Cost analysis of different solar still configurations

The enhancement of the productivity of the solar desalination system, in a certain location, could be attained by a proper modification in the system design. Therefore, different design configurations could be found in literatures. However, the increase in the system productivity with high system cost may increase also the average annual cost of the distillate. Cost analysis of different design configurations of solar desalination units is essential to evaluate the benefit of modification from the economical point of view. The main objective of this work is to estimate the water production cost for different types of solar stills. In this paper 17 design configurations are considered. Systems with higher and lower values of productivity are considered in this investigation. A simplified model for cost analysis is applied in this study. The results show that, the best average and maximum daily productivity are obtained from solar stills of single-slope and pyramid-shaped. The higher average annual productivity for a solar still is about 1533 l/m² using pyramid-shaped while the lower average annual productivity is about of 250 l/m² using modified solar stills with sun tracking. The lowest cost of distilled water obtained from the pyramid-shaped solar still is estimated as 0.0135 $/l while highest cost from the modified solar stills with sun tracking is estimated as 0.23 $/l.     

Fossil fuels substitution by the solar energy utilization for the hot water production in the heating plant “Cerak” in Belgrade

The main objective of this paper is to evaluate energy and environmental benefits of the large-scale solar heating system connection with district heating system. The assessment of fossil fuels substitution by the solar energy for the hot water production for domestic use, during the summer period, is done. Hot water for district heating and domestic use is produced in heating plant “Cerak” placed in the suburb of Belgrade. The existing production and distribution system are based on fossil fuel energy, mainly on the natural gas. In the first phase of the project plan was to install about 10,000 m² of solar collectors to substitute nearly 25% of natural gas consumption. During the summer period, the saving of natural gas calculated for presented system is approximately 430,000 m³ and in this way 900 t of the CO₂ emissions would be reduced.     

A truncated pyramid non-tracking type multipurpose domestic solar cooker/hot water system

For impressive dissemination of the solar thermal gazettes, it is imperative to keep on changing the device design features so as to cater to the different demands of diverse section of the society. Domestic solar hot water systems are not suitable for cooking and the capacity of domestic solar box type cookers for water heating is very low. We report truncated pyramid geometry based multipurpose solar device which could be used for domestic cooking as well as water heating. The device is designed, fabricated and tested. Cooking tests approved by Bureau of Indian Standards were performed in different seasons and the device was found to meet the requirement stipulated on two figures of merit. The performance of the design was also evaluated as a hot water system and the maximum efficiency was found to be 54%. The day-time and average night-time heat-loss coefficients were found to be 5.7 W/°C m² and, 3.74 W/C m², respectively, which are comparable to those of flat-plate collector based solar hot water systems. A simple economic analysis illustrate that this kind of multi-purpose design could be financially viable and physically useful.     

Techno-economic analysis and modelling of a remote photovoltaic water pumping system in the desert of Tunisia

For estimating the performance of a photovoltaic (PV) water pumping system without battery storage, a simple algorithm has been developed. This simulation program uses the hourly global solar radiation, the hourly ambient temperature and the hourly wind speed as the input, moreover the characteristics of region (latitude, longitude, ground albedo) and characteristics of PV water pumping system (orientation, inclination, nominal PV module efficiency, NOCT, PV array area, PV temperature coefficient, miscellaneous power conditioning losses, miscellaneous PV array losses, temperature of reference, moto-pump efficiency and inverter efficiency). This work allows evaluating the economic interest of a remote PV water pumping systems in the desert of Southern Tunisia, which will have to satisfy an average daily volume of 45 m³ throughout the year compared to another very widespread energy system in the area, the diesel genset (DG), by using the method of the life-cycle cost (LCC). The cost per m³ of water was calculated for this system. It is found that the LCC for PV system is 0.500 TND/m³ and the LCC DG is 0.837 TND/m³. The present study indicates economic viability of PV water pumping systems in the desert of Tunisia.     

