Green hydrogen — produced by splitting water into hydrogen and oxygen using renewable energy — is central to global decarbonisation efforts. While photovoltaic (PV) systems are widely used to power hydrogen production, new research highlights the potential of an emerging technology: photovoltaic-thermal (PV-T) systems. Unlike standard PV panels, PV-T systems simultaneously generate electricity and capture heat, presenting an opportunity to maximise solar energy efficiency.
A study from Qatar University [25.4°N, 51.4°E] provides a comprehensive comparison between PV and PV-T systems, revealing fresh insights into their efficiency, economics, and potential for optimising hydrogen production across varied climates.
What Makes PV-T Systems Different?
PV-T systems integrate the functions of traditional PV panels with solar thermal collectors. They generate electricity as PV panels do, but they also channel excess heat into a water circuit, cooling the panels and improving their efficiency. This dual-output—electricity and heated water—directly enhances the performance of the hydrogen production process, especially by improving the efficiency of water electrolysis.
The research breaks new ground by comparing PV and PV-T systems across three diverse locations — Doha, Tunis, and Stuttgart — accounting for differences in solar irradiance and ambient temperatures. This is the first study to evaluate how the use of preheated water from PV-T systems affects hydrogen production, offering an integrated look at both performance and cost.
Key Findings
1. Enhanced Hydrogen Production
PV-T systems outperformed PV panels in hydrogen output across all climates:
- 78% more hydrogen in Doha
- 59% more hydrogen in Tunis
- 25% more hydrogen in Stuttgart
The preheated water supplied by PV-T systems boosts electrolyzer efficiency by reducing energy losses in the electrolysis process. Additionally, the thermal cooling of PV-T panels prevents overheating, maintaining their energy conversion efficiency.
2. Climatic Adaptability
The study reveals how climatic conditions influence the relative performance of PV-T systems:
- Doha (hot, high solar irradiance): PV-T systems excel due to their ability to handle excess heat, converting it into useful thermal energy.
- Tunis (moderate): PV panels perform well due to lower ambient temperatures but still lag behind PV-T systems.
- Stuttgart (cool, low irradiance): PV-T systems provide less added value as the thermal component is underutilised.
3. Economic Considerations
While PV-T systems deliver more hydrogen, they remain costlier. The levelised cost of hydrogen (LCOH) analysis shows:
- PV panels are the cheaper option, with costs ranging from $4.92/kg in Tunis to $9.66/kg in Stuttgart.
- PV-T systems’ costs vary more widely, from $6.66/kg in Doha to $16.80/kg in Stuttgart.
Nevertheless, PV-T’s dual energy output and potential for future cost reductions make it an attractive option for regions with high solar potential and hydrogen demand.
Optimisation Strategies
To maximise PV-T efficiency, the study explored the impact of varying water flow rates. Higher flow rates cooled the collectors more effectively, increasing electricity output but slightly lowering water temperature. The optimal balance, identified at a flow rate of 0.23 m³/h, achieved a 15% increase in electricity generation and a 30.9% boost in hydrogen production.
Implications for a Sustainable Future
This research underscores the transformative potential of PV-T systems for sustainable energy:
- Efficiency gains: By leveraging thermal energy, PV-T systems enable more efficient use of land and resources, critical for large-scale green hydrogen projects.
- Climate adaptability: The technology is well-suited for hot climates, where its cooling function significantly enhances performance.
- Scalability: With ongoing improvements in manufacturing and economies of scale, PV-T systems could rival PV panels in affordability.
For policymakers and investors, the findings offer a clear call to action: regions with high solar potential should prioritise the development of PV-T systems alongside hydrogen infrastructure. For individuals and businesses, PV-T represents an innovative pathway to maximising the value of renewable energy investments.
Green hydrogen production is not just about meeting energy demands; it’s about doing so sustainably and efficiently. This research shows that integrating PV-T systems into solar projects can unlock new levels of performance, driving the energy transition forward while making the most of the sun’s potential.
Source
Harnessing enhanced solar efficiency for green hydrogen production: A comparative analysis of PV and PV-T systems, International Journal of Hydrogen Energy, 2025-01-13
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