Review of Solar Panel Soiling Studies

Transcription

1 Review of Solar Panel Soiling Studies In developing SolarClear, we reviewed over 53 scientific studies other have been published, but are no longer readily available. These papers represent work carried out in over 16 countries (sadly, Australia, with amongst the best solar resource and the highest penetration of small-scale solar in the world, is not amongst them) since 1988; the bulk of the studies have been conducted in the past 10 years. The results vary enormously, with the lowest recorded being 1.4% degradation per year in Oregon, USA, and the highest being 92% in Bhopal, India. Even within one area, results can vary: four studies conducted in Southern California vary from % annual average loss to 11.5%/month. This variation is due to a number of factors: Variation in local micro-climates (rainfall frequency, dust intensity, etc.) Different test methods, including different test durations Different reporting criteria (output loss measured in Watts, Short circuit and/or open circuit Volts current or voltage, loss in panel efficiency in percent note that when brand new, panel efficiency varies between about 15 and 21%, etc.) Different averaging time-scales (peak daily, annual average, increase per day/week/month, etc.) The availability of test sites in more arid and dusty zones. In general, the higher results are in newer studies, and more arid climates. For those studies that we could confirm were reporting losses of power output (i.e., not panel efficiency), the average loss was 35.4%; the median 28.6%. Map 1.4%/yr Up to 10% 8-22% % 0.21%/day, % annual ave, 11.5%/month, 4.7-8% >20% 72-93% 60% 16-20% 92% 30% 5%/month % 50%, 40% 26%, 16% 50%, 85% 34%, 37% 2.8-7%/month Ironstone Technology Pty Ltd trading as EarthCare Technology 79 Barney St, Kiama, NSW, 2533 Australia +61 (0) info@ earthcaretech.com.au

2 The Papers (alphabetical order) Adinoyi, Said: Effect of Dust Accumulation on the Power Outputs of Solar Photovoltaic Modules. (Dhahran, Saudi Arabia, 2013) The study indicates that power decrease by as much as 50% can be experienced for solar PV modules that are left unclean for a period of over six months. Al-Hasan, Ghoeneim: A new correlation between photovoltaic panel s efficiency and amount of sand dust accumulated on their surface. (Shuwaikh, Kuwait, 2005) It has been found that the short circuit current and the maximum output power decrease significantly as dust particles start to accumulate on the panel surface up to a concentration of 1 g/m2, but the rate of decrease is slower for concentrations beyond that value. The reduction in short circuit current in one sample of study is found to be 40%, whereas it is 34% in the maximum output power. Al-Hasan: A new correlation for direct beam solar radiation received by photovoltaic panel with sand and dust accumulated on its surface. (Modelling study) AlBusairi, Möller: Performance evaluation of CdTe PV modules under natural outdoor conditions in Kuwait. (Safat, Kuwait, 2010) Highest monthly losses due to dust accumulation were recorded in May from 4% for the vertical surface to 37% in Isc for the flat surface, mainly due to the presence of dusty rain or dry dust accumulation followed by light rain. Earlier observations have shown that yield losses can be even higher. Ali (H.), Zafar, Bashir, Nasir, Ali (M.), Siddiqui: Effect Of Dust Deposition On The Performance Of Photovoltaic Modules In Taxila, Pakistan. (Taxila, Pakistan, 2015) Photovoltaic module test stand (from AlBusairi, Möller) The monocrystalline and polycrystalline modules showed about 20% and 16% decrease of average output power respectively compared to the clean modules of same type. Alnaser (N. W.), Dakhel, Al Othman, Batarseh, Lee, Najmaii, Alnaser (W. E.): Dust Accumulation Study on the Bapco 0.5MW PV Project at the University of Bahrain. (Kingdom of Bahrain, 2015) PV panels have shown power reduction in excess of 60% due to dust particles. the density of the accumulated dust ranged from 5-12g/m2 with an average PV power drop to 40% of the maximum available. Beattie, Moir, Chacko, Buffoni, Roberts, Pearsall: Understanding The Effects Of Sand And Dust Accumulation On Photovoltaic Modules. (Simulation & modelling study) Beattie, Moir, Chacko, Buffoni, Roberts, Pearsall: Understanding the effects of sand and dust accumulation on photovoltaic modules. Benatiallah, Ali, Abidi, Benatiallah, Harrouz Mansouri: Experimental Study of Dust Effect in Mult-Crystal PV Solar Module. (Adrar, Algeria (2012)) Our results show that the dust provoked a fall of the electric parameters of the module, the power deliver by module decreases of % according to sand density, as well as the efficiency that falls of % and the current Icc following a fast variation of 72 to 93%. - Page 2 of 7 -

