Power System Flexibility in the Energy Transition

Power system flexibility is becoming increasingly important as electricity systems undergo rapid structural change.

Traditional power systems were largely based on controllable generation from centralised power plants. Electricity demand followed relatively predictable patterns, while system operators adjusted generation to maintain the balance between supply and demand.

The transition towards renewable energy changes this operating environment.

Solar and wind generation are variable and depend on weather conditions. At the same time, electricity demand is becoming more dynamic as transport, heating, cooling and industrial processes become increasingly electrified.

The growth of distributed energy resources also increases the number of assets connected to electricity networks. These resources can include:

rooftop solar PV;
battery storage;
electric vehicles;
flexible industrial loads;
heat pumps;
distributed generation;
demand-response resources.

As a result, flexibility is no longer provided only by conventional power plants.

Modern electricity systems can obtain flexibility from a combination of generation, storage, networks and electricity demand.

The International Renewable Energy Agency (IRENA) identifies flexibility as an essential component of a secure and affordable power-sector transformation. Flexibility allows electricity systems to respond to variations in demand and renewable-energy generation while maintaining reliable system operation.

Flexibility Across Different Timescales

Flexibility requirements do not occur over a single period of time.

Some changes in electricity supply and demand occur within hours, while others can persist for several days, weeks or months.

IRENA's 2026 analysis distinguishes between three broad timescales of power system flexibility:

daily flexibility;
weekly flexibility;
monthly flexibility.

Different flexibility resources are better suited to different timescales.

Understanding these differences is important because a technology that performs well for short-duration balancing may not provide an economical solution for longer periods of low renewable-energy availability.

Daily Flexibility

Daily flexibility refers to variations in electricity supply and demand that occur within a typical day.

Examples include:

increases in electricity demand during morning and evening periods;
reductions in solar generation after sunset;
changes in wind generation;
daily variations in industrial and commercial electricity use.

The growing deployment of solar PV can create particularly significant daily flexibility requirements.

Solar generation often reaches its highest output during the middle of the day and declines rapidly in the evening, while electricity demand may increase as solar generation falls.

This creates a need for resources that can respond over relatively short periods.

Resources that can contribute to daily flexibility include:

battery storage;
pumped-storage hydropower;
demand response;
flexible hydropower;
flexible thermal generation;
electric vehicles;
smart charging;
interconnections.

Battery storage is particularly well suited to many daily flexibility requirements because it can store electricity during periods of high generation and release it during periods of higher demand.

Weekly Flexibility

Weekly flexibility refers to variations that persist over several days.

These can result from:

prolonged periods of low wind generation;
changes in weather patterns;
differences between weekdays and weekends;
sustained changes in electricity demand.

Short-duration batteries may provide some contribution, but longer periods of imbalance can require other flexibility resources.

Potential sources of weekly flexibility include:

larger energy-storage systems;
hydropower;
interconnections between electricity systems;
flexible generation;
demand-side management;
long-duration energy storage.

The importance of weekly flexibility depends on local weather conditions, electricity demand patterns and the composition of the renewable-energy mix.

Monthly Flexibility

Monthly flexibility addresses longer-lasting variations in electricity supply and demand.

These can include:

seasonal changes in solar generation;
seasonal changes in wind resources;
prolonged weather patterns;
variations in heating and cooling demand;
hydrological changes affecting hydropower production.

These longer-duration requirements can be more difficult to address using technologies designed primarily for short-duration balancing.

Potential solutions include:

long-duration energy storage;
seasonal storage;
large hydropower reservoirs;
strong interconnections between regions;
flexible low-carbon generation;
long-term demand management.

The appropriate combination depends on the characteristics of the electricity system.

A system with significant geographical diversity in renewable resources may reduce some longer-duration flexibility requirements through interconnection, while isolated systems may require greater reliance on storage or local flexible resources.

Growing Flexibility Needs

IRENA's 2026 analysis shows that flexibility requirements are expected to increase significantly as electricity demand grows and the share of solar and wind generation expands.

Under IRENA's 1.5°C Scenario, global daily flexibility needs in 2030 are estimated to be around three times higher than their 2019 level.

