In the global quest to squeeze every possible watt of energy from solar panels, researchers often pursue complex and costly materials science breakthroughs. Nonetheless, a group of scientists in Iran has proven that a remarkable improvement in efficiency can be realized without reinventing the cell, but instead, rethinking the simple cooling channel. Their pioneering study using computational simulation shows that an easy-to-use twisted tape inserted into the water-cooling channels of a photovoltaic (PV) module can lead to an impressive decrease in operating temperature and an increase in electrical efficiency of up to 11.84%.

The persistent plague of the “temperature coefficient” is a fundamental challenge for the solar industry. For each degree Celsius that a solar panel operates above the standard 25°C test condition, it can potentially lose around 0.4% to 0.5% of its power output. In regions with plenty of sun, modules can reach 70°C or greater, leading to even greater efficiency losses, in some cases, over 15%. Thermal degradation reduces energy yield per day and quickens material degradation over the lifetime of the module, damaging its longevity. Actively water cooling solar modules is a good way to treat thermal loss, yet the energy and complexity involved in this technology usually negates the benefits of solar for a large-scale producer. The Iranian research was examining ways to solve this footprint reducing the cooling method extremely effective.

The Science of Swirl: From Laminar to Turbulent Flow

The research team employed sophisticated Computational Fluid Dynamics (CFD) software to create a virtual model of a PV module with integrated water-cooling channels. The core of their investigation was the insertion of a twisted tape—a thin strip of metal or polymer twisted along its length—into these channels.

The innovation lies in its manipulation of fluid dynamics. In a standard, empty cooling channel, water tends to flow in a smooth, “laminar” manner. The water closest to the hot surface of the PV module heats up and forms a stagnant, insulating boundary layer that acts as a thermal blanket, hindering further heat transfer.

“The twisted tape is a brilliantly simple vortex generator,” explained a lead researcher on the project. “It doesn’t just let the water slide past; it forces it into a violent, spiraling motion. This swirling action continuously scours away that insulating hot water layer, bringing fresh, cooler fluid from the center of the channel into direct contact with the heated walls. This process, known as convective heat transfer enhancement, is dramatically intensified.”

Parametric Optimization: Finding the Perfect Twist

The work was much more than a simple proof-of-concept. The researchers conducted a very thorough parametric study in which they systematically tested several different physical characteristics of the twisted tape to the final result. Among the major variables were:

• Twist Ratio: Twist ratio is simply defined as the length of one full, 180-degree twist divided by the width of the tape, and the group tested low-twist (tight wind) and high-twist (looser wind) configurations to find the sweet spot between maximizing turbulence and minimizing pumping power.
• Material of the Tape: Simulations compared materials of common, low-cost but less conductive polymers to highly conductive metals, like copper.
• Flow velocity: Evaluating the interaction of the twisted tape with the coolant water as the speed of the tank was deemed the most energy-efficient operating point of the 3 tested schemes.

The results were clear: an optimally designed twisted tape insert could lower the average operating temperature of the PV module by 15-20°C under peak solar irradiance. This significant cooling effect was the direct driver behind the simulated electrical efficiency increase of 11.84%. The study successfully identified specific parameter combinations that maximized heat transfer while keeping the hydraulic resistance—and thus the pumping power needed—at an acceptable level, ensuring the net energy gain remained highly positive.

Broader Implications and Future Pathways

The implications of this simulation study extend far beyond the specific water-cooled system modeled. It provides a powerful conceptual blueprint for enhancing thermal management across a wide spectrum of renewable energy systems.

“This research validates a core principle: passive flow disruption is a highly effective and energy-smart strategy for PV cooling,” the researcher noted. “While our model used water, the fundamental physics of breaking up boundary layers applies equally to air. The next step is to develop and test practical, low-cost twisted tape or similar vortex-generating inserts for passive air-cooling systems, which could be retrofitted to existing solar farms around the world at a minimal cost.”

This technology possesses a vast range of possibilities. For a utility-scale solar plant with a capacity of 1 MW, an 11% lift in energy output translates into several million kilowatt hours of electricity produced per year, which significantly contributes to the efficiencies in both the economics of the project and its land use. As the average temperatures are cooler, this will also extend the operational lifespan of the solar panels, thus lowering the long-term costs of both solar energy and electronic waste.

The research team is now moving to the prototyping stage, constructing physical models to compare their simulation data with real performance. They are also looking for collaborations with solar module manufacturers to incorporate this cooling geometry into new solar panel designs— this work represents a strong and meaningful validation of the idea that in the pursuit of energy and climate solutions, a small geometric variation on a simple idea can, in some cases, produce substantial gains compared to even the best laboratory.