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January 20, 2026
A new baseline for Thailand’s rooftop solar deployment
Taking stock of current deployment trends with TransitionZero’s latest imagery
Summary
Thailand’s rooftop solar market is back in focus as the government pushes a ‘Quick Big Win’ package to accelerate deployment, especially of residential systems, against a backdrop of high gas reliance and slower overall solar growth compared with regional peers.
TransitionZero used high-resolution satellite imagery and machine learning-based labelling and extrapolation to produce an updated estimate of Thailand’s rooftop solar deployment, finding ~3.60 GWac installed nationwide, notably higher than official 2023 figures.
The results suggest rooftop solar uptake has accelerated since 2023 and provide a repeatable methodology to track progress, helping policymakers, developers, and corporates understand where deployment is happening now and where targeted reforms could unlock faster growth as Thailand works toward a 2050 net-zero pathway.
Introduction
Thailand is pursuing a broad range of solar power deployment pathways to deliver affordable and clean electricity to its people. The ‘Quick Big Win’ energy initiative, unveiled by energy minister Atthapol Rerkpibul in October 2025, sets out a number of priority areas and targeted incentives meant to accelerate solar power growth in the near term, from the grassroots level upward.
The name says it all. Solar power – whether through small-sized community projects, residential rooftop installations, or large-scale floating solar farms on hydroelectric dams – is considered the technology with the greatest potential to rapidly deliver future-proof low-cost electricity. This focus is particularly salient given Thailand’s continued reliance on natural gas and imported LNG, which together account for 58% of total power generation.
Until 2023, rooftop solar was the primary driver of overall solar growth in Thailand. According to the latest statistics from the energy ministry’s Department of Alternative Energy Development and Efficiency (DEDE), installed rooftop solar capacity increased by 32% year-on-year in 2023, while other solar segments recorded little change.
Under the Quick Big Win initiative, the residential rooftop solar segment is again a central focus, with income tax deductions of THB200,000 (US$6,400) offered to as many as 90,000 participating households, in an effort to reignite deployment momentum.
This article presents an updated assessment of Thailand’s rooftop solar market. TransitionZero’s Machine Learning team applies its in-house distributed solar estimation methodology – previously deployed in Pakistan, Vietnam, and Malaysia – to produce a more up-to-date and granular estimate of Thailand’s rooftop solar deployment status.
Solar in Thailand: from early adopter to regional laggard
Thailand was once a solar energy pioneer of Southeast Asia. Until 2018, it was consistently the region's biggest adopter of solar power, before being overtaken by Vietnam from 2019 onward. In recent years, other neighbouring markets, such as Malaysia and the Philippines have also accelerated their solar build-out, further eclipsing Thailand, where capacity growth has remained relatively flat, according to IRENA statistics.
Rooftop solar has played an important role in Thailand’s overall solar adoption. As of late 2023, it accounted for 35% of total installed solar capacity, reaching 1.77 GWp, according to DEDE.
Thailand was also the earliest country in the region to introduce policy incentives for rooftop solar. In 2013, it launched a feed-in-tariff scheme that was applicable to both residential and commercial and industrial (C&I) installations. Over time, however, policy support has shifted away from broad-based revenue incentives toward greater regulatory clarity and permitting simplification. Revenue support, such as grid buy-back rates, has been limited in scope, offered only to residential customers and for defined time periods. As a result, self-consumption has remained the primary deployment model for rooftop solar systems in Thailand.
Rooftop solar began to gain momentum from 2018, driven largely by the C&I segment. Strong corporate demand for clean energy access and decarbonisation options, especially amidst Thailand’s fossil fuel-dominated power mix, has underpinned this growth. Notably, uptake was also supported by the absence of quotas limiting capacity buildout, which have oftentimes been imposed in neighbouring markets.
Given Thailand’s vertically integrated electricity market, where the state utility EGAT acts as the single buyer, on-site rooftop solar installations remain the primary decarbonisation option available to corporates, alongside the purchase of renewable energy certificates (RECs) through green electricity tariffs. Slightly behind regional peers, Thailand has yet to operationalise a corporate power procurement framework that would allow businesses to directly source electricity from renewable energy generators.