Assessing sizing optimality of OFF-GRID AC-linked solar PV-PEM systems for hydrogen production

Herein, a novel methodology to perform optimal sizing of AC-linked solar PV-PEM systems is proposed. The novelty of this work is the proposition of the solar plant to electrolyzer capacity ratio (AC/AC ratio) as optimization variable. The impact of this AC/AC ratio on the Levelized Cost of Hydrogen (LCOH) and the deviation of the solar DC/AC ratio when optimized specifically for hydrogen production are quantified. Case studies covering a Global Horizontal Irradiation (GHI) range of 1400–2600 kWh/m²-year are assessed. The obtained LCOHs range between 5.9 and 11.3 USD/kgH₂ depending on sizing and location. The AC/AC ratio is found to strongly affect cost, production and LCOH optimality while the optimal solar DC/AC ratio varies up to 54% when optimized to minimize the cost of hydrogen instead of the cost of energy only. Larger oversizing is required for low GHI locations; however, H₂ production is more sensitive to sizing ratios for high GHI locations.     

A technoeconomic simulation model for A hybrid solar water heating system

A simple mathematical model has been developed to evaluate the technoeconomic performance of a hybrid solar water heating system for commercial and industrial applications. Numerical calculations, corresponding to Delhi climatic data and for the prevalent cost of a solar energy system in the Indian market, show that the optimum collector area (meeting nearly 45 percent of the daily hot water demand M litres) is 0–0075 Mm²; either a reduction of about 35 per cent in the present solar collector costs or a more than 20 per cent rise in the cost of presently subsidized diesel oil makes the solar option economic. With the present parameters the cost of useful solar energy is higher than that obtained from the conventional system.     

Performance of a multi-functional direct-expansion solar assisted heat pump system

This paper reports on the long-term performance of a direct-expansion solar assisted heat pump (DX-SAHP) system for domestic use, which can offer space heating in winter, air conditioning in summer and hot water during the whole year. The system employs a bare flat-plate collector array with a surface area of 10.5 m², a variable speed compressor, a storage tank with a total volume of 1 m³ and radiant floor heating unit. The performance under different operation modes is presented and analyzed in detail. For space-heating-only mode, the daily-averaged heat pump COP varied from 2.6 to 3.3, while the system COP ranged from 2.1 to 2.7. For water-heating-only mode, the DX-SAHP system could supply 200 l or 1000 l hot water daily, with the final temperature of about 50 °C, under various weather conditions in Shanghai, China. For space-cooling-only mode, the compressor operates only at night to take advantage of a utility’s off-peak electrical rates by chilling water in the thermal storage tank for the daytime air-conditioning. It shows that, the multi-functional DX-SAHP system could guarantee a long-term operation under very different weather conditions and relatively low running cost for a whole year.     

Feasibility study of a solar-assisted heating/cooling system for an aquatic centre in hot and humid climates

This paper reports on a feasibility study of a solar-powered heating/cooling system for a swimming pool/space combination in a tropical environment. The system utilizes an absorption chiller and a cooling tower to meet the facilities and locker room load. The heating is accomplished by employing hot water generated by heat exchange with the solar collector working fluid. Two thermal storage tanks were employed for the collector and domestic use. The absorption chiller utilizes hot water to regenerate the LiBr solution. The proposed system enables the swimming season to be extended from sixteen weeks to fifty-two weeks. Simulation results indicate that a combination of a double glazed collector area of 600–4800 m² and a storage tank volume of 11·36 m³ results in a 25–37% reduction in the consumption of natural gas. Economic analysis is performed based on the life-cycle-cost method and takes into account the effects of discount rate, fuel price and fuel inflation rate. Different scenarios for which the solar-assisted system is economical are presented and analysed. © 1997 John Wiley & Sons, Ltd.     

Thermodynamic analysis of an oxy-hydrogen combustor supported solar and wind energy-based sustainable polygeneration system for remote locations

In this study, a solar and wind energy-based system integrated with H₂O₂ combustor is developed to produce fresh water from sea-water desalination, electricity, cooling, hydrogen, and oxygen as well as to provide food drying and domestic water heating. The main components of the proposed system contains concentrated solar power (CSP), wind turbine, Rankine cycle, multi stage flash (MSF) desalination unit, water electrolyzer, a refrigeration unit, a food drying system, oxy-hydrogen combustor, domestic water heater, as well as hydrogen and oxygen storage units. Furthermore, for continuous operation of the system during night time and in cloudy weather conditions, a thermal energy storage (TES) unit and oxy-hydrogen combustion unit are integrated to the system. Based on energy and exergy balances, performance assessment of the proposed system is conducted. Moreover, effects of various parameters such as solar irradiation, wind speed and ambient temperature on some of the outputs of the system are investigated. The results illustrate that the proposed system fulfills most of the remote community requirements in an efficient, environmentally benign and uninterrupted way. The obtained results for the reference case show that with installation of parabolic trough concentrators (PTCs) on an area of 111,728 m², the plant produces net electrical power of approximately 11.4 MW, approximately 828 m³/day of freshwater, about 36 kg/s of hot air for food drying, about 31 kg/s of heated domestic water, approximately 920 kg/day of H₂ and about 2.26 MW of cooling. The overall energy efficiency of the system is found to be 50%, while the exergy efficiency of the system is 34%. In addition, the energy and exergy efficiencies of single generation in which there is only electrical power output are approximately 15% and 16%, respectively.     

Performance of solar still with a concave wick evaporation surface

Surfaces used for evaporation and condensation phenomenon play important roles in the performance of basin type solar still. In the present study, a concave wick surface was used for evaporation, whereas four sides of a pyramid shaped still were used for condensation. Use of jute wick increased the amount of absorbed solar radiation and enhanced the evaporation surface area. A concave shaped wick surface increases the evaporation area due to the capillary effect. Results show that average distillate productivity in day time was 4.1 l/m² and a maximum instantaneous system efficiency of 45% and average daily efficiency of 30% were recorded. The maximum hourly yield was 0.5 l/h. m² after solar noon. An estimated cost of 1 l of distillate was 0.065 $ for the presented solar still.     

Solar-assisted gas-energy water-heating feasibility for apartments

Studies of residential energy use, solar-energy technology for building, and the requirements for implementing technology in the housing industry led to a project to develop a solar water heater for apartments. A design study for a specific apartment was used to establish a solar water-heater cost model which is based on plumbing contractor bids and manufacturer estimates.The cost model was used to size the system to minimize the annualized cost of hot water. The annualized cost of solar-assisted gas-energy water heating is found to be less expensive than electric water heating but more expensive than gas water heating. The feasibility of a natural gas utility supplying the auxiliary fuel is evaluated. It is estimated that gas-utilizing companies will find it profitable to offer solar water heating as part of a total energy service option or on a lease basis when the price of new base-load supplies of natural gas reaches $2·50–$3·00 per 10⁶ Btu.     

Optimal use of solar collectors for residential buildings

Solar radiation is an abundant free resource which may be used in the form of solar heated water. This is achieved in solar collectors which, unfortunately, are expensive devices and, further, the warm water must be stored in accumulators—items which also cost money. This paper shows how we have optimized the situation for a block‐of‐flats in Sweden. In order to find this point we have used the minimum life‐cycle cost (LCC) concept as a criterion. The best solution is therefore found when that cost finds its lowest value. It is also examined under which conditions solar collectors are part of the optimal solution and further it is calculated what happens if this optimal point is abandoned, i.e. how much will the LCC increase if other than optimal solutions are chosen. LCC optimization for multi‐family buildings almost always results in a heating system with low operating costs such as district heating or dual‐fuel systems where a heat pump takes care of the base load and an oil boiler the peak. The installation cost must, however, be kept to a reasonable level. Expensive solar panel systems are therefore normally avoided if the lowest LCC shall be reached, at least for Swedish conditions. This is so even if the solar system has a very low operating cost. For buildings where the only alternative energy source is electricity, solar collectors seem to be on the rim of profitability, i.e. for an energy price of about 0.6 SEK kWh^?1. Copyright © 2001 John Wiley & Sons, Ltd.     

Thermoeconomic analysis and artificial neural network based genetic algorithm optimization of geothermal and solar energy assisted hydrogen and power generation

The study aims to optimize the geothermal and solar-assisted sustainable energy and hydrogen production system by considering the genetic algorithm. The study will be useful by integrating hydrogen as an energy storage unit to bring sustainability to smart grid systems. Using the Artificial Neural Network (ANN) based Genetic Algorithm (GA) optimization technique in the study will ensure that the system is constantly studied in the most suitable under different climatic and operating conditions, including unit product cost and the plant's power output. The water temperature of the Afyon Geothermal Power Plant varies between 70 and 130 °C, and its mass flow rate varies between 70 and 150 kg/s. In addition, the solar radiation varies between 300 and 1000 W/m² for different periods. The net power generated from the region's geothermal and solar energy-supported system is calculated as 2900 kW. If all of this produced power is used for hydrogen production in the electrolysis unit, 0.0185 kg/s hydrogen can be produced. The results indicated that the overall energy and exergy efficiencies of the integrated system are 4.97% and 16.0%, respectively. The cost of electricity generated in the combined geothermal and solar power plant is 0.027 $/kWh if the electricity is directly supplied to the grid and used. The optimized cost of hydrogen produced using the electricity produced in geothermal and solar power plants in the electrolysis unit is calculated as 1.576 $/kg H₂. The optimized unit cost of electricity produced due to hydrogen in the fuel cell is calculated as 0.091 $/kWh.     

Solar electric powered reverse osmosis water desalination system for the rural village,Al Maleh: design and simulation

Desalination of brackish water by using reverse osmosis (RO) system powered by solar PV has not been tried and examined in Palestine until now. This paper proposes rural village Al Maleh for erection and testing of the first PV-powered RO system. Al Maleh is highly qualified for testing of such systems since it has a lot of mineral hot water springs of about 3400?ppm salinity. Based on the climate conditions in Al Maleh, the paper presents the design of the PV-powered RO water desalination system. The obtained design results can be used for an economic feasibility study of this technology [Mahmoud, M. Techno-economic feasibility of PV-powered water desalination in Palestine. Special Case: Al Maleh Village (to be published).]. The performance of the designed system is investigated by software simulation. The obtained results show that a daily production of 1?m³ from the brackish water in Al Maleh would require about 820 peak watt of PV generator.     

Optimization of tank and flat-plate collector of solar water heating system for single-family households to assure economic efficiency through the TRNSYS program

Solar water heating systems are widely used in Brazil for domestic purposes in single-family households. The exploitation of the potential energy of the water from the upper tank and the thermosyphon phenomena for hot water circulation constitutes the absolute majority of the residential solar water heating systems in the country. But, these water heating systems are usually sized according to tables provided by the manufacturers, which show the number of plates required based on the size of the family and the number of hot water outlets. This sizing is based much more on intuition rather than on scientific data. For that reason, this work has developed an optimization model for water heating systems design parameters, using a numerical simulation routine, in a long-term transient regime. The optimized design gives the slope and area of the flat plate collector, which results in the minimum cost over the equipment life cycle. The computing procedure was executed considering specific characteristics of the project. A thermosyphon solar water heating system with flat-plate collector for Sao Paulo's climate was simulated. The practice of Brazilian designers and manufacturers is to recommend the maximization of the energetic gain for the winter. This paper has analyzed in economic terms if it is more attractive to increase the gain of solar energy in the winter period, with the consequence of reduction of the solar energy gain along the year, or to adopt the adequate slope, which improves the yearly solar energy gain.     

System performance and economic analysis of solar-assisted cooling/heating system

The long-term system simulation and economic analysis of solar-assisted cooling/heating system (SACH-2) was carried out in order to find an economical design. The solar heat driven ejector cooling system (ECS) is used to provide part of the cooling load to reduce the energy consumption of the air conditioner installed as the base-load cooler. A standard SACH-2 system for cooling load 3.5 kW (1 RT) and daily cooling time 10 h is used for case study. The cooling performance is assumed only in summer seasons from May to October. In winter season from November to April, only heat is supplied. Two installation locations (Taipei and Tainan) were examined.It was found from the cooling performance simulation that in order to save 50% energy of the air conditioner, the required solar collector area is 40 m² in Taipei and 31 m² in Tainan, for COP_j = 0.2. If the solar collector area is designed as 20 m², the solar ejector cooling system will supply about 17–26% cooling load in Taipei in summer season and about 21–27% cooling load in Tainan. Simulation for long-term performance including cooling in summer (May–October) and hot water supply in winter (November–April) was carried out to determine the monthly-average energy savings. The corresponding daily hot water supply (with 40 °C temperature rise of water) for 20 m² solar collector area is 616–858 L/day in Tainan and 304–533 L/day in Taipei.The economic analysis shows that the payback time of SACH-2 decreases with increasing cooling capacity. The payback time is 4.8 years in Tainan and 6.2 years in Taipei when the cooling capacity >10 RT. If the ECS is treated as an additional device used as a protective equipment to avoid overheating of solar collectors and to convert the excess solar heat in summer into cooling to reduce the energy consumption of air conditioner, the payback time is less than 3 years for cooling capacity larger than 3 RT.     

Integrated solar heating systems: From initial sizing procedure to dynamic simulation

The sizing of the solar installation of an individual dwelling is a problem which can be solved in many ways. The approach described in this paper is a simplified procedure of considerable interest. It requires only a small quantity of data and can be computed in a short time. The performance of this procedure was evaluated by a more complex sizing method based on detailed simulation. The simplified procedure was applied to the case of an individual dwelling using a solar collector field to produce domestic hot water and space heating. The building and the solar installation have then been modelled with the software TRNSYS 16 and their behaviour was simulated during a whole year. The results obtained are particularly close to the ones expected by the simplified sizing procedure.     

Space solar cells—tradeoff analysis

This paper summarizes the study that had the objective to tradeoff space solar cells and solar array designs to determine the best choice of solar cell and array technology that would be more beneficial in terms of mass, area and cost for different types of space missions. Space solar cells, which are commercially now available in the market and to be available in the near future, were considered for this trade study. Four solar array designs: rigid, flexible, thin film flexible and concentrator solar arrays were considered for assessment. Performance of the solar cells along with solar array designs were studied for two types of space missions: geo synchronous orbit (GEO) and low earth orbit (LEO) spacecraft. The Solar array designs assumed were to provide 15 kW power for 15 years mission life in GEO and 5 kW power for 5 years mission life in LEO altitudes. To perform tradeoff analysis a spread sheet model was developed that calculates the size, mass and estimates the cost of solar arrays based on different solar cell and array technologies for given set of mission requirements. Comparative performance metrics (W/kg, W/m², kg/m², and $/W) were calculated for all solar arrays studied and compared, at the solar array subsystem level and also at the spacecraft system level. The trade analysis results show that high-efficiency multijunction solar cells bring lot of cost advantages for both types of missions. The trade study also show that thin film solar cells with moderate efficiency with ultra lightweight flexible array design may become competitive with well-established single crystalline solar cell technologies in the future.     

Monitoring and operational results of a hybrid solar-biomass heating system

Solar thermal systems, that provide auxiliary energy for space heating, represent a growing opportunity in European countries like Austria and Germany. However, such systems are as yet not widely known in the rest of Europe, unlike thermosyphon water heating systems. In addition, the need for energy conservation and reduction of CO₂ emissions, to combat climate change, demands the use and advance of renewable energy sources in new sectors than for common domestic water heating.The purpose of this research work is to present a full cycle of operational results of a hybrid solar thermal-biomass space heating system in Greece.The hybrid heating system was installed at the Centre for Renewable Energy Sources (CRES), Pikermi, central Greece in September 2005 with the intension to provide all the heat requirements for a specific office block of 60 m² area. The system was analyzed and optimized over a period of 6 months. The solar contribution during the actual measurement period (60% of the operating period) covered 52.9% of the total heating demand.The operational results of this unit from November 2005 till April of 2006 are presented and analyzed. The main parameters presented here include the operation of the system, the results, the coverage fraction (f%) of the solar and the biomass subsystems, the actions taken to increase its efficiency and the technical problems faced along with possible solutions to overcome them.     

Methodology for estimation of potential for solar water heating in a target area

Proper estimation of potential of any renewable energy technology is essential for planning and promotion of the technology. The methods reported in literature for estimation of potential of solar water heating in a target area are aggregate in nature. A methodology for potential estimation (technical, economic and market potential) of solar water heating in a target area is proposed in this paper. This methodology links the micro-level factors and macro-level market effects affecting the diffusion or adoption of solar water heating systems. Different sectors with end uses of low temperature hot water are considered for potential estimation. Potential is estimated at each end use point by simulation using TRNSYS taking micro-level factors. The methodology is illustrated for a synthetic area in India with an area of 2 sq. km and population of 10,000. The end use sectors considered are residential, hospitals, nursing homes and hotels. The estimated technical potential and market potential are 1700 m² and 350 m² of collector area, respectively. The annual energy savings for the technical potential in the area is estimated as 110 kW h/capita and 0.55 million-kW h/sq. km. area, with an annual average peak saving of 1 MW. The annual savings is 650-kW h per m² of collector area and accounts for approximately 3% of the total electricity consumption of the target area. Some of the salient features of the model are the factors considered for potential estimation; estimation of electrical usage pattern for typical day, amount of electricity savings and savings during the peak load. The framework is general and enables accurate estimation of potential of solar water heating for a city, block. Energy planners and policy makers can use this framework for tracking and promotion of diffusion of solar water heating systems.