PHOTOVOLTAIC SOLAR ENERGY MODULAR TRAINER DL SOLAR-B Manual

Transcription

1 PHOTOVOLTAIC SOLAR ENERGY MODULAR TRAINER DL SOLAR-B Manual

2 DL SOLAR-B Contents 1. Solar energy: our commitment 5 to the environment 1.1. Basic principles and concepts 6 Mechanical work, energy and power: 6 definitions, laws and units Transformation of mechanical energy 7 History of energy-conversion technology 8 Electrical energy and power: definitions 8 and units Heat energy: definitions and units Energy from the Sun Electricity directly from the Sun 15 Photovoltaic effect and photovoltaic cells: 15 history and definitions How does a photovoltaic cell work Solar energy received on land 16 surface Positioning of solar panels 16 Standard Test Conditions (STC) and its 21 aplication 1.5. Characteristics of a solar cell DL SOLAR B Basics of the Solar Trainer Identification of the components of the 26 trainer Current, voltage and power measurements 41 Exercise 1: Measuring the load current, voltage and power 2.2. Irradiation and Temperature Measurements Exercise 1: Setting the solar panel to the most irradiated position Exercise 2: Changing the inclination of the solar panel Exercise 3: Changing the azimuth of the 47 solar panel Exercise 4: Covering the solar panel with 48 different materials 2.3. Solar Irradiation throughout the 49 Day Exercise 1: Obtaining the solar irradiation 49 data 2.4. Solar Panel Voltage-Irradiation 53 Curve, Current-Irradiation Curve and Resistance of the Solar Panel Exercise 1: Obtaining the solar panel 54 voltage-irradiation curve Exercise 2: Calculating the inner 56 resistance of the solar panel 2.5. Current-Voltage Characteristics of 58 the Solar Panel Exercise 1: Obtaining the solar panel 59 current-voltage curve 2.6. Solar Panel Power Measurements 65 Exercise 1: Obtaining the solar panel 67 current-power curve Exercise 2: Overloaded solar panel 70 measurements 2.7. Using Solar Panel to Charge the 72 Battery Exercise 1: Battery charging Using Solar Panel and Battery to 75 Power DC Load Exercise 1: Supplying DC load Using Solar Panel and Battery to 78 Power AC Load Exercise 1: Supplying AC load 79 Appendix 81 Index 83

3 1 to Solar energy: our commitment the environment Basic principles and concepts Energy from the Sun Electricity directly from the Sun Solar energy received on land surface Characteristics of a solar cell

4 Basic principles and concepts Key words Mechanical work, energy and power: definitions, laws and units Mechanical energy is capacity of the body for doing work. E is the symbol used to represent energy. The SI derived unit for energy is the J (joule). 1 J = 1 Nm, where N is the SI unit for the force and m is the SI unit for the distance. Mechanical energy is the sum of kinetic energy and potential energy. E = E k + E p Kinetic energy is a form of energy that an object or a particle has due to its motion. E mv 2 k 2 v R p Gravitational potential energy is an energy that an object possesses because of its reference position (R p ) in a gravitational field. The reference position (R p ) is usually chosen to be the position of zero displacement (Figure 1.1-1). E p = mgh h reference line Mechanical work is a measure of energy transfer that occurs when an object is moved over a distance s [m] by an external force F [N] Airplane taking off from the land W = F s [J] Mechanical power is the time rate of doing mechanical work W or delivering energy E, expressible as the amount of work done W, or energy transferred, divided by the time interval t. P W t Mechanical work The SI derived unit for power is the W (watt). Another unit for measuring power, often used in automobile industry, is horsepower (HP). 1 HP = W function of machines in terms of forces and motions. Because of friction, the work, energy or power output from a machine is always lower than 6 DL SOLAR-B

