As India moves towards a greener future, the transport sector is doing its part by promoting electrification and sustainable mobility options. The Indian Railways and road transport systems are both playing a crucial role in this shift. With a goal of achieving net-zero carbon emissions by 2030, the Indian Railways strives to add an estimated 30 gigawatts (GW) of renewable energy capacity. Further, the National Highways Authority of India (NHAI) has partnered with the Solar Energy Corporation of India to explore solar deployment along national highways.These developments clearly signal the next phase of India’s energy transition, wherein transport infrastructure is not just a consumer of energy but also a source of clean energy. With attention now turning to how India’s road and railway infrastructure could double as clean energy generators, the emerging concept of rail/road-integrated photovoltaics (RIPV) offers a promising answer.RIPV: From pilot to practiceRIPV involves integrating solar photovoltaic (PV) systems directly into existing rail and road infrastructure. PV technology converts sunlight directly into electricity through the photovoltaic effect, where semiconductor materials in a PV cell absorb photons (particles of energy) from sunlight and release electrons, generating flow of electricity. How photovoltaic technology works.What sets it apart from conventional solar PV systems is that it eliminates the need for dedicated land for installation. Instead, solar panels can be installed along railway tracks, highway dividers, and medians or onto other structures. This not only overcomes land constraints but also brings energy generation closer to the point of consumption.Several European countries are exploring ways to integrate solar PV systems into the transport infrastructure. For instance, a solar noise barrier has been installed along the A50 motorway in the Netherlands, which is capable of supplying around 40-60 households with green electricity. Solar systems are also being installed along motorways near Germany’s Garzweiler open-pit lignite mine. Italy is also piloting PV guardrails, where solar panels are integrated into highway safety barriers.For rail-integrated applications, solar panels have been installed between the tracks of a railway line near Buttes in western Switzerland. The system generates about 16,000 kilowatt-hours (kWh, which measures the total amount of electricity one uses) of electricity annually — enough to meet the average consumption of 4-6 households. Lithuania, too, has installed its first railway noise barrier fitted with solar panels in Juodšiliai and is expected to generate up to 14 megawatt-hours of electricity each year.Story continues below this adThese installations may vary in design, but they share a common goal: delivering clean power without placing additional pressure on land resources.Building on global momentum, India has installed its first vertical solar plant (50 kWp) on the viaduct at Delhi Metro’s Okhla Vihar station, using bifacial panels that generate electricity from both sides. kWp refers to kilowatt-peak, which represents the maximum theoretical power a solar PV system can generate under ideal, bright laboratory conditions.Also in Explained | Power subsidies are slowing household solar adoption. A solution: More subsidiesThe National Capital Region Transport Corporation and Indian Railways have also piloted “solar-on-track” systems for the Namo Bharat network and at Banaras Locomotive Works in Varanasi, respectively. NHAI also plans to install solar panels on elevated sections of the Delhi-Dehradun Expressway and replicate the model across national highways.Despite being implemented on a small scale, these projects demonstrate that RIPV systems can be deployed and operated under Indian conditions, helping validate the concept for wider adoption and future scale-up.Story continues below this adAccording to data from the Ministry of Road Transport and Highways and the Indian Railways Civil Engineering Portal, India has over 1.4 lakh km of national highways and 99,000 km of railway tracks. These networks form the backbone of the country’s logistics and freight movement. As freight traffic increases and transport systems become more electrified, electricity demand from the sector will grow.Given India’s clean energy and sustainability goals, this demand will need to be met through renewable energy sources. Relying solely on conventional renewable energy systems, however, may not always be practical or cost-effective, especially in areas with limited land.RIPV could serve as a solution here. Recent assessments show significant potential for RIPV in India. A national-level study conducted under the Indo-German Solar Partnership estimates over 150 GW of RIPV potential, with railway corridors accounting for around 79 GW and highways around 75 GW. Harnessing even a fraction of this potential could make a meaningful contribution to India’s renewable energy expansion and transport decarbonisation goals.Supporting India’s energy transitionIn a land-constrained country like India, RIPV can support clean energy generation without requiring large areas of land, making better use of existing or underutilised spaces. Story continues below this adRIPV can also help reduce transmission losses by generating electricity closer to where it is needed, such as logistics hubs and traction substations. One important application is powering electric vehicle (EV) charging stations, which are rapidly increasing along India’s highways. RIPV systems can be installed alongside or near EV charging stations, enabling these stations to be powered by locally generated renewable energy.Also read | Green energy can’t yet bend climate curveAs India works towards achieving 300 GW of non-fossil fuel capacity by 2030 and net-zero emissions by 2070, while continuing to face land-use constraints, the overall benefits of RIPV could be significant.What nextThe main barriers to deploying RIPV in India are not technological. Solar PV systems and related technologies are already well established. Rather, the key challenges are institutional, regulatory, and financial.Government agencies are still gaining experience with solar PV integration into transport corridors. Several issues need to be addressed, including design standards, safety and security requirements, operation and maintenance practices, financing mechanisms, and project approvals.Story continues below this adCost is another important concern: RIPV systems can be more expensive than conventional solar PV because they often require additional structures for installation. But they remain an attractive option because they avoid additional land procurement costs and maximise the use of existing infrastructure and underutilised spaces.NewsletterFollow our daily newsletter so you never miss anything important. On Wednesday, we answer readers' questions.SubscribeFor RIPV to move beyond pilot projects and become a mainstream solution, several gaps need to be addressed. Clear technical standards, larger demonstration projects across highways and railway corridors, and tailored financing models are crucial.Policy support will also play a key role. India has successfully expanded rooftop solar and agricultural solar systems through initiatives such as PM Surya Ghar Muft Bijli Yojana and PM-KUSUM. As a largely land-neutral solution that can support both renewable energy growth and freight decarbonisation, RIPV is well positioned to benefit from similar policy backing.Ultimately, the future of RIPV in India will depend on the success of ongoing pilots and the policy measures that follow. If these efforts prove successful, RIPV could evolve from a set of isolated demonstrations into a scalable solution that contributes to India’s clean energy and transport transition.Story continues below this adThe writer is the sector coordinator for renewables and energy conservation at the Center for Study of Science, Technology and Policy (CSTEP), a research-based think-tank.