Hamad Fahad Al Awad company Business Center Building king khaldi st.Cross 8 P.O BOX 6915, Al-khobar 31952 Saudi Arabia


Solar PV system sizing

1. 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

  1. Calculate total Watt-hours per day for each appliance used.
  2. Add the Watt-hours needed for all appliances together to get the total Watt-hours per day which must be delivered to the appliances.

  3. Calculate total Watt-hours per day needed from the PV modules.
  4. Multiply the total appliances Watt-hours per day times 1.3 (the energy lost in the system) to get  the total Watt-hours per day which must be provided by the panels.

2. Size the PV modules

Different size of PV modules will produce different amount of power. To find out the sizing of PV module, the total peak watt produced needs. The peak watt (Wp) produced depends on size of the PV module and climate of site location. We have to consider “panel generation factor” which is different in each site location. For Thailand, the panel generation factor is 3.43. To determine the sizing of PV modules, calculate as follows

  1. Calculate the total Watt-peak rating needed for PV modules
  2. Divide the total Watt-hours per day needed from the PV modules (from item 1.2) by 3.43 to get  the total Watt-peak rating needed for the PV panels needed to operate the appliances

  3. Calculate the number of PV panels for the system
  4. Divide the answer obtained in item 2.1 by the rated output Watt-peak of the PV modules available to you. Increase any fractional part of result to the next highest full number and that will be the number of PV modules required.

3. 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 total Watts of appliances. In case of appliance 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 same as PV array rating to allow for safe and efficient operation.

4. Battery sizing

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.

5. Solar charge controller sizing

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

Solar Site Analysis

  • Azimuth and Altitude
  • Array Tilt and Orientation
  • Site Analysis Tools
  • Mounting
  • Types of Mechanical Mountings
  • Accessories for Mountings
  • Inter Row Spacing

Design the solar system-based on site location in PV syst software and calculating PV array sizing, MPPT selection, Inverter sizing, battery system sizing etc.