International Journal of Industrial Electronics and Electrical Engineering, ISSN(p): 2347-6982, ISSN(e): 2349-204X Volume-8, Issue-6, Jun.-2020, http://ijieee.org.in PHOTOVOLTAIC SOLAR PANELS TYPES AND POSITIONING ON SOLAR POWERED ELECTRIC VEHICLE

1MARCIN KOWALSKI, 2KAMIL BURZYNSKI, 3MARCIN KEDZIORA, 4PIOTR LADONSKI, 5MATEUSZ GRZESIAK, 6RAFAL NOWAK

1,2,3,6Faculty of Electrical, Electronic, Computer and Control Engineering, Lodz University of Technology, Poland 4Faculty of Mechanical Engineering, Lodz University of Technology, Poland 5Faculty of Management and Production Engineering, Lodz University of Technology, Poland E-mail: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected]

Abstract - This paper provides detailed overview of solar power cells types, summarizing their advantages and disadvantages. Moreover it describes choice take by Lodz Solar Team and shows the possible way of implementation. The primary target of this paper are technical students, young constructors wanting to install solar panels stationary or these aiming to build their own . However more experienced designers may find useful ideas contained in this paper. The content of this article might be considered as step-by-step guide photovoltaic panels choice for teams planning to take part in the next Bridgestone World Solar Challenge edition in 2021.

Keywords - Solar Powered Vehicle, Solar Panels Positioning, Electric Car, Bridgestone World Solar Challenge

I. INTRODUCTION development of electric cars. Electric vehicles are currently a very popular trend, especially in the last 1.1 Photovoltaic technology 15 years. According to Global EV Outlook 2017 Photovoltaic (PV) panels have been popular for a (International Energy Agency), by the end of 2016 long time. Space satellites have been equipped with there were 2 million cars with electric or hybrid drive. solar cells since the 1950s. Forecasts shows that by the end of 2020 between 9 Typical works in several steps. Firstly million and 20 million electric cars may be registered photons (sunlight) hit the being absorbed worldwide, and five years later up to 70 million. by semiconducting materials (e.g. silicon) . Electrons hit by photons are excited, knocked out from their One of the possibilities of supplying the car with position and travel through the cell until it reaching electricity is the installation of solar panels on its an electrode. Solar cells arranged in an arrays convert body. solar energy into noticeable amount of direct current. The continuous development of photovoltaic 1.3 Lodz Solar Team technology allows efficiency of solar cells to Electric cars are part of the current global trend. increase. The price of PV panels also constantly Technologies are constantly being developed by large falling, making them more affordable and more automotive corporations as well as smaller teams. attractive to average users. The Lodz Solar Team places great emphasis on developing modern technologies that can protect our environment. For this reason, the team has been building solar powered electric vehicles for over 5 years. The Lodz Solar Team is currently one of only two student projects in Poland aimed at total zero emissions, using only clean solar energy vehicles.Lodz Solar Team consists of 30 people from different faculties and has already built two solar vehicles that annually take high positions in international races.

Eagle 1 was the powered electric vehicle built by the Lodz Solar Team in 2014. With the help Fig. 2Trend in Renewable Energy (installed capacity of Eagle 1 the team drove over 3000 kilometers of solar photovoltaic panels) over 2008-2018 . Source: (around 1900 miles) route through the middle of TheInternational Renewable Energy Agency. Australia during the Bridgestone World Solar Challenge 2015. A year later, during the Sasol Solar 1.2 Electric vehicles Challenge 2016 the car manager to ride across South The obvious next step for the automotive industry Africa making 2817 km (1750 miles). after resignationfrom fossil fuel vehicles is the

Photovoltaic Solar Panels types and Positioning on Solar Powered Electric Vehicle

49 International Journal of Industrial Electronics and Electrical Engineering, ISSN(p): 2347-6982, ISSN(e): 2349-204X Volume-8, Issue-6, Jun.-2020, http://ijieee.org.in their performance suffers as temperature goes to much up.  Polycrystalline panels - are one of the most popular products currently, due to less sensitivity to weather conditions (lower power drop with increasing temperature) compared to monocrystalline panels. Solar cells are made of many silicon crystals, so they can form a square Fig. 2Silhouette of the first car - Eagle One shape. The efficiency of polycrystalline panels is lower than that of monocrystalline and oscillates Eagle 2, the second car built by Lodz Solar Team, around 14-16%. was created to start in Bridgestone World Solar  CIGS cells - the name comes from the chemical Challenge 2017. elements from which they are built ( in order: The car has been redesigned in every detail from copper, indium, gallium and selenium). Their suspension, through aerodynamics ending with the efficiency ranges from 12-14%. number of seats inside.  CdTe solar cells - are made mainly of cadmium Being better than Eagle 1 in terms of both telluride semiconductor. CdTe panels, being mechanical and electrical construction, required made usually from single cell, parameters differ greater emphasis on selection and layout of significantly from solar photovoltaic panels.Battery capacity and solar panel panels. CdTe efficiencyy oscillates around 10- area have been increasedup to the maximum 12%. Both CdTe and CIGS cells are so-called allowable value. thin-film cells (thickness does not exceed a few micrometers).  Solar Panels - made from non-crystalline form of silicon. Due to the lowest efficiency, which is form 6% to maximum 10%, their price is also the lowest among other types of solar cells. The average lifetime of amorphous silicon solar panels is 2 times shorter Fig. 3Render of Eagle 2 vehicle than monocrystalline silicon solar cells lifetime and lasts around 10 years. Eagle 3, the third vehicle from Lodz Solar Challenge In addition to the types listed below, there are also is planned to be released by the end of 2020. One of multijunction solar cells. However they are out of the key decisions will be the choice between reach of the Lodz Solar Team and will be omitted in photovoltaic panels technologies, as well as the area this study. they will cover and their arrangement. Photovoltaic panels types together with the reasons for the selection and best way (subjectively) to arrange them on vehicle’s roof (on the example of Eagle 2) will be covered in this paper.

II. SOLAR PANEL TYPES

2.1. Construction of solar cell Fig. 4Comparison between panel types showing size that is Currently only five types of photovoltaic panels are in needed to obtain 1kW common use. Depending on price and performance it is possible to choose between:  Monocrystalline Silicon Solar Cells are made of monocrystalline silicon (grown using the Czochralski process and sliced into wafers). Their efficiency is the highest among all other types of solar modules and ranges from 15% to 19%. Due to the silicon production technique shape of solar cells resembles truncated circle or square with cut corners – which is the most characteristic feature. Monocrystalline silicon solar cells are sensitive to weather conditions, tend to be more efficient in warm weather, but

Photovoltaic Solar Panels types and Positioning on Solar Powered Electric Vehicle

50 International Journal of Industrial Electronics and Electrical Engineering, ISSN(p): 2347-6982, ISSN(e): 2349-204X Volume-8, Issue-6, Jun.-2020, http://ijieee.org.in Fig. 5Upper row from left: Monocrystalline Silicon Solar Cells, In the original plans, Eagle 2 had 326 solar cells, the Polycrystalline panels, CIGS cells. Lower row from left: CdTe solar cells, Amorphous Silicon Solar Panels area of the panels exceeded 5 square meters. In this configuration the vehicle started during the 2017 According to Fraunhofer ISE: Reportin Bridgestone World Solar Challenge race. the last 10 years, the efficiency of average Present panels in Eagle 2 have a total area of 4.993 commercial silicon modules increased from square meters, so they are within the current limit. In about 12% to 17% and for CdTe module increased order to work more efficiently they were divided into from 9% to 18%. The record efficiency is 4 banks with a similar number of solar. The total 26.7% for monocrystalline and 22.3% for number of cells is 322. Price of the whole set polycrystalline siliconwafer-based technology. exceeded 20 thousand Euro. The highest lab efficiency in thin film technology is 23.4% for CIGS and21.0% for CdTe solar cells.

2.2. Major factors The efficiency of a solar panel depends mainly on the silicon / semiconductor layer. The choice of panels must be made taking into account their performanceas well as price and market availability. The second important factor, depending on the Fig. 6List of solar cell bank that form the entire photovoltaic structure of the vehicle, is the roof slope - the panels panel roof of Eagle Two vehicle. are the most efficient whensun rays falls on them perpendicularly. The Eagle 2 shape divides the panel Each bank is equipped with its own MPPT plane into two parts – top parallel plane and skewed (Maximum Power Point Tracking regulator). MPPT one. This ensures maximum performance when are devices thanks to which the efficiency of the driving in full sun. entire solar system increases. It is a type of regulator that has been equipped with an algorithm for tracking 2.3. Decision the largest power point of the panel. Thanks to MPPT Having taken into consideration all the reasons the the system’s efficiency increased. decision seemed obvious. We have chosen Depending on the size of the bank, monocrystalline silicon solar panels for performance it generates from 299 to 320W. Total value of reasons. Due to the Bridgestone World Solar supplied power is 1250W, which (according to Challenge regulations the most important features in calculations) is sufficient, with a little help from the the solar vehicle that is built by Lodz Solar Team are energy stored in the battery,for driving. load capacity (the number of people driving in the car) and the speed with which vehicle could travel. Solar cells sections and particular banks are shown in The performance of the photovoltaic panels plays a fig. 7. The first version (left) was mounted on Eagle 2 key role. in years 2017-2019,while from September 2019. Originally panels were divided into 12 banks, III. IMPLEMENTATION currently they are into 4. The size of the panels has been reduced. 3.1. Bridgestone World Solar Challenge regulations. According to regulations Eagle 2 vehicle represents the Cruiser class. Maximum surface limitations for solar panels depends on the type of panels and vehicle class. In order to meet all race requirements, the surface of solar panels (Monocrystalline Silicon) should not exceed 5 square meters. The size of Eagle One panels exceeds 6 square meters. For this reason it was necessary to build new vehicle.

3.2. Eagle 2 design Having assumed that energy from photovoltaic cells, while maintaining a sufficiently low drag coefficient and low vehicle weight, is enough to cover a distance of 3000 km (with support from charged vehicle battery).

Photovoltaic Solar Panels types and Positioning on Solar Powered Electric Vehicle

51 International Journal of Industrial Electronics and Electrical Engineering, ISSN(p): 2347-6982, ISSN(e): 2349-204X Volume-8, Issue-6, Jun.-2020, http://ijieee.org.in Fig. 7Comparison between old and new arrangement of panels IV. CONCLUSION on the roof of Eagle 2 vehicle. 3.3. Sensors PV panels made of monocrystalline silicon, despite To ensure full control of the conditions in which solar their high price, work are best suited for use in panels mounted on Eagle 2 work, different sensor amateur constructions.The highest efficiency where mounted. Solar radiation and temperature guarantees the highest amount of power from the sensor are the most important to maintain the whole same surface covered with solar cells. system working. The design of panels must be well thought out. Often not only technological restrictions, but also competition regulations are major factors.

REFERENCE

[1] Photovoltaics Report, Fraunhofer ISE, July 28, 2014. [2] FUTURE OF SOLAR PHOTOVOLTAIC: Deployment, investment, technology, grid integration and socio-economic aspects. November 2019 [3] Solar Power Europe (2019a), Global market outlook for solar power, SolarPower Europe, Brussels, Belgium [4] Renewable energy capacity statistics: The International Renewable Energy Agency (IRENA) [5] End-of-Life Management: Solar Photovoltaic Panels. International Renewable Energy Agency (June 2016). Retrieved 6 March 2019. [6] Almansouri, Ibraheem; Ho-Baillie, Anita; Bremner, Stephen P.; Green, Martin A. (2015). "Supercharging Silicon Solar Cell Performance by Means of Multijunction Concept". IEEE Journal of Photovoltaics. 5 (3): 968–976. [7] Bullis, Kevin (13 June 2014) Record-Breaking Solar Cell Points the Way to Cheaper Power. MIT Technology Review [8] H. Kiess, W. Rehwald: On the ultimate efficiency of solar cells. 1995 [9] D. D. Smith, P. Cousins, S. Westerberg, R. De Jesus- Tabajonda, G. Aniero: Toward the Practical Limits of Silicon Solar Cells, 2014

Fig. 8Location of temperature sensors (marked with red letter ‘S’).

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Photovoltaic Solar Panels types and Positioning on Solar Powered Electric Vehicle

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