Average Daily Solar Irradiance Research Articles

Ecological evaluation of the development of Neanderthal niche exploitation

Understanding the ecological niche occupied by Neanderthals and their ancestors is at the forefront of many Palaeolithic investigations. In this study, a complex characterization of the environments once occupied by these hominins in Western Eurasia were performed. It included the determination of the biome and climatic zones occupied, the potential wind exposures, the classification of the karst regions where they lived, the direction of the entrance of caves inhabited and the average daily total solar irradiation values. In addition, the climatic suitability of the Mediterranean mosquito fauna, tick-borne encephalitis and four large mammal species as potential mammal hosts were also studied. It was found that Western Eurasian hominins occupied a wide ecological niche range from the semi-arid to the subarctic climates. Between the MIS20-MIS4 interval, the biomes occupied by Neanderthals and their ancestors shifted from the woodland-shrubland to the boreal biomes, indicating the increasing general biocultural adaptation to the more continental environments. These populations inhabited territories with weak to moderate wind exposure (Beaufort 2–5) and usually occupied caves with a south or southwest-oriented entrance. This habitat selection indicates the recognition of local microclimatic factors and a conscious choice of shelters. In the glacial periods, the increasing extension of temperate-subpolar karst regions at the expense of the more habitable subtropical karst areas might have adversely affected the overwintering chances of ancient western Eurasian populations in West, Central Europe, and Central Asia. The supraorbital area of ancient hominins with low receding foreheads and prominent supraorbital ridges may have been exposed to a greater risk of the development of frontal sinusitis and its complications than modern humans with more gracile skulls. Neanderthals and their predecessors were exposed to moderate average daily solar radiation values, although these values exhibit heterogenic picture in the comparison of Central and Southern Europe. While the southern European Neanderthal populations were dominantly exposed to the risk of mosquito-borne diseases, the northern and central populations could suffer from tick-borne diseases. However, both tick-borne encephalitis virus and its medium-large mammal hosts were present in most sites dwelled by Neanderthals and their ancestors.

A concentrating light multistage rising film solar distiller with a central cooling structure

This paper presents a concentrating light multistage rising film solar distiller with a central cooling structure (RFSD). The RFSD mainly consists of the semicircular concentrator, a rising film device and a central cooling structure. The structure design of the semicircular concentrator is introduced in this paper. The relationship between the light receptivity of the semicircular concentrator and the solar incident angle was obtained by optical simulation. The mathematical model of RFSD was established, and the process of heat and mass transfer in RFSD was analyzed theoretically. Based on theoretical analysis, an experimental device was built. Furthermore, the device's water yield performance and energy utilization efficiency were tested under actual weather conditions. The experimental results show that when the average daily solar irradiance is 606.0 W/m2, the freshwater yielded by the device can reach 4450 g/m2, and the average daily efficiency is 81.6%. The comparison between the theoretical and experimental results shows that the theoretical model in this paper can well predict the device's operating parameters. The deviation of the theoretical operating temperature from the experimental value is within 2.3 °C, and the deviation of the daily water yield efficiency is on a scale of 14.1% to 24.8%.

Optimal Configuration and Energy Scheduling Algorithm for an Off-Grid Hybrid Microgrid

Off-grid hybrid microgrid which combines power sources from different technologies based on the availability of such resources and the economic/environmental considerations is gaining global interest due to the unreliable nature of conventional power systems. This research seeks to obtain an optimal configuration and develop a simple energy scheduling algorithm for a modern market using PV/Battery storage/Diesel generator technologies. HOMER software was used in obtaining the optimal configuration and economic/environmental analysis. The development of the scheduling algorithm was done based on the concept of energy flow in an off-grid hybrid microgrid using MATLAB software. An estimated load of 389.79 kW and average daily solar irradiance of 164.09W/m2 was recorded for the study site. The simulation results yielded Net Present Cost (NPC) of $6,405,234.36 and $0.2414 Cost of Energy (COE). A Greenhouse Gas (GHG) emission reduction of 42% was recorded for an off-grid system with solar renewable source. These clearly indicate that the use of optimized hybrid electrical energy resources with simple scheduling could greatly reduce both operational cost and environmental pollution.

