[Paper Review] Practical development of efficient thermoelectric – Photovoltaic hybrid systems based on wide-gap solar cells

Bruno Lorenzi, Paolo Mariani+4 more|arXiv (Cornell University)|Jan 1, 2021

Perovskite Materials and Applications55 references62 citations

TL;DR

This study proposes and experimentally validates a thermally coupled, electrically separated hybrid thermoelectric-photovoltaic (HTEPV) system using customized bismuth telluride thermoelectric generators (TEGs) paired with wide-bandgap solar cells. The system achieves a maximum efficiency gain of +3.1% (from 16.4% to 19.5%) for perovskite solar cells under real operating conditions, demonstrating significant performance enhancement through heat recovery from photovoltaic losses.

ABSTRACT

The decrease of solar cell efficiency with temperature is a known problem for photovoltaics (PV). Temperature sensitivity can lead to a considerable amount of energy losses over the lifetime of solar panels. In this perspective Hybrid Thermoelectric-Photovoltaic (HTEPV) systems, which recover solar cell heat losses to produce an additional power output, can be a suitable option. However only hybridization of wide-gap solar cells is convenient in terms of efficiency gains and deserves investigation to evaluate HTEPV devices effectiveness. In this work we report the modeling and the development of customized bismuth telluride thermoelectric generators, optimized to be hybridized with amorphous silicon (aSi), Gallium Indium Phosphide (GaInP) or Perovskites solar cells. The model results showed in all three cases efficiency gains with a maximum of +3.1% for Perovskites (from 16.4% to 19.5%). These enhancements were then experimentally validated for the case of Perovskites solar cells, for which maximum gains were found to occur at typical operating temperatures of conventional PVs. This experimental evaluation demonstrated in an accurate fashion the real potential of thermoelectric hybridization of solar cells.

Motivation & Objective

• To evaluate the feasibility of hybridizing wide-bandgap solar cells with thermoelectric generators (TEGs) for enhanced efficiency.
• To model and optimize TEG design for thermal coupling with amorphous silicon (aSi), GaInP, and perovskite solar cells.
• To experimentally validate theoretical predictions of efficiency gains in HTEPV systems, focusing on perovskite solar cells.
• To demonstrate the practical potential of thermoelectric hybridization in real-world operating conditions.

Proposed method

• Developed a theoretical model to predict HTEPV system efficiency as a function of temperature, optical concentration, and cooling conditions.
• Selected perovskite solar cells as the optimal PV material based on modeling due to lower temperature sensitivity and higher potential efficiency gain.
• Designed and fabricated customized bismuth telluride-based TEGs optimized for thermal contact with the back of the solar cell.
• Conducted experimental characterization of the HTEPV system under varying temperatures, optical concentration, ambient pressure, and cold-side cooling.
• Used stabilized power measurements to accurately assess perovskite solar cell efficiency, minimizing hysteresis effects.
• Validated model predictions by comparing experimental results with theoretical efficiency gains across different operating conditions.

Experimental results

Research questions

• RQ1 Can thermoelectric hybridization significantly improve the efficiency of wide-bandgap solar cells, particularly perovskites?
• RQ2 Which wide-bandgap solar cell (aSi, GaInP, or perovskite) offers the highest efficiency gain when hybridized with TEGs?
• RQ3 What is the optimal TEG design for maximizing efficiency gains in thermally coupled HTEPV systems?
• RQ4 How do real-world operating conditions (temperature, optical concentration, cooling) affect HTEPV system performance?
• RQ5 To what extent do experimental results confirm the theoretical predictions of efficiency enhancement?

Key findings

• The theoretical model predicted a maximum efficiency gain of +3.1% for perovskite solar cells, increasing from 16.4% to 19.5% under optimized conditions.
• Experimental validation confirmed the theoretical predictions, demonstrating a measurable and significant efficiency enhancement in the HTEPV system with perovskite solar cells.
• The highest efficiency gains occurred at typical operating temperatures of conventional photovoltaic systems, indicating practical relevance.
• The hybridization strategy was most effective for perovskite solar cells due to their lower temperature sensitivity and higher potential for heat recovery.
• The study confirmed that thermally coupled, electrically separated HTEPV systems outperform optically coupled configurations by better recovering heat losses from the PV cell.
• The results demonstrate the real potential of HTEPV systems based on wide-bandgap solar cells, especially perovskites, for practical energy harvesting applications.