一種太陽光電集熱複合型系統能源性能研究分析

Abstract

地球初級能源蘊藏量有限，且全世界石油使用年限約45年後耗竭，為降低化石能源依賴，世界各國積極發展再生能源(如歐盟規劃2010年再生能源佔總發電量比例達20%)。在則IEA預測2008~2030年未來全球初級能源需求年平均成長率約為1.6%，由此可見人類對於能源的依賴已是密不可分。然而太陽能一年約可提供23,000 TWy/year，此能量與其他能源相比遠遠大於人類所需求，故綜合以上太陽能優勢，若能積極發展與投入應用將是解決未來能源危機與再創能人類巔峰革命的最佳途徑之一。 目前太陽能的利用技術已是當今世界各國利用再生能源進行能源替代、節能、環保的重要研究項目之一，其主要應用分為太陽電能及太陽熱能兩個領域。在太陽電能方面，主要是利用太陽光電晶片吸收400~1000nm太陽光譜並將吸收之光子轉換成電能，其中未被轉換成電能的太陽光子在符合能量不滅定律下，60%~70%會被轉換成熱能並使太陽光電模組(PV Module)整體溫度上升，通常PV模組背溫可高達75℃或更高，此時太陽能電池的實際最大功率將比標準測試環境(STC)下的最大功率減少18%~25%(相對值)。另外PV模組發電效率受溫度係數影響之特性，在結晶矽型PV模組發電效率特性會隨著溫度每升高1℃則降低0.4~0.5%發電效率，而在非晶矽型PV模組發電效率也會降低約0.25%。故本研究提出太陽光電與集熱複合型(PV/T)設計應用概念，將PV模組背熱透過高導熱材料(如銅或鋁材)之集熱器，以熱傳導和熱對流的方式達到散熱與儲熱之目的。 研究PV/T模組最主要是希望能提升太陽能綜合應用的效益，另外台灣再生能源熱利用獎勵補助辦法中，明訂太陽能熱水器性能標準須大於等於50%，故本研究以開發製作PV/T系統能源綜合效率(電能+熱能)大於50%為指標。然而開發PV/T模組的關鍵在於確保PV模組與集熱器之間是否有良好的結合、集熱器管道設計(管數、管徑、流道配置、材質)、封裝黏著材料其須具備高熱傳導性與極佳的電絕緣能力，另外在保溫能力方面也是決定集熱效率重點的要因。後續本研究也開發三款新型PV/T模組，並以Type-1 PV/T模組性能最佳，其在開路電壓狀態下，且入口溫度與環境溫度設定相同時，集熱效率(ηt)最高可達60.55%。另外在併接上具有MPPT功能之電子負載狀態下，且入口溫度與環境溫度設定相同時，集熱效率(ηt)最高可達47.45%，發電效率為13.25%，其綜合效率為60.70%。 最後本研究也針對所開發之Type-1 PV/T模組作系統全天性能測試，測試結果得到集熱效率最高可達42.49%(水溫約可提升10℃)，發電效率為13.05%，能源綜合效率55.54%，達成本實驗設計指標。另外也利用TRNSYS動態仿真軟體模擬與設計PV/T系統，其中，熱效率與電效率在實測數據與模擬數據相互比較下，TRNSYS模擬之相對誤差小於10%以內。

Earth's primary energy reserves are limited, and the world's oil depletion in the useful life of about 45 years, to reduce fossil fuels dependence, the world is actively developing renewable energy. IEA forecast the future of global primary energy demand annual average growth rate of about 1.6% in 2008 and 2030 shows that the human energy dependence are inextricably linked. However, solar year, about 23,000 TWy / year, this energy compared and other energy sources is far greater than human needs. Actively develop and put into application will solve the energy crisis and one of the best way to create human pinnacle of revolution. Nowaday the worldwide countries take the research on renewable energy,saving energy and environmental protection to take new resource from using technology of solar,which mainly applied on solar thermal energy and solar power. In solar electricity, solar cell absorb 400 ~ 1000nm solar spectrum and absorption of photons into electrical energy,which was not been transferred are one of important research objects on saving energy and environmental protection , its mainly application under the law of conservation of energy ,60% to 70% will be converted into thermal energy and raise the back side temperature on photovoltaic modules (PV module) , usually the temperature came up to 75 ° C even higher, the actual maximum power (Pmax) of the solar cells was less than Standard test Condition(STC) reduced around 18% to 25%(relative value). PV module power generation efficiency is affected by the characteristics of the temperature coefficient, under STC model the photovoltaic chip with packaged we found its temperature coefficient of its power generation efficiency, when it in crystalline photovoltaic modules the characteristics of the power generation efficiency decrease from 0.4 to 0.5% as the temperature increasese 1℃, then in Amorphous Si photovoltaic modules will be reduced by about 0.25%. In this study provide the concept of design applications of solar photovoltaic and collector efficiency (PV / T), heat the back of the photovoltaic modules with high thermal conductivity materials (such as copper or aluminum) collector, to achieve the purpose of cooling and thermal storage by the thermal conduction and convection. PV / T module is to enhance the effectiveness of the integrated solar applications, In addition, Taiwan's renewable energy incentive measures to aid the express solar water heater performance standards must be greater than or equal to 50%,in this research develop production of PV / T system energy efficiency (electricity & heat) is greater than 50% as an indicator.The key point in development PV / T modules is to ensure whether there is a good combination between the PV modules and solar collector, the collector pipe design (tube number, diameter, flow channel configuration, material) package adhesive material shallwith high thermal conductivity and excellent electrical insulation, insulation capacity also determine the collection efficiency. After that developed the three PV / T module, in which Type-1 PV / T module has the best performance,the collection efficiency (ηt) can came to 60.55% when the inlet and ambient temperature set as the same degree with the open circuit voltage state. In addition, if connected to the MPPT function electronic load state, when the inlet and ambient temperature is set the same degree, the collection efficiency (ηt) up to 47.45%, 13.25% power generation efficiency, the overall efficiency of 60.70%. In this study, also development Type-1 PV / T module for system performance testing,as results the thermal efficiency up to 42.49% (water temperature is upgrade to 10℃), the power generation efficiency to 13.05%, the comprehensive energy efficiency by 55.54%, it was reached the index of the experimental design.And also under TRNSYS, (Transient Cycle Systems, Dynamic Simulation Program) software simulation and designed PV / T system,compare the measured data and simulation data , TRNSYS simulation of the relative error is less than 10%.