落塵堆積於太陽能板表面使得玻璃罩穿透率降低，隨著時間會讓落塵堆積導致太陽能板的效率損失；而臺灣少有相關的研究可以提供落塵堆積與太陽能板效率損失的關係，由於落塵對於穿透率的影響在不同的氣候帶與地區不盡相同，在臺灣需要在地戶外實驗數據舉證說明落塵對於穿透率的影響。本研究的目的為在臺灣的環境將玻璃樣本放置於戶外，改變不同的實驗變因，觀察自然落塵、氣候、實驗變因間的關係，進而發展在臺灣較為可信的落塵與穿透率的變化式子，期能據以提供較佳的架設方式與表面塗層選擇，並能選擇適當的時間清理太陽能系統上之落塵。
本研究於2017年1月到2018年5月於臺南市歸仁區設置戶外實驗設備，將不同表面塗層、傾斜角度、玻璃尺寸的玻璃放置於戶外，每兩週進行一次量測；同時量測不同條件玻璃樣本上的落塵重量、穿透率變化，並利用光電板的輸出功率比較不同表面塗層對光電系統的整體輸出影響。
本研究中蒐集到的單位面積落塵量 (W_d) 介於0 ~ 1.88 g/m^2 間，並且W_d 與降水量、降水分布密切相關；雨季時穿透率減少集中在5%上下，乾季時則有機會高達21%。本研究選用的塗層當中，除塵能力以二氧化鈦光觸媒最佳，在乾季時平均能減少12%的自然落塵量，但二氧化鈦光觸媒穿透率會減少0.5 ~ 1%；傾斜角度為23°的樣本較水平擺放的樣本能減少25~30%的落塵量。本研究選用的玻璃尺寸中，尺寸較大時會蒐集到較高的單位面積自然落塵，然而此項結果有待進一步驗證。根據降水分布與落塵量的觀察，建議若連續30日未降雨則有必要對太陽能系統表面的落塵進行清理工作。

The energy output delivered by photovoltaic module or solar thermal collector is highly dependent on how much the irradiance can reach the panel. The efficiency of the system relies on its design. However, most studies have calculated power output based on the ideal situation, that is, clean surface of the panel. One critical factor is that the output of solar system will decline as suspended dust is deposited on the cover of the solar panel.
In order to investigate the effects of dust soiling, a set of glass samples was placed at the Gurien campus of National Cheng Kung University. Three factors were considered: surface modification, size, and tilt angle. Knowing how these factors influence dust deposition helps determine a better design for a specific location.
It was found that the average transmittance reduction for the tilted glass samples is 3.38% and is 7.29% in the dry season (October to April) and in rainy season (May to September), respectively.
Among the four coatings under consideration, the anti-reflection coating performed the best due to having the highest initial transmittance while the TiO2 coating performed the worst. Tilt angle was found to have a significant influence on dust soiling, where a larger tilt angle resulted in less dust being deposited.
As for the sample size, size and dust deposition have an obvious positive relation, where in this study, the side length of the square glass ranged between 50 mm to 300 mm.
Based on the observations of precipitation and dust deposition, if there is no rain for a whole month, it is recommended that the surface of the solar panel be cleaned to recover the transmittance to high value.

[1]Boyle, L., Flinchpaugh, H., & Hannigan, M. (2014, June). Ambient airborne particle concentration and soiling of PV cover plates. In Photovoltaic Specialist Conference (PVSC), 2014 IEEE 40th (pp. 3171-3173). IEEE
[2]Boyle, L., Flinchpaugh, H., & Hannigan, M. P. (2015). Natural soiling of photovoltaic cover plates and the impact on transmission. Renewable Energy, 77, 166-173.
[3]Cuddihy, E. F. (1980). Theoretical considerations of soil retention. Solar energy materials, 3(1-2), 21-33.
[4]El-Shobokshy, M. S., & Hussein, F. M. (1993). Degradation of photovoltaic cell performance due to dust deposition on to its surface. Renewable Energy, 3(6-7), 585-590.
[5]Elminir, H. K., Ghitas, A. E., Hamid, R. H., El-Hussainy, F., Beheary, M. M., & Abdel-Moneim, K. M. (2006). Effect of dust on the transparent cover of solar collectors. Energy conversion and management, 47(18-19), 3192-3203
[6]Hegazy, A. A. (2001). Effect of dust accumulation on solar transmittance through glass covers of plate-type collectors. Renewable energy, 22(4), 525-540.
[7]Jiang, H., Lu, L., & Sun, K. (2011). Experimental investigation of the impact of airborne dust deposition on the performance of solar photovoltaic (PV) modules. Atmospheric Environment, 45(25), 4299-4304.
[8]Ju, F., Fu, X., “Research on impact of dust on solar photovoltaic (PV) performance. In: Proceedings of 2011 international conference on electrical and control”, engineering (ICECE); 2011. p. 3601-3606.
[9]Maghami, M. R., Hizam, H., Gomes, C., Radzi, M. A., Rezadad, M. I., & Hajighorbani, S. (2016). Power loss due to soiling on solar panel: A review. Renewable and Sustainable Energy Reviews, 59, 1307-1316
[10]Moser, B. G., and Landel, R. F., “A Theory of Particle – Particle Interaction Describing the Mechanical Properties of Dental Amalgam.” Jet Propulsion Laboratory SPS No. 37-40, Vol. IV (1966) p. 84.
[11]Picotti, G., Borghesani, P., Cholette, M. E., & Manzolini, G. (2017). “Soiling of solar collectors–modelling approaches for airborne dust and its interactions with surfaces.” Renewable and Sustainable Energy Reviews.
[12]Sayigh, A. A. M., Al-Jandal, S., & Ahmed, H. (1985, September). Dust effect on solar flat surfaces devices in Kuwait. In Proceedings of the workshop on the physics of non-conventional energy sources and materials science for energy (pp. 353-367). ICTP Triest, Italy.
[13]Schneider, H., “Subtask I of Spacecraft Cleaning and Decontamination Techniques” Ch. 6 of Planetary Quarantine, Ann. Rev. Space Technology and Research, Jet Propulsion Laboratory (February 1973)TR-900-597
[14]Sulaiman, S. A., Hussain, H. H., Leh, N. S. H. N., & Razali, M. S. (2011). Effects of Dust on the Performance of PV Panels. World Academy of Science, Engineering and Technology, 58(2011), 588-593.
[15]鍾易達，”應用於太陽能集熱器之自然落塵對效率影響之研究與歸仁地區戶外實測之結果分析”，國立成功大學碩士論文，2016年。