Techno-economic evaluation of a grid-connected PV-trigeneration-hydrogen production hybrid system on a university campus

Many universities have plans to reduce campus energy consumption with developed energy efficiency strategies, supply the energy needs of the university campus with renewable energy and create a green campus. In order to serve this purpose, this study focuses on the simulation of the installation of an on-grid photovoltaic (PV) power system at the Vocational Colleges Campus, Hitit University. On the other hand, the integration of the simulated PV system with a gas fired-trigeneration system is discussed. Moreover, the study explores opportunities for solar hydrogen generation without energy storage on campus. For the PV system simulation, three different scenarios were created by using web-based PV system design software (HelioScope). Installed powers in the simulation were found as 94.2 kWe, 123.9 kWe, and 157.5 kWe for the low scenario (on the rooftop), high scenario (on the rooftop), and the high + PV canopy arrays scenario (on the rooftop and an outdoor parking area), respectively. The levelized cost of electricity (LCOE) values were 0.061 $/kWh, 0.065 $/kWh, and 0.063 $/kWh for the low scenario, high scenario, and the scenario including PV canopy, respectively. The energy payback time is found to be 6.47–6.94 years for the 20–25 years lifetime of the PV plant. The simulation results showed that the PV system could support it by generating additional electrical energy up to 25% of the existing system. The campus can reduce GHG emissions of 1546–2272 tonnes-CO₂eq, which is equivalent to 142–209 ha of forest-absorbing carbon unused during the life of the PV system. Depending on the production and consumption methods utilized on campus, which is a location with relatively large solar potential, the levelized cost of hydrogen (LCOH) of hydrogen generation ranged from 0.054 $/kWhH₂ (1.78 $/kgH₂) to 0.103 $/kWhH₂ (3.4 $/kgH₂). Consequently, with proper planning and design, a grid-connected PV-trigeneration-hydrogen generation hybrid system on a university campus may operate successfully.     

Performance of off-grid residential solar photovoltaic power systems using five solar tracking modes in Kunming,China

This paper compares the performance of a 2.02 kW_p off-grid residential solar photovoltaic (PV) power system using PVSYST simulation software for a household in Kunming, Yunnan province, China. The monthly available solar energy; missing energy; array, final, and reference yields, performance ratio; and array capture and system losses were analyzed for five solar tracking modes: fixed tilted plane, seasonal tilt adjustment, horizontal axis tracking, vertical axis tracking, and dual axis tracking. Although there were some similar aspects across the five systems, minimum available solar energy (2461 kWh/y) and maximum missing energy (134.68 kWh/y) were obtained using the fixed tilted plane system (tilt angle = 25°, azimuth angle = 0°), whereas maximum available solar energy (3081 kWh/y) and minimum missing energy (48.53 kWh/y) in October were obtained using the dual axis tracking system. Average monthly performance ratio was maximal for the fixed tilted plane system (0.689), and minimal for the dual axis tracking system (0.596).     

Performance analysis and economic competiveness of 3 different PV technologies for hydrogen production under the impact of arid climatic conditions of Morocco

For green hydrogen production, the choice of the appropriate renewable energy source to drive the water electrolysis process is crucial. Currently, solar Photovoltaic (PV) energy is one of the most popular and cheapest renewable energy sources; however, the performance of this technology is highly affected by the weather condition especially after the exposition to harsh climate conditions for long periods. Accordingly, the aim of this study is to assess the appropriate PV technology for hydrogen production under the impact of arid climatic conditions. For this reason, we evaluated the hydrogen production from 3 PV technologies, namely: monocrystalline (m-Si), polycrystalline (p-Si) and amorphous (a-Si) technologies exposed outdoors for a period of 3 years under the arid climatic conditions of Errachidia, Morocco. In addition, the degradation rate of each technology has been calculated and its impact on hydrogen production and its cost has been investigated.The results show that, the technology with the higher yearly hydrogen yield is the p-Si with 37.07 kg/kWp, followed by the m-Si with 36.84 kg/kWp and finally the a-Si with 36.68 kg/kWp. As for the cost of hydrogen production, the lowest cost was found in the case of the p-Si technology as well with 4.89 $/kg, whereas for the m-Si and a-Si technologies it was found equal to 5.48 $/kg and 6.28 $/kg respectively. However, the evaluation the impact of the PV modules degradation reveals that p-Si is technology affect the most with an annual degradation rate of 0.92%, followed by the a-Si with 0.72% and m-Si technologies with 0.45%. Nonetheless, when taken in consideration the impact of the degradation on the cost of hydrogen production, the p-Si remain the most cost effective technology even though the cost has increase to 5.32 $/kg, 5.78 $/kg and 6.67 $/kg for the p-Si, m-Si and a-Si technologies respectively.     