3 Cabanillas, Munguía: Dust Accumulation Effect on Efficiency of Si Photovoltaic Modules. (Laboratory and modelling study) Caron, Littmann: Direct Monitoring of Energy Lost Due to Soiling on First Solar Modules in California. (California, USA, 2013) Soiling rates of up to 11.5% per month are observed in heavy agricultural areas. El-Shobokshy, Hussein: Degradation of photovoltaic cell performance due to dust deposition on to its surface. El-Shobokshy, Hussein: Effect of dust with different physical properties on the performance of photovoltaic cells. Elminir, Ghitas, Hamid, El-Hussainy, Beheary, Abdel-Moneim: Effect Of Dust On The Transparent Cover Of Solar Collectors. (Simulation & modelling study) Fagnani: The PV Module Soiling Issue: Best Solutions. (Meta-study, 2016) bad maintenance is responsible for significant production losses for solar PV plants. Gandhi, Akshay,Vijay: Investigation of the Effects of Dust Accumulation, and Performance for Mono and Poly Crystalline Silica Modules. (Simulation & modelling study) Garcıa, Marroyo, Lorenzo, Perez: Soiling Build up of mineral deposits is visible on the surface of the glass (from Elminir, Ghitas, Hamid, El-Hussainy, Beheary, Abdel-Moneim) And Other Optical Losses In SolarTracking PV Plants In Navarra. (Tudela, Spain, 2011) daily optical energy losses ranged from 1 to 8% in the case of tracking surfaces and from 8 to 22% in the case of fixed horizontal surfaces. Garg: Effect of dirt on transparent covers in flat plate solar energy collectors. Ghosh (B), Ghosh (A): Effect of Dust on Solar PV Modules Efficiency. (Laboratory study, 2014) dust assimilation on the surface of solar PV panels can reduce system output to 16-40% in a month investigation. Goosens, van Kerschaever: Aeolian dust deposition on photovoltaic solar cells: the effects of wind velocity and airborne dust concentration on cell performance. Haeberlin, Graf: Gradual reduction of PV generator yield due to pollution. (Burgdorf, Switzerland, 1198) In course of time, a development of a permanent strip was observed which caused a gradual reduction of energy yield of up to 10% View of a part of the PV array showing visible pollution, (from Haeberlin, Graf) - Page 3 of 7 -

