Grid Connection & Surplus Power Acceptance: The Process for Businesses Investing in Solar Power

When a business invests in a rooftop solar power system for its factory or facility, connecting to the national grid is an essential step. This allows the system to synchronize with the grid and, if surplus electricity is generated, sell it back. The grid connection process ensures the system operates stably, complies with technical regulations, and helps the business maximize the benefits of its renewable energy source.

According to EVN’s (Vietnam Electricity) guidelines on rooftop solar development, the project owner must register for grid connection to be eligible for the surplus power purchase mechanism and to receive technical support when needed.

The Solar Power Grid Connection Process for Businesses

Registering the Need for Connection

The business submits a grid connection registration application to the local Power Company, providing information on the location, planned capacity, and a preliminary design diagram.

Survey and Technical Connection Agreement

The Power Company conducts a survey of the connection point (medium/low-voltage circuit, power lines, substation). If the system connects to the low-voltage grid, it must be ensured that the total connected capacity does not exceed the rated capacity of the power line or distribution transformer.

Installation of a Bi-directional Meter for Measurement

After the system is approved for connection, the power utility installs a bi-directional meter to measure the electricity bought and sold between the business’s system and the grid. In many localities, the installation of this meter is provided free of charge by EVN, according to current regulations (issued in the 2020-2023 period and currently applicable to rooftop solar systems ≤1MW).

Testing, Acceptance, and Grid Synchronization

The technical unit performs tests, measuring the system’s voltage, current, and efficiency according to standard testing procedures. The dispatch authority or a grid management representative reviews the results before granting official synchronization with the main grid. The testing and supervision process is issued under Decision 25/QD-DTDL.

Finalizing Documentation and Payment for Surplus Power

The factory submits a proposal to sell surplus power, including technical documents, equipment certifications, and the acceptance test approval. According to Decree 58/2025, the maximum amount of surplus power that can be sold to the grid shall not exceed 10-20% of the actual generated output, depending on the source type.

Key Points and Technical Conditions

• Surplus Power Purchase Price: According to Decree 58/2025, surplus electricity will be paid for at the average market electricity price or the avoided cost, depending on the project type.
• Metering & Data Transmission Equipment: The business must be equipped with remote data transmission devices and compliant meters that adhere to grid technical standards.
• Surplus Power Ratio Limit: The amount of power sold must not exceed the surplus ratio specified in the power purchase agreement.
• Compliance with Measurement Standards: The meter must meet the technical standards of DLVN-39:2019 to ensure accuracy and protect the interests of both parties.

Clear Benefits of Completing Grid Connection & Acceptance Testing

Completing the grid connection process is not just a legal requirement; it also brings numerous tangible benefits to the business. First, the business can sell surplus electricity to the grid, creating an additional revenue stream during operation. The bi-directional metering system ensures transparency in electricity production and costs, safeguarding the interests of both parties.

Furthermore, the official acceptance and grid synchronization record serves as crucial legal proof, confirming that the system is qualified for stable, long-term operation. This is particularly valuable when a business needs to demonstrate compliance and safety in its energy audit reports.

More importantly, grid connection and the formal recognition of green electricity generation help the business integrate this achievement into its ESG strategy, demonstrating environmental responsibility and enhancing its reputation with international partners, especially in export-oriented industries under pressure to reduce emissions.

Advice for Businesses During the Grid Connection Process

To ensure a smooth grid connection and acceptance process, businesses should note several key points. First, select a contractor with experience in implementing solar power projects who thoroughly understands the technical regulations for connection and acceptance. A reputable contractor can help shorten timelines, reduce errors in documentation, and provide direct support when working with the power utility.

Next, the business should proactively prepare all technical documents, detailed drawings, and equipment certifications from the very beginning. This helps save time during the appraisal process and avoids the need for multiple revisions.

Additionally, it is advisable to regularly monitor new guidance documents from EVN and the Ministry of Industry and Trade to ensure compliance with the latest regulations. Finally, investing in an operational monitoring system is a necessary step to track performance, detect technical faults early, and maintain efficiency after grid synchronization.

With experience in implementing hundreds of solar energy projects for factories, workshops, and industrial parks nationwide, INS Energy not only provides a turnkey solution—from design and construction to grid connection and acceptance—but also assists businesses in working with power authorities to complete legal documentation quickly and accurately.

Contact INS Energy for a detailed consultation on grid connection solutions and the acceptance process for your business’s solar power project.