跟踪式光伏发电系统研究

根据某地实测的太阳辐射数据,仿真比较了配备有单轴跟踪和双轴跟踪等4种跟踪控制的光伏发电系统与固定式光伏发电系统的太阳辐射利用率。并在此基础上对4种跟踪系统的跟踪角控制规律及跟踪控制方式进行了详细的分析,得出倾纬度角单轴跟踪系统控制规律最为简单,算法实施更为实用的结论。同时,也在理论上证明了采用步进式控制方式的跟踪系统能够在保持较高太阳辐射利用率情况下简化控制系统设计,有利于工程设计及应用。     

Efficient STEP (solar thermal electrochemical photo) production of hydrogen – an economic assessment

A consideration of the economic viability of hydrogen fuel production is important in the STEP (Solar Thermal Electrochemical Photo) production of hydrogen fuel. STEP is an innovative way to decrease costs and increase the efficiency of hydrogen fuel production, which is a synergistic process that can use concentrating photovoltaics (CPV) and solar thermal energy to drive a high temperature, low voltage, electrolysis (water-splitting), resulting in H₂ at decreased energy and higher solar efficiency. This study provides evidence that the STEP system is an economically viable solution for the production of hydrogen. STEP occurs at both higher electrolysis and solar conversion efficiencies than conventional room temperature photovoltaic (PV) generation of hydrogen. This paper probes the economic viability of this process, by comparing four different systems: (1) 10% or (2) 14% flat plate PV driven aqueous alkaline electrolysis H₂ production, (3) 25% CPV driven molten electrolysis H₂ production, and (4) 35% CPV driven solid oxide electrolysis H₂ production. The molten and solid oxide electrolysers are high temperature systems that can make use of light, normally discarded, for heating. This significantly increases system efficiency. Using levelized cost analysis, this study shows significant cost reduction using the STEP system. The total price per kg of hydrogen is shown to decrease from $5.74 to $4.96 to $3.01 to $2.61 with the four alternative systems. The advanced STEP plant requires less than one seventh of the land area of the 10% flat cell plant. To generate the 216 million kg H₂/year required by 1 million fuel cell vehicles, the 35% CPV driven solid oxide electrolysis requires a plant only 9.6 mi² in area. While PV and electrolysis components dominate the cost of conventional PV generated hydrogen, they do not dominate the cost of the STEP-generated hydrogen. The lower cost of STEP hydrogen is driven by residual distribution and gate costs.     

Management of photovoltaic excess electricity generation via the power to hydrogen concept: A year-round dynamic assessment using Artificial Neural Networks

This paper assesses energetically and economically the power-to-hydrogen concept by exploring the excess power resulting from the mismatch between the photovoltaic (PV) generation and the electric demand of a medium-size commercial structure located in Morocco. The variability in the building electric load is considered and the power flows from the PV field to the building are predicted using Artificial Neural Networks for a time-resolution of 15 min. A MATLAB code was implemented to estimate the instantaneous hydrogen production based on a semi-empirical mathematical formulation of an Alkaline type electrolyzer with a nominal capacity of 15 kW. These combined approaches are for the first time adopted to evaluate the feasibility of integrated PV hydrogen systems under the Moroccan context. Using a set of 5 electrolyzers coupled to the 104 kW_p currently installed solar PV field, it was possible to generate about 18,622 Nm³/year of hydrogen by exploring the PV excess power. The overall efficiency of the integrated system ranged from 9.5% (in March) to 10.1% (in May). Such an approach allowed enhancing the effective efficiency and capacity factor to values of 9.873% and 26.87%, respectively compared to 6.325% and 10.163% for the base case scenario without hydrogen systems. From an economic perspective, it was found that the integrated PV-hydrogen plant engendered levelized cost of electricity and hydrogen of 12.56 c$/kWh and 21.55 $/kg, respectively.     