By 2050, daily flexibility needs could reach approximately ten times their 2019 level.

The growth in flexibility requirements is influenced by several factors:

increasing electricity demand;
greater deployment of solar PV;
greater deployment of wind power;
electrification of transport and heating;
changes in electricity-demand patterns;
the location and diversity of renewable-energy resources;
the availability of grid infrastructure.

However, higher renewable-energy capacity does not automatically mean that flexibility needs increase at the same rate everywhere.

The amount and type of flexibility required depends on the characteristics of the electricity system.

For example, a diverse mix of wind and solar resources can reduce variability compared with a system that relies heavily on a single renewable-energy technology.

Geographical diversity can also reduce aggregate variability when electricity systems are interconnected.

The Importance of a Portfolio Approach

No single technology can economically provide all forms of power system flexibility.

Batteries can be highly effective for short-duration balancing but may become increasingly expensive when required to provide energy over very long periods.

Interconnectors can allow regions to share electricity resources, but their value depends on differences in generation and demand between connected systems.

Demand-side management can reduce or shift electricity consumption, but the available flexibility depends on consumer behaviour, technology and market incentives.

Long-duration energy storage can address longer periods of imbalance but may require further technological development and investment.

For this reason, IRENA's analysis highlights the importance of combining different flexibility resources.

A flexible electricity system may therefore include:

battery storage;
pumped-storage hydropower;
flexible renewable generation;
demand-side management;
smart charging of electric vehicles;
transmission expansion;
regional interconnections;
long-duration energy storage;
other flexible generation resources.

The objective is not to identify a single technology that can provide all flexibility requirements, but to develop a combination of resources that can respond effectively across different timescales.

The Role of Electricity Networks

Electricity networks are themselves an important source of system flexibility.

Transmission expansion and stronger interconnections can allow electricity to move between regions with different demand patterns and renewable-energy conditions.

For example, low wind generation in one region may coincide with stronger wind conditions in another.

Similarly, solar generation and electricity demand can vary across geographically dispersed areas.

Interconnection can therefore reduce the need for every individual electricity system to maintain sufficient local flexibility for all possible conditions.

However, grid infrastructure requires long-term planning and investment.

The development of renewable generation, storage and transmission should therefore be considered together.

Planning these resources separately can result in unnecessary costs or insufficient infrastructure.

Key Flexibility Resources in Modern Power Systems

As flexibility needs increase, electricity systems are likely to rely on a combination of technologies and operational strategies.

IRENA's 2026 analysis highlights the complementary roles of battery storage, electricity interconnections, demand-side flexibility and long-duration energy storage.

Each resource has different technical characteristics and is therefore better suited to particular flexibility requirements.

Battery Energy Storage

Battery energy storage has become one of the most rapidly deployed sources of power system flexibility.

Batteries can respond quickly to changes in electricity supply and demand. They can charge when electricity generation exceeds demand and discharge when additional electricity is required.

This makes battery storage particularly useful for short-duration and daily flexibility.

Common applications include:

shifting solar electricity from daytime to evening periods;
providing frequency regulation;
reducing peak electricity demand;
supporting electricity-network operation;
reducing renewable-energy curtailment;
providing reserve capacity;
improving the reliability of isolated and weak-grid systems.

The rapid growth of solar PV has increased the importance of battery storage in many electricity systems.

During periods of high solar generation, batteries can absorb excess electricity. As solar output declines, stored electricity can be released to help meet demand.

However, batteries are not automatically the lowest-cost solution for all flexibility requirements.

As the required storage duration increases, larger battery systems are needed to store sufficient energy. This can increase investment costs.

Battery storage is therefore generally most suitable for short-duration flexibility, although technological improvements and changing costs may expand its role over time.

Interconnections and Regional Power Trade

Interconnections allow electricity to be exchanged between different regions or countries.

This can provide flexibility by allowing systems with different electricity-demand patterns and renewable-energy resources to support each other.

For example:

one region may have strong wind resources while another has low wind generation;
solar generation may peak at different times across geographically dispersed areas;
electricity demand may differ because of climate, industry or time zones;
hydropower resources may complement solar and wind generation.

Stronger interconnections can therefore reduce the amount of flexibility that each individual system needs to provide independently.