Thus, disclosures from rooftop solar developers operating in Thailand indicate particularly strong uptake in industrial parks and commercial facilities.
Recent policy developments suggest a continued focus on reducing regulatory barriers to rooftop solar installations rather than introducing new revenue support mechanisms, in contrast to approaches adopted in neighbouring markets such as Malaysia and Vietnam. Notable measures include a 2024 policy waiving factory license requirements for installations of all sizes, as well as the 2025 regulation exempting rooftop solar projects from building modification permit requirements across all building types, an exemption previously limited to residential systems.
Let’s zoom in
Against this backdrop and in anticipation of how the market may respond to these latest policies, TransitionZero’s Machine Learning team applied an in-house methodology to assess the latest status of rooftop solar build-out in Thailand. The approach was first deployed in a report estimating the penetration of rooftop and ground-mounted distributed solar in Pakistan, and subsequently applied in similar analyses for Vietnam and Malaysia.
The methodology provides a structured way to take stock of Thailand’s rooftop solar landscape, and can be repeated in the future to track deployment progress over time.
Given that acquiring high-resolution imagery for the entire country would be prohibitively expensive, we instead purchased detailed images for selected representative areas across Thailand. Approximately 1,500 images were procured, 95% of which were taken in the 12 months leading to November 2025. The sampling offers reasonable coverage of Thailand’s most densely populated provinces, and captures more recent developments than those reflected in the energy ministry’s 2023 statistics.
Within these samples, we identified and labelled solar installations, before examining how installation rates vary by building size, region, and urban or rural setting. Analysis of these labelled datasets was then used to develop an extrapolation model that estimates rooftop solar capacity across Thailand and its regions.
The detailed technical methodology can be found here.
What we found
The results were mapped using a hexagonal grid to visualise how rooftop solar capacity is distributed across Thailand. In the heatmap, taller, 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 3.60 GW of installed rooftop solar capacity in Thailand, notably higher than official statistics as of 2023.
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 yields an estimated range of 3.02 GW - 4.17 GW of total rooftop solar capacity nationwide.
The tables below show a breakdown by administrative region and sector.
Relative to deployment trends in Southeast Asia, Thailand’s rooftop solar installation rate exhibits a distinct pattern. Specifically, Thailand outperforms both Malaysia and Vietnam in installations on smaller rooftop areas (below 1,000 square metres). This indicates that, on residential properties or small commercial buildings, the installed solar systems tend to be larger in area size than those typically deployed in the other two markets.
However, for rooftop areas above that threshold, Thailand’s installation rates fall between those observed in Malaysia and Vietnam. This positioning underscores Thailand’s comparatively lower solar adoption rate than Vietnam, but higher than Malaysia, across larger – most likely C&I – rooftops and buildings.
What’s next?
The Thai government has recently updated its commitment to achieve net zero emissions by 2050, bringing the timeline forward by 15 years compared to its previous pledge. The long-awaited draft power development plan has once again been scrapped, and a new drafting panel convened with the mandate to produce a more ambitious blueprint to align with a 2050 net zero trajectory.
While long-term planning continues, incremental policy measures to support rooftop solar deployment are already being rolled out. TransitionZero estimates indicate that uptake has increased notably since 2023.
Closely tracking market responses in a timely and systematic manner will be critical to informing fast policy refinements. TransitionZero’s rooftop solar estimation methodology can be deployed on a recurring basis to support this objective, particularly as Thailand must accelerate renewable energy deployment to strengthen energy security and contain electricity costs.
*Note: All solar capacities expressed in this blog are in alternating current (AC).
This is part of a series of blogs presenting our findings on the status of rooftop solar deployment in Southeast Asia and South Asia. Check out our earlier blogs on Pakistan, Vietnam, and Malaysia, and stay tuned for upcoming analyses featuring Indonesia and Bangladesh.