Techno-Economic Feasibility Analysis of a Solar Photovoltaic Hybrid System for Rural Electrification in Sierra Leone for Zero Carbon Emission

Remote area electrification is a crucial need in sub-Saharan Africa’s drive to attain universal electrification. In Sierra Leone, with a rural population of over 5 million, the electrification rate accounts for less than 10% of the total inhabitants. This paper presents a comparative techno-economic analysis carried out to determine the most feasible of four individual options for off-grid mini-grid power generation system utilizing sources that include: Solar Photo Voltaic (SPV), Diesel Generator (DG), and Battery Storage (BS) system, to provide electricity for a rural and remote village located in the northwestern part of Sierra Leone (longitude 9.1°W and latitude 12.6°N), with an average daily solar irradiance between 4.6 and 6 kWh/m2/day. An assessment of the total electrical load estimated an expected daily consumption of 178 kWh. Simulation, optimization, and sensitivity analyses of each one of the individual power generation systems were carried out using HOMER software. Economic parameters such as Cost of Capital (CC), Net Present Cost (NPC), Levelized Cost of Electricity (LCOE)), technical parameters (energy production characteristics), and greenhouse gases emissions were compared and analyzed. Key findings from the simulation result indicate that systems consisting of DG only ($29,750) and SPV/BS ($110,131) obtained the least and highest CC, respectively. Similarly, in a respective manner, the highest and least NPC were obtained for systems with DG only ($496,336) and PV/DG/BS ($152,491) over a 25-year project lifetime. Furthermore, the least LCOE was obtained for the system comprising PV/DG/BS ($0.336/kWh). With an expected annual generation of (75,121 kWh), PV/DG/BS was obtained to be the most optimal solution. The sensitivity analysis observed that a reduction in the discount rate consequently reduces the LCOE of such a system. Furthermore, the model accounts for a 90% renewable energy fraction, with a significant reduction in the amount of annual GHG emissions, when compared with a generation system using diesel generator only.

Review and validation of photovoltaic solar simulation tools/software based on case study

Abstract Photovoltaic (PV) systems are an excellent solution to meet energy demand and protect the global environment in many cases. With the increasing utilization of the PV system worldwide, there is an increasing need for simulation tools to predict the PV system’s performance and profitability. This research includes testing and comparison of PV tools: photovoltaic geographical information system (PVGIS), PVWatts, SolarGIS, RETScreen, BlueSol, PVsyst, HelioScope, PV*SOL, Solarius PV, Solar Pro, PV F-Chart, PolySun, solar advisor model (SAM), and hybrid optimization model for electric renewables (HOMER), based on experimental data obtained from fixed on-grid 2 kWp PV system in 2019. The PV system is part of a research project related to the examination of the PV system operation in real climatic conditions in Niš. This research investigates the most appropriate PV software for PV systems design by testing the most commonly used PV tools. It was accomplished by comparing experimental data obtained by a 2 kWp PV system in Niš and estimated data obtained from different PV tools. The study shows that annually, the experimentally measured average daily solar irradiation on the inclined plane was 5,270 Wh/m2/day, and the lowest deviation of the simulation results compared to experimental measurements was obtained by SolarPro. Total annual electricity production from the given system was 2455.621 kW h, and the lowest deviation of the simulation results compared to experimental measurements was obtained by PVGIS. By analyzing and publishing the actual solar irradiation and PV power output data, this study could help researchers to increase the PV systems modeling accuracy.

