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November 27, 2025
Mapping Vietnam’s rooftop solar landscape with machine learning
Data gaps, policy shifts, and what TransitionZero’s new imagery reveals about growth in this often overlooked area
Summary
Commercial and industrial (C&I) rooftop solar has been quietly driving Vietnam’s solar growth since 2020, but this trend has not been fully captured in official statistics.
TransitionZero has applied an enhanced methodology to provide a more comprehensive view of smaller rooftop solar systems across the country. This builds on insights from the Solar Asset Mapper (TZ-SAM), which detects utility-scale solar assets worldwide using satellite imagery.
The analysis identifies 6.93 GW of rooftop solar capacity nationwide, with 71% being allocated to C&I installations.
Rooftop solar: the dark horse of the global energy boom
The solar revolution is unfolding unevenly around the world. Some countries are racing ahead, while others are only beginning to catch the sun.
The challenges to adoption are many and varied: entrenched fossil fuel generation that limits solar penetration, inadequate grid infrastructure that struggles to move electricity from solar farms to load centres, resistance from utilities wary of managing intermittent renewables, and high upfront investment costs, among others.
Rooftop solar has the potential to address many of these system planning challenges, but is often overlooked in long-term energy planning. Unlike large-scale solar farms, it does not compete for land with other economic activities, can be scaled up quickly, and allows households and businesses to participate directly in power generation for greater energy security. By generating power close to where it is consumed, rooftop solar can also help ease pressure on overstretched grids, a key concern for planners and utilities.
One of rooftop solar’s key features – and also a challenge for planners – is that adoption can accelerate rapidly while remaining under-represented in official statistics. Systems can be captive, behind-the-meter, or do not export excess power to the main grid, and thus may not be fully captured by the utilities. As uptake expands, however, shifts in on-grid electricity consumption will directly impact power system planning and operations, such as reduced daytime demand and underutilised power plants.
This data project by TransitionZero’s Machine Learning team aims to provide a clearer picture of rooftop solar adoption in selected Southeast Asia and South Asia markets. It also seeks to establish a replicable methodology for tracking how policy improvements translate into measurable growth in rooftop solar deployment.
Rooftop solar growth in Vietnam
Vietnam continues to dominate the region’s leaderboard as the largest solar power market in Southeast Asia, with grid-connected capacity reported at 17 GW as of November 2025, according to the grid operator NSMO. Notably, rooftop solar accounts for 46% of this capacity, although no additional capacity has been registered since 2021.
Most of this buildout occurred between 2019 and 2020, driven by generous government incentives in the form of feed-in-tariffs – ranging between 8.4 to 9.4 US cents per kWh for 20 years – applicable to projects commissioned before the cut-off date of 31 December 2020.
By the deadline, besides the large solar farms, rooftop systems had also mushroomed across the country – on urban homes, commercial buildings, factories, and even in rural areas and agricultural lands.
After the incentives were discontinued, Vietnam’s power system faced a situation of solar overcapacity and grid congestion, resulting in a period of policy limbo. Consequently, the local solar market came to a near standstill, with reportedly no new plants entering operation between 2021 and 2023.
In the early 2020s, however, interest in rooftop solar grew among commercial and industrial (C&I) stakeholders. Global geopolitical tensions and supply chain shifts brought manufacturing investments and purchase orders to Vietnam, especially in electronics, textiles, footwear, and furniture. As multinational consumer brands with Scope 2 emissions commitments increased their manufacturing footprint, demand grew for renewable energy solutions to decarbonise supply chains.
The absence of a clear policy framework for rooftop solar – which lasted between 2021 to 2024 – governing everything from system size limits to whether third-party developers could sell electricity to host factories – delayed deployment, particularly for corporates seeking regulatory clarity and contractual certainty.
Yet, there was also growing evidence that Vietnam’s rooftop solar market has been more dynamic than official statistics suggest. Reported portfolio growth by leading C&I rooftop solar developers points to a quiet but persistent buildout during this period of uncertainty.
Evidence of commercial and industrial rooftop solar growth
This trend is reflected in TransitionZero’s Solar Asset Mapper (TZ-SAM), which detects and tracks utility-scale solar assets worldwide via satellite imagery.