5 the input energy. For this reason, the, which is the ratio of the two, is always less than 100 percent. Efficiency is the ratio of the work, energy or power output and the work, energy or power input. 1 W o o o = 100 = 100 = 100 [%] W i E E i P P i James Prescott Joule ( ) Conservation law, also called the law of conservation implies that energy can be neither created nor destroyed, although it can be changed from one form (mechanical, kinetic, chemical, etc.) into another. Transformation of mechanical energy An ideal system A simple example of a system in which energy is being converted from one form to another is provided in the descending of a wagon with mass m from the top, its speed and thus its kinetic energy E k increases. At the same time gravitational potential energy E p descreses. Total sum of energy has not changed, i.e. it is constant. Applying the law of conservation and conversion of energy and assuming there is no friction in the air, Ek1+ Ep1= Ek2+ Ep2 2 2 mv1 mv2 + mgh1 = + mgh Transformation of potential to kinetic energy E mv 2 k 2 E p = mgh m [kg] - mass v m s g m - gravity acceleration s 2 h [m] - hight from zero point 1 - start 2 - end Solar energy: our commitment to the environment 7

6 1 Key words 1.4. Solar energy received on land surface Positioning of solar panels a) In northern hemisphere, solar panel should be oriented towards the south (S). b) In southern hemisphere, solar panel should be oriented towards the north (N). This is known under name of azimuth. In an ideal case, on the northern hemisphere an azimuth should be changed from south-east in the morning to south-west in the evning tracking the path of the Sun trough the day. includes both, azimuth and angle of inclination, represented by and angle of latitude below. Optimal angle of inclination (α) is equal to latitude Solar panel is positioned in point A oriented to the north on the earth surface under angle of 0, parallel with the earth surface. Sun rays target to point on the panel surface under the angle 120. This is far away from ideal angle of 90. How can we correct this value? Obviously, we have to decrese it, as shown in figure below. = Orientation from north (N) to south (S) in northern hemisphere Orientation from south (S) to north (N) in southern hemisphere Angle of inclination in fact is the latitude of a point A where the solar panel is placed Inclination and azimuth of solar panel in northern hemisphere Inclination and azimuth of solar panel in southern hemisphere. 16 DL SOLAR-B

7 Solar system. The Earth has third position from the Sun. Notice: all planets rotate around the Sun on the same plane, named plane of the Ecliptic Oscilation Earth axis around the cone. Summer on the north hemisphere. Unfortunatly, the Earth does not rotate around its axis perpendicular to the plane of the Ecliptic. Its axis is incliqhg XQGHU DQJOH RI Ȝ $YHUDJH YDOXH RI WKLV LQFOLQDWLRQ LV Earth axis is inclined under average angle of Changing of sezons through the year is due to oscilatirq RI 1 6 D[LV DURXQG WKH FRQH JXUH DQG,Q JXUH WKH IROORZLQJ VLWXDWLRQ LV REVHUYHG Sun rays target the Arctic area (N) under the angle ȕ. At the same time, the Antarctic area (S) is hiden in the shade.,q JXUH WKH VLWXDWLRQ LV H[DFWO\ WKH RSSRVLWH Sun rays target the Antarctic area (S) under the angle ȕ. At the same time, the Arctic area (N) is hiden in the shade. 7KLV IDFW FRPSOLFDWHV WKH SUHYLRXV H[SODQDWLRQ RI GH ning an optimal angle of solar panel. Fortunately, an answer is very simple. The explanation is provided on the next page. Interesting facts TDJMBUJPO &BSUI BYJT BSPVOE UIF DPOF 8JOUFS PO UIF OPSUI hemisphere. In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees (marked with ). The equator has a latitude of 0, the North pole has a latitude of 90 north (written 90 N), and the South pole has a latitude of 90 south (written 90 S). Solar energy: our commitment to the environment 17

8 1 &RPSDUH JXUHV DQG )LUVWO\ ZH FDQ QRWLFH D VLPSOH IDFW Sun rays target equator (B) under same angles, J Bs and J Bw, during the summer and winter periods. This is the explanation why we have the same weather in equatorial area in all sezons. Compare angles J As and J Aw between Earth surface and sun rays. J As < J Aw This means that the sun rays target point A under angle FORVHU WR LGHDO LQ WKH VXPPHU,Q WKH VDPH WLPH VXQ rays target point A in the winter under angle far from LGHDO Because of that, we have to correct conclusion from previous page Summer on the north hemisphere Optimal angle of inclination (α) is equal to latitude corrected with corrective angle. &RUUHFWLYH DQJOH YDOXHV DUH SURYLGHG LQ WKH WDEOH These values depend on latitude and season. &RUUHFWHG WRWDO RULHQWDWLRQ is represented by the forpxod Į ij FRUUHFWLYH DQJOH D]LPXWK Latitude WR WR WR WR DQG PRUH JOUFS PO UIF OPSUI IFNJTQIFSF Table-3 Corrective angles 18 DL SOLAR-B &RUUHFWLYH DQJOH In Winter In Summer ± ± ± ±

