Unlocking the value of battery energy storage

India’s push toward net-zero emissions and a robust renewable energy future hinge on scaling up battery energy storage systems (BESS). Veena Gupta, senior vice president for management consultancy at Mott MacDonald, shares industry know-how about how to design and deliver effective battery energy storage solutions.

The race is on in India to scale-up battery energy storage capacity to optimise the flow of renewable energy to the grid when it is most needed.

With the right know-how, battery energy storage systems (BESS) can significantly improve the efficiency, reliability and cost competitiveness of solar and wind generation versus conventional energy.

While solar and wind are clean and abundant, they come with a major caveat: variability. Daily and seasonal fluctuations in energy supply lead to grid instability and a mismatch with demand.

By 2031-32, India will need 74 GW of storage capacity with an energy output of 411.4 GWh – 236.2 GWh from batteries and the remainder from pumped hydroelectric systems.

Lessons are still being learned globally about how to deploy energy storage technology and infrastructure effectively: improving battery procurement, sizing BESS technology, developing supporting infrastructure and bringing the elements together to deliver large-scale renewables plants.

From concept to operation

Developing cost-effective BESS projects requires precision across key areas:

• Energy calculations: sizing BESS in hybrid solar-wind set-ups involves forecasting generation, analysing load profiles and accounting for battery degradation to optimise storage needs.
• Battery procurement: choosing the right supplier requires an evaluation of cell design, assembly quality, thermal control, safety, cybersecurity and long-term service capabilities.
• Operational strategy: effective BESS performance depends on an integrated approach to energy generation, storage and load management. Poor battery health or system imbalance leads to inefficiency and higher costs.
• Storage sizing: undersized systems limit energy output; oversized systems inflate infrastructure and maintenance costs. Right-sizing is essential for optimal returns.

Driving decarbonisation

Today in India a substantial proportion of solar power generated during peak sunlight hours is wasted or ‘curtailed’ because the grid cannot absorb all the energy supplied by solar plants. Some estimates suggest that 20% to 30% of solar generated is lost in this way.

Grid congestion and lack of storage are recurring problems in high wind states, such as Rajasthan, Gujarat, Maharashtra, Karnataka and Tamil Nadu. Many high wind regions lack adequate grid infrastructure. In Tamil Nadu alone, it is reported that 70M units per week were curtailed due to grid congestion.

A different, but growing, problem for developers is that new sites offer weaker wind – these projects need advanced turbines and stronger grid links.

Hybrid wind-solar-storage models are emerging as a powerful solution to the constraints India faces in scaling up renewable energy. By combining the strengths of each technology, these systems offer a more stable, efficient, and cost-effective way to deliver clean power.

Using batteries to stabilise grid supply would reduce energy losses and help to meet peak energy requirements, even when solar or wind plants are not generating energy.

BESS could also help to lift the maximum grid penetration limits for renewables in some Indian states, which are in place to protect the stability and reliability of the grid.

This would drive decarbonisation by enabling solar and wind producers to contribute more to the country’s energy mix, which is around 43% including hydro, in 2025.

Battery storage is key to the viability of 24-hour solar generation by enabling five times as much solar capacity for the same grid connection, according to a recent report by Ember, a global energy think tank (June 2025).

The report finds that 24-hour solar generation is now cheaper than coal and nuclear, based on 97% uninterrupted solar with battery over 365 days a year.

Demonstrating project viability

We are supporting many BESS projects globally, which are advancing best practice and knowledge about how to deliver economically viable projects.

In India, we have provided technical advisory for a 70 MW/140MWh standalone BESS project in Gujarat. The project on completion will provide energy storage capacity to Gujarat Urja Vikas Nigam Limited on an on-demand basis.

We recently assessed the technical feasibility of a grid-connected hybrid renewable 662 MW (AC)/960 MW (DC) solar power project with a 1.76 GWh BESS output, which is being developed in Rajasthan.

In the Philippines, we are owner's engineer on the Terra Nueva Solar PV Project, which is under construction. The plant combines solar with battery energy storage and will be able to supply a steady 850MW of power to the grid in 2027 during high-demand periods.

We’re responsible for the electrical, civil and renewable energy engineering as well as strategic contracting. This included advised on battery storage technology, how to size the plant properly for climate conditions in the Philippines and how to get the infrastructure built.

Terra Nueva will allow the country to decrease its reliance on coal imports, ultimately reducing coal usage by approximately 1.4M tonnes annually.  We’re also supporting BESS projects in Indonesia, Singapore, Abu Dhabi, Europe and Australia.

Accelerating India’s growth and investment

India’s battery storage is expanding rapidly to boost clean energy and grid reliability. As of mid-2025, installed capacity stands at 205 MW, with 3,300 MW set to come online in two years and 12,500 MW under tender.

To meet BESS demand, the country is investing in lithium-ion batteries for electric vehicles and grid use, exploring sodium-ion as a cost-effective option for stationary storage, and developing zinc-based and metal-air technologies for safer, long-duration applications. Applying industry best practice will be vital if India is to achieve its ambitious targets.

Investment is needed, in turn, to meet India’s government renewables capacity targets by 2032 – 365 GW of solar and 121 GW of wind power – as outlined in the latest National Electricity Plan and will position India as a global leader in renewable energy development.

To accelerate BESS investment in India, the government’s Viability Gap Funding Scheme is providing support to BESS to accelerate clean energy adoption and grid stability. Along with the VGF scheme, India’s energy storage obligations policy requires renewable projects to include storage.

Another positive trend is the significant reduction in storage costs over the past few years due to increased manufacturing capacity (150 GWh domestic battery manufacturing capacity has been announced), technology advances and lower raw material costs. India’s storage sector is no longer experimental – it’s entering a cost-competitive, scalable phase.

Battery safety and disposal

One of the major hurdles in the clean energy shift is the safe use and disposal of batteries used in electric vehicles and grid-scale storage.

Lithium-ion batteries are at risk thermal runaway, where overheating can trigger fires or explosions, while toxic metals they contain pose an environmental threat if not properly recycled.

Research institutions are developing advanced recycling technologies and industries are building safer, modular systems with battery management systems. Regulators are also enforcing recycling targets, such as India’s 2022 Battery Waste Management Rules.

Together, these efforts aim to build a sustainable, closed-loop battery ecosystem, where batteries are safely used, repurposed and recycled.