Session 02 - Part 3 Solar Energy (PV Array Efficiency and Output).pptx
- 1. 1 Session :Design of Solar Panel Energy System Punjab Energy Development Agency, PEDA Solar Passive Complex-Sector 33-D,Chandigarh
- 2. 2 Content 1. How a PV cell works 2. PV Cell Electrical Characteristics 3. PV Modules 4. Quantifying PV Module Performance 5. Types of PV Modules technology 6. PV Module Protection 7. Module Reliability 8. PV Module specifications
- 3. 3 How a PV Cell Works • Solar photovoltaic (PV) cells convert sunlight into electricity. • Photovoltaic (PV) cells generate electricity by absorbing sunlight and using that light energy to create an electrical current. • Most photovoltaic (PV) panels are made from crystalline silicon-type solar cells. These cells are composed of layers of silicon, phosphorous, and boron.
- 4. • The I–V curve of a solar cell is found by setting up the solar cell in series with a variable resistor.As the resistance changes, the current and voltage are measured and plotted to form an I-V curve, this known as the load line method. Circuit used to determine the I–V curve of a solar cell using the load line method. PV Cell Electrical Characteristics 2. The I–V Curve • The I–V curve of a solar cell shows the relationship between the current and voltage of the electricity generated by the cell. Each point along the curve represents a possible operating point of the solar cell. The I–V relationship is dependent on the internal resistance of the solar cell and is affected by the levels of solar radiation being received and the temperature of the cell.
- 5. PV Cell Electrical Characteristics • The Solar Cell I-V Characteristic Curves shows the current and voltage (I-V) characteristics of a particular PV cell, module or array. • It gives a detailed description of its solar energy conversion ability and efficiency. • The current-voltage (I-V) characteristic is the basic descriptor of photovoltaic device performance. This is plotted on a graph with voltage (the independent variable) on the x axis and current (the dependent variable) on the y axis, while keeping irradiance and temperature levels constant. I-V characteristics curve of a PV module
- 6. PV Cell Electrical Characteristics The power produced by a solar cell is found by multiplying the current and voltage. 𝑃 = 𝐼×𝑉 This power output is known as I-V curve. There is a point on the I-V curve that shows the maximum amount of power this is known as the maximum power point (MPPT). This point is at the ‘knee’ of the I-V curve , and occur when the load resistance is equal to the internal cell resistance. Power output plotted for each point on the I-V curve
- 7. • a)The I–V characteristics of a single cell; b) the I–V characteristics of three of those cells connected in series. • If dissimilar solar cells are wired together in series, the voltage output will be equal to the combined voltage outputs of those cells, but the current output will be equal to the lowest individual cell current output. PV Modules 1. Creating a PV Module • PV modules are units of series interconnected PV cells that have been encapsulated to protect the cells and their interconnecting wires from external damage. Connecting identical solar cells in series results in the same current output as a single cell but having a combined voltage output.
- 8. 1. Creating a PV Module • Since the PV module will then have electrical characteristics that are defined by the cells, the I-V characteristics are the following: • Maximum power point (MPP): the point on the I-V curve at which the PV module will produce the most power • Maximum power (PMP): the maximum power output of the PV module • Voltage at PMP (VMP): the PV module voltage at the MPP of the I-V curve • Current at PMP (IMP): the PV module current at the MPP of the I-V curve • Open circuit voltage (VOC): the maximum voltage of the PV module when there is no load connected to it and hence no current output • Short circuit current (ISC): the maximum current available from the PV module when the terminals of the module are connected together with no resistance (short circuited) and hence with no voltage differential across the cell PV Modules (a) The I–V characteristics of two dissimilar cells (b) The resulting I–V characteristic two dissimilar cells connected in series
- 9. PV Modules 2. Combining PV Modules • Solar modules are connected in series to form a PV string, and PV strings are connected in parallel to form a PV array. • The electrical specifications of the required array will determine the number of modules in each string and how many strings there will be in total. • As with solar cells, connecting solar modules in series results in a voltage output that is equal to the combined voltage outputs but a current output that is equal to the lowest individual module output. • Connecting strings in parallel results in a voltage output that is equal to the lowest output of the individual strings and a current output that is equal to the combined current outputs of the strings.
- 10. Standards and certification of PV Modules Standards: • IEC61215: Crystalline Silicon Terrestrial Photovoltaic (PV) modules - Design QualificationAnd TypeApproval • IEC 61730 (Part 1): Photovoltaic (PV) Module Safety Qualification Part 1 Requirements for Construction • IEC 61730 (Part 2): Photovoltaic (PV) Module Safety Qualification Part 2 Requirements for Testing • IEC 61701:2020: Salt mist corrosion testing of photovoltaic (PV) modules • IEC 60068-2-68:1994: Environmental testing - Part 2-68: Tests - Test L: Dust and sand • IEC 62716:2013: Ammonia (NH3) Corrosion Testing • IEC 62804-1:2015: Photovoltaic (PV) modules - Test methods for the detection of Potential-Induced Degradation.
