While the revised peak-hour schedule does not increase electricity prices, businesses' electricity costs will depend on how effectively they manage their energy use.

NSMO said the Time-of-Use (TOU) retail electricity tariff is one of the most widely used demand-side management tools worldwide, helping regulate electricity demand, improve power system efficiency and optimize customers' electricity costs.

Under the TOU mechanism, different electricity prices apply at different times of the day, encouraging customers to adjust their consumption patterns in line with actual system operating conditions.

In Vietnam, TOU tariffs, which divide electricity use into peak, normal and off-peak periods, helped large industrial consumers adjust their electricity consumption. Under Circular No16/2014, the current peak periods are from 9:30am to 11:30am and from 5pm to 8pm.

However, Vietnam's power system has changed dramatically since 2018. Regarding power supply, installed renewable energy capacity had increased more than 40-fold by the end of 2025 compared with 2018. Solar power, in particular, has become a major daytime electricity source, fundamentally changing the traditional power dispatch model.

As for the load, the share of electricity consumption in the industrial sector has risen from 30 percent to over 50 percent of the total commercial electricity output, while the residential consumption share dropped from 50 percent to 33 percent.

As a result, the peak hours defined under the existing framework no longer fully coincide with the periods when the power system experiences its greatest strain. On many hot-season days, peak demand now occurs in the evening as solar generation drops sharply while household electricity consumption rises. 

At that time, the system must dispatch more flexible but more expensive generation sources, including combined-cycle gas turbines, LNG-fired plants and even oil-fired backup units.

"Therefore, adjusting peak hours is necessary to ensure that electricity price signals more accurately reflect the marginal cost of the power system," NSMO said.

NSMO noted that not every kilowatt-hour carries the same system cost. A kilowatt-hour consumed during the day, when supported by solar generation, differs significantly from one consumed in the evening.

Therefore, revising the daily TOU schedule is not simply a change in electricity pricing but an effort to ensure price signals better reflect actual system operating conditions.

The primary objective of the TOU tariff is to create economic incentives for customers to shift electricity consumption away from periods when the system faces the greatest pressure, thereby reducing peak demand or redistributing consumption to periods with greater available capacity, improving the load factor and making better use of existing power infrastructure.

When electricity prices accurately reflect system conditions, customers are encouraged to shift demand to lower-priced hours, optimize production schedules and adopt energy storage and electricity management solutions.

In Vietnam, where solar power now accounts for an increasing share of electricity generation, the system can produce tens of thousands of megawatts of solar electricity around midday on sunny days. If demand does not shift accordingly, part of this renewable energy may not be fully utilized or may even have to be curtailed.

In the evening, however, the system must rely on LNG-, gas- or oil-fired generation with higher operating costs. Shifting demand from the evening to daytime therefore means moving electricity consumption from periods of higher costs to periods when cleaner and less expensive electricity is available.

Electricity costs 

At the end of April, the Ministry of Industry and Trade issued Decision No. 963, establishing new peak, off-peak and normal operating hours for Vietnam's national power system.

Under the new framework, peak hours apply from Monday to Saturday between 5:30pm and 10:30pm, totaling five hours per day. Peak pricing does not apply on Sundays.

Normal hours run from 6am to 5:30pm and from 10:30pm to midnight from Monday to Saturday, totaling 13 hours per day. On Sundays, normal hours extend continuously from 6am to midnight.

Off-peak hours remain unchanged at midnight to 6am every day.

NSMO stressed that the revised peak-hour schedule is not intended to increase customers' electricity costs but to enable them to manage energy expenses more efficiently.

Removing the morning peak period will also make it easier for many businesses to arrange uninterrupted production during regular working hours. Customers with flexible operating schedules can take advantage of price differences between time periods to lower production costs.

NSMO emphasized that the adjustment does not change existing electricity prices. Electricity tariffs remain those approved by the authorities.

Tran Chung