Long-term field test of solar PV power generation using one-axis 3-position sun tracker

The 1 axis-3 position (1A-3P) sun tracking PV was built and tested to measure the daily and long-term power generation of the solar PV system. A comparative test using a fixed PV and a 1A-3P tracking PV was carried out with two identical stand-alone solar-powered LED lighting systems. The field test in the particular days shows that the 1A-3P tracking PV can generate 35.8% more electricity than the fixed PV in a partly-cloudy weather with daily-total solar irradiation H_T = 11.7 MJ/m² day, or 35.6% in clear weather with H_T = 18.5 MJ/m² day. This indicates that the present 1A-3P tracking PV can perform very close to a dual-axis continuous tracking PV (Kacira et al., 2004). The long-term outdoor test results have shown that the increase of daily power generation of 1A-3P tracking PV increases with increasing daily-total solar irradiation. The increase of monthly-total power generation for 1A-3P sun tracking PV is between 18.5-28.0%. The total power generation increase in the test period from March 1, 2010 to March 31, 2011, is 23.6% in Taipei (an area of low solar energy resource). The long-term performance of the present 1X-3P tracking PV is shown very close to the 1-axis continuous tracking PV in Taiwan (Chang, 2009). If the 1A-3P tracking PV is used in the area of high solar energy resource with yearly-average H_T > 17 MJ/m² day, the increase of total long-term power generation with respect to fixed PV will be higher than 37.5%. This is very close to that of dual-axis continuous tracking PV.The 1A-3P tracker can be easily mounted on the wall of a building. The cost of the whole tracker is about the same as the regular mounting cost of a conventional rooftop PV system. This means that there is no extra cost for 1A-3P PV mounted on buildings. The 1A-3P PV is quite suitable for building-integrated applications.     

A technical and economical assessment of hydrogen production potential from solar energy in Morocco

In this study, a techno-economic analysis of the capacity of Morocco to produce hydrogen from solar energy has been conducted. For this reason, a Photovoltaic-electrolyze system was selected and the electricity and hydrogen production were simulated for 76 sites scattered all over the country. The Global Horizontal Irradiation (GHI) data used for the simulation were extracted from the CAMS-Rad satellite database and meteorological stations at ground level.Before simulations, the accuracy of the GHI values from the satellite dataset has been checked, and their uncertainties was calculated against accurate data measured in-situ. After that, the simulated values of the hydrogen mass were interpolated using a GIS software to create a Hydrogen production map of Morocco. Finally, an economical investigation of electricity and hydrogen production costs has been conducted by calculating the $LCOE$ and $LC{O}_{H_2}$.Results show that the satellite dataset has a mean average deviation of 6.8% which is a very acceptable error rang. Also, it was found that Morocco have a high potential for hydrogen production, with a daily annual production that varies between 6489 and 8308 Tons/km². Moreover, the cost of electricity and hydrogen production in the country are in the range of 0.077–0.099 $/kWh and 5.79–4.64 $/Kg respectively.The findings of this study are with high importance as they provide an overall perspective of the country potential of hydrogen production for policy makers and investors, and it was motivated by the lack of information on the subject in the literature since it's, at the best of our knowledge, the first study assessing the hydrogen production from solar for the whole country.     

Techno-economic appraisal of a dish/stirling solar power plant in Greece based on an innovative solar concentrator formed by elastic film

As the environmental problems caused by the use of conventional fuels have risen significantly and due to the increase in fossil fuel prices, the importance of reducing society dependence on non-renewable energy sources becomes more and more urgent. It is clear that this could only happen by switching to extensive use of clean energy sources such as renewable energy sources. In this paper a technical feasibility and economic viability study of a dish/Stirling solar power plant in Greece is presented. The proposed power plant uses Dish/Stirling technology and has nominal power 10 MW. The proposed solar concentrator system consists of a primary mirror, formed by elastic film, used to focus the sun's rays onto a secondary mirror which then deviates this radiation into the receiver (Stirling engine). TRNSYS program was developed to simulate Dish/Stirling power plant operation in order to investigate its performance in Greece. The simulation predicted that the proposed power plant could produce 11.19 GWh annually. Project investment cost is approximately 27,000,000 €, while payback is achieved after 16 years of operation. The total profit at the end of the analysis period of 25 years is estimated to be 25,500,000 €.     

