For Ir. Shanmugam Thoppalan, Head of Grid System Operator at Tenaga Nasional Berhad, Malaysia’s renewable-energy transition is not only about how much capacity is installed. The more important question is whether that capacity can deliver dependable energy when the system needs it most. In this edition of In-Between the Lines, he explains why Malaysia’s power-sector transition must be measured not just in megawatts, but in reliability, flexibility, grid readiness and real energy delivered to consumers.  

From Installed Capacity to Dependable Energy 

Renewable capacity is one of the clearest ways to express energy-transition ambition. It is measurable, visible and useful for setting direction. Clear renewable targets have been established to guide the transformation of the national power system. 

Installed megawatts are the starting point of this transition. The planning approach also considers how many megawatt-hours will be available when demand requires them, how much dependable capacity each resource contributes during critical periods, and whether the network can transport the output from the point of generation to the point of consumption. 

As renewable penetration increases, system planning distinguishes between installed capacity, energy contribution, and firm or dependable capacity. This ensures that renewable capacity delivers usable energy, displaces higher-emission generation in actual system dispatch, and is integrated within the grid's physical and operational limits. 

The ambition is therefore supported not only by the capacity announced or installed, but by a clear focus on dependable energy delivered to consumers. 

The System Must Meet Demand Every Second 

Decarbonisation is achieved through the energy that is actually generated and supplied. The transition framework accordingly links renewable-capacity growth to energy delivery, system readiness and operational performance. 

Solar capacity can be scaled rapidly, and the planning framework appropriately recognises that its output is concentrated during daylight hours and varies with weather conditions. The system is therefore being developed with the dependable resources, flexibility and reserves required to complement solar generation during evening peaks, periods of lower solar output and system contingencies. 

Malaysia is developing solutions suited to the distinctive characteristics of its own power system as it moves towards a very high renewable-energy mix. The country's renewable profile is expected to remain predominantly solar-centric, with a relatively short period of high output, a brief midday peak, and many hours characterised by continuous ramping up and down. These variations are further influenced by Malaysia's tropical climate, where cloud cover and weather conditions can change rapidly across different locations. Malaysia's approach therefore combines storage, flexible generation, demand response, network reinforcement, improved forecasting and grid-support technologies to meet its particular operating requirements, rather than simply replicating solutions adopted elsewhere. 

The role of thermal generation will evolve as more renewables enter the system. The balanced transition retains sufficient dependable capacity, operating reserves, flexibility and essential system services to balance supply and demand continuously and maintain system strength throughout this evolution. 

Progress can therefore be assessed through the timing of energy delivery, its predictability and controllability, and the effectiveness of the balancing resources supporting it. 

This gives renewable-capacity growth clear operational value and ensures that each stage of the transition strengthens the overall power system. 

Storage Is an Enabler, Not an Energy Source 

Battery energy storage is a key enabler in the transition because it can shift solar energy beyond its immediate production period, manage rapid ramps, provide fast response and improve the utilisation of a shared grid connection. 

Advances in solar, battery and power-electronic technologies also allow these assets to be configured to provide system-strength and grid-support functions that enhance overall resilience. 

The planning framework recognises that storage shifts and manages energy rather than creating it. Its contribution is therefore evaluated according to its charging source, power rating, discharge duration, efficiency and available state of charge. 

Its system value is maximised through appropriate sizing, location and operation, supported by the visibility and controllability required by the grid operator under both normal and stressed operating conditions. 

Co-locating batteries with solar generation can optimise the use of a shared connection and defer specific network reinforcements. Integrated planning also ensures that transmission investment continues wherever it is required to support future power flows and system reliability. 

Solar generation and storage are therefore being considered as an integrated system resource, with clear performance obligations for dependable capacity and critical grid-support services. 

The planning focus extends beyond the quantity of storage to the services, duration and locations that provide the greatest value to the national power system. 

Reliability and System Security Enable the Transition 

The next phase of renewable growth is being advanced with system security embedded as a core enabler of the transition. 

The planning framework addresses the greater variability, faster ramps and changing power flows associated with higher renewable penetration, together with the corresponding requirements for frequency, voltage and system-strength support. 

It also accounts for large and concentrated new loads, such as data centres, and the operational interaction of power-electronic equipment and uninterruptible power supply systems with grid disturbances. 

Through comprehensive system studies, operational planning and technical standards, the grid operator assesses actual operating conditions and credible contingencies. This confirms that sufficient reserves and flexible resources are available, generation facilities and demand customers can ride through faults, voltage and frequency can recover within acceptable limits, transmission capacity and redundancy are adequate, and the system can be restored safely following a major disturbance. 

Reliability is not a barrier to renewable growth; it is the foundation of this approach, enabling renewable energy to expand securely, sustainably and at scale. 

A More Complete Measure of Progress 

Capacity targets are supported by a broader set of system-performance measures, including renewable energy delivered, curtailment, dependable capacity contribution, storage duration and availability, system flexibility, grid-hosting capacity, transmission readiness and the provision of essential system services. 

This comprehensive approach strengthens renewable ambition. It connects capacity targets to the operational investments, technical standards and market arrangements required for successful delivery. 

Capacity targets set the ambition. The integrated approach is translating renewable capacity into dependable energy at the time and location it is needed — transported through an adequate grid, supported by storage and flexibility, and capable of displacing higher-emission generation while maintaining system security. By considering capacity, energy, flexibility, network readiness and essential system services together, the country is well positioned to achieve its renewable targets while preserving a secure and resilient power system. In-Between the Lines with Ir. Shanmugam Thoppalan, Head, Grid System Operator, Tenaga Nasional Berhad (TNB), Malaysia