Solar PV system includes different components those should be selected according to the system type, site location and application. These are described below.
4.4.1 The PV module details
The first component for solar PV system is solar PV module which converts sunlight into DC electricity. PV Power operates on the principle that electricity will flow between two semiconductors (typically crystalline silicon) when they are put in contact with each other and exposed to light. By linking a number of these 'cells' into a Panel (also called a Module), a useful flow of electricity can be generated.
Only a few days back solar PV modules were imported from China or other countries.
Nowadays some companies produce solar PV modules in Bangladesh. They design, manufacture, supply and install renewable energy solutions. ―Electro Solar Power Limited' is a leading company in this sector.
The Electra solar band solar PV module adopts high efficient mono-crystalline silicon and is making up of solar cell, EV coating, iron-thinned toughened glass and TPT.
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These modules adopt advanced and reliable far infrared automatically welding technique, high vacuum heating lay pressure craftwork, anode oxidation treatment aluminum alloy side frame, water-proof cable box etc, characterized by reasonable structure, anti-ultraviolet, and aging resistances and wind¬proof intensity 2400 Mpa 200 Wp Mono-crystalline solar module has been selected for this system designing.
The specifications provided by the company are given in Appendix A. In figure 4.2 the mono-crystalline silicon solar panel is shown
4.4.2 Sizing the inverter
Inverters are used to convert the DC output of PV or a storage battery to AC electricity, either to be fed into the grid or to supply a stand-alone system. There are many different types of power electronic topologies used in the market. This solar system is the grid connected one. The on grid solar inverter be used with a connection to grid or power lines.. The advantage of this type is not to worry any power waste because by connecting inverter to the grid, it can save any surplus electricity.
20 kW grid connected solar inverter with high efficiency for plant manufactured by Hubei Tress Technologies Co., Ltd is used for our system. The product details are given in Appendix A. In figure 4.3, Grid connected solar inverter is shown.
Figure4.3: Grid connected solar inverter Figure 4.2 : Mono-crystalline Silicon Solar panel
53 4.4.3 Sizing the battery
The battery type recommended for using in solar PV system is deep cycle battery. Deep cycle battery is specifically designed for to be discharged to low energy level and rapid recharged or cycle charged and discharged day after day for years. The battery should be large enough to store sufficient energy to operate the appliances at night and cloudy days. To find out the size of battery, calculation are shown below:
1. Calculate total Watt-hours per day used by appliances.
2. Divide the total Watt-hours per day used by 0.85 for battery loss 3. Divide the answer obtained in item 2 by 0.6 for depth of discharge.
4. Divide the answer obtained in item 3 by the nominal battery voltage
5. Multiply the answer obtained in item 4.4 with days of autonomy (the number of days that you need the system to operate when there is no power produced by PV panels) to get required Ampere-hour capacity of deep-cycle battery.
Battery Capacity (Ah) = (Total Watt-hours per day used by appliances × Days of autonomy) / (0.85 x 0.6 x nominal battery voltage)
4.4.4 Charge controller rating
The solar charge controller is typically rated against Amperage and Voltage capacities.
Select the solar charge controller to match the voltage of PV array and batteries and then identify which type of solar charge controller is right for your application. Make sure that solar charge controller has enough capacity to handle the current from PV array.
For the series charge controller type, the sizing of controller depends on the total PV input current which is delivered to the controller and also depends on PV panel configuration (series or parallel configuration).
According to standard practice, the sizing of solar charge controller is to take the short circuit current (lsc) of the PV array, and multiply it by 1.3
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Solar charge controller rating = Total short circuit current of PV array ×1.3
4.4.5 Connecting accessories and safety components 4.4.5.1 PV Combiner box:
Combiner box is used to connect the solar panels and grid tied solar inverter. The Product details of the combiner box are given in Appendix .Combiner box is shown in figure 4.4.
Figure 4.4 : PV Combiner Box 4.4 5.2 Mounting Structures
Solar Panel Bracket of Flat Roof manufactured by the company Haining Chuangyaun Solar Energy Technology Co, Ltd. Used for mounting the modules with the flat root.
Technical details are given in Appendix . Mounting Structures is shown in Figure 4.5
Figure 4.5: Mounting Structures
55 4.4.5.3 Filter
Power converter's output signal harmonic control is currently becoming immensely important in medium and high power applications due to the development of new grid codes. Otherwise, inverters generate harmonics that are subsequently transmitted into the power bus of the grid. So filters are used for system stability stability. The specifications of PV Photovoltaic Inverter Series Filters ROHS compliance is provided in Appendix .