Regional electricity trade can also improve the utilisation of renewable resources.

However, the benefits of interconnection depend on sufficient transmission capacity, compatible technical standards, coordinated system operation and appropriate electricity-market arrangements.

Cross-border electricity trading can also require political cooperation and long-term institutional arrangements.

For developing regions, regional power pools and interconnections can provide an important opportunity to share generation resources and improve electricity-system reliability.

Demand-Side Flexibility

Flexibility can also be provided by changing the timing or level of electricity consumption.

This is commonly referred to as demand-side flexibility.

Instead of responding to a change in electricity demand by increasing electricity generation, system operators or consumers can reduce, increase or shift electricity use.

Examples include:

shifting industrial processes to periods of high renewable generation;
delaying electric-vehicle charging;
adjusting heating or cooling systems;
controlling water pumping;
managing refrigeration loads;
temporarily reducing non-critical electricity consumption.

Digital technologies, smart meters and automated energy-management systems can make demand-side flexibility easier to implement.

Consumers may respond to:

electricity prices;
financial incentives;
automated control signals;
demand-response programmes.

Demand-side flexibility can reduce peak demand and help electricity systems absorb higher levels of renewable generation.

However, not all electricity demand can be shifted.

The available flexibility depends on the type of consumer, the technology being used, operational requirements and the willingness of consumers to participate.

Appropriate market incentives and regulatory frameworks are therefore important.

Long-Duration Energy Storage

Long-duration energy storage can provide electricity-system flexibility over periods longer than those typically served by short-duration batteries.

Potential technologies include:

pumped-storage hydropower;
flow batteries;
compressed-air energy storage;
thermal energy storage;
hydrogen-based storage;
other emerging storage technologies.

Long-duration storage may become increasingly important as electricity systems rely on larger shares of solar and wind power.

Periods of low renewable generation can sometimes persist for several days or longer.

Addressing these events may require storage technologies capable of retaining and delivering energy over longer periods.

The most appropriate technology depends on local geography, resource availability, infrastructure and electricity-system requirements.

Pumped-storage hydropower, for example, requires suitable geographical conditions. Hydrogen-based storage may provide very long-duration storage but requires additional infrastructure and involves energy losses during conversion and reconversion.

Long-duration storage technologies are therefore likely to play complementary roles alongside batteries and other flexibility resources rather than replacing them entirely.

Combining Flexibility Resources

Different flexibility resources can complement one another.

A battery may respond rapidly to short-term changes in electricity supply and demand, while an interconnector may provide access to electricity from another region.

Demand-side flexibility can reduce the amount of additional generation required, while long-duration storage can contribute during prolonged periods of low renewable generation.

A modern flexibility strategy should therefore consider how resources interact.

For example, an electricity system may use:

batteries for intraday balancing;
demand response for peak reduction;
interconnections for regional balancing;
hydropower for dispatchable flexibility;
long-duration storage for extended periods of low renewable generation.

The optimal combination will vary between electricity systems.

Important factors include:

renewable-energy resources;
electricity-demand patterns;
existing generation capacity;
grid infrastructure;
geographical conditions;
financing costs;
fuel availability;
regulatory frameworks.

Flexibility and Grid Expansion

Flexibility resources and electricity networks should not be treated as completely separate investment decisions.

Grid expansion can provide flexibility by allowing electricity to move between regions.

At the same time, local storage and demand-side flexibility can reduce congestion and defer some network investments.

The appropriate balance between grid expansion and other flexibility resources depends on the characteristics of the electricity system.

For example, building additional transmission may provide long-term benefits by connecting regions with complementary renewable resources.

In other cases, strategically located battery storage or demand-side flexibility may provide a faster or more cost-effective solution to local network constraints.

Power-system planning should therefore evaluate transmission, storage, generation and demand-side resources together.

Flexibility and Renewable Energy Curtailment

Renewable-energy curtailment occurs when available renewable electricity cannot be used or delivered to consumers.

Curtailment can result from:

insufficient grid capacity;
low electricity demand;
system-security requirements;
limited storage capacity;
transmission congestion.