Solar Energy Potentials of Some Selected Locations in Northeastern Nigeria

Sunlight is the primary source of clean and cheap energy but its intensity varies from one location to another depending on the latitude, altitude, atmospheric absorption and scattering by air molecules, dust particle and water vapour among others. The aim of this work is to determine the solar energy potentials of Gombe ( latitude 10° 16' 59.9988'' N and longitude of 11° 10' 0.0012'' E), Jalingo (latitude 8° 53' 34.2672'' N and Longitude 11° 22' 37.74'' E), Damaturu (Latitude 11° 44' 49.1856'' N and Longitude 11° 57' 58.2912'' E) and Bauchi (latitude 10° 18' 50.9724'' N and longitude 9° 50' 46.6152'' E) in northeastern Nigeria, the process involves obtaining the solar irradiation data for these four locations from a renewable energy simulation package ( photovoltaic geographical information system, PVGIS) for a period of 10 years, a daily, monthly and annual solar irradiation was obtained for each of these locations. A peak monthly values was obtained in the month of January for Gombe, Jalingo and Bauchi while the month of March has the peak value for Damaturu, an average daily solar irradiation of 5.8977kWh/m2/day, 5.9026 kWh/m2/day, 6.0337 kWh/m2/day and 5.9821kWh/m2/day and an annual values of 2154.44kWh/m2/yr, 2056.17 kWh/m2/yr, 2202.30kWh/m2/yr and 2150.60kWh/m2/yr for Gombe, Jalingo, Damaturu and Bauchi respectively. These locations have very similar atmospheric conditions and hence a closer range of solar energy potentials compared to places like Lagos, Onitsha and Sapele in Delta state with (4.42kWh/m2/day), (4.43kWh/m2/day, and 5.31 kWh/m2/day respectively. Damaturu has the highest solar irradiance among the four locations studied. Grid- connected PV system and thermal system (concentration thermal technology) can be built to support electricity generation and hot water production respectively for residential and industrial use. The utilization of Solar oven, cookers and coolers technology should be encourage by government and non-governmental organization, this will help stop global warning and desert encouragement and hence conserve other natural resources( such as forest) for other use ( furniture construction).

ASSESSMENT OF SOLAR ENERGY POTENTIAL OF NIGERIA FOR SOLAR POWER GENERATION THROUGH NUMERICAL SOLAR IRRADIANCE MAPPING

Any thorough analysis of solar energy applications in the country requires a solar resources map. Many maps have been developed, but they only show distributions presented in colour intensities. Solar irradiance can only be estimated from such maps. Using on the spot experimental data for solar map production does not provide accurate maps because various climatic and environmental conditions such as dust haze and cloud cover affect the amount of solar energy that reaches the ground in various locations in Nigeria. This is particularly true during the harmattan period. Therefore data generated from such methods cannot be used to develop accurate numerical solar maps. Data for such applications should be collected from outer space and over a long time for various locations. The National Aeronautics and Space Administration (NASA) provides a resources base for such data. The data used in this study covered 25 years (1994-2018). The average daily global solar irradiance for various longitude-latitude nodes is calculated from such data. With these data available, it is possible to estimate the average daily global solar irradiance for any location provided the longitude and latitude is known. Irradiance values for 300 locations in the country are evaluated from details presented by the maps. To validate the map, experimental irradiance values for selected locations are compared with values extracted from the solar irradiance map. Calculated irradiance values are found to agree satisfactorily with experimental values. The maximum percentage difference between calculated and experimental values is 6.8%. This proved that the solar map developed is a satisfactory provides a satisfactory representation of solar data for the various locations and can be used for other locations where such data does not exist. KEYWORDS: Solar Energy, Solar Maps, Irradiance, Energy Patterns,

ASSESSMENT OF SOLAR ENERGY POTENTIAL OF NIGERIA FOR SOLAR POWER GENERATION THROUGH NUMERICAL SOLAR IRRADIANCE MAPPING

Any thorough analysis of solar energy applications in the country requires a solar resources map. Many maps have been developed, but they only show distributions presented in colour intensities. Solar irradiance can only be estimated from such maps. Using on the spot experimental data for solar map production does not provide accurate maps because various climatic and environmental conditions such as dust haze and cloud cover affect the amount of solar energy that reaches the ground in various locations in Nigeria. This is particularly true during the harmattan period. Therefore data generated from such methods cannot be used to develop accurate numerical solar maps. Data for such applications should be collected from outer space and over a long time for various locations. The National Aeronautics and Space Administration (NASA) provides a resources base for such data. The data used in this study covered 25 years (1994-2018). The average daily global solar irradiance for various longitude-latitude nodes is calculated from such data. With these data available, it is possible to estimate the average daily global solar irradiance for any location provided the longitude and latitude is known. Irradiance values for 300 locations in the country are evaluated from details presented by the maps. To validate the map, experimental irradiance values for selected locations are compared with values extracted from the solar irradiance map. Calculated irradiance values are found to agree satisfactorily with experimental values. The maximum percentage difference between calculated and experimental values is 6.8%. This proved that the solar map developed is a satisfactory provides a satisfactory representation of solar data for the various locations and can be used for other locations where such data does not exist. KEYWORDS: Solar Energy, Solar Maps, Irradiance, Energy Patterns,