9 1 Example 7 - a) during the winter season Result: b) during the sommer season w corrective angle w w corrective angle s s s Interesting facts Described determination of ideal panel orientation with azimuth 180 strictly to the south on the northern hemisphere and to the north on the southern hemisphere is suitable for the panels installed on the fixed objects, for example roofs, like in example 7. Twice in the year we have to adjust angle of latitude depending on the season using values from the table 3, corrective angles. But can we determinate the orientation of moveble objects? Take a look at the picture right. From our own experience we know: The Sun heats on the best way if we turn strictly against it. Early in the morrning azimuth is less then 180 and panel is oriented almost to the east against the Sun. In the noon azimuth is equal 180 and panel is oriented strictly to the south against the Sun. Finally, in the evning, azimuth is great then 180 and panel is oriented almost to the west against the Sun. Simply, the best orientation of the panel is Solar energy: our commitment to the environment 19

10 1 R h 2 ] R i 2 ] Januar 54 February March 94 April May 158 June July August September 111 October November 54 December Annual sum 1179 Table-4 Monthly iradiation for the panel positioned horizontaly (R h ) and inclinated (R i ) Example 8 Imagine your home somewhere in Central Europe on the latitude 2 a) positioned horizontaly b) positioned under the best angle a 2 R h = 158 kwh/m 2 R i 2 a) E h b) E i c) E i E h Result: a) E h = R h a E h = 158 kwh/m 2 2 E h = 474 kwh b) E i = R i a E i 2 2 E i c) E i E h E i E h = 6 kwh Dailly sum of global irradiation per month R h - horisontaly positined panel (α = 0 ) R i - panel positined optimaly under angle of inclination (α = 36 ) 20 DL SOLAR-B

11 2 DL SOLAR B Basics of the Solar Trainer Irradiation and Temperature Measurements Solar Irradiation throughout the Day Solar Panel Voltage-Irradiation Curve, Current- Irradiation Curve and Resistance of the Solar Panel Current-Voltage Characteristics of the Solar Panel Solar Panel Power Measurements Using Solar Panel to Charge the Battery Using Solar Panel and Battery to Power DC Load Using Solar Panel and Battery to Power AC Load

12 Using Solar Panel and Battery to Power AC Load Objective of the exercise Note The following are the main characteri- Input voltage. Module DL 9013 range is V. Output voltage. Corresponding to the supply network. Power to supply Output waveform. Since DL 9013 plying circuits with inductive characteristics. Efficiency. This characteristic corresponds to the energy transfer factor and is expressed in percentages. The optimum value 100% cannot be achieved. Module DL 9013 has an efficiency close to 90%. Use both solar power and energy stored in the battery to power the AC load. Learn the application of inverters. Required equipment Solar panel, battery, protective module (DL 9014), measurement module (DL 9021), charge regulation module (DL 9012S), inverter (DL 9013), AC load module (DL 9017) Introductory examples 4. Describe the pulse-width modulation basics. 78 DL SOLAR-B

13 2 Exercise 1: Supplying AC load Connection scheme of exercise 1 1. Find the position in which the solar panel provides highest irradiation (read the azimuth using compass and inclination using the angle-me- the circuit. Using the charge regulation module DL 9012S read the voltage of the battery. Using the charge regulation module DL 9012S read the load current 6. Calculate the DC power. DL SOLAR B 79

14 2 8. Knowing input and output power to the inverter, calculate the inverter 9. Switch off the halogen lamp and switch on the LED lamp. 11. Switch on the halogen lamp. 12. Repeat points 4-8. from the circuit. Voltage (V) Load current (A) DC power (W) AC power (W) Questions for evaluation 1. Which element limits the load power that can be supplied in this exer- 80 DL SOLAR-B

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