A Concise Overview on Solar Resource Assessment and Forecasting

China’s recently announced directive on tackling climate change,namely,to reach carbon peak by 2030 and to achieve carbon neutrality by 2060,has led to an unprecedented nationwide response among the academia and industry.Under such a directive,a rapid increase in the grid penetration rate of solar in the near future can be fully anticipated.Although solar radiation is an atmospheric process,its utilization,as to produce electricity,has hitherto been handled by engineers.In that,it is thought important to bridge the two fields,atmospheric sciences and solar engineering,for the common good of carbon neutrality.In thisüberreview,all major aspects pertaining to solar resource assessment and forecasting are discussed in brief.Given the size of the topic at hand,instead of presenting technical details,which would be overly lengthy and repetitive,the overarching goal of this review is to comprehensively compile a catalog of some recent,and some not so recent,review papers,so that the interested readers can explore the details on their own.

Assessment of global solar resource development

With the increasing severity of environmental problems,many countries have set energy transition targets to promote the realization of the Paris Agreement.There has been a global consensus on utilizing solar energy resources as alternatives to conventional sources to support this energy transition.In this regard,analyzing the“location,”“quantity,”and“quality”of global solar energy resources will not only assist an individual country to efficiently utilize these resources but also promote the realization of large-scale intercontinental resource utilization and complementation.This study established the basic database,model methods,and platform tools for global solar energy assessment,Then,a global solar energy resource assessment was conducted,which included the theoretical reserves(TRs),technical installed potential capacity(TPIC),and average development cost(ADC).A comparative analysis of the assessment results for all continents was also performed.After that,based on big data analysis and geographic information system(GIS)calculations,the distribution characteristics of the global solar power TPIC were calculated with the two core indicators,namely the capacity factor and ADC.Furthermore,a data-driven quantitative evaluation of the refined development potential of solar energy resources was performed.Finally,the reasonableness and coincidence analysis of the resource assessment results were verified using data from global and specifically Chinese photovoltaic(PV)bases.

Spatial and Temporal Distribution Characteristics of Solar Energy Resources in Tibet

The Tibet Plateau is one of the regions with the richest solar energy resources in the world.In the process of achieving carbon neutrality in China,the development and utilization of solar energy resources in the region will play an important role.In this study,the gridded solar resource data with 1km resolution in Tibet were obtained by spatial correction and downscaling of SMARTS model.On this basis,the spatial and temporal distribution characteristics of solar energy resources in the region in the past 30 years(1991–2020)are finely evaluated,and the annual global horizontal radiation resource is calculated.The results show that:1)The average annual global horizontal radiation amount in Tibet is 1816 kWh/m^(2).More than 60%of the area belongs to the“Most abundant”(GHI≥1750 kWh/m^(2))area of China’s solar energy resources category A,and nearly 40%belongs to the“Quite abundant”(1400≤GHI<1750)area of China’s solar energy resource category B.2)In space,the solar energy resources in Tibet increased gradually from north to south and from east to west.Lhasa,Central and Eastern Shigatse,Shannan,and Southwestern Ali are the most abundant cities,with a maximum annual radiation level of 2189 kWh/m2.3)In terms of time,the total horizontal radiation in Tibet was the highest in May and the lowest in December.74%of the total area belongs to the“Very stable”(R_(w)≥0.47)area of solar resource stability category A,and 26%belongs to the“stable”(0.36≤R_(w)<0.47)area of solar resource stability category B.Solar energy resources in the region show the characteristics of both strong and stable.Average solar energy resources in the region have shown a fluctuating downward trend over the past 30 years,with an average decline of about 12.86(kWh/m2)per decade.4)In terms of solar radiation resources reaching the earth’s surface,the theoretical total amount of annual horizontal radiation in Tibet is about 240.07 billion tons of standard coal or 222.91 billion kilowatts on average.

Solar Energy Resource Characteristics of Photovoltaic Power Station in Shandong Province

[Objective] The aim was to analyze characters of solar energy in photo- voltaic power stations in Shandong Province. [Method] The models of total solar radiation and scattered radiation were determined, and solar energy resources in pho-tovoltaic power stations were evaluated based on illumination in horizontal plane and cloud data in 123 counties or cities and observed information in Jinan, Fushan and Juxian in 1988-2008. [Result] Solar energy in northern regions in Shandong proved most abundant, which is suitable for photovoltaic power generation; the optimal angle of tilt of photovoltaic array was at 35°, decreasing by 2°-3° compared with local latitude. Total solar radiation received by the slope with optimal angle of tilt exceeded 1 600 kw.h/（m2.a）, increasing by 16% compared with horizontal planes. The maximal irradiance concluded by WRF in different regions tended to be volatile in 1 020-1 060 W/m2. [Conclusion] The research provides references for construction of photovoltaic power stations in Shandong Province.

Preliminary assessment of the solar resource in the United Kingdom

Solar radiation resources data are the foundation of knowledge for programs of large-scale deployment of solar energy technologies.This article summarizes the analysis of a new weather stations network in the United Kingdom.The analysis used three years(January 2015-December 2017)of data from 27 weather stations distributed across the country.The data comprises global horizontal irradiance(GHI),diffuse horizontal irradiance,direct normal irradiance and the ambient temperature.Network design,implementation and data quality assurance are described to document the network extent and quality.From all observed datasets,we found that Plymouth(located in southwest England)has the dominant GHI and ambient temperature among all other 26 locations.The least GHI is observed for Aberdeen(located in northeast Scotland)estimated at 77.3 kWh/m2.The least average ambient temperature is equal to 9.1℃;the data were detected by the weather station located in the capital of Scotland(Edinburgh).Although continued measurements are needed to understand the interannual resource variability,the current study should have significant applications for preliminary technology selection,power plant modeling and resource forecasting.

