NGCP welcomes new capacity from Terra Solar Project; cautions on potential grid impact

NGCP welcomes Terra Solar Power Project as a significant addition to the country’s growing renewable energy capacity, supporting national efforts toward a cleaner energy mix. Terra Solar has a total capacity of 2,500 Megawatts (MW), supported by a 1,125MW battery energy storage system (BESS) capable of sustaining output for around four hours.

NGCP, however, cautioned that heavy reliance on intermittent power sources such as solar generation, may pose operational challenges to grid stability, potentially causing fluctuations in system frequency and voltage that if not properly managed, could lead to under-frequency load shedding or rotating power interruptions in some areas.

“Renewable energy initiatives such as the Terra Solar Power Project are welcome. Any new power source introduced into the system will help keep supply stable. However, not all renewable energy technologies are equal. Some technologies (such as wind or solar) are, by nature, variable or supply intermittently, and therefore need to be handled more carefully.

There are operational considerations that must be carefully managed on both the side of the transmission, and more importantly, on the side of the generating plant. Doing so will help grid stability and mitigate any fluctuations inherent in variable renewable energy sources (VREs). In addition, all required facilities on the plant side, as determined in the system impact study, must be fully complied with,” NGCP said.

This concern was underscored by a recent voltage fluctuation incident in parts of North Luzon, which occurred due to the unstable output of renewable energy sources in the area. The incident highlighted how sudden variability in RE generation can affect voltage levels and system stability, prompting NGCP to take mitigating actions to prevent further disturbances.

“Operational experience at the San Marcelino Solar Farm in Zambales indicates that short term solar variability of up to 300MW can occur due to brief cloud cover. While such variability can be effectively managed with fast-acting resources, conventional generation (such as coal power plants) has limited capability to respond quickly due to longer ramping times. Battery energy storage systems are among these “fast-acting resources,” and therefore play a critical role in providing rapid support to maintain frequency stability as solar penetration increases,” the company said.

The Terra Solar Power Project will be supplying 850MW to MERALCO through a Power Supply Agreement, mainly during the daytime, while the remaining 1,650MW will be injected into the grid via the Wholesale Electricity Spot Market (WESM). As a variable renewable energy source, Terra Solar operates on a must-dispatch basis under Republic Act 9513. The law mandates that all variable renewable energy sources, including solar farms, must be given priority in scheduling plants for dispatch into the transmission grid.

NGCP reiterated its call on the Department of Energy (DOE) for more incisive and progressive policies on the entry of VREs, focusing on grid stability as the primary consideration. The company stressed that the entry of bulk VRE should be complemented by dependable baseload and fast-ramping energy resources to ensure a stable and reliable power supply for the country. #