THE CHRONOLOGICAL SYSTEM FOR SOLAR TRACKING IMPLEMENTED ON MOBILE SOLAR GENERATOR

Transcription

1 THE CHRONOLOGICAL SYSTEM FOR SOLAR TRACKING IMPLEMENTED ON MOBILE SOLAR GENERATOR Miloš D. Jovanović, Mihajlo Pupin Institute, University of Belgrade, Serbia, Željko V.Despotović, Mihajlo Pupin Institute, University of Belgrade, Serbia, Đorđe Urukalo, Mihajlo Pupin Institute, University of Belgrade, Serbia, 1

2 Introduction In order to increase the energy efficiency, within the device Mobile Solar Generator (MSG), developed in Institute Mihajlo Pupin (IMP)-Centre of Robotics, was performed several optimization. One of the most important optimization is done on a system for solar tracking. The system is based on two-axis (azimuth and elevation) DC drive, enabling the chronological track of the Sun path. In this paper is presented in detail the specific developed system of chronological tracking. Chronological tracking is based on natural observation of the Sun position in a given area and a given time period during the year. This method of positioning is independent of cloud cover because it is track the Sun at any time. The only thing, that needs to take into account the orientation of the local coordinate system of solar panels in relate to the global coordinate system (Earth). The paper presents a developed tracking, as well as some of its most important performance related to energy savings and increased energy efficiency of the mobile solar unit (generator). 2

3 Types of tracking There are three methods of tracking: -passive tracking -active tracking -chronological tracking 3

4 Passive Sun tracking systems are the simplest and cheapest. The simplest passive tracking system is based on the manual adjustment of the solar panel's inclination towards the Sun, with the solar panel pointing to the south side, while the azimuth angle is fixed. Usually for this given season, and for the location on the Earth's surface, this tilting angle is known. Therefore, the tilt adjustment is standardized in four or in some cases, twice a year. The system does not require any energy consumption in any form (electrical, thermal, hydraulic, etc.). The system is inexpensive and does not require any major material expenditure. 4

5 Active Sun tracking systems: - the position of the Sun in the sky during the day is continuously determined by sensors. The sensors will trigger the motor or actuator to move the mounting system so that the solar panels will always face the Sun throughout the day. This method of Sun-tracking is reasonably accurate except on very cloudy days when it is hard for the sensor to determine the position of the Sun in the sky thus making it hard to reorient the structure 5

6 The chronological tracking is a time-based, whereby the structure is moved at a fixed rate throughout the day. The theory behind this is that the Sun moves across the sky at a fixed rate. Thus the drive motors are programmed to continuously rotate at a slow average rate of one revolution per day (15 degrees per hour). This method of Sun-tracking is very accurate. However, the continuous rotation of the motor or actuator means more power consumption and tracking the Sun on a very cloudy day is unnecessary. 6

7 Realisation-Mobile Solar Generator The mobile solar generator in exploitation conditions The structural scope of the two-axes drive on the mobile solar generator 7

8 Disposition of two-axis motion drive and the time gradient of azimuth and elevation 8

9 According to the current date and time, current global position in the field provided by the satellite using global GPS sensor, measuring the magnetic North by the compass and using the correction of the angle of the current position by measuring the inclination by two axis inclinometer it is possible to correctly determine where is the current Sun position on the horizon. According to this mathematical measurement and correction two axis position system (azimuth and elevation) is capable to find current position of the Sun on the horizon. Block diagram of two-axes control system of solar tracking implemented on mobile solar generator MobiSun Pro Energy 9

10 Experimental results The Sun trajectory from Sunrise to Sunset, for location on Belgrade (2013); (a)22 December, (b) 21 September, (c) 21 March, (d) 22 May. 10

11 The average daily of energy production in the all months, for stationary and two-axis solar tracking system 11

12 Conclusion and further improvements The realized two-axis DC drive on the solar generator Mobi Sun Pro Energy, provides the optimal operation of solar tracking system. In the paper are presents the key experimental results relate to energy production of mobile solar generator (for stationary and twoaxis systems) obtained in the real exploitation conditions. The obtained experimental results are comparing, and it is concluding that two-axes solar system provides better energy production of 30-40%, relate to stationary solar system. 12

13 References Braun J.E, Mitchell J.C., Solar Geometry for Fixed and Tracking Surfaces Solar Energy, 31(5): , Camacho E.F., Berenguel M., Rubio F.R., Martínez D., Control of Solar Energy Systems Deger Energie. Deger Energie Solar Tracking, Kalogirou, S. A., Design and Construction of a One-axis Sun-tracking System, Solar Energy, 57 (1996), 6, pp Barsoum N., Fabrication of Dual-Axis Solar Tracking Controller Project, Intelligent Control and Automation, 2011, 2, Solar Tracker, Sun Path Diagram Image, Al-Mohamad, A., Efficiency Improvements of Photo-voltaic Panels Using a Sun-tracking System, Applied Energy, 79 (2004), pp Abouzeid, M., Use of a Reluctance Stepper Motor for Solar Tracking Based on a Programmable Logic Array (PLA) Contoller, Renewable Energy, 23 (2001), pp Mančić, D., Petrušić, Z., Radmanović, M., Algoritam proračuna solarne geometrije kod rotirajućih sistema za optimalno praćenje pozicije Sunca, Zbornik radova Simpozijuma INFOTEH-JAHORINA 2007, Jahorina, Bosna i Hercegovina, mart 28-30, 2007, Vol. 6, pp Stevanović I., Popić S., Rodić A., Despotović Ž., Jovanović M., Pokretni robotizovani solarni generator, primer konstruktivnog rešenja mehaničke strukture, 57.Konferencija za elektroniku, telekomunikacije, računarstvo, automatiku i nuklearnu tehniku-etran, Zlatibor, 3-6. Jun Rodic A., Despotovic Z.V., Jovanovic M.D., Popic S., Stevanovic I., "Mobile Robotic Solar Generator MobiSunProEnergy - Application in New Energy Tehnologies", VIII International Forum for Clean Energy Technologies 2014 ENERGY CHARTER = SUSTAINABLE DEVELOPMENT OF SERBIA, Novi Sad, 30th September 1st October

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