Coordination Between DSOs and the National Energy System Operator

Detailed Explanation With Case Laws

1. Introduction

Distribution System Operators (DSOs) manage local electricity distribution networks, while the National Energy System Operator manages the wider electricity system. Effective coordination between them is necessary because electricity networks are interconnected. A decision taken at the distribution level can affect the national electricity system.

In South Africa, this issue has become increasingly important because electricity-sector reform is creating a clearer separation between transmission/system operation and distribution functions. The Electricity Regulation Amendment Act 38 of 2024 provides for a Transmission System Operator (TSO) and assigns system-operation functions to it. The Act commenced on 1 January 2025. (Government of South Africa)

2. Meaning of DSO and National System Operator

A DSO operates and manages a distribution network. Its responsibilities may include:

connecting consumers;

maintaining distribution lines;

managing substations;

handling local congestion;

integrating rooftop solar and batteries;

managing local outages; and

maintaining local network reliability.

The National Energy System Operator has a wider responsibility. Under the 2024 amendments, the system operator must operate the integrated power system in a safe, secure, efficient and sustainable manner, undertake forecasting and dispatch scheduling, and plan for development and strengthening of the national transmission system. (Government of South Africa)

Therefore, coordination means that DSOs and the national operator must work together while retaining their respective responsibilities.

3. Exchange of Information

One of the most important parts of coordination is information sharing.

DSOs should provide the national operator with information about:

electricity demand;

available distribution capacity;

outages;

network constraints;

embedded generation;

battery storage;

electric vehicles; and

planned maintenance.

The national operator can provide information about national supply conditions, transmission constraints, expected generation and system requirements.

This information allows both levels to make decisions based on the same understanding of the electricity system.

4. Coordination of Distributed Energy Resources

Modern electricity systems contain many small energy resources such as rooftop solar, batteries, flexible loads and electric vehicles.

A DSO may have thousands of small generators connected to its network. Individually they may appear small, but together they can significantly affect national electricity flows.

For example, if large amounts of rooftop solar suddenly reduce local demand, electricity may flow back towards higher-voltage networks. The DSO therefore needs to communicate relevant information to the national system operator.

Coordination is especially important for forecasting, voltage management, congestion management and balancing.

5. Emergency and Outage Coordination

During major electricity failures, responsibilities must be clearly divided.

The DSO normally manages local network faults, while the national operator manages wider system conditions. During a major emergency, the national operator may need information from DSOs to determine the effect of local outages on the wider grid.

Similarly, restoration must be coordinated so that local networks are reconnected safely and do not create instability in the national system.

6. Legal Framework in South Africa

The Electricity Regulation Act 4 of 2006 establishes the national regulatory framework for generation, transmission, distribution and trading and makes NERSA the custodian and enforcer of that framework. (Government of South Africa)

The Electricity Regulation Amendment Act 38 of 2024 is particularly important because it provides for the establishment of the Transmission System Operator and gives the system operator functions including system operation, forecasting and dispatch scheduling. (Government of South Africa)

The Constitution also supports cooperation between different governmental institutions. Section 40 recognises national, provincial and local spheres as distinctive, interdependent and interrelated, while section 41 requires cooperative government.

7. Important Case Laws

City of Cape Town v NERSA (2020)

This case is highly relevant to institutional coordination. The dispute concerned the City's proposed procurement of electricity from independent power producers and the powers of the Minister and NERSA.

The court emphasised the importance of cooperation between organs of state and held that the parties had duties relating to cooperative government. (SAFLII)

The case is therefore useful for understanding how municipal electricity functions must interact with the national regulatory framework.

Eskom Holdings SOC Ltd v Lekwa Ratepayers Association; Eskom v Vaal River Development Association (2022)

The Supreme Court of Appeal discussed the regulatory structure governing electricity generation, transmission and distribution and confirmed NERSA's statutory regulatory role. (SAFLII)

The case demonstrates why clearly defined institutional responsibilities are important in electricity governance.

Pharmaceutical Manufacturers Association v President (2000)

The Constitutional Court established that public power must have a lawful basis and satisfy rationality. This principle applies to decisions made by electricity authorities and operators when exercising statutory powers.

Bato Star Fishing v Minister of Environmental Affairs (2004)

The case provides important principles concerning administrative review and specialised decision-making. Electricity operators may use technical expertise, but their decisions must remain within legal limits.

Joseph v City of Johannesburg (2010)

The case concerned electricity disconnection and procedural fairness. Although it was not directly about DSO-system-operator coordination, it is relevant by analogy because electricity-network decisions can directly affect consumers and must respect applicable public-law requirements.

8. Main Coordination Challenges

Several difficulties can arise:

Different operational priorities – DSOs focus on local reliability while the national operator focuses on system-wide stability.

Data problems – incomplete or delayed network information can affect forecasting.

Distributed generation – rooftop solar makes electricity flows less predictable.

Cybersecurity – greater digital coordination creates additional security risks.

Cost allocation – institutions may disagree about who should pay for network upgrades.

Legal uncertainty – unclear responsibilities can create disputes between institutions.

9. Conclusion

Coordination between DSOs and the National Energy System Operator is essential for a reliable modern electricity system. DSOs manage local networks, while the national system operator protects the stability and security of the wider electricity system.

Effective coordination requires clear legal responsibilities, real-time information sharing, common technical standards, coordinated emergency procedures, data protection and regulatory oversight.

South Africa's 2024 electricity reforms strengthen the legal basis for national system operation, while cases such as City of Cape Town v NERSA, Eskom v Lekwa Ratepayers Association, Pharmaceutical Manufacturers, Bato Star and Joseph provide useful principles concerning institutional cooperation, regulatory authority, legality, administrative fairness and consumer protection.