因應地球暖化氣候變遷，為確保地球永續經營，再生能源成為未來之重要課題。因此各國政府均積極推展再生能源，如風力、水力、洋流、生質能及太陽能。其中太陽光電及太陽光熱的應用在再生能源中扮演著很重要的角色。
由於臺灣位於北迴歸線附近，日照時數長，所以我國推廣太陽能熱水器具有相當優勢。隨著政府補助節能裝備政策之進行，民間裝設太陽能熱水器也相當普遍。
太陽熱水器為符合使用者需求，熱水溫度不足部分需以電熱方式加熱。但臺灣各地因氣候條件不同，如南北位置和不同季節下之氣溫、太陽輻射與需求溫度設定等差異，均會影響輔助電熱能之需求。
本研究嘗試以學術界與業界最常使用的套裝軟體 TRNSYS 對經典氣象年中的太陽氣象資料加以運算，希望能模擬出可靠性及準確度較高的結果，以便後續對太陽熱能相關的運用能有適當及可靠的評估依據。
首先以一般國內最常用面蓋式平板太陽能熱水器輻射量數據驗證所收集的實際量測數值，選擇低中高不同每日累積太陽輻射量進行運算，以占比天數最高的中輻射量相關數據之模擬結果最符合實際儲水桶水溫變化。接著以前述驗證結果針對TRNSYS套裝軟體關鍵參數進行最佳化設定，然後利用TRNSYS參數進行最佳化設定試著模擬出我國各地區使用太陽能熱水器所需輔助電量消耗及太陽分率。
影響TRNSYS模擬耗電量與太陽分率之主要因素有二:
(1).TRNSYS集熱板熱效率設定:對一般國內常用面蓋式平板太陽能熱水器輻射量實際數據驗證，以選擇最佳參數設定。
(2).需求溫度設定:因每增加1°C，以儲水桶體積240公升而言，能量需求約增加0.28度電，考慮電熱損失5%，需求溫度提高1度會增加輔助電量為0.28 / 95% = 0.29度電。本研究採用略高於體溫的設定(夏季40°C，冬42°C)。
地理位置因素包含太陽輻射量及環境溫度，普遍來看臺灣地區夏季期間，太陽能熱水系統大都能發揮作用加熱至需求溫度以上。冬季則隨區域差異而有不同表現。如東北部與部分離島冬季受東北季風影響，太陽輻射量較小且環境溫度偏低，同時冬季比夏季更有熱水需求，這些也都影響此等地區年度輔助電能消耗與太陽分率表現。
以年度耗電量(含電熱損5%)來看，北部都會區(臺北、板橋與新竹)平均為660度，而基隆受東北季風影響，年耗電量較高為808度。東部地區而言，臺東、成功及大武平均年耗電量約420度。花蓮因東北季風影響，模擬年耗電量為646度電。離島部分(不含馬祖)，年度耗電量約600度。尤其是馬祖因東北季風及冬季低溫影響，模擬年耗電量約1036度。南部都會區 (嘉義、臺南及高雄)因日輻射量強，且環境平均溫度也高，平均年耗電量約為256度。尤其是恆春年耗電量僅約140度。整體年度耗電量表現呈現本島東北部高於中南部及離島高於本島的趨勢。
年度太陽分率來看，東北部約為太陽分率大多為60~70%之間，彭佳嶼、淡水與基隆位於東北季風迎風面，導致太陽分率偏低。離島部分則是50~70%，尤其是馬祖，緯度最高，東北季風強，冬季低溫，太陽分率也最小(53.5%)。中南部太陽分率則都有80多到90%的表現，明顯優於東北部。整體年度太陽分率表現呈現本島中南部於東北部及本島高於離島的趨勢。
同時年度模擬耗電量與太陽分率大約呈現直線負相關的趨勢，也就是說太陽分率越高的話，年度耗電量越低。
總而言之，不論是年度耗電量或太陽分率，以量化趨勢而言，整體表現均呈現中南部明顯優於其他地區，本研究成果希望作為往後相關太陽熱能研究時有所幫助。

In response to global warming and climate change, renewable energy has become an important topic. Therefore, the governments of various countries are actively promoting renewable energy sources, such as wind power, water power, ocean currents, biomass energy, and solar energy. Among them, photovoltaic and solar heat play important roles in renewable energy applications.
Since Taiwan is located across the Tropic of Cancer and has long hours of sunshine, it has considerable advantages in terms of promoting solar water heaters. With the implementation of governmental subsidies for energy-saving equipment and policies supporting their use, the installation of solar water heaters by the private sector is also quite common in Taiwan.
In order to meet the hot water needs of users, a solar water heater has to be accompanied with a supplementary electrical heating device. However, different climatic conditions in various places in Taiwan, such as locational differences, the ambient temperature in different seasons, solar radiation intensity, and demand temperature settings, etc., will affect the demand for auxiliary electrical heat.
TRNSYS software, which is commonly used in academia and industry, is used in this research to calculate the solar energy absorbed by a solar water heater based on meteorological data collected for typical meteorological years.
The supplementary heat required to reach the setting water temperature for bathing is determined with the difference between the setting temperature and the hot-water-tank temperature at the time of 18:00. If the hot-water-tank temperature is not lower than the setting temperature, no supplementary heat is required. The short part is heated by an auxiliary electrical heater.
The overall annual power consumption performance showed a trend suggesting that the northeastern part of Taiwan has higher consumption than the central and southern parts and that the outlying islands consume more than the Taiwan Main Island.
The overall annual solar fraction performance showed a trend indicating that the central and southern parts of Taiwan have higher solar fractions than the northeast and that the Taiwan Main Island is higher than the outlying islands.
At the same time, the annual simulated power consumption and solar fraction were found to be approximately linearly negatively correlated; that is to say, a higher solar fraction means lower annual power consumption.
Overall, whether one considers the annual power consumption or the solar fraction, in terms of quantitative trends, the overall performance of the central and southern regions was found to be significantly better than the other regions under consideration.
It is hoped that results of this research will be helpful in understanding the distribution of the supplementary heat demand for use of solar water heater in Taiwan.

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