Flexibility resources can reduce curtailment by creating additional options for using renewable electricity.

For example:

batteries can store electricity for later use;
flexible demand can increase consumption during periods of high renewable generation;
interconnectors can export electricity to other regions;
smart charging can align electricity consumption with renewable availability.

However, eliminating all curtailment may not always be economically efficient.

In some cases, building additional storage or transmission capacity to avoid a relatively small amount of curtailment may cost more than accepting limited renewable-energy losses.

The objective of flexibility planning should therefore be to optimise the overall electricity system rather than to eliminate curtailment under all circumstances.

Planning Flexibility as a System

Power-system flexibility should be considered during long-term electricity planning.

The deployment of solar, wind, storage, transmission and flexible demand affects the flexibility requirements of the system as a whole.

Planning one resource independently can lead to unnecessary investment or missed opportunities for coordination.

Integrated planning can consider:

expected electricity-demand growth;
future renewable-energy capacity;
hourly and seasonal generation patterns;
existing and planned grid infrastructure;
storage requirements;
regional interconnection;
flexible electricity demand;
reliability requirements;
technology costs.

This approach can help identify combinations of resources that provide reliable electricity at lower overall system cost.

Flexibility in Developing Countries

Power system flexibility is relevant to developing countries as electricity systems expand and incorporate increasing amounts of renewable energy.

Many developing electricity systems face a combination of growing electricity demand, limited generation capacity, constrained transmission networks and difficulties accessing affordable finance.

Flexibility planning can help these systems make better use of existing and new infrastructure.

Potential flexibility resources include:

battery storage;
hydropower;
demand-side management;
mini-grid energy management;
distributed solar PV;
interconnections;
flexible electricity generation;
long-duration storage.

The appropriate combination depends on the characteristics of each electricity system.

In some systems, strengthening transmission and regional interconnections may provide substantial flexibility. In others, distributed batteries, demand-side management or improved operation of existing hydropower resources may be more appropriate.

Flexibility should therefore be assessed as part of broader electricity-system planning rather than treated as a separate technology category.

Flexibility in Africa

African electricity systems have significant opportunities to benefit from increased flexibility.

The continent has substantial solar, wind and hydropower resources, but these resources are distributed unevenly across countries and regions.

Greater regional interconnection could allow countries to share electricity generated from complementary resources.

For example, hydropower resources can provide flexibility to systems with high shares of solar and wind generation, while strong solar resources can complement hydropower during periods of lower water availability.

Potential flexibility measures in Africa include:

regional power-pool development;
transmission interconnection;
battery energy storage;
pumped-storage hydropower;
demand-side management;
digital energy-management systems;
flexible operation of existing generation;
renewable-energy forecasting;
distributed energy resources;
mini-grid storage.

The development of flexibility resources should be considered alongside efforts to increase electricity access.

For isolated communities, battery storage and intelligent energy management can improve the reliability and utilisation of renewable-energy-based mini-grids.

For larger electricity systems, transmission expansion, regional electricity trade and utility-scale storage may provide greater system-level benefits.

Policy and Market Considerations

Investment in flexibility requires appropriate policy and market conditions.

Electricity markets traditionally reward the production and sale of electricity but may not adequately compensate resources that provide flexibility, capacity or other system services.

Market design can therefore influence whether flexibility resources are developed.

Potential mechanisms include:

time-of-use electricity tariffs;
demand-response programmes;
ancillary-service markets;
capacity mechanisms;
competitive procurement;
storage incentives;
flexibility markets;
long-term power purchase agreements;
regional electricity-trading arrangements.

Regulatory frameworks should also enable distributed resources such as batteries, electric vehicles and flexible consumers to participate where technically appropriate.

Challenges to Flexibility Deployment

Several barriers can limit the deployment of flexibility resources.

Investment Costs

Flexibility technologies can require significant upfront investment.

This is particularly relevant for storage and transmission infrastructure, which may have long development periods and require substantial capital.

Access to affordable finance can therefore strongly influence the feasibility of flexibility projects.

Regulatory Barriers

Existing electricity regulations may not have been designed for batteries, aggregators, demand response or distributed energy resources.

Clear rules are needed to define how these resources can connect to the grid, participate in electricity markets and provide system services.