4 Hammond, Srinivasan, Harris, Whitfield, Wohlgemuth: Effects of soiling on PV module and radiometer performance. (Arizona, USA, 1997) Soiling effects increase as the angle of incidence increases. Losses increased from 2.3% at normal incidence to 4.7% at 24 and 8% at 58. Hegazy: Effect of dust accumulation on solar transmittance through glass covers of plate-type collectors. For moderately dusty places, weekly cleaning of the glass covers of solar panels is strictly recommended as part of the maintenance routine, but equipment should be cleaned immediately after a dust storm to retain nominal operating efficiency. Jiang, Lu, Sun: Experimental Investigation Of The Impact Of Airborne Dust Deposition On The Performance Of Solar Photovoltaic (PV) Modules. (Hong Kong, China, 2011) With dust deposition density increasing from 0 to 22 g m#2, the corresponding reduction of PV output efficiency grew from 0 to 26%. Kaldellis, Fragos, Kapsali: Systematic Experimental Study Of The Pollution Deposition Impact On he Energy Yield Of Photovoltaic Installations. (Athens, Greece, 2011) a considerable deterioration of the PV-panels performance is obtained, i.e. almost 30% energy reduction per hour or 1.5% efficiency decrease (in absolute terms) Kaldellis, Fragos: Ash deposition impact on the energy performance of photovoltaic generators. Kaldellis, Kapsali: Simulating The Dust Effect On The Energy Performance Of Photovoltaic Generators Based On Experimental Measurements. Kaldellis, Kokala, Kapsali: Natural Air Pollution Deposition Impact on the Efficiency of PV Panels in Urban Environment. (Athens, Greece, 2010) the performance of PVs may be considerably reduced, i.e. 0.4% efficiency decrease or 5% power output reduction, even after a small period of time (i.e. a month) of PVs exposure into the atmospheric air pollution. Kaldellis, Kokala: Quantifying The Decrease Of The Photovoltaic Panels Energy Yield Due To Phenomena Of Natural Air Pollution Disposal. (Athens, Greece, 2010) the presence of dust considerably affects the PV-panels performance since even a relatively small dust deposition density (z1 g/m2) may result in remarkable energy losses corresponding almost to 40 /kwp on an annual basis. The experimental PV-generator (from Kaldellis, Kokala) - Page 4 of 7 -

5 Kimber, Mitchell, Nogradi, Wenger: The effect of soiling on large grid-connected photovoltaic systems in California and the southwest region of the United States. (California, USA, 2006) 0.2% per day without rainfall in dry climates. This daily loss finding equates to an annual energy loss between % depending on system location. Koronakis, Sfantos, Paliatsos, Kaldellis, Garofalakis, Koronaki: Interrelations of UV-global-global-diffuse solar irradiance components and UV-global attenuation on air pollution episode days in Athens, Greece. (Athens, Greece, 2002) a buildup of O3 and NOx inside the urban Athens plume during cloudless and windless warm days could cause: (i) UV-global irradiance depletion between 5.4% and 14.4%. (ii) Diffuse solar irradiance enhancement up to 38.1%. (iii) Global solar irradiance attenuation ranging up to 6.3%. Kumar, Sarkar, Behera: Soiling and Dust Impact on the Efficiency and the Maximum Power Point in the Photovoltaic Modules. (Metastudy, 2013) In an arid climate, PV systems can suffer dramatic losses between rain events due to the accumulation of soiling. Mani, Pillai: Impact Of Dust On Solar Photovoltaic (pv) Performance: Research Status, Challenges And Recommendations. (Metastudy) Martin, Ruiz: Calculation of the PV modules angular losses under field conditions by means of an analytical model. (Modelling study) Mejia, Kleissl, Bosch: The effect of dust on solar photovoltaic systems. (California, USA, 2014) Soiling losses were found to be 0.21% per day. Mohamed, Hasan: Effect of Dust Accumulation on Performance of Photovoltaic Solar Modules in Sahara Environment. ( Mourzuq, Libya, 2012) The results indicated a significant gradual decrease of power, so frequent weekly water washing maintaining performance losses between (2 Dust accumulation on PV panel in UCSD (from Mejia, Kleissl, Bosch) 2.5%). Molki: Dust affects solar cell efficiency. Moon: Google Studies How Dirt Affects Solar Panel Efficiency. (California, USA, 2009) 15 months after installation of the panels, the Google crew cleaned them up as part of this study. For the flat panels, the result was astounding - energy output doubled overnight. After this first experiment, the Google crew waited another eight months and cleaned the panels again, with the flat panels exhibiting in a 36 percent improvement in efficiency. Nahar, Gupta: Effect of dust on transmittance of glazing materials for solar collectors under arid zone conditions of India. Pang, Close, Lam: Study on effect of urban pollution to performance of commercial copper indium diselenide module. (Hong Kong, China, 2006) From Table 2 it is noted that hstc in dirty condition has decreased 1.794% (or % in relative terms) compared with the one in clean condition. Piliougine, Carretero, Sidrach-De-Cardona, Montiel, Sánchez-Friera: Comparative Analysis Of The Dust Losses In Photovoltaic Modules With Different Cover Glasses. (Malaga, Spain, 2008) results show that losses due to accumulated dirt in modules can reach values about the 15% for period without rain. - Page 5 of 7 -