Exergoeconomic and environmental impact analyses of a renewable energy based hydrogen production system

In this study, exergoeconomic and environmental impact analyses, through energy, exergy, and sustainability assessment methods, are performed to investigate a hybrid version renewable energy (including wind and solar) based hydrogen and electricity production system. The dead state temperatures considered here are 10 °C, 20 °C and 30 °C to undertake a parametric study. An electrolyzer and a metal hydride tank are used for hydrogen production and hydrogen storage, respectively. Also, the Proton Exchange Membrane Fuel Cell (PEMFC) and battery options are utilized for electricity generation and storage, respectively. As a result, the energy and exergy efficiencies and the sustainability index for the wind turbine are found to be higher than the ones for solar photovoltaic (PV) system. Also, the overall exergy efficiency of the system is found to be higher than the corresponding overall energy efficiency. Furthermore, for this system, it can be concluded that wind turbine with 60 gCO₂/month is more environmentally-benign than the solar PV system with 75 gCO₂/month. Finally, the total exergoeconomic parameter is found to be 0.26 W/$, when the energy loss is considered, while it is 0.41 W/$, when the total of exergy loss and destruction rates are taken into account.     

Simulation model for sizing of stand-alone solar PV system with interconnected array

Solar PV arrays made of interconnected modules are comparatively less susceptible to shadow problem and power degradation resulting from the aging of solar cells. This paper presents a simulation model for the sizing of stand-alone solar PV systems with interconnected arrays. It considers the electricity generation in the array and its storage in the battery bank serving the fluctuating load demand. The loss of power supply probability (LPSP) is used to connote the risk of not satisfying the load demand. The non-tracking (e.g., fixed and tilted) and single-axis tracking aperture arrays having cross-connected modules of single crystalline silicon solar cells in a (6×6) modular configuration are considered. The simulation results are illustrated with the help of a numerical example wherein the load demand is assumed to follow uniform probabilistic distribution. For a given load, the numbers of solar PV modules and batteries corresponding to zero values of LPSP on diurnal basis during the year round cycle of operation are presented. The results corresponding to the surplus and deficit of energy as a function of LPSP are also presented and discussed to assess the engineering design trade offs in the system components.Furthermore, a simple cost analysis has also been carried out, which indicates that for Delhi the stand-alone solar PV systems with fixed and tilted aperture arrays are better option than those with single-axis tracking aperture (with north–south oriented tracking axis) arrays.     

Domestic hydrogen production using renewable energy

A brief review shows that domestic production of hydrogen to fuel a car is feasible by using various means. Among these, the solar––photovoltaic electricity––electrolysis process seems to be the most practical if a renewable energy source is to be used. A simplified model has been developed to determine and optimize the thermal and economical performance of domestic photovoltaic-electrolyzer systems, either with fixed or sun tracking panels using annual total solar radiation on a horizontal surface and climatic data. Twelve locations in the United Sates from four climatic zones (tropical-sub tropical, dry, temperate, cool snow-forest) have been selected. Simulations have been carried out to produce data for hydrogen production for these various locations and the resulting data have been correlated to obtain hydrogen production in kg/kW_p/year photovoltaic system as a function of total annual solar radiation on horizontal surface. The economical feasibility has been studied by taking the photovoltaic and electrolyzer systems' price as variable parameters. It is assumed that the necessary capital is 100% borrowed from a financial institution to pay back in monthly installments. It has been found that the hydrogen production with fixed photovoltaic panels varies from 26 to 42 kg/kW_p/year and the cost from 25 to 268 $/GJ.     

