By Gautam Mohanka, Chief Executive Officer, Gautam Solar
India’s solar ambitions demand a clear focus on the right solar technologies that align with the country’s unique climate, land availability and industrial readiness. Two technologies dominate the advanced Photo Voltaic landscape globally – tunnel oxide passivated contact (TOPCon) and back contact (BC).
This article discusses the key highlights of both technologies and concludes that TOPCon has emerged as the most practical and impactful choice for India’s near and mid term solar manufacturing evolution…
TOPCon
TOPCon has quickly become the leading contender for countries aiming to transition from conventional passivated emitter and rear cell (PERC) technology to next-generation solar modules. With cell efficiencies ranging from 24 to 25.5 per cent, TOPCon offers a significant upgrade over the average 22 per cent efficiency of standard PERC modules. Its superior temperature coefficient (approximately 0.29 per cent per °C) ensures high performance even during extreme summer conditions typical across India, where daytime temperatures often exceed 40 °C.
Real-world performance metrics validate TOPCon’s technical promise. In Rajasthan, where ambient temperatures and irradiance are among the highest in the country, TOPCon modules generated 8.2 per cent more annual energy than equivalent PERC systems installed under the same conditions. This gain is especially important in a country like India, where solar power plays a growing role in grid stability and peak demand management.
TOPCon’s bifacial capability enhances its appeal even further in the Indian context. Bifacial modules capture reflected sunlight from the ground in addition to direct sunlight from above, generating 22-30 per cent more energy output per square metre, depending on site conditions. In land-constrained or premium land cost regions, such as industrial parks, rooftop systems and agrivoltaic farms, this performance gain is critical.
The benefits extend beyond just energy production. Bifacial TOPCon technology makes projects more compact, helping developers meet energy goals within smaller footprints. In densely populated or agriculturally sensitive regions, this land efficiency translates to faster project execution and higher returns per acre. For example, in Maharashtra, a 10 MW plant using TOPCon modules was found to generate 330 MWh more annual energy than a comparable PERC plant, offering significantly higher revenue with the same land and infrastructure.
BC technologies
While BC technologies such as interdigitated back contact also deliver impressive performance – with efficiencies of 24.5-25.8 per cent – they come with greater manufacturing complexity and higher production costs. BC modules eliminate front-side metal contacts by moving them to the rear, improving light capture and reducing shading losses. This also gives them a visually appealing uniform front, making them a preferred choice in premium residential and building-integrated solar applications.
However, BC modules demand sophisticated cell architecture, precise alignment of rear contacts and specialised encapsulation techniques. These processes are capital-intensive and not easily integrated into existing manufacturing lines. As a result, BC modules remain a niche product, better suited for markets where aesthetics and space efficiency justify higher module prices, such as luxury residences or architecturally integrated systems.
For India, which currently aims for high-volume, cost-effective solar deployment, the trade-offs of BC technology outweigh the benefits. The price-sensitive utility-scale and commercial rooftop markets do not offer the margins required to absorb the higher cost of BC modules. While BC may have a place in the future, its present role in India’s large-scale solar growth remains limited.
Why TOPCon fits India’s solar road map
TOPCon’s edge goes beyond field performance – it lies in its ease of adoption within existing manufacturing infrastructure. Most Indian module manufacturers currently operate PERC production lines. With relatively modest investment, these lines can be upgraded to produce TOPCon cells and modules, avoiding the need for complete factory overhauls.
Compared to the set up of new lines required for more complex technologies, TOPCon upgrades require up to 40 per cent lower capex. This makes it a practical step forward for manufacturers seeking to improve their competitiveness without making prohibitively expensive changes. More importantly, Indian manufacturers are already demonstrating success with this transition: several domestic producers have achieved TOPCon cell efficiencies exceeding 24.5 per cent, with annual degradation rates under 0.4 per cent, a significant improvement over PERC averages.
This alignment with existing industrial infrastructure makes TOPCon the ideal transitional technology, allowing the country to scale its manufacturing base, boost quality and reduce its dependence on imported technologies. TOPCon modules are typically built with glass-to-glass architecture, which enhances mechanical strength, protects against moisture ingress and extends module lifespan. Combined with their lower degradation rates, these features result in higher life time energy yields and better levelised cost of energy.
For utility developers and project financiers, this means lower operating costs and more predictable returns. From a technical perspective, these characteristics also contribute to lower failure rates, reduced operations and maintenance intervention, and improved performance ratios over 25-year project lifespans.
What India needs today is not just innovation but deployable innovation. TOPCon stands out because it is both technologically advanced and industrially viable. It allows India to evolve from assembling basic modules to producing globally competitive, high-efficiency products while maintaining affordability and scalability.