Contrastive Observation of Solar Thermal and Photovoltaic Resource

Solar thermal and photovoltaic applications are the most w idely used and the most successful w ay of commercial development in solar energy applications. Observation and assessment of solar thermal and photovoltaic resources are the basis and key of their large-scale development and utilization. Using the observational data carried out from Beijing southern suburbs observation station of China M eteorological Administration in summer of 2009,preliminary solar thermal and photovoltaic resources characteristics for different w eather conditions,different angle and different directions are analyzed. The results show that:(1) In sunny,cloudy or rainy w eather conditions,both of solar thermal and photovoltaic sensors daily irradiance have consistent change in trend. Solar thermal irradiance is larger than photovoltaic. Under sunny conditions,solar thermal global radiation has about 2.7%higher than the photovoltaic global radiation. Under cloudy w eather conditions,solar thermal global radiation has about 3. 9%higher than the photovoltaic. Under rainy w eather conditions,solar thermal global radiation has about 20% higher than the photovoltaic.(2) For different inclined plane daily global radiation,southern latitude-15 °incline is the maximum and southern vertical surface is the minimum. The order from large to small is southern latitude-15 ° incline,southern latitude incline,southern latitude+15 °incline,horizontal surface and southern vertical surface. Southern latitude-15 °incline global radiation has about 41% higher than the southern vertical surface.(3) For different orientation vertical surface daily global radiation,southern vertical surface is the maximum and w estern vertical surface is the minimum,w hich eastern vertical surface is in the middle. Southern vertical surface global radiation has about 20% higher than the w estern vertical surface.

Solar PV Electrification in Nigeria: Current Status and Affordability Analysis

Rural households represent, by far, the greater percentage of dwellings globally without access to the electricity supply. For reasons of low loads, distance from the grid and speed of deployment, distributed energy systems are now considered viable options for rural electrification. This paper presents the status of solar Photovoltaic (PV) in Nigeria and discusses the way forward for aggressive PV penetration in Nigeria’s energy mix, especially in rural communities. At present, distributed PV penetration in Nigeria is comparatively low based on the International Energy Association’s recommended PV market potential. This shows that there is a gap between the government’s policy targets and reality. The solar resource potential across the six geo-political zones in Nigeria is also presented, which ranges from 3.393 - 6.669 kWh/m2/day, with the Northern zones exhibiting better potentials over the Southern zones. It is shown that the levelised cost of electricity from PV system ranges from 0.387 - 0.475 $/kWh, whereas it is 0.947 US$/kWh and 0.559 US$/kWh for the diesel generator and glass-covered kerosene lamp, respectively. While this study shows that PV for rural household lighting is more affordable as compared to glass-covered kerosene lamps and fossil-fuelled generators for lighting, fiscal and energy policies for market creation are critical if PV systems are to deliver on their promise for rural electrification and climate change mitigation.

On the Development of Spatial/Temporal Solar Radiation Maps:A Minas Gerais(Brazilian)Case Study

Appropriate information on solar resources is very important for a variety of technological areas, such as agriculture, meteorology, forestry engineering, and water resources, particularly for an innovative technology such as solar energy. In the market entry process of an innovative technology such as solar energy, the increased and sustained deployment of this energy technology strongly depends on the economy and reliability of the solar systems installed. The economy and reliability of a system are the consequences of a well-prepared project, resulting from an accurate knowledge of the solar resource available. Therefore, knowing the potential of the solar resource accurately is not only a need but also an imperative for the larger diffusion and use of the solar energy. The existing sources of the information on radiation in MG are quite varied, both at the institutional level and in different types of publications. The publications containing this information are project reports, internal reports of institutions, and several magazines. Thus, the quality of the data varies considerably, the information presents spatial and temporal discontinuity;moreover, the instruments and the measurement units are not standardised. The general objective of this paper is to recover, to qualify, to standardize, and to make available the best information from the current existing solar resource in MG, Brazil, either in the form of isoline charts of solar radiation or a numerical database. In this paper, the procedure to elaborate the maps of daily solar radiation and insolation, along with the monthly and annual averages, is described. We present one map with the localisation of the recording stations in addition to one annual and 12 monthly contour maps. The map of the daily global solar irradiation and the annual average determined in this project show that solar radiation on the state of Minas Gerais ranges from 4.5 to 6.5 kWh/m2. The maximum values occur in the northern region of Minas Gerais, and the minimum values occur in the southeast region, where there are areas of higher altitude (Mantiqueira and Serra do Caparaó) and the rainfall is more intense, with total annual rainfall greater than 1400 mm. The North and Northeast Regions of MG, where the largest annual irradiation of 6.5 kWh/m2 occurs, are characterised by a semiarid climate with annual rainfall between 600 - 800 mm and altitudes between 400 - 600 m. The maritime tropical air mass that acts between Brazil and Africa is the main climatic factor that inhibits cloud formation and, consequently, the rainfall in this region. Finally, the map of annual insolation reveals a consistent correlation between the daily rainfall and the solar radiation annual average.

POWER GENERATION POTENTIAL OF BIPV APPLICATION IN CHINA

This paper discusses the potential and prospect of building-integrated photovoltaics (BIPV) for solar electrical power generation in China.The BIPV technology has been identified as the most economical renewable energy resource to contribute to world electrical energy demand for protecting environment from reduced fossil fuel consumption.The available solar energy resource of 14 cities and the potential power generation from PV claddings in buildings in China were estimated.The economical analysis of BIPV application is discussed.It is found that the potential is significant and the government should play an important role in its development.