Example of PV System Design Presented By, Sudarshan B S Assistant Professor, Dept. of EEE RVCE, Bangalore

Example - 1 In a PV micro-inverter system shown below, power electronic converter systems are used to convert DC power produced by a PV panel to AC form, and supply this AC power to the utility grid. The DC boost converter boosts the PV panel voltage Vpv to the high voltage DC bus Vbus. Assume that the voltage Vbus is constant at 110V. The following DC loads are connected. Load Device wattage Hours of daily use Lights 150 5 Laptop 60 TV 4 DC Fan 50 3 Assume system nominal voltage to be 24V and effective sun hours is 6hrs/day. Determine the number of panels required in series and parallel to obtain the required voltage and current.

Example-1 solution Total DC watt-hours = (60*5)+(150*5)+(60*4)+(50*3) = 1440watt-hours System nominal voltage = 24V; corresponding rated current = 4.44A (from datasheet) Total DC ampere-hours per day = (DC watt hours)/(system nominal voltage) = 1440 / 24 = 60 ampere-hours We should also consider losses. Assume 20% losses. Thus, Total DