Renewable Energy Global Innovations features: Optimal Arrangement of Photovoltaic Panels Coupled with Electrochemical Storages

Significance Statement

Maximizing power generation using photovoltaic panels can be achieved by combining the perfect azimuth and tilt angle for a given site and climate throughout the year. Nonetheless, in many contemporary projects of sustainable buildings, the surface occupied by the photovoltaic cells is composed of subsurface of varying alignments and gradients. In already existing buildings, exploitation of all the available roof surface is necessary since there is little or no choice left at all. However, in new buildings the photovoltaic panels maybe hosted in different azimuth and tilt angles in order to maximize electricity generation with continuity during the day, by talking optimum advantage of surfaces inclined towards the sun in different periods of the day, with greater match with the demand time profile. In the latter scenario, the utmost purpose would be to maximize the building’s autarchy, even if at the cost of larger photovoltaic panel surface and hence a higher installation cost. However, the relevant decline in photovoltaic system costs and their consequent rapid spread are moving the attention from the achievement of the maximum areal electricity generation to a photovoltaic generation profile in agreement with building energy needs.

Italian researchers Antonio Carbonari and Massimiliano Scarpa from the University IUAV of Venice investigated various configurations of photovoltaic systems supported by electrochemical storages, aiming at the increment of electricity self-consumption, considering climates in two different cities: Venice and Trapani. They compared various configurations of the photovoltaic system by means of computer simulations. Their research work is now published in Energy Procedia.

Carbonari and Scarpa began by defining the ideal photovoltaic panel configuration for the two localities. The consequent photovoltaic generation was then compared with the ones characterizing other configurations, derived from actual projects. The research team then considered a case study consisting of a residential building typical of the Italian suburbs. Eventually, two possible orientations of the building’s main axis and consequent possible photovoltaic panel arrangements were considered and compared from various points of view: electricity generation and life cycle assessment of primary energy.

They observed that for buildings having greater surface exposed according to the ideal arrangement provide a higher yearly electricity yield thus, in the case study, the East-West of the building’s main axis is slightly more convenient than the North-South orientation in terms of annual electric generation and consequent payback time of the plant.

The study successfully presented a comprehensive analysis of various configurations of photovoltaic systems supported by electrochemical storages, aiming at increase of electricity self-consumption in two Italian climates. From this analysis, it is possible to deduce that the use of storage system allows to increase significantly the degree of self-consumption of the building, therefore its self-sufficiency.

Fig. 7. Venice E-W orientation, uses of generated electricity and imports during the year [kWh/month], without storage (a) and with storage (b).

About The Author

Antonio Carbonari he graduated in architecture from 1983 at the University IUAV of Venice, is Assistant Professor in the field “Building’s Physics” from 1997 at the same University in the Department of Design and Planning in Complex Environments

Research interests: analysis of urban energy demand, buildings energy balance and solar radiation: energy and luminous aspects, acoustic of interiors.

Reference

Antonio Carbonari, Massimiliano Scarpa. Optimal arrangement of photovoltaic panels coupled with electrochemical storages. Energy Procedia, volume 113(2017) pages 35-42.

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Renewable Energy Global Innovations features: Coupled electrochemical thermal modelling of a novel Lithium-ion battery pack thermal management system

Significance Statement

Thermal management systems are crucial for a lithium ion battery pack. High performance, safe operation and longer battery life can be achieved when the battery is operated within a small temperature variation around the room temperature. This demands the application of a thermal management system so as to maintain a safe temperature operation range. Air cooling is among the simplest cooling systems but drawbacks such as low thermal conductivity and low heat capacity discourages its use. This has therefore motivated the development of new liquid coolant thermal management systems for the lithium ion battery pack used mainly for vehicular propulsion.

In a recent paper published in Applied Energy, Suman Basu and colleagues presented a new coupled electrochemical thermal modelling of Lithium-ion battery pack thermal management system. Their aim was to develop an economically feasible, safe, compact and high performance thermal management system for the lithium ion battery pack mainly used in the electric vehicles.

First, the research team designed the novel liquid cooling based thermal management system for the lithium ion pack which comprised of commercially available cells in 6S5P formation (Fig. 1). The design ensured safety and compactness by thermally connecting the cells with conduction elements made of aluminum which are used to conduct the heat away. They then developed a coupled electrochemical thermal model for the battery pack and simulated it. A three-dimensional computational fluid dynamics was then developed and validated based on numerical model for the electrochemical thermal modeling of the battery pack at high accuracies. The performance of the battery pack under various arrangements and operating conditions was then investigated and reported.

Fig1: Geometry of the Li-ion battery pack and thermal management system.

They observed that the heat generation from the cells is the function of local temperature and reaction rate which had to be resolved so as to predict the thermal performance correctly. The three-dimensional electrochemical model was used to obtain a complete description of the heat generation from the battery pack system. The system also helped in validation against experimental results used to evaluate the performance of the thermal management system under various operating conditions. Thermal contact resistances at the conduction element-channel and cell-conduction element interfaces were observed to be the main hindrance to the operation of this thermal management system (Fig. 2).

Excellent agreement has been achieved between the experimental measurements and simulation predictions from the tests conducted. Application of the thermal interface material at the interfaces is seen to reduce the contact resistances and improve the heat transfer. The thermal management system is seen to cool the pack effectively even at minimal coolant flow rates. At high discharge rate and low coolant flow rate, the maximum temperature rise is kept at a small range. Therefore, this novel and compact thermal management system can work effectively under stringent conditions and is a suitable candidate for electric vehicle battery pack.

Fig 2: Temperature contours of the first set of parallel cells in the pack as a function of contact resistance at the solid-solid interfaces at 0.9 C discharge rate and 0.2 ms-1 flow velocity.

About the author

Suman Basu received his PhD from the Pennsylvania State University working in Electrochemical Engine Center with Prof. C. Y. Wang. He is working in Li-ion battery modelling and simulation project in Samsung R&D India – Bangalore. His main interests are in electrochemical energy storage system, Li-ion battery management system including thermal management and capacity fade, two-phase flow modeling and heat transfer in PEMFC. He received his bachelors and masters degree in Mechanical Engineering from Jadavpur University, Kolkata and Indian Institute of Technology, Kanpur respectively.

Reference

Suman Basu¹, Krishnan S. Hariharan¹, Subramanya Mayya Kolake¹, Taewon Song², Dong Kee Sohn², Taejung Yeo². Coupled electrochemical thermal modelling of a novel Li-ion battery pack thermal management system. Applied Energy volume 181 (2016) pages 1–13

Show Affiliations

1. Next Generation Research (SAIT-India), Samsung R&D Institute India-Bangalore, #2870 Phoenix Building, Bagmane Constellation Business Park, Outer Ring Road, Doddanekundi Circle, Marathahalli Post, Bangalore 560 037, India
2. Energy Material Lab, SAIT, Samsung Electronics, Republic of Korea

 

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