Estimating global production and supply costs for green hydrogen and hydrogen-based green energy commodities

Green energy commodities are expected to be central in decarbonising the global energy system. Such green energy commodities could be hydrogen or other hydrogen-based energy commodities produced from renewable energy sources (RES) such as solar or wind energy. We quantify the production cost and potentials of hydrogen and hydrogen-based energy commodities ammonia, methane, methanol, gasoline, diesel and kerosene in 113 countries. Moreover, we evaluate total supply costs to Germany, considering both pipeline-based and maritime transport. We determine production costs by optimising the investment and operation of commodity production from dedicated RES based on country-level RES potentials and country-specific weighted average costs of capital. Analysing the geographic distribution of production and supply costs, we find that production costs dominate the supply cost composition for liquid or easily liquefiable commodities, while transport costs dominate for gaseous commodities. In the case of Germany, importing green ammonia could be more cost-efficient than domestic production from locally produced or imported hydrogen. Green ammonia could be supplied to Germany from many regions worldwide at below the cost of domestic production, with costs ranging from 624 to 874 $/t NH₃ and Norway being the cheapest supplier. Ammonia production using imported hydrogen from Spain could be cost-effective if a pan-European hydrogen pipeline grid based on repurposed natural gas pipelines exists.     

Performance comparison of a double-axis sun tracking versus fixed PV system

In the present study, performance results of two double axis sun tracking photovoltaic (PV) systems are analyzed after one year of operation. Two identical 7.9 kWp PV systems with the same modules and inverters were installed at Mugla University campus in October 2009. Measured data of the PV systems are compared with the simulated data. The performance measurements of the PV systems were carried out first when the PV systems were in a fixed position and then the PV systems were controlled while tracking the sun in two axis (on azimuth and solar altitude angles) and the necessary measurements were performed. Annual PV electricity yield is calculated as 11.53 MW h with 1459 kW h/kWp energy rating for 28 fixed tilt angle for each system. It is calculated that 30.79% more PV electricity is obtained in the double axis sun-tracking system when compared to the latitude tilt fixed system. The annual PV electricity fed to grid is 15.07 MW h with 1908 kW h/kWp for the double axis sun-tracking PV system between April-2010 and March-2011. The difference between the simulated and measured energy values are less than 5%. The results also allow the comparison of different solutions and the calculation of the electricity output.     

Solar photovoltaic electricity: Current status and future prospects

We review the technical progress made in the past several years in the area of mono- and polycrystalline thin-film photovoltaic (PV) technologies based on Si, III-V, II-VI, and I-III-VI₂ semiconductors, as well as nano-PV. PV electricity is one of the best options for sustainable future energy requirements of the world. At present, the PV market is growing rapidly at an annual rate of 35-40%, with PV production around 10.66 GW in 2009. Si and GaAs monocrystalline solar cell efficiencies are very close to the theoretically predicted maximum values. Mono- and polycrystalline wafer Si solar cells remain the predominant PV technology with module production cost around $1.50 per peak watt. Thin-film PV was developed as a means of substantially reducing the cost of solar cells. Remarkable progress has been achieved in this field in recent years. CdTe and Cu(In,Ga)Se₂ thin-film solar cells demonstrated record efficiencies of 16.5% and almost 20%, respectively. These values are the highest achieved for thin-film solar cells. Production cost of CdTe thin-film modules is presently around $0.76 per peak watt.     

The potential of harnessing solar radiation in Iran: Generating solar maps and viability study of PV power plants

This paper assesses the potential of harnessing solar radiation in different regions of Iran. In this regard, solar radiation maps are generated for five different cases: total radiation on a south facing fixed surface tilted at the latitude angle; total radiation on a surface tilted at the latitude angle with East–West tracking; total radiation on a surface tilted at the latitude angle with azimuth tracking; direct beam radiation on a horizontal surface with East–West tracking; and direct beam radiation on a surface with two axis tracking. The first three cases are generally applicable to photovoltaic (PV) power plants while the last two are generally used for concentrating solar power (CSP) plant design. In the second part of the paper, a 5 MW PV power plant is considered for 50 cities of Iran. Capacity factors, electricity generated and annual greenhouse gases emission reductions are compared. The results show a great potential for central and southern parts of the country.     

