As solar development accelerates in the Philippines, the next question may no longer be only how much renewable energy the country can build, but how much renewable energy the grid can reliably absorb.

For Trina Storage APAC Head of Energy Storage Dr. Leo Zhao, battery energy storage systems, or BESS, are becoming a key enabler of the country’s solar buildout by helping make renewable energy smoother, more flexible, and easier for the grid to manage.

“The adding [of] energy storage seems to be an enabler for enabling more renewable generation,” Zhao said in an interview with Power Philippines.

Why solar needs storage

Solar has become one of the most attractive renewable energy technologies because of improving economics, growing energy demand, and the need for countries to strengthen energy security. For the Philippines, the case is particularly relevant as the country continues to face high electricity prices, dependence on imported fuels, and a need for additional generation capacity.

However, solar is also variable. Its output changes depending on sunlight, weather conditions, and time of day, creating a challenge for power systems that must constantly balance electricity supply and demand.

Zhao said renewable energy lacks the same built-in grid inertia provided by conventional power plants. Traditional fossil fuel plants rely on large rotating machines that help stabilize grid frequency, while solar, wind, and batteries are connected through inverters.

This makes storage more important as renewable energy penetration rises. By storing excess energy and releasing it when needed, batteries can help make solar generation more controllable.

Responding to grid concerns

Grid operators have raised concerns over how much variable renewable energy the Philippine grid can safely accommodate, especially as larger solar projects enter the development pipeline.

Zhao said these concerns are precisely why storage should be developed alongside renewable energy.

“Adding the energy storage component will make the solar plus battery a more firm and dispatchable energy generation,” he said.

Dispatchable power refers to electricity that can be controlled or delivered when needed. Solar alone is not fully dispatchable because it depends on sunlight. When paired with batteries, excess solar generation can be stored and released later, making the output easier to manage.

Zhao said this can help smooth renewable energy generation and reduce its impact on the power grid. However, he noted that storage should complement continued investment in grid infrastructure, not replace it.

DOE policy moves toward solar-plus-storage

The Department of Energy has already begun pushing the market toward greater integration of renewable energy and storage.

Zhao cited the Integrated Renewable Energy and Energy Storage Systems, or IRESS, framework as one example of policy direction encouraging the co-location of solar and battery projects.

Co-located solar and storage means the power plant and battery system are developed together or placed at the same site, allowing energy generated during sunny periods to be stored and delivered when needed.

The DOE has also required larger renewable energy projects to include storage equivalent to 20% of their capacity. While some developers have warned that mandatory storage could raise upfront costs, Zhao said the issue should be viewed from the perspective of the whole power system.

Looking beyond upfront cost

According to Zhao, renewable energy projects are often assessed through the levelized cost of electricity, which looks at the cost of generating power from a plant over its lifetime. But for storage, he said the better question is how the project affects the entire power system.

He pointed to the concept of levelized cost of a system, which considers not only generation cost, but also the broader cost of integrating that power into the grid safely and reliably.

“Purely from [a] capex point of view, there’s additional capex to be invested,” Zhao said. “But if you look [from] a whole system perspective, actually adding batteries are helping system stability.”

This distinction could become more important as the Philippines adds more solar and wind capacity. Without storage or other flexibility resources, renewable energy growth may require additional grid reinforcements or operational measures to manage variability.

A tool for island communities

Battery storage could also play a role beyond large grid-connected solar plants.

For island and off-grid communities, Zhao said solar-plus-battery systems can support the development of microgrids that rely more on local renewable generation instead of diesel.

A microgrid is a smaller power system that can serve a local area, such as an island or remote community. This is especially relevant for the Philippines, where many communities are separated by geography and still rely on diesel generation for electricity.

“Those island areas definitely will benefit a lot by going into, for example, with solar and battery as a main source of generation,” he said.

For these communities, BESS is not only a grid stability tool. It can also support energy access, fuel cost reduction, and a shift away from diesel dependence.

Lessons from Australia

As renewable energy penetration grows, Zhao said the Philippines can look to Australia for both lessons and caution.

Australia has already experienced the challenges of integrating high levels of renewable energy across a large and geographically dispersed power system. Zhao pointed to South Australia’s 2016 blackout as an example of how renewable-heavy systems require careful planning, technical standards, and grid-supporting capabilities.

The incident led to reforms around generation performance standards, which require power generation assets to demonstrate how they will behave when connected to the grid. In the Philippines, Zhao said a similar role is played by system impact studies, which model how new generation or load will affect the power system before a project is connected.

For Zhao, this kind of pre-planning becomes more important as more renewable energy projects are added to the grid.

Grid-forming renewables as the next frontier

As solar, wind, and battery systems become more common, the next technical frontier may involve making renewable energy assets behave more like conventional power plants from a grid stability perspective.

Zhao explained that conventional power plants provide physical inertia through large rotating equipment. Renewables do not naturally provide the same physical inertia because they are connected through power electronics and inverters.

However, inverter-based technologies can be designed to provide what Zhao described as “virtual inertia,” allowing renewable energy and battery systems to help support grid stability.

In simple terms, grid-forming renewables are systems designed not only to supply electricity, but also to help maintain the stability of the grid. Zhao said this trend is already becoming more important in markets such as Australia and could eventually become more relevant for the Philippines as renewable energy penetration rises.

Why the Philippines remains attractive

Despite grid challenges, Zhao said the Philippine market remains attractive for solar and storage.

He pointed to high electricity prices, the need for more generation capacity, policy support, and revenue opportunities for batteries providing ancillary services. Ancillary services are support services that help maintain grid reliability, such as frequency control and reserves.

Zhao also cited the DOE’s renewable energy policies and the allowance of 100% foreign investment in renewable energy as factors supporting market growth.

“If economic return is there, and then demand is also there,” he said, adding that many factors are already aligned for investment.

However, he also said the Philippines’ island grid creates physical constraints, including limits on how power can be dispatched across different regions. By pairing renewable energy with batteries, developers can help reduce the strain of variable generation while supporting the country’s need for additional supply.

Solar and batteries go hand in hand

Trinasolar sees the Philippines as part of a wider regional shift toward solar-plus-storage.

Zhao said many solar and wind companies are moving into energy storage because of its natural fit with renewable energy. Storage reduces variability, improves system strength, and allows more renewables to be added to the grid.

He said the trend is already visible in markets such as Australia, Malaysia, Indonesia, and Vietnam, where policy frameworks and tenders are increasingly shifting from standalone solar to solar-plus-storage or standalone battery projects.

“Solar with battery in the future will go hand in hand and will become the main source of energy long term,” Zhao said.

For Trinasolar, this also aligns with its own direction as a company. After decades in solar, the company has expanded more aggressively into storage, positioning itself around the combined deployment of renewable energy and batteries. This also allows the company to support developers looking to plan solar generation and battery storage together, rather than treating them as separate procurement and integration tracks.

Batteries as the bridge

The Philippines’ renewable energy ambitions will increasingly depend on whether solar can be integrated in a way that supports grid reliability.

Solar may remain one of the country’s strongest growth engines for clean energy, but batteries may determine how much of that solar can be used effectively.

As more projects enter the pipeline, storage could become the bridge between renewable energy ambition and grid reality, helping make solar smoother, more dispatchable, and better aligned with the needs of a power system that still requires reliability, stability, and flexibility.

As the Philippines accelerates solar development, will battery storage become the key to turning renewable energy growth into reliable power for the grid?

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