Distributed solar energy presents a significant opportunity to bridge the gap between rising electricity demand and Tamil Nadu’s clean energy transition goals. Tamil Nadu’s total solar distributed energy resources (DER) potential is estimated at 129,166 MW, which includes multiple solar photovoltaics (PV) applications such as rooftop solar (RTS), urban PV, building integrated PV, floating PV, canal top solar PV, rail PV and road integrated PV systems. Of this, RTS alone accounts for 60,479 MW. However, as of April 2025, only 0.78% of the total DER potential and 1.66% of the RTS potential had been realised, highlighting a major implementation gap.
The Tamil Nadu Solar Energy Policy 2019 set a target of 9,000 MW of installed solar capacity by 2023, with 3,600 MW designated for the consumer category, including RTS and other distributed systems. As of April 2025, RTS deployment stands at 1,003.30 MW, representing only 27.87% of the target for the consumer category. This installed capacity also accounts for less than 10% of Tamil Nadu’s total installed solar capacity.
Tamil Nadu’s full solar DER potential could generate 203.67 TWh annually—enough to meet 100% of the state’s projected electricity demand in 2030–31 and 82% by 2034–35. RTS alone could supply 95.40 TWh annually, covering 47% and 38% of demand for those respective years. In comparison, thermal power generation (coal, oil, and gas) stood at 74.22 TWh in 2024–25. This could be entirely offset by deploying just 37% of the DER potential or 78% of the RTS potential.
Tamil Nadu has planned an addition of 18,400 MW of solar capacity between 2024–25 and 2034–35. If this entire capacity is allocated to DER systems, it would meet only 14.25% of the total DER potential. If fully dedicated to RTS, it would address 30% of the RTS potential. Thus, a significant portion of the state’s solar resource remains untapped.
The expansion of DER, including RTS and other distributed renewable energy resources, provides multiple network level benefits such as avoided costs of energy (ACE), transmission (ATCC), distribution (ADCC), and generation (AGCC) capacity costs. At the societal level, DER deployment contributes to emissions reduction, job creation across the renewable energy value chain, and cost savings for consumers. It also enhances climate resilience and energy security by decentralizing production and improving access during extreme events.
Lastly, district-level data reveals significant variation in solar DER potential across Tamil Nadu, suggesting opportunities for targeted interventions. Given the state’s high solar potential and growing electricity demand, Tamil Nadu can accelerate DER deployment across all applications, not just RTS.
