Solar photovoltaic system or Solar power system is one of renewable energy system which uses PV modules to convert sunlight into electricity. The electricity generated can be either stored or used directly, fed back into a grid line, or combined with one or more other electricity generators or more renewable energy sources. A solar PV system is a very reliable and clean source of electricity that can suit a wide range of applications such as residence, industry, agriculture, livestock, etc.
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Major system components
Solar PV system includes different components that should be selected according to your system type, site location, and applications. The major components for the solar PV system are the solar charge controller, inverter, battery bank, auxiliary energy sources, and loads (appliances).
- PV module converts sunlight into DC electricity.
- Solar charge controller regulates the voltage and current coming from the PV panels going to battery and prevents battery overcharging and prolongs the battery life.
- Inverter converts DC output of PV panels or wind turbines into a clean AC current for AC appliances or fed back into the grid line.
- Battery stores energy for supplying electrical appliances when there is a demand.
- Load is electrical appliances that connected to solar PV systems such as lights, radio, TV, computer,
- Auxiliary energy sources – is diesel generator or other renewable energy sources.
Solar PV System Sizing
- Determine power consumption demands:
The first step in designing a solar PV system is to find out the total power and energy consumption of all loads that need to be supplied by the solar PV system as follows:
- Size the PV modules:
Different sizes of PV modules will produce different amounts of power. To find out the sizing of the PV module, the total peak watt produced needs. The peak watt (Wp) produced depends on the size of the PV module and climate of site location. We have to consider the panel generation factor which is different in each site location.
- Inverter sizing:
An inverter is used in the system where AC power output is needed. The input rating of the inverter should never be lower than the total watt of appliances. The inverter must have the same nominal voltage as your battery. For stand-alone systems, the inverter must be large enough to handle the total amount of Watts you will be using at one time. The inverter size should be 25-30% bigger than the total Watts of appliances.
In the case of the appliance, the type is motor or compressor then inverter size should be minimum 3 times the capacity of those appliances and must be added to the inverter capacity to handle surge current during starting. For grid-tie systems or grid-connected systems, the input rating of the inverter should be the same as PV
array rating to allow for safe and efficient operation.
- Battery sizing:
The battery type recommended in solar PV system is a deep cycle battery. A 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.
- Solar charge controller sizing: The solar charge controller is typically rated against Amperage and Voltage capacities. We need to select a solar charge controller to match the voltage of the PV array and batteries and then identify which type of solar charge controller is right for your application. Make sure that the solar charge controller
has enough capacity to handle the current from the 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