溫度、濕熱及電極密度對聚光型太陽電池轉換效率影響之研究

Influence of Temperature, Damp Heat and Metal Grid Density on Energy Conversion Efficiency of Concentration Solar Cells

洪慧芬(Hwen-Fen Hong)

指導教授 ： 黃倉秀

國立清華大學/工學院/材料科學工程學系/博士(2014年)

https://doi.org/10.6843/NTHU.2014.00105

摘要

本論文主要研究溫度應力、濕熱應力以及金屬電極密度對III-V族 InGaP/InGaAs/Ge多接面聚光型太陽電池能量轉換效率之影響。在可靠度研究方面，係利用步階式加速老化試驗方法，以分析特性衰退之原因；為加速觀察到特性衰退現象，太陽電池沒有光學膠保護。在溫度應力試驗方面，根據照光與不照光的電流-電壓量測數據，分析結果顯示，特性衰退主要原因為太陽電池元件周圍產生缺陷，以致復合電流增加，開路電壓下降，使得光電轉換效率下降。在濕熱應力試驗方面，實驗結果顯示電池邊緣處，鍺基板在濕熱環境之下產生崩裂，造成漏電途徑，致使太陽電池失效。
太陽電池在聚光條件之下，會產生較多之電流，較密之電極線雖能有效且快速地收集電流，但是電極線過密，會減少太陽電池表面之集光面積。本論文應用一套理論模式，分析太陽電池之線型指叉式金屬電極的不同柵狀電極密度，對太陽電池特性參數之影響，並與實際戶外測試數據比較，作為最佳化設計之參考依據。結果顯示，在低聚光比時，整體功率損失由電極遮蔽率主導，在高聚光比時，則必須由遮蔽率與金屬電極阻抗兩者折衷優化。

關鍵字

步階式應力加速老化試驗 ； 溫度應力 ； 濕熱應力 ； 聚光型太陽電池 ； 金屬電極 ； 戶外測試

並列摘要

The object of this dissertation is to study the influences of temperature stress, damp heat stress and metal grid density on the energy conversion efficiency of InGaP/InGaAs/Ge multi-junction concentration solar cells. In the reliability studies, step stress accelerated degradation tests were employed to investigate the degradation of cell. In order to accelerate the observation of degradation, solar cell were not encapsulated with protective silicone layer. In the temperature stress studies, the dark and light current-voltage measurements indicated that recombination current increased, open circuit voltage decreased and energy conversion efficiency decreased. These results were caused by defects generated in the peripheral region of solar cells. In the damp heat stress studies, experimental results indicated that cracks generated at Ge substrate in the edge region of solar cell, which induced leakage path and failure of solar cell.
Under light concentration condition of solar cell, more metallic electrodes can rapidly collect current and thus generate more current; however more denser electrode will also decrease the light collection area of cell. This dissertation employs a theoretical model to analyze the influence of the grid density of linear metallic grid on the electro-optical characteristics of concentration solar cells. These results were compared with outdoor experimentally measured data in order to provide the basic references for optimal designation of cell. It is found that the total power loss was dominated by grid shadowing effect at lower concentration levels, while there existed an optimal condition for compromise between grid shadowing effect and resistance of metal lines at higher concentration levels.

並列關鍵字

step stress accelerated degradation test ； temperature stress ； damp heat ； concentration solar cells ； metal grid ； outdoor test

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