Comparative performance study of different types of solar dryers towards sustainable agriculture

Solar drying is becoming a popular option to replace mechanical dryers due to the high cost of energy, and the increased awareness of consumer orientation to clean energy products. In this study, three different low-cost solar dryers, viz. natural convection dryer (NCD), forced convection dryer (FCD), and heat pump integrated dryer (HPD) were examined, and thin-layer mushroom (agaricus bisporus) drying experiments were carried out on each. In this study, three main topics were determined: (i) to analyse the drying characteristics of mushroom slices in different thicknesses, (ii) to determine the effect of pretreatment on the drying time, (iii) to compare the collector efficiencies. For these purposes, 12 experiments were conducted between 9:00–18:00, the average daily solar irradiance was around 790 W/m2. In 10 drying experiments out of 12, it was observed that the samples were completely dried out within the experiment period, while the drying process of the half-cut mushrooms in NCD and FCD were completed after 18:00. The results show that cutting thin slices reduced the drying time by an average of 40.83 mins. Also, the process of pretreatment caused shorter drying time by an average of 26.66 mins, almost 7% in all cases. The average thermal efficiencies were found 59.74%, 67.66%, and 77.45% for NCD, FCD and HPD, respectively. According to these results, the most affecting factor in overall drying process is found to be drying air which is hot and holds less moisture. In addition, it turned out that the drying rate increases with the increase of the temperature and speed of the drying air.

Vertical Farms With Integrated Solar Photovoltaics

Abstract This paper outlines a method for determining the maximum number of floors of a vertical farm (VF) that can be powered by building-integrated solar photovoltaic panels for supplying artificial lighting to the plants. The panels are mounted on all the walls and the rooftop of the building. It takes into account the location of the site, the monthly average daily solar irradiation, parameters associated with the luminaires, the geometrical dimensions and orientation of the layout, the tilt angle and row spacing between the rooftop panels, and the efficiency of the conversion system. It then provides linear equations representing the year-round electricity demand of the luminaires and the yearly electric yield from the panels. These equations are solved simultaneously to estimate the maximum number of floors. The results show that design performance can be maximized by optimizing the floor dimensions, layout orientation, tilt angle, and row spacing. Hypothetical 300 m2 vertical farms, partially occupied by growing trays, located in Auckland and Dubai, were found to have maximum heights of 1.87 and 3.47 floors, respectively. A free online tool is also presented to help designers and researchers analyze designs located anywhere in the world.

Određivanje optimalnih nagibnih uglova fotonaponskih panela uz uvažavanje smanjenja direktne komponente iradijacije usled efekata senki u fotonaponskim sistemima

This paper considers the influence of the tilt angle of photovoltaic (PV) panels on the total amount of insolation on the surface of these panels on a monthly and annual basis, with and without consideration of shading effect. Based on the obtained results, optimal tilt angles of the PV panels in order to achieve maximum insolation, are determined, as well as the optimal tilt angles for achieving maximum generated electrical energy, taking into account the temperature of the panel. Special attention in the paper is paid to the shading effect created by the panel rows within the PV system and its influence on the reduction of direct component of irradiation and optimal tilt angles for different distances between PV panel rows. In the paper two different models for solar insolation calculation were considered and described in detail, clear day model and real cloud condition model. In order to obtain the average daily solar irradiation on the inclined surface, in addition to appropriate extraterrestrial irradiations, available measurements of the irradiation on the horizontal surface during one year period were used.

A Multi-Level World Comprehensive Neural Network Model for Maximum Annual Solar Irradiation on a Flat Surface

