scholarly journals review of "Long-term variability of solar irradiance and its implications for photovoltaic power in West Africa"

2020 ◽  
2020 ◽  
Author(s):  
Ina Neher ◽  
Susanne Crewell ◽  
Stefanie Meilinger ◽  
Uwe Pfeifroth ◽  
Jörg Trentmann

Abstract. This paper addresses long-term changes in solar irradiance for West Africa (3° N to 20° N and 20° W to 16° E) and its implications for photovoltaic power systems. Here we use satellite irradiance (Surface Solar Radiation Data Set-Heliosat, Edition 2.1, SARAH-2.1) to derive photovoltaic yields. Based on 35 years of data (1983–2017) the temporal and regional variability as well as long-term trends of global and direct horizontal irradiance are analyzed. Furthermore, at four locations a detailed time series analysis is undertaken. The dry and the wet season are considered separately. According to the high resolved SARAH-2.1 data record (0.05° x 0.05°), solar irradiance is largest (with up to 300 W/m² daily average) in the Sahara and the Sahel zone with a positive trend (up to 5 W/m²/decade) and a lower variability (


2020 ◽  
Author(s):  
Ina Neher ◽  
Susanne Crewell ◽  
Stefanie Meilinger ◽  
Uwe Pfeifroth ◽  
Jörg Trentmann

<p><span><span>West Africa is one of the least developed regions in the world regarding the energy availability and energy security. Located close to the equator West Africa receives high amounts of global horizontal irradiance (GHI). Thus, solar power and especially photovoltaic (PV) systems seem to be a promising solution to provide electricity with low environmental impact. To plan and to dimension a PV power system climatological data for global horizontal irradiance (GHI) and its variability need to be taken into account. However, ground based measurements of irradiances are not available continuously and cover only a few discrete locations.</span></span></p><p><span><span>Data records of surface irradiance based on satellite measurements have the advantage of covering wide spatial regions and being available over long time periods. The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Satellite Application Facility on Climate Monitoring (CM SAF) provides the Surface Solar Radiation Data Set-Heliosat, Edition 2.1 (SARAH-2.1), a 35 year long climate data record in an half hourly resolution, covering the whole of Africa and Europe.<br></span></span></p><p><span><span>In this study, the SARAH-2.1 data record (1983-2017) is used to analyze the impact of 35 years atmospheric variability and trend on GHI and PV yields over West Africa (defined as the region from 3°N to 20°N and 20°W to 16°E). The trend and the variability of solar irradiance is analyzed separately for the wet and dry season as well as for annual data. Furthermore, a simplified model provides high-resolution potential PV yields. </span></span></p><p><span><span>According to the SARAH-2.1 data record, solar irradiance is largest (with up to 300 W/m 2 daily average) in the Sahara and the Sahel zone with a positive trend (up to 5 W/m</span></span><sup><span><span>2</span></span></sup><span><span>/decade). Whereas, the solar irradiance is lower in southern West Africa with a negative trend (up to -5 W/m</span></span><sup><span><span>2</span></span></sup><span><span>/decade). The positive trend is mostly connected to the dry season, while the negative trend occurs during the wet season. PV yields show a strong meridional gradient with lowest values around 4 kWh/kWp in southern West Africa and reach more than 5 kWh/kWp in the Sahara and Sahel zone.</span></span></p><p><span><span>T</span></span><span><span>his poster will discuss the long-term trend and variability analysis of solar irradiance and highlight the implications for photovoltaic-based power systems in West Africa.</span></span></p>


2020 ◽  
Vol 20 (21) ◽  
pp. 12871-12888
Author(s):  
Ina Neher ◽  
Susanne Crewell ◽  
Stefanie Meilinger ◽  
Uwe Pfeifroth ◽  
Jörg Trentmann

Abstract. This paper addresses long-term historical changes in solar irradiance in West Africa (3 to 20∘ N and 20∘ W to 16∘ E) and the implications for photovoltaic systems. Here, we use satellite irradiance (Surface Solar Radiation Data Set – Heliosat, Edition 2.1 – SARAH-2.1) and temperature data from a reanalysis (ERA5) to derive photovoltaic yields. Based on 35 years of data (1983–2017), the temporal and regional variability as well as long-term trends in global and direct horizontal irradiance are analyzed. Furthermore, a detailed time series analysis is undertaken at four locations. According to the high spatial resolution SARAH-2.1 data record (0.05∘×0.05∘), solar irradiance is largest (up to a 300 W m−2 daily average) in the Sahara and the Sahel zone with a positive trend (up to 5 W m−2 per decade) and a lower temporal variability (<75 W m−2 between 1983 and 2017 for daily averages). In contrast, the solar irradiance is lower in southern West Africa (between 200 W m−2 and 250 W m−2) with a negative trend (up to −5 W m−2 per decade) and a higher temporal variability (up to 150 W m−2). The positive trend in the north is mostly connected to the dry season, whereas the negative trend in the south occurs during the wet season. Both trends show 95 % significance. Photovoltaic (PV) yields show a strong meridional gradient with the lowest values of around 4 kWh  kWp−1 in southern West Africa and values of more than 5.5 kWh  kWp−1 in the Sahara and Sahel zone.


Author(s):  
Finn Fuglestad

The small Slave Coast between the river Volta and Lagos, and especially its central part around Ouidah, was the epicentre of the slave trade in West Africa. But it was also an inhospitable, surf-ridden coastline, subject to crashing breakers and devoid of permanent human settlement. Nor was it easily accessible from the interior due to a lagoon which ran parallel to the coast. The local inhabitants were not only sheltered against incursions from the sea, but were also locked off from it. Yet, paradoxically, this small coastline witnessed a thriving long-term commercial relationship between Europeans and Africans, based on the trans-Atlantic slave trade. How did it come about? How was it all organized? Dahomey is usually cited as the Slave Coast's archetypical slave raiding and slave trading polity. An originally inland realm, it was a latecomer to the slave trade, and simply incorporated a pre-existing system by dint of military prowess, which ultimately was to prove radically counterproductive. Dahomey, which never controlled more than half of the region we call the Slave Coast, represented an anomaly in the local setting, an anomaly the author seeks to define and to explain.


Solar Physics ◽  
1994 ◽  
Vol 152 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Judit M. Pap ◽  
Richard C. Willson ◽  
Claus Fr�hlich ◽  
Richard F. Donnelly ◽  
Larry Puga

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