對台灣地區而言，再生能源當中，屬太陽能應用最為廣泛。因為台灣位於亞熱帶地區，日照充足，適合發展太陽光電與太陽熱能應用。由於太陽能所應用的太陽輻射量來源分為兩部分：直射輻射量與漫射輻射量，而兩者間的比例很直接地影響到太陽能的應用方式，例如聚光型的太陽能中高溫裝置，該裝置利用反射或是透鏡將直射輻射量集中，達到增幅接受量的效果，因此了解台灣本島的漫射比率，有助於針對中高溫的太陽熱能應用及聚焦暨光電系統開發進行深度研究，也同時可以了解台灣各地區的太陽能裝置在安裝上的適合度。本研究將以台南市歸仁區的漫射率量測值，搭配自中央氣象局購買的氣象數據，以迴歸分析法建立一個台灣地區適用的漫射率模組。而後以中央氣象局近十年所量測的氣象數據，依照典型氣象年的規範設定一個氣象數據資料庫，該典型氣象年資料庫的資料可以代表台灣地區的常態氣候分佈情況。將此常態氣候的數據代入台灣地區的漫射率模組中，經過擴張與內插方法，可求得一個特定日照時間下，台灣地區穩定氣候下的漫射率等高線示意圖。
由結果發現台灣大部份地區的漫射率皆介於40至50%之間，越北越高，台北高達55%。冬季的平地地區漫射率較山地地區高，夏季的平地地區漫射率較山地地區低。本研究建立台灣地區十二個月漫射率分佈圖，希望可以針對太陽能應用的相關研究提供直射率與漫射率間的基本認知。

Solar energy is the most available green energy for Taiwan where is located in Subtropics with abundant solar irradiation. Thus, Taiwan is suitable to develop solar energy applications. The global solar intensity is consisted of two parts: beam radiation and diffuse radiation, the portion of these two parts would affect the way how we design the application systems of solar energy. Concentration of solar intensity can be performed through the concentrating techniques. It is necessary to understand the distribution of solar diffusion fraction in Taiwan. This research utilizes the diffuse radiation data measured at Kuei-Jen in Tainan together with the global radiation data measured by the Taiwan station of Central weather Bureau and, then, fit a model by means of linear regression. Next, to set a database in a so called Typical Meteorological Year (TMY) which represents a long term solar data for Taiwan.
This research predicts a diffuse fraction map of Taiwan for each month. The result shows that the average diffuse fraction is among 40% to 50% for almost everywhere in Taiwan, and with the following tendencies: (1) the diffuse fraction increases with the latitude is increased, 55% in Taipei. (2) the diffuse fraction in the plains region is higher than that in the mountain area in the winter season, and it becomes opposite in the summer season. The yearly distribution of the diffuse fraction in Taiwan area in finally constructed.

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