falls or electricity demand increases.
Reduced renewable curtailment: Where grid or demand constraints cause renewable generation to be curtailed, a battery can absorb some of the available surplus when it has sufficient capacity.
Improved matching of supply and demand: Energy storage can shift renewable electricity from periods of higher generation to periods when electricity is needed.
Grid support: Appropriately configured BESS can provide services such as frequency regulation and help electricity systems respond to changes in supply and demand.
The benefits depend on the renewable resource, battery configuration, site demand, grid conditions, and operating strategy. A BESS should therefore be designed around the specific requirements of the renewable energy project rather than treated as a one-size-fits-all solution.
Conclusion
Battery Energy Storage Systems can play an important role in integrating solar and wind power by giving energy systems greater control over when renewable electricity is stored and used. A BESS can absorb surplus generation, shift stored energy to periods of higher demand, reduce some renewable energy curtailment, and provide flexibility to the grid.
However, battery storage does not solve every challenge associated with variable renewable generation. Its effectiveness depends on the renewable generation profile, energy capacity, power rating, storage duration, grid conditions, and operating strategy.
For each project, the BESS should be sized and configured around the specific relationship between renewable generation, electricity demand, and the requirements of the connected energy system.
Frequently Asked Questions About BESS and Renewable Energy Integration
Can a BESS store excess solar energy?
Yes. A BESS can store surplus solar electricity when generation exceeds immediate demand and discharge the stored energy later when solar output decreases or demand increases. The amount of energy it can store depends on the system's energy capacity and operating limits.
How does battery storage help integrate wind power?
A BESS can store electricity when wind generation is high and release it when wind output falls. This can help manage variations in wind generation and provide greater flexibility between renewable supply and electricity demand.
Can BESS reduce renewable energy curtailment?
A BESS can reduce some renewable energy curtailment by storing surplus electricity that cannot be immediately used or exported. However, its effectiveness depends on factors such as available battery capacity, power rating, storage duration, state of charge, and grid constraints.
How long can a BESS store renewable energy?
The storage duration depends on the relationship between the battery's energy capacity and its power output. For example, a system with 4 MWh of usable energy capacity delivering 1 MW could theoretically provide that output for four hours. Actual performance depends on operating conditions and system limits.
Is battery storage necessary for renewable energy integration?
No. Renewable energy can operate without battery storage, but BESS can provide additional flexibility where renewable generation does not match electricity demand or where the grid needs support. The value of storage depends on the generation profile, load, grid conditions, and project objectives.
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