According to TZ-SAM’s Q3 2025 release, 96% of total detected solar capacity in Vietnam to date are estimated to have been built before the end of 2020, the cut-off date of the feed-in-tariff incentives. The remaining 4% are assets constructed from 2021 onwards, the majority comprising rooftop solar installations on factories, warehouses, shopping malls, and parking lots.
These time-lapse images from the Copernicus Sentinel-2 satellite show the build-out of rooftop solar systems on factories and commercial premises in Thanh Hoa, Thai Nguyen, and An Giang (formerly Kien Giang) provinces between 2022 and 2025.
The size of these systems, and clusters of systems, ranges between 0.4 MW and 10 MW, indicating the presence of very large rooftop solar systems in industrial parks. However, a limitation of TZ-SAM is that it can only detect assets larger than roughly the size of a tennis court. Smaller systems below 0.4 MW, such as those on residential or public buildings, are therefore not fully captured.
Finding the missing pieces
To address this data gap, TransitionZero’s Machine Learning team developed an enhanced methodology to estimate smaller-sized rooftop solar assets. The approach aims to balance cost, accuracy, scalability, and replicability, and was first deployed in our report estimating the capacity of rooftop and ground-mounted distributed solar assets in Pakistan.
Because purchasing high-resolution imagery for the entire country would be prohibitively expensive, we instead acquired detailed images for selected representative areas across Vietnam. These images, taken between December 2023 and September 2025, ensure both recency and reasonable coverage of the latest market developments.
We then identified and labelled solar installations within these samples, examining how installation rates vary by building size, region, and urban or rural setting. We then used this information to build a model that estimates rooftop solar capacity across Vietnam and its regions.
The detailed technical methodology can be found here.
What we found for Vietnam
The results were mapped using a hexagonal grid to visualise how rooftop solar capacity is distributed across Vietnam. In the heatmap below, darker hexagons represent areas with higher estimated rooftop solar capacity, with the values adjusted to make differences easier to see.
Following this methodology, we estimate 6.93 GW of rooftop solar capacity across Vietnam.
To account for uncertainties such as labelling confidence, panel efficiency, sampling bias, accuracy of external datasets and panel tilt, an error margin of 16% was applied. This results in a 5.82 GW - 8.04 GW range of total rooftop solar capacity in Vietnam.
Because this method relies on building data for extrapolation, the results may undercount quasi-rooftop installations in rural areas, such as those built on standalone structures rather than buildings. However, we note that such installations were widespread during the feed-in-tariff period before 2021 and were included in official rooftop solar statistics, contributing to the discrepancy between those figures and TransitionZero’s estimates.
The tables below show a breakdown by region and sector.
The higher concentration of rooftop solar in Southern and Central regions reflects the stronger irradiation levels there, which improve project payback and reinforce the investment case in the country’s main industrial hubs. Meanwhile, the 71% dominance of rooftop solar on C&I premises highlights the key driver of rooftop solar in Vietnam: manufacturing supply chain decarbonisation.
Furthermore, our analysis also reveals a clear correlation between solar coverage and building rooftop areas. This does not simply indicate that larger buildings host more solar panels. Rather, the data suggests that large facilities, such as those in industrial parks, are more likely to contain solar installations, and when they do, the proportion of rooftop covered is likely to be higher than for smaller buildings.
Looking ahead
In 2025, Vietnam issued official guidelines on rooftop solar development, covering both self-consumption and third-party sale models (through power purchase agreements between system owners and power consumers). This long-awaited framework provides much-needed clarity for investors and consumers alike, and reaffirms the government’s support for distributed power generation. According to the latest power development plan, rooftop solar coverage is targeted at 50% of public buildings and residential homes by 2030.
Vietnam’s rooftop solar market is now poised for steady growth. Indications of further loosening of permitting procedures, expanded sell-back quotas, and new financial incentives for households are likely to sustain this momentum.
Early market responses have been encouraging: new projects are breaking ground, particularly in the supply-constrained northern provinces; more international developers are entering the market; and registration activities at local authorities are rising. Together, these developments underscore the importance of tracking this emerging trend and assessing its implications for Vietnam’s power system planning.
*Note: All solar capacities expressed in this blog are in alternating current (AC).
This is the second in a series of blogs presenting our findings on the status of rooftop solar deployment in Southeast Asia and South Asia. Check out our first analysis featuring Pakistan and stay tuned for upcoming releases on Malaysia, Thailand, Indonesia, and Bangladesh.