- 11. Types of PV Modules Technology Commercially available technology: Solar Cell Technology Silicon Crystalline cells Monocrystalline Polycrystalline Thin-film cells Amorphous Silicon(a-Si) Cadmium Telluride(CdTe) Copper-Indium gallium di-selenide(CIGS)
- 12. Types of PV Modules Technology (There are three types of PV cell technologies dominating) Lab efficiency: 26% Field efficiencies of 18 – 22.5% Maximum capacity 710 Wp Lab efficiency: 22% Field efficiencies of 15 – 19% Maximum capacity 500 Wp Lab efficiency: 22.1% Field efficiencies of 6 – 18% Maximum capacity 450 Wp
- 13. • If a cell is damaged or shaded, the current from the whole module is reduced. This reduces the current of the whole string. • If a cell is damaged, the whole array can force current through this failure point, producing a significant temperature rise in the cell, which then leads to further damage of that cell. This phenomenon is called ‘hot-spot’ formation and results in reduced array output. In the extreme case of an open circuit cell, the array output will be zero. • The effect of the above situation can be minimised by the use of bypass diodes and/or blocking diodes. PV Module Protection
- 14. PV Module Protection 2. Blocking Diodes • Blocking diodes (or series or isolation diodes) can prevent current from flowing backwards through the modules at night and to prevent current flowing into a faulty parallel string. • Blocking diodes are used in systems that contain an external power source, such as a battery, which can possibly cause reverse power flow at night. • They are less commonly used in system today as many charge controllers now also have inbuilt functions preventing reverse current. Blocking diode in series with a PV module.
- 15. Module Reliability • Modules generally last for around 25 years. However, throughout this time they will be exposed to numerous internal and external factors that affect this value: weather exposure, yellowing, micro fractures, hot spots and potential induced degradation. 1. Weather Exposure • Solar PV systems should be installed in locations that receive suitable solar radiation. These locations will also experience other weather conditions that modules must be resistant to, including: □ Rain and Humidity □ Hail □ Thermal Cycling □ Wind and Snow
- 16. Module Reliability Yellowing: • Module manufacturing involves solar cells being laminated to glass using encapsulant of EV Awhich may discolour over time known as yellowing • It is likely to affect all of the module in a batch • It do not effect the module performance but due to discolouring of EV Alayer become opaque and prevent light from hitting the cells Microfractures: • Microfractures are discrete cracks occurring in the cells used in a PV Module • These cracks can be caused by localized pressure and can occur during module manufacturing or during installation • It can effect the performance of the module.
- 17. Generation Loss: 1. Operating Temperature 2. Dirt or Soiling 3. Tilt angle and orientation 4. Shading Losses in PV System Losses in PV system 17
- 18. Losses in PV System Loss due to temperature of the PV module: • As cell temperature increases, the short circuit current marginally increases • As cell temperature increases, the open-circuit voltage decreases • As cell temperature increases, the maximum power decreases • These temperature coefficients can be used to determine the change in voltage, current and maximum power when the cell temperature is above or below STC temperature. Module Type Typical Power temperature coefficient Mono-crystalline - 0.38% to - 0.40%/oC Poly-crystalline - 0.45% to - 0.50%/oC Thin film - 0.2% to – 0.3%/oC 18
- 19. Losses in PV System Loss due to Dirt (Soilage) • Are the modules installed at an angle of elevation so that rain will wash any dirt or debris away? • Is there pollution that will form a film on the glass? • Is the site dusty? • How often does it rain? • Is water used for cleaning the module is hard? Example of soiling along the bottom edge of a PV module 19
- 20. Loss due to shading 1. If enough of the array is shaded, then, MPPT voltage may drop outside the inverter voltage window 2. If a string inverter is used and there are multiple solar module strings, the shading on one string may affect the output of the other strings Losses in PV System 20
- 21. Orientation and tilt angle for solar modules Loss due to orientation & module tilt angle • The amount of irradiation available to the PV array will be affected by their tilt angle and orientation. Solar data for the specific site may be available at a range of orientation and tilt angles, or tables with radiation ‘efficiency’ factors relative to irradiance on the horizontal plane or optimal tilt for the latitude can be used to determine the actual incident irradiation. • For Off-Grid PV systems, the tilt angle is decided based on a comparison of the available irradiation and the load demand of a site for each month. Losses in PV System 21
- 22. Types of Inverter DC to AC Conversion: Inverters Solar Inverter Off-grid Inverter Grid connected Inverter Hybrid Inverter 22
- 23. 9 Image Credit: Arin Energy Off-Grid PV system Types of Solar Inverter 23
- 24. 10 Image Credit: Arin Energy On-Grid PV system Types of Solar Inverter 24
- 25. 11 Image Credit: Arin Energy Hybrid PV system Types of Solar Inverter 25
- 26. Following parameters are considered while estimating load requirement • Type of load (AC or DC) • Number of Loads • Power rating of each load • Hours of operation • Energy requirement per day(wh/day) Load estimation
- 27. Load estimation Households Load Wattage Hr/day Number Wh LED 4 5 2 40 FAN 40 8 1 320 TV 150 5 1 750 Total energy required per day 1,110 wh/day SME loads Wattage Hr/day Number of business Wh Milling and pressing 1100 3 1 3,300 Welding workshop 2500 6 1 15,000 Total energy required per day 18,300 wh/day
- 28. LOVEROOP SINGH, Project Manager, PEDA Ex. Scientific officer, MoE(erstwhile MHRD) #9878837500 (loveroop.singh91@punjab.gov.in) THANK YOU