ENGINEERING FOR RURAL DEVELOPMENT Jelgava, 24.-26.05.2023. 644 ENERGY BALANCE ANALYSIS OF SOLAR-POWERED CATAMARAN Dainis Berjoza, Inara Jurgena, Janis Laceklis-Bertmanis Latvia University of Life Sciences and Technologies, Latvia dainis.berjoza@lbtu.lv, inara.jurgena@lbtu.lv, janis.bertmanis@lbtu.lv Abstract. In the last decade, alternative energy is being used in various vehicles due to the depletion of fossil energy resources. One of the kinds of alternative energy is electricity. Electric drive can be used in land vehicles, aircraft and watercraft. To identify the possibility of using electric watercraft and the technical parameters, an experiment was conducted in real navigation conditions in the territory of Jelgava city on the Driksa canal on a 1.62 km long route. The experiment used a data logger to take measurements of parameters of the motor and the solar cell, as well as of solar intensity. The experiment was done with a rebuilt pedal-powered catamaran equipped with a 445 W solar panel, a 40 Ah lithium-ion battery and a Minn Kota Endura C2 34 electric motor. The experimental data were processed to identify the power and energy generated and consumed parameters for the electric motor, the solar panel and the battery of the watercraft. On the day of the experiment at a solar intensity of 500-600 W·m -2 , the catamaran could cover an unlimited distance at power settings 3 to 5 at a speed of 2.73 km h -1 to 3.79 km h -1 . At power setting 5, the electric motor consumed a power input of 320-330 W – a power output generated by the solar cell in sunny weather. If the battery is discharged, the solar cell charges it when the watercraft is anchored in the port, as well as when moving in case the solar cell generates more energy than the motor consumes at a particular power setting. According to the results of the experiment, low-speed electric-drive watercraft equipped with solar cells can be operated without additional battery charging at all power settings at geographical latitudes up to 57º and solar altitudes up to 35º-56º. Keywords: solar catamaran, energy, experimental route, solar intensity, voltage, current. Introduction As energy resources are depleted in the world, non-fossil energy sources are sought. Therefore, at the beginning of this century, constructors and scientists sought for a possibility of using electricity in several transport industries. Currently, electric drive is used not only in land vehicles – various automobiles, tractors and trucks – but also in aircraft and watercraft. The use of electric drive in watercraft is relatively simple. Solar energy is easier to use in watercraft than in land vehicles because the horizontal surface areas of watercraft are usually larger than those of land vehicles. Initially, electric watercraft stored energy in batteries. With the development of solar cell technology, solar cells began to serve as an additional source of energy for watercraft, which could provide a longer range per charge and battery charging when anchored in the port. Over the last 10 years in the world, several kinds of solar-powered watercraft of various sizes and capacities have been exploited both in the tourism industry and in commercial transport [1]. Rosa Zuloeta Bonilla et al. have simulated the use of solar-powered boats in the Amazon basin and compared them with internal combustion engine boats. The research involved a 12 m long twelve-seater boat and a 10 m long twenty-seater catamaran. The results showed that on calm water, a 3-kW motor was sufficient for the boat, whereas in a river with a current, the power should be increased to 10 kW. The simulation found that the average speed of the catamaran was 2.8-3.9 m·s -1 , which could be achieved by a motor with a power output in the range of 1.4-5.4 kW [2; 3]. There are available several prototypes of autonomous watercraft [4]. It is easier to robotize an electric solar-powered boat than a conventional internal combustion-powered watercraft. There have been developed prototypes of autonomous solar-powered taxis as well [5; 6]. The development of such prototypes considers the fact that less traffic and lower speeds are on water than on land. Lapko A. has researched the possibilities of using an electric-drive boat. The motorboat batteries were charged on shore, similarly to an electric car. If the weight of a watercraft is 3-10 t, it needs a motor with a power output of 3.5 to 20 kW. Batteries with a capacity of 10-60 kWh are required to operate such a watercraft for 3-4 hours [7]. Safak Hengirmen Tercan et al. have found that if switching from internal combustion-powered tourist boats to ones running on alternative energy sources and being equipped with 60 kWh batteries, the payback period is 9 years, while for the boats equipped with batteries twice as capacious, it is 13 years [8]. For a light-duty watercraft, matching the power output of its solar panels with that of the motor can significantly reduce the cost of the watercraft, yet in this case the watercraft achieves a lower speed. DOI: 10.22616/ERDev.2023.22.TF131