Energy policymakers are unsure whether peak electricity demand will meet their estimation because of the fast growth of off-grid power supply and independent power supply (IPS).
Peak demand is below the most recent projections because of unstable weather, including frequent rainstorms.
Twarath Sutabutr, director-general of the Energy Policy and Planning Office (Eppo), said peak demand was estimated at 31,000 megawatts this year, up 2.3% from 30,300MW in 2017.
Eppo estimated peak demand at 32,060MW during summer season last year, but real peak demand tallied 30,300MW. Last year's circumstances were similar to this year, with frequent rainstorms, a prolonged winter season and rapid growth of IPS, he said.
"This will be the second year power demand is lower than Eppo's expectation," said Mr Twarath.
IPS has grown rapidly over the last three years as solar power costs declined, encouraging investors to allocate budget towards generating their own power.
Moreover, progressive promotion of renewable power by policymakers is also causing declines in power demand, he said.
Mr Twarath said combined registration of IPS capacity is 2,700MW, with 1,700MW from fossil-fuel power generators and 1,000MW from biomass and solar power, particularly from rooftop installations.
The Energy Regulatory Commission (ERC) reported last Monday IPS from the solar rooftop scheme is expected to grow faster because development costs have declined and the average power tariff is three baht per kilowatt-hour (unit).
Viraphol Jirapraditkul, ERC's commissioner, said solar rooftop capacities have grown by 4-5MW per month, particularly at large firms such as Central Pattana Plc, Tesco Lotus and mainly industrial plants.
Many corporations have invested in solar panels because the price per unit is cheaper compared with purchasing power from state utilities.
"Although policymakers are not worried about the power supply because of a high-reserve power generation system, they still plan to integrate power supply systems between three state utilities," said Mr Viraphol.
The integration is expected to enhance the efficiency of the demand response scheme, which is aimed at curbing power demand once natural gas supplies become scarce.
The scheme is set for large power users to avoid using power during peak hours to prevent shortages, particularly in the southern region where demand nearly equals supply. Gas dominates 65% of the power supply and the main gas resources are frequently disrupted from the Gulf of Thailand and Gulf of Martaban in Myanmar, where many production wellheads are old and need frequent maintenance.