With the growing demand for clean and economically feasible renewable energy, solar photovoltaic (PV) system usage has increased. Among many factors, the tilt and azimuth angles are of great importance and influence in determining the photovoltaic panel’s efficiency to generate electricity. Although much research was conducted related to solar PV panels’ performance, this work critically determined the tilt and azimuth angles for PV panels in all countries worldwide. The optimum tilt and azimuth angles are estimated worldwide by the photovoltaic geographic information system (PVGIS). Also, annual and average daily solar irradiation incident on the tilted and oriented plate optimally (AR1 and DR1) are calculated. Besides, annual and average daily solar irradiation incident on plate tilt optimally and oriented because of the south in the northern hemisphere and because of the north in the southern hemisphere (AR2 and DR2) are estimated. PVGIS is also used to calculate the annual and average daily solar irradiation incident on the horizontal plate (AR3 and DR3). The data collected from PVGIS are used to develop an efficient and accurate artificial neural network model based on feed-forward neural network approach. This model is an essential subpart that can be used in an embedded system or an online system for further PV system analysis and optimization. The developed neural model reflected very high accuracy in predicting the PV panels’ optimal tilt and azimuth angles worldwide. The benefit of tilting is generally increased by increasing the latitude. As the latitude increases, the tilt factor (F) increases because of the increase in the optimum tilt angle by increasing the latitude. The optimal orientation is due to the north in the southern hemisphere and due to the south in the northern hemisphere for most cities worldwide. In sum, it can be concluded that the optimum tilt angle is equal to or greater than the latitude until the latitude 30°. The optimum tilt angle becomes less than the latitude, and the difference is increased until it reaches more than 20°. Hence in this study the aim is to develop a simple neural network model which can accurately predict the annual radiation and optimum tilt and azimuth angle in any region of the world and can be easily implemented in a low-cost microcontroller.

The Quality of Elephant Ginger Dried by Using Modified Hohenheim Dryer under Tropical Climate

The objective of the study was to determine the quality of elephant ginger (Zingiber officinale) dried by using a modified Hohenheim dryer designed based on the Hohenheim type tunnel dryer at University of Kassel, Germany. Drying is the oldest method could be used to extend the shelf-life of the product, and the thickness of the material is one of the factors that will influence the drying process. The study was conducted under the tropical climate, in Banda Aceh, Indonesia. The elephants ginger were sliced at different thickness of 3, 4 and 5 mm. Research parameters included solar irradiation, temperature, relative humidity (RH), drying time, drying rate, moisture content, ash content, yield, and colour. To assess the consumer acceptance to the dried ginger, a consumer test was also run to 25 respondents by using hedonic scale on the colour and flavour properties. The study showed that the drying of elephant ginger by using a modified Hohenheim dryer was promising to apply at slice thickness of 3 mm under the tropical climate. The average daily solar irradiation was 403.2 W/m² and the average temperature of drying chamber was 49.5˚C, and the total drying time was 7h. The drying curve of ginger did not follow the ideal drying rate curve; therefore, the modification of the dryer is still needed to improve its performance. However, the quality of dried ginger was good since it had met the export standard for moisture. Nevertheless, the ash content should be reduced to meet this standard by pilling the tuber. According to the sensory analysis, the respondents preferred the colour of ginger dried at slice thickness 3 mm to 4 and 5 mm, but they preferred the flavour of both slice thickness 3 and 4 mm to 5 mm. The colour properties at slice thickness of 3 mm were R-value by 204, G-value by 187, B-value by 119, L-value by 76, a-value by -3 and b-value by 36 and the colour properties among different slice thickness of dried ginger were strongly explained by b-value.

Experimental study on a direct water heating PV-T technology

This paper details a field study and a theoretical model of a PhotoVoltaic-Thermal (PV-T) system consisting of a solar PV panel with a thermally insulated water reservoir underneath. Unlike conventional PV-T systems, water is in direct contact with the glass solar PV panel. Thus, metallic tubular heat exchangers are omitted in this design. During operation, the PV-T panel is tilted, and cold water is pumped into the reservoir from the side closest to the ground. This achieves an active cooling of the PV panel maintaining an optimal electrical efficiency. Generated electricity is used to operate pumps and run the control system, while excess electricity is stored in a battery to be utilised as desired. The system and the inlet water absorb solar thermal energy and as a result they increase in temperature. In our field study, we explore the viability of this system as a self-powered, off-grid, solar collector and find that it can provide enough hot water of approximately 80 °C for a household of four in areas where average daily solar irradiance is >4.5 kWh/m2. We varied (1) the exposure angle, (2) PV panel type and (3) reservoir depth and found that in the limited ranges covered by our experiments the optimised configuration is with (1) an exposure angle of 14.7°, (2) a bifacial mono-crystalline solar PV panel and (3) a reservoir depth of 12 mm (given a fixed inlet water flow rate). The theoretical model of the device that is built, tracks energy losses with time and outputs the average reservoir temperature at each five-minute time-step. We validated this model with the obtained data during the field study. Then, this model is used to perform a sensitivity analysis on the parameters in testing and beyond (such as primarily insulation types and thicknesses), to provide a direction for further development and improvement.

