Manila: The cost of ancillary service (AS) drove the rise of transmission rates in August 2025, which increased by 7.09 percent to PHP1.4171 per kilowatt hour (kWh), the National Grid Corporation of the Philippines (NGCP) said Tuesday.

According to Philippines News Agency, NGCP reported that the average transmission rate in July was PHP1.3233/kWh. The rise in AS rates contributed significantly, with an increase of PHP0.0787/kWh last August from the previous month's PHP0.6659/kWh. The NGCP explained that 'AS rates are pass-through costs for power supplied by AS providers during supply-demand imbalance.'

The charges, as NGCP noted, are directly remitted to generating companies with bilateral contracts with NGCP and to the Independent Electricity Market Operator of the Philippines (IEMOP) for AS sourced from the Reserve Market. The corporation clarified that it 'does not earn from AS and does not benefit from changes in AS prices.'

Despite the increase in AS, the grid operator mentioned that the transmission wheeling rate, or the payment for delivering power through the grid, remained nearly unchanged. The wheeling rate last August rose to PHP0.5970/kWh, up by PHP0.0047/kWh from the previous month's PHP0.5923/kWh.

NGCP further added that for August 2025, it charges approximately PHP0.5970/kWh for its transmission service, with Ancillary Services remaining the largest component of transmission-related costs.