Institutional Capacity

Effective flexibility planning requires technical capabilities in areas such as:

power-system modelling;
electricity-market design;
renewable-energy forecasting;
storage planning;
demand-side management;
grid operation;
data analysis.

Capacity building is therefore an important component of long-term flexibility development.

Data and Planning Limitations

Flexibility planning requires detailed information about electricity demand, generation, transmission constraints and renewable-resource variability.

Where data is incomplete or unreliable, it can be difficult to estimate the amount and type of flexibility required.

Improving data collection and power-system modelling can therefore support better investment decisions.

Technology-Specific Limitations

Every flexibility resource has technical and economic limitations.

Batteries have finite energy-storage duration and experience degradation.

Interconnectors require transmission investment and coordination between connected systems.

Demand response depends on the availability and willingness of flexible consumers.

Long-duration storage technologies may have higher costs or limited commercial deployment in some markets.

Flexibility planning should therefore avoid dependence on a single technology.

Flexibility and Energy Security

Flexibility can contribute to energy security by improving the ability of electricity systems to respond to unexpected changes in supply and demand.

A system with diverse flexibility resources can be better positioned to respond to:

sudden generator outages;
changes in renewable-energy output;
transmission constraints;
demand spikes;
fuel-supply disruptions;
extreme weather events.

Diversifying flexibility resources can also reduce dependence on a single source of backup generation.

In systems with high renewable-energy penetration, flexibility can therefore support both decarbonisation and electricity-system resilience.

Future Outlook

The importance of power-system flexibility is expected to increase as electricity demand grows and renewable-energy deployment accelerates.

The transition is likely to involve a broader portfolio of flexibility resources rather than a single dominant technology.

Short-duration battery storage is expected to remain important for daily balancing, while longer-duration storage, demand-side management, hydropower and interconnections can provide flexibility over longer periods.

Digitalisation will also increasingly connect flexibility resources.

Smart meters, automated controls, artificial intelligence, energy-management systems and distributed-energy-resource management platforms can allow large numbers of small resources to operate collectively.

This could transform electricity consumers from passive users into active participants capable of providing flexibility to the power system.

Regional electricity integration may also become increasingly important, particularly in regions where renewable resources and electricity demand vary substantially between countries.

Conclusion

Power system flexibility is becoming a central requirement for the transition towards secure, affordable and renewable electricity systems.

As the share of solar and wind generation increases, electricity systems need greater ability to respond to variations in renewable generation and electricity demand.

Flexibility is required across multiple timescales. Daily variations can often be addressed through batteries, demand response and flexible generation, while weekly and monthly variations may require longer-duration storage, hydropower, interconnections and other system-level solutions.

No single technology can provide all flexibility requirements economically.

A resilient electricity system therefore needs a portfolio of complementary resources, supported by appropriate grid infrastructure, market mechanisms, digital technologies and institutional capacity.

IRENA's 2026 analysis indicates that global flexibility requirements will increase substantially as electricity systems transform. This makes flexibility planning an increasingly important component of long-term power-system development.

For developing countries and African electricity systems, flexibility can support both renewable-energy integration and improved electricity-system reliability. Regional interconnection, storage, demand-side management and improved operation of existing infrastructure can all contribute.

Ultimately, flexibility should not be considered as an additional technology that is deployed after renewable generation has been planned. It should be incorporated into electricity-system planning from the beginning, with generation, networks, storage and demand considered as interconnected components of a single system.

External Links

References

International Renewable Energy Agency (IRENA) (2026). Flexibility for a Secure and Affordable Power Sector Transformation. Abu Dhabi: IRENA.

Attribution

This article has been substantially expanded and updated using information from the International Renewable Energy Agency (IRENA) publication Flexibility for a Secure and Affordable Power Sector Transformation (2026).

The original Energypedia article provides the foundation for the discussion of power-system flexibility and its principal flexibility resources. The additional material introduces recent analysis of flexibility requirements across daily, weekly and monthly timescales and the changing role of storage, interconnections and demand-side flexibility.

Readers should consult the original IRENA publication for its complete methodology, scenarios, assumptions and detailed analysis.

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