The Assessment of Off-Grid Photovoltaic (PV) Systems for Rural Electrification in Indonesia

There are many rural areas in Indonesia without electricity, especially in remote islands which are challenging to access. The limited access to electricity inhibits people in rural areas to increase their welfare and quality of life. Identifying the urge for electricity access in remote areas and for increasing the utilization of renewable energy resources in Indonesia, the off-grid photovoltaic (PV) systems can be the solution. The paper aims to assess the off-grid PV systems for rural electrification in Indonesia. The Levelized cost of energy (LCOE) is conducted to assess the cost-effectiveness of the off-grid PV systems compared to other rural electrification solutions in Indonesia, such as diesel and micro-hydro. It results that LCOE of the PV battery has the highest LCOE with 0.30 US$/kWh. Another off-grid PV configuration: PV battery diesel (hybrid system) has LCOE ranging from 0.19 to 0.22 US$/kWh. This hybrid system can compete with the LCOE of diesel generator (0.17 – 0.24 US$/kWh). The range of LCOE reflects the variation of retail diesel prices in remote areas. The micro-hydro power plant has the lowest LCOE, 0.16 US$/kWh. However, this solution is only reliable in the areas that have stable water flow rate with different elevation. In this case, the off-grid PV systems are more reliable to generate electricity in remote areas because the average daily solar irradiation is 4.8 kWh/m2/day across Indonesia. Additionally, the trend of cost reduction in PV systems and the improvement in PV technologies can be game-changing that make off-grid PV systems more competitive compared to other solutions. Then, the paper analyses the fundamental issues regarding the off-grid PV systems application and it also recommends the policies that can be taken by the Government of Indonesia and the local government to provide sustainable rural electrification based on the off-grid PV systems.

Techno-economic analysis of a solar photovoltaic/thermal (PV/T) concentrator for building application in Sweden using Monte Carlo method

The solar energy share in Sweden will grow up significantly in next a few decades. Such transition offers not only great opportunity but also uncertainties for the emerging solar photovoltaic/thermal (PV/T) technologies. This paper therefore aims to conduct a techno-economic evaluation of a reference solar PV/T concentrator in Sweden for building application. An analytical model is developed based on the combinations of Monte Carlo simulation techniques and multi energy-balance/financial equations, which takes into account of the integrated uncertainties and risks of various variables. In the model, 11 essential input variables, i.e. average daily solar irradiance, electrical/thermal efficiency, prices of electricity/heating, operation & management (OM) cost, PV/T capital cost, debt to equity ratio, interest rate, discount rate, and inflation rate, are considered, while the economic evaluation metrics, such as levelized cost of energy (LCOE), net present value (NPV), and payback period (PP), are primarily assessed. According to the analytical results, the mean values of LCOE, NPV and PP of the reference PV/T connector are observed at 1.27 SEK/kW h (0.127 €/kW h), 18,812.55 SEK (1881.255 €) and 10 years during its 25 years lifespan, given the project size at 10.37 m2 and capital cost at 4482–5378 SEK/m2 (448.2–537.8 €/m2). The positive NPV indicates that the investment on the selected PV/T concentrator will be profitable as the projected earnings exceeds the anticipated costs, depending on the NPV decision rule. The sensitivity analysis and the parametric study illustrate that the economic performance of the reference PV/T concentrator in Sweden is mostly proportional to solar irradiance, debt to equity ratio and heating price, but disproportionate to capital cost and discount rate. Together with additional market analysis of PV/T technologies in Sweden, it is expected that this paper could clarify the economic situation of PV/T technologies in Sweden and provide a useful model for their further investment decisions, in order to achieve sustainable and low-carbon economics, with an expanded quantitative discussion of the real economic or policy scenarios that may lead to those outcomes.

