“ DESIGN OF GRID-CONNECTED PV SYSTEM”

1. “DESIGN OF GRID-CONNECTED PV SYSTEM” By IR. TUNKU MUHAMMAD NIZAR BIN TUNKU MANSUR Edited By IR. DR. MUHAMMAD IRWANTO PPK SISTEM ELEKTRIK

2. METHODOLOGY Undertaking a thorough site audit Determining the system sizing Selecting and matching the individual components Determining location for installation of the components 4 Grid-Connected PV System EET433 Renewable Energy System

3. UNDER TAKING SITE SURVEY • To determine the solar access for the site. • To determine whether any shadowing will occur and estimating its effect on the system • Estimating the solar resource for the site. • To determine the available space for the PV array. • To determine whether the roof is suitable for mounting the PV array. • To determine how the modules are mounted on the roof. • To determine where the switchboard is located, where the inverter, and junction boxes will be installed, cabling route and therefore estimate the lengths of the cable runs. Grid-Connected PV System EET433 Renewable Energy System

4. SOLAR ACCESS TO THE SITE • The solar access could be reduced due to: • Natural landscapes such as mountains or hills. • Trees or other vegetation. • Other buildings. • Parts of the actual building where the system will be located such sections of roof, TV aerials. • Needs to consider future development of the site that may block the solar access. Grid-Connected PV System EET433 Renewable Energy System

5. SOLAR RESOURCES AT THE SITE • This irradiation varies as a result of: • Tilt Angle of the array. • Direction the array is facing. • Shading effect of objects. Grid-Connected PV System EET433 Renewable Energy System

6. HOW PV ARRAY ARE MOUNTED ON THE ROOF Retrofit Building Intergrated Grid-Connected PV System EET433 Renewable Energy System

7. AVAILABLE SPACE ON THE ROOF • Calculating available space area and number of PV module that could fit on the roof. • Arrangement of PV Module either length-wise up or length-wise across. Length-wise Up Length-wise Across Grid-Connected PV System EET433 Renewable Energy System

8. CALCULATING MAXIMUM NUMBER OF PV MODULE THAT COULD BE INSTALLED BASED ON ARRANGEMENT Length-wise Across Grid-Connected PV System EET433 Renewable Energy System

9. CALCULATING MAXIMUM NUMBER OF PV MODULE THAT COULD BE INSTALLED BASED ON ARRANGEMENT Length-wise Up Grid-Connected PV System EET433 Renewable Energy System

10. CALCULATING MAXIMUM NUMBER OF PV MODULE THAT COULD BE INSTALLED BASED ON ARRANGEMENT • Other factor to consider • Gap spacing between PV modules. • Offset spacing for PV array from all edges of roof. Grid-Connected PV System EET433 Renewable Energy System

11. CALCULATING MAXIMUM NUMBER OF PV MODULE THAT COULD BE INSTALLED BASED ON ARRANGEMENT Example 1: You are given the roof with the following dimension. By using Yingli YL250P-29b 250Wp PV module, determine how many modules could be installed on the roof. Allow 20mm gap between each module and 1m offset spacing from all edges of the roof. 12m 6m Grid-Connected PV System EET433 Renewable Energy System

12. DESIGN OF OFF GRID-PHOTOVOLTAIC SYSTEMS The design of off grid-photovoltaic system following items below. • Data of Solar radiation and peak sun hour (PSH) • The solar radiation and PSHs are needed to calculate a minimum size of PV module 2. PV module system From the load energy in watt hours, minimum size of PV module can be calculated using this formula : Grid-Connected PV System EET433 Renewable Energy System

13. DESIGN OF OFF GRID-PHOTOVOLTAIC SYSTEMS 3. Battery capacity The battery is used in this design and can operate the load for 4 days, if the weather is cloudy or raining . Its ampere hours can be calculated using this formula. 4. Solar charger The size of solar charger can be calculated using this formula: Grid-Connected PV System EET433 Renewable Energy System

14. DESIGN OF OFF GRID-PHOTOVOLTAIC SYSTEMS Example 2: Design and sketch the schematic diagram of 25 W, 12 V street light system which it operates 07.00 pm to 07. 00 am every day following the data as stated fellow. Grid-Connected PV System EET433 Renewable Energy System

15. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Photovoltaic (PV) – generating stations are designed based on connecting PV modules to generate the required power (the terms PV module ). One PV module has a limited power rating; therefore, to design a higher power rating, it is constructed a string by connecting a number of PV modules in series. SV = String voltage for series-connected PV modules NM = Number of PV modules per string Voc= Open circuit voltage of a PV module Grid-Connected PV System EET433 Renewable Energy System

16. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS The string power, SP is the power that can be generated by one string. PM = Power produced by a PV module For producing higher rated power from a PV-generating station, it can connect a number of strings in parallel and create an array. The array power, AP is equal the number of string times the string power. NS = Number of string Grid-Connected PV System EET433 Renewable Energy System

17. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS To obtain the maximum power output of a PV array, the maximum power point (MPP) tracking method is used. The MPP tracking method locates the point on the trajectory of power produced by an array where the array voltage and array current are at in its maximum point and the maximum power output for the PV array. The PV array MPP is defined as: VAMPP = PV array voltage at MPP tracking IAMPP = PV array current at its maximum power point tracking (MPPT) Grid-Connected PV System EET433 Renewable Energy System

18. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS An PV array is connected to an inverter or a booster converter and the control system operates the array at its MPP tracking. The inverter output voltage is controlled by controlling the inverter amplitude modulation index. To process the maximum power by an inverter, the amplitude modulation index, Ma should be set at maximum value without producing the unwanted harmonic distortion. The value of Ma is set less than one and in the range of 0.95 to produce the highest AC output voltage. Grid-Connected PV System EET433 Renewable Energy System

19. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS The inverter input voltage is given by (Single-phase) (Three-phase) Vidc = inverter input voltage Vac = ac voltage The number of PV modules to be connected in series in a string is given by The string voltage, SV is given by Grid-Connected PV System EET433 Renewable Energy System

20. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Example 3: • Design a PV system to process 10 kW of power at 230 V, 60 Hz single phase AC. Determine the following (Ma= 0.9): • Number of PV modules in a string and number of strings in array • Inverter specification for switching frequency of 6 kHz and one-line diagram • The PV module data is given below Grid-Connected PV System EET433 Renewable Energy System

21. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Solution 1: i) The load voltage is specified as 230 V single –phase AC. To acquire maximum power from the PV array and Ma=0.9, the inverter input voltage is given by The inverter is designed to operate at the MPPT of PV array. Therefore, the number of PV modules to be connected in series in a string is given by Grid-Connected PV System EET433 Renewable Energy System

22. DESIGN OF ON GRID- PHOTOVOLTAIC SYSTEMS Solution 1: String voltage is given by The power generated by one string is given by: To calculate the number of string for a 10 kW PV system, the PV power is divided by power per string. Therefore, the PV modules are configured by 5 in 7 array configuration. Grid-Connected PV System EET433 Renewable Energy System

23. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Solution 1: Photovoltaic specification for 10 kW Generation ____________________________________________________ Number of String Number of String voltage PV module per array arrays (V) Per string ____________________________________________________ 7 5 1 354.2 ____________________________________________________ Grid-Connected PV System EET433 Renewable Energy System

24. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Solution 1: ii) In the final design, the inverter should be rated such that it is able to process generation of 10 kW and supply the load at 230 V AC from its array at its MPPT. The string voltage, SV is specified as Vidc= 354.2 V The modulation index, Mais given by The frequency modulation index, Mfis given by Grid-Connected PV System EET433 Renewable Energy System

25. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Solution 1: Inverter specification ____________________________________________________ Input Output Power Amplitude Frequency voltage , voltage, rating Modulation Modulation Vidc (V) Vac (V) (kW) index,Maindex, Mf ____________________________________________________ 354.2 230 10 0.92 100 ____________________________________________________ Grid-Connected PV System EET433 Renewable Energy System

26. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Solution 1: Grid-Connected PV System EET433 Renewable Energy System

27. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Example 4: • Design a PV system to process 500 kW of power (each array has 20 kW) at 460 V, 60 Hz three-phase AC. Determine the following (Ma= 0.9): • Number of PV modules in a string and number of strings in array • Inverter and boost specification . One inverter is 100 kW andfs= 5.04 kHz. One boost converter is 20 kW. • The one-line diagram • The approximate string voltage is 550 V and a boost converter can boost the string voltage to the required DC input voltage of three-phase inverter. Grid-Connected PV System EET433 Renewable Energy System

28. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Example 2: The PV module data is given below Grid-Connected PV System EET433 Renewable Energy System

29. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Solution 2: i) The load is 500 kW rated at 460 V. Based on the load and an amplitude modulation index, Ma=0.9, the three-phase inverter input DC voltage is given by Following the approximate string voltage, SV, thus the number of PV modules to be connected in series in a string is given by Grid-Connected PV System EET433 Renewable Energy System

30. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Solution 2: The actual string voltage is given by The string power, SP can be calculated as In the design, each array generates a power of 20 kW, then the number of string, NS in a array is given by Grid-Connected PV System EET433 Renewable Energy System

31. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Solution 2: The number of PV array, NA, for the total power generation of 500 kW is Photovoltaic specification ____________________________________________________ Number of String Number of String voltage PV module per array arrays (V) Per string ____________________________________________________ 11 6 25 556.6 ____________________________________________________ Grid-Connected PV System EET433 Renewable Energy System

32. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Solution 2: ii) The inverter should be rated to withstand the output voltage of boost converter and should be able to supply the required power. The inverter is rated at 100 kW with input voltage of 835 V DC and an amplitude modulation index, Ma=0.9. The output voltage of inverter is 460 V AC. The number of inverter, NI, needed to process a generation of 500 kW is given by Grid-Connected PV System EET433 Renewable Energy System

33. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Solution 2: Five inverters should be connected in parallel to supply the load of 500 kW, if a switching frequency is set at 5.04 kHz, the frequency modulation index, Mf Inverter specification ____________________________________________________ Number of Input Power Output Amplitude Frequency Inverters voltage rating voltage Modulation Modulation Vidc (V) (kW) VAC(V) Index, Ma Index, Mf ___________________________________________________ 5 835 100 460 0.9 84 ____________________________________________________ Grid-Connected PV System EET433 Renewable Energy System

34. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Solution 2: The number of boost converters needed is the same as the number of arrays, which is 25, and the power rating of each boost converter is 20 kW. The boost converter input voltage is equal to the string voltage: The output voltage of boost converter is equal to the inverter input voltage: Grid-Connected PV System EET433 Renewable Energy System

35. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Solution 2: The duty ratio of boost converter is given by Boost converter specification for a generation of 500 kW ____________________________________________________ Number of Input Power Output Duty boost voltage rating voltage ratio, D converter Vi(V) (kW) Vo(V) ___________________________________________________ 25 556.6 20 835 0.33 ____________________________________________________ Grid-Connected PV System EET433 Renewable Energy System

36. DESIGN OF ON GRID-PHOTOVOLTAIC SYSTEMS Solution 2: iii) The one line diagram is given figure below. Grid-Connected PV System EET433 Renewable Energy System