6 Qasem, Betts, Gottschalg: Effect of shading caused by dust on cadmium telluride photovoltaic modules. Qasem, Betts, Müllejans, AlBusairi, Gottschalg: Dust-induced shading on photovoltaic modules. (Modelling study) The worst case is amorphous silicon, where a 33% reduction in photocurrent is predicted for a dust concentration of 4.25mg/cm2. Similarly, crystalline silicon and CIGS technologies are predicted to be less affected, with 28.6% and 28.5% reductions in photocurrent, respectively. Rajput, Sudhakar: Effect of Dust on the Performance of Solar PV Panel. (Bhopal, India, 2013) From the graph we can see that we get the maximum efficiency 6.38%, minimum 2.29% without dust & maximum efficiency 0.64%, minimum 0.33% with dust. The result shows that dust considerably reduces the power production by 92.11% and efficiency as 89%. Ryan, Vignola, McDaniels: Solar cell arrays: Degradation due to dirt. (Oregon, USA, 1988) The performance of the washed solar cell array has remained constant over the six year period while that of he unwashed solar cell array has deteriorated at a rate of about 1.4% per year. Said: Effects of dust accumulation on performances of Experiment Setup (from Rajput, Sudhakar) thermal and photovoltaic flat-plate collectors. (Riyadh, Saudi Arabia, 1990) For the photovoltaic panel, the average degradation rate of the efficiency was 7% per month, whereas, for the thermal panels, the average degradation rate on the optical efficiency ranged from 2.8% to 7% per month for this maritime-desert-subzone type of environment. Sayyah, Horenstein, Mazumder: Energy yield loss caused by dust deposition on photovoltaic panels. (Metastudy) Soleimani, Farhangi, Zabihi: The effect of tilt angle, air pollution on performance of photovoltaic systems in Tehran. (Tehran, Iran, 2001) Air pollution can reduce the energy output of solar modules by more than 60%. Sulaiman, Hussain, Nik Leh, Razali: Effects of Dust on the Performance of PV Panels. (Perak, Malaysia, 2011) accumulated dust on the surface of photovoltaic solar panel can reduce the system s efficiency by up to 50%. Sulaiman, Singh, Mokhtar, Bou Rabee: Influence of Dirt Accumulation on Performance of PV Panels. (Perak, Illustration 1: Three types of silicon solar modules mounted with tilt angle of Malaysia, 2014) 45 ; two multicrystalline, 16monocrystalline and one thin film solar panels. (from Soleimani, Farhangi, Zabihi) It was found that the external resistance could reduce the photovoltaic performance by up to 85%. Sulaiman, Singh, Mokhtar, Bou-Rabee: Influence of Dirt Accumulation on Performance of PV Panels. - Page 6 of 7 -

7 Zorrilla-Casanova, Piliougine, Carretero, Bernaola, Carpena, Mora-López, Sidrach-deCardona: Analysis of dust losses in photovoltaic modules. (Malaga, Spain, 2011) In long periods without rain, daily energy losses can be higher than 20%. Zorrilla-Casanova, Piliougine, Carretero, Bernaola-Galván, Carpena, Mora-López, Sidrachde-Cardona: Losses produced by soiling in the incoming radiation to photovoltaic modules. (Malaga, Spain, 2013) After long periods without rain, daily irradiation losses can be higher than 20%. The experimental setup used in the measurements. (from Zorrilla-Casanova, Piliougine, Carretero, Bernaola, Carpena, Mora-López, Sidrach-de-Cardona) - Page 7 of 7 -