Multi-pass solar air heating collector system for drying of screw-pine leaf (Pandanus tectorius)

An experimental investigation of solar drying of screw-pine leaf has been conducted in the open space of the solar research site, Universiti Teknologi PETRONAS Malaysia (4.385693° N, 100.979203° E). Screw-pine leaf has been used for handcraft in many villages in Asia and Africa. A transient state lumped element analysis was developed to determine the thermal performance of the multi-pass solar collector system (MSCS) in accordance with ASHRAE standards. The facility was assessed under the average daily solar irradiance of 412.6 Wm−2 and ambient temperature of 30 °C over an air mass flow rate range from 0.010 kgs−1 to 0.032 kgs−1. Drying kinetics profiles of screw-pine have been obtained and an improved range from 22% to 26% of instantaneous thermal collector efficiency has been recorded over the double pass collector system (DPCS) while thermal energy storage has contributed 5–8% to system performance. MSCS performance has been determined and achieved the thermal collector, pickup, drying and exergy efficiencies of 58.73%, 66.95%, 36.04% and 27.23–86.82%, respectively. The level of risk on the investment in MSCS has been measured using economic indices to obtain a payback period of 0.75 year. The thermal loss through conventional collector back plate has been prevented by integration of collector unit and the drying cabinet of the system. There is still need to further improve the system performance efficiency through enhanced energy saving innovation technique.

Feasibility of daylight-mediated photodynamic therapy for actinic keratosis throughout the year in Central and South America: a meteorological study.

Daylight-mediated photodynamic therapy (DL-PDT) is an efficacious treatment option for thin actinic keratosis (AK) that offers advantages over conventional PDT in terms of tolerability, treatment duration, and cost. A clinical study conducted in Australia determined the mean irradiance during a 2-hour exposure to be 305.8 W/m(2) (range: 40-585 W/m(2) ). The protoporphyrin IX light dose is influenced by latitude, weather conditions, and time of year. A recent study of meteorological data concluded that DL-PDT can be performed effectively throughout the year in Australia. Based on the same hypothesis and applying the same methodology, the present study investigated the suitability of daylight to perform DL-PDT in Central and South America. Solar radiation and weather data were gathered and analyzed to assess daylight irradiance (light intensity) throughout a full year across 32 geographical locations in Central and South America. The minimum average daily solar irradiance reported was above 305.8 W/m(2) in all locations investigated throughout the year. Annual averages of daily irradiance ranged from 578 W/m(2) in Chihuahua, Mexico, to 321 W/m(2) in Puerto Montt, Chile. Daylight-mediated PDT for AK can be performed effectively throughout the year in Central and South America given that weather conditions permit a comfortable 2-hour direct exposure to daylight.

An Empirical Study on Energy Performance of 6㎾ Grid-connected Photovoltaic System in Summer Season

This paper carried out empirical evaluation on generating characteristics and energy performance of 6 ㎾ grid-connected photovoltaic (PV) system in summer season. The PV system was installed to provide power for lighting and appliance of a nursery accommodating about 100 children and teachers. According to the analysis of the monitoring data, average daily solar irradiance was measured to be 5.44, 2.82 and 4.98 ㎾h/㎡ from June to August, respectively. Meanwhile, average daily power generation of the system was computed to be 29.5, 14.3 and 25.8 ㎾h for each month, and the minimum and maximum values during three months were computed to be 1.2 and 36.4 ㎾h. Therefore, it is considered the power output of the PV system is closely related to the variation in solar radiation. In addition, it was observed that average daily load-sharing ratio of the system was 24, 4 and 25% in each typical day, and average weekly load-sharing ratio was 32, 15 and 23% in each typical week. Therefore, this results show that grid-connected systems is more suitable than stand-alone system in case of last rainy days during the summer season aside from the advantage that are not necessary to install an expensive battery.

Modeling monthly mean variation of the solar global irradiation

The monthly mean variation of the solar global reaching the Earth's surface has been characterized at a global level by a regression model. This model considers the monthly variation itself (to different horizons and even the maximum annual variation) as the study variable, and it is applied without using data corresponding to measured meteorological variable. Two explicative variables have been used, the variation of the extraterrestrial irradiation and the variation of the clear sky global horizontal irradiation. The work has been carried out from datasets including average global daily solar irradiation for each month of the year measured on the ground. The model quality has been proven to be very dependent of the temporal variation considered, in such a way that higher variations, that is to say, higher distances between months, lead to an improvement in the model outcomes.