Experimental evaluation of V-trough (2 suns) PV concentrator system using commercial PV modules

V-trough photovoltaic (PV) concentrator systems along with conventional 1-sun PV module is designed and fabricated to assess PV electricity cost ($/W) reduction. V-trough concentrator (2-sun) system is developed for different types of tracking modes: seasonal, one axis north–south and two axes tracking. Three design models based on these tracking modes are used to develop the V-trough for a 2-sun concentration. Commercially available PV modules of different make and types were evaluated for their usability under 2-sun concentration. The V-trough concentrator system with geometric concentration ratio of 2 (2-sun) increases the output power by 44% as compared to PV flat-plate system for passively cooled modules. Design models with lower trough angles gave higher output power because of higher glass transmittivity. PV modules with lower series resistance gave higher gain in output power. The unit cost ($/W) for a V-trough concentrator, based on different design models, is compared with that of a PV flat plate system inclined at latitude angle (Mumbai, φ=19.12°).     

Off-grid hybrid renewable energy system with hydrogen storage for South African rural community health clinic

Most inhabitants of rural communities in Africa lack access to clean and reliable electricity. This has deprived the rural dwellers access to modern healthcare delivery. In this paper, an off-grid renewable energy system consisting of solar PV and wind turbine with hydrogen storage scheme has been explored to meet the electrical energy demands of a health clinic. The health clinic proposed is a group II with 10 beds located in a typical village in South Africa. First, the wind and solar energy resources of the village were analysed. Thereafter, the microgrid architecture that would meet the energy demand of the clinic (18.67 kWh/day) was determined. Some of the key results reveal that the average annual wind speed at 60 m anemometer height and solar irradiation of the village are 7.9 m/s and 4.779 kWh/m²/day, respectively. The required architecture for the clinic composes of 40 kW solar PV system, 3 numbers of 10 kW wind turbines, 8.6 kW fuel cell, 25 kW electrolyser and 40 kg hydrogen tank capacity. The capital cost of the microgrid was found to be $177,600 with a net present cost of $206,323. The levelised cost of energy of the system was determined to be 2.34 $/kWh. The project has a breakeven grid extension distance of 8.81 km. Since this distance is less than the nearest grid extension distance of 21.35 km, it is established that the proposed renewable energy microgrid with a hydrogen storage system is a viable option for the rural community health clinic.     

A multipurpose dual-axis solar tracker with two tracking strategies

This paper deals with a multipurpose dual-axis solar tracker that can be applied to solar power systems. This tracker employs a declination-clock mounting system that locates the primary axis in east-west direction. Based on this mounting system, normal tracking strategy and daily adjustment strategy are developed for flat Photovoltaic (PV) systems and Concentrating Solar Power (CSP) systems respectively. While the former strategy keeps the tracking errors smaller than the pre-specified values, the latter one simplifies the tracking process by adjusting the primary axis once a day and driving the secondary axis to rotate at a constant speed of 15°/h. Results of the accuracy test indicate that the tracking error of the normal tracking strategy is within 0.15°. The other strategy may have greater tracking errors, but its annual average cosine loss for flat PV systems is estimated to be below 1.3%. Furthermore, in the test on the output of the PV modules, it is found that the average energy efficiency of the normal tracking PV, compared with the fixed PV, is more than 23.6%. And the average energy efficiency of the daily adjusted PV is more than 31.8%. Results of the experiment show that the two tracking strategies are both feasible for the developed tracker.     

Design and analysis of a combined floating photovoltaic system for electricity and hydrogen production

The current study deals with a potential solution for the replacement of fossil fuel based energy resources with a sustainable solar energy resource. Electrical energy demand of a small community is investigated where a floating photovoltaic system and integrated hydrogen production unit are employed. Data are taken from Mumcular Dam located in Aegean Region of Turkey. PvSyst software is used for the simulation purposes. Furthermore, the obtained results are analyzed in the HOMER Pro Software. Photovoltaic (PV) electricity provides the required load and excess electricity to be used in the electrolyzer and to produce hydrogen. Saving lands by preventing their usage in conventional PV farms, saving the water due to reducing evaporation, and compensating the intermittent availability of solar energy are among the obtained results of the study for the considered scenario. Stored hydrogen is used to compensate the electric load through generating electricity by fuel cell. Floating PV (FPV) system decreases the water evaporation of water resources due to 3010 m² shading area. FPV and Hydrogen Systems provides %99.43 of the electricity demand without any grid connection or fossil fuel usage, where 60.30 MWh/year of 211.94 MWh/year produced electricity is consumed by electric load at $0.6124/kWh levelized cost of electricity (LCOE).