Solar rooftops and micro-grids require guiding breakthrough policy directions

Mai Van Trung

According to the latest update from Electricity of Vietnam (EVN), the country has commissioned roughly 745 megawatt peak (93 MWp in June, 79MWp in May, and 56MWp in April). The aim to put 1,000MWp rooftop solar under commercial operation at the end of this year might be easily achieved because local and international developers are accelerating their investments to meet the feed-in tariff (FiT) deadline.

The attraction of the solar rooftop market in Vietnam is fostered by the fact that an electricity shortage from next year until perhaps 2025 will be faced by the country.

The prolonged concerns about electrical and construction regulations associated with rooftop solar systems may not be rectified within this year. However, there is hope as organisations like the Clean Energy Council of Australia or Solar Energy Research Institute of Singapore to supervise the solar installation, operation, and maintenance across the country.

The technical specifications and regulations will be available sooner or later but the capacity installation limit of one megawatt for each rooftop solar system is still a hot topic to discuss among the investment community.

Particularly, industrial manufacturers are purchasing huge electricity from EVN through 110 kilovolt lines. Many of them have a monthly electric bill from five to 10 million kilowatt hour. A rooftop solar system of 1MW can contribute around 2-3 per cent of the demand.

The savings are insignificant for energy-extensive manufacturing firms. The availability of space to house from 5-10MW is common which can save the company at least 10 per cent of its total demand.

There should be a breakthrough in policy direction to adopt rooftop solar systems whose capacity is less than 5MW and eligible for those using more than 5 million kWh a month. The mandatory condition of the current energy usage stated is to assure the nature of self-consumption. And the project development approval should be assigned to the provincial level to shorten the process.

Grid congestion with such a model might be avoided by regional load dispatch centres when there is no load demand by the company covering their rooftop with solar modules from 1-5MW. If it is necessary, it is able to regulate the integration of energy storage of at least 15 minutes to make sure the load dispatch centres can manage the operation of such a system. It is stated that many manufacturers are taking advantage of the low electricity tariffs but it is not opened yet for them to power their unused rooftop. The FiT plays no role with these companies but the age and strength of their factories’ steel structures does.

The International Monetary Fund has forecast Vietnam’s GDP to grow at 2.7 per cent this year which is among the best performers in Asia. Also, the movement of manufacturers from China to Vietnam enables a busy year for industrial developers.

As of the end of May, there were 561 industrial zones covering 201,000 hectares, equivalent to 0.6 per cent of the country’s total area. Of this, 374 industrial zones were built on 114,400ha and 259 others were under construction or in the land clearance stage on 86,600ha.

The pressures to power those industrial zones might be comparable with the constructions of transmission lines to address the curtailment of solar and wind power plants. Each industrial zone requires 50-100MW depending on their scales. The investment of a 110-kV substation and 22kV lines to deliver the power to the tenants inside the zone seems to be a waste at the beginning due to the fact that factories will be gradually built and fully operational after five years.

It is where distributed power supplies in a micro-grid can find its application because of its growing nature. A micro-grid is a decentralised group of electricity sources (solar modules, wind turbines, energy storage, and diesel gensets) and loads.

The combination of these energy sources and smart load control algorithms will mobilise renewable energy as much as possible before diesel gensets are switched on.

The micro-grid might receive power from EVN through a 110-kV substation at 25MW or, in some cases, 10MW from 22 kV. The configuration will save public investment a great amount. The factories in the industrial park can enjoy very competitive electricity prices, even a fixed cost over their lease term.

Not only electricity but other utilities (water, heating, cooling, and communications) can also be supplied in similar ways. A breakthrough is needed in policy direction to allow industrial developers to use land to mount solar modules and small wind turbines instead of rooftops only.