Natural Sciences Grade 9 Natural Sciences Grade 9 Term 3 2022 Project Term 3 2022 Project 4.2 Which factors were kept constant (which variables were controlled) during this experiment? (3) 4.3 Identify the independent variable in this experiment. (1) 4.4 The tilt angle of the panels is important because solar panels will produce a maximum energy when the sun is directly perpendicular to them. During the winter, for example, the sun is low in relation to the horizon. In this case, for the solar panels to get their best performance, a steep angle or tilt of 60" is best. During the spring the best angle is 45", and during the summer when the sun is high in the sky, it's best to have lower tilt, in the region of 20". It is, however, not practical to adjust the tilt of solar panels after they have been installed on roof structures, poles etc. "In summertime the sun sits high above the horizon in the sky." Use this statement and explain why a fixed tilt angle of 90° produced such a low energy-output value. You can make use of a labelled sketch to explain your answer. SECTION C (3) [14] 60° Winter 45 Spring Summer 20° A project was launched to establish the best fixed tilt angle at which solar panels should be installed, which will give the user the maximum amount of energy-output when measured over a period of one year (annual energy-output). Energy-output refers to the amount of energy in kWh which is converted from sunlight energy to electrical energy and made available to output devices such as electrical appliances. Seven solar panels were installed in an open field. Each panel was installed at a different foxed tilt angle. The energy-output of the seven panels were then measured over a period (time) of exactly one year (365 days). The RESULTS can be found in the table below: APPLICATION: WIRING SOLAR PANELS IN SERIES OR PARALLEL? The important difference between wiring panels in series or in parallel is that it affects the voltage of the circuit. In a series circuit, you sum the voltage of each panel to get the overall voltage. With panels connected in parallel, the voltage of the overall circuit stays the same with every panel added in parallel. Series When you connect your solar panels in series, you are wiring each panel to the next. This creates a string circuit. The wire running from the panel's positive terminal is connected to the next panel's negative terminal and so forth down the line, for one path of current for a continuous, closed loop. Panel number Tilt (angle with the horizontal plane) 1 0° 2 10° 3 20° 4 30° 5 40° 6 50° 7 90° 4.1 12V 12V 12V Corresponding circuit diagram Total annual energy-output of the panel [4] (kWh/year) 350 370 390 Three solar panels connected in series Total voltage is 36 V 410 385 360 220 In a series circuit, the sum of the voltage of each panel is equal to the overall voltage of the array (combination of panels). Draw a bar graph to illustrate the annual energy-output at different tilt angles for the seven solar panels. 4.1.1 Which tilt angle gives the highest annual energy-output? (6) (1)