Scenario: an FDI factory has 12,000 m² of empty roof, a steadily rising power bill and a parent-company ESG target. Self-consumption rooftop solar is the obvious answer — but its legal framework has just changed: Decree 58/2025/ND-CP dated 3 March 2025 replaced Decree 135/2024/ND-CP after only a few months. This article updates the current mechanism and the points a roof tenant must lock down before signing an installation contract.
The current legal framework
Clause 15, Article 4 of the Law on Electricity 61/2024/QH15 defines self-generated, self-consumed power as a source an organisation or individual develops mainly for its own needs, with surplus saleable to the power utility under the State’s mechanism. The governing guidance is now Decree 58/2025/ND-CP dated 3 March 2025 on self-consumption rooftop solar development, replacing Decree 135/2024/ND-CP. Three core mechanics: one, surplus sales are capped under a two-stage ceiling: before 26 June 2026, the cap was no more than 20% of the electricity generated at the output point of the source, under Clause 2, Article 14 of Decree 58/2025/ND-CP; from 26 June 2026, Decree 243/2026/ND-CP raises the cap to a maximum of 50% of the electricity generated at the output point, and until 31 December 2030 the two sides may further agree a ratio above 50% where the regional grid can absorb it while ensuring safe operation — after 2030 the ceiling stays at a maximum of 50% (monthly generated output = PVout coefficient × actual installed capacity, measured at the output point) — the system must still be sized first to the self-consumption load, not to export ambitions; two, the investor must notify and register the power source, sign a connection agreement with the power unit and install bidirectional metering separating self-use from grid export; three, for large systems of 1,000 kW or more, Decree 58/2025/ND-CP adds procedures on power development planning and electricity activity licensing, reflecting tighter management of industrial-scale rooftop systems.
The construction and safety side: light, but not empty
Mounting panels on an existing roof without changing load-bearing structure or function normally triggers no new construction permit for the solar system itself. Three technical duties remain in full: certify the roof’s load capacity after adding panel, racking and wind loads — the investor must hold this document even though no authority pre-approves it; comply with electrical and fire safety for the system (cabling, inverters, connection points) under current standards; and respect the industrial park’s planning and height controls. If the project raises the roof, strengthens structure or extends area, that work returns to the construction-permit regime under the Construction Law 135/2025/QH15. Field experience shows the most common failure is an old metal roof without long-term load capacity: the economics of a 20–25-year system cannot rest on a roof structure with 8 years of life left.
When the roof is not yours
Most FDI factories sub-lease land or rent ready-built factories in industrial parks, so the real legal problem is roof-use rights. The agreement with the building owner should fix: installation rights and roof access for the system’s whole life; allocation of waterproofing, roof-structure maintenance and panel removal for roof repairs; system ownership, transfer rights to third parties (an ESCO or power buyer) and removal/roof-restoration duties if the lease ends before the system’s life; and coordination on fire insurance and rooftop work safety. On the utility side, the power-source registration should name one consistent entity — the entity operating the factory — to avoid divergence from the land sub-lease and the investment registration certificate. Only with these three layers settled — the electricity mechanism under Decree 58/2025/ND-CP, structural safety, and roof-use rights — is the project ready for financing or a leasing/internal PPA structure.
Frequently Asked Questions
Does rooftop solar on a factory roof need a construction permit?
A rooftop solar system mounted on an existing roof, without altering the building’s load-bearing structure or function, falls in the equipment-installation category and normally needs no new construction permit for the solar part. The investor must still: verify structural safety (a design unit must certify the roof load after installation), comply with fire safety for the electrical system, and complete the electricity procedures under Decree 58/2025/ND-CP. If the installation involves roof alteration, raising or structural change, that alteration requires a construction permit under the Construction Law 135/2025/QH15.
How can surplus rooftop solar power be sold?
Under Decree 58/2025/ND-CP dated 3 March 2025 (replacing Decree 135/2024/ND-CP), self-generated, self-consumed rooftop solar may sell surplus power to the power utility under a two-stage cap. Before 26 June 2026, the cap was 20% of the electricity generated at the output point of the source (monthly generated output = PVout coefficient × actual installed capacity), under Clause 2, Article 14 of Decree 58/2025/ND-CP. From 26 June 2026, Decree 243/2026/ND-CP amending Decree 58/2025/ND-CP raises the cap to a maximum of 50% of the electricity generated at the output point; until 31 December 2030, the two sides may further agree a ratio above 50% where the regional grid can absorb it while ensuring safe operation (after 2030, the ceiling stays at a maximum of 50%). Electricity discharged from a storage system charged by the rooftop solar itself also counts as saleable surplus. The purchase price for surplus power is the average market electricity price of the immediately preceding year, capped at the maximum of the generation price frame for ground-mounted solar plants. Output above the applicable cap is not paid for as commercial power. Decree 58/2025/ND-CP also tightens management of large systems: rooftop systems of 1,000 kW or more must complete additional procedures on power development planning and electricity activity licensing under electricity law, instead of mere notification as for small systems.
Does the factory roof need a structural assessment before panels are installed?
Yes, and this step must not be skipped for safety reasons, not merely legal ones: the panel system with its mounting frames and auxiliary equipment adds permanent load to a roof structure originally designed for wind and maintenance loads under its original standard. Before installation, the investor must engage a competent structural firm or engineer to assess the existing roof’s load capacity; an insufficient roof must be reinforced first. The structural assessment is also a condition for insurers to accept the system’s fire and property risks, and for the factory owner (where the investor is a sub-lessee) to consent to installation. Installing without a structural assessment and suffering a roof collapse puts civil and administrative liability squarely on the system owner.
If I self-consume 100% and sell no surplus, is the procedure simpler?
Simpler on the commercial side, but not exempt from the core procedures. Under Decree 58/2025/ND-CP on self-generating, self-consuming rooftop solar, a system selling no surplus needs no power purchase agreement and no surplus-sale arrangement with the utility; but the investor must still notify and register the power source development with the competent authority and the utility according to capacity scale, meet connection technical requirements, and in particular ensure no reverse feed into the grid without an agreement. The 1,000 kW threshold applies in full: systems of 1,000 kW or more trigger additional planning procedures and an electricity activity license even if they sell not a single kWh. In short: the commercial contract drops away, the technical and regulatory procedures do not.
This article has been quality-reviewed by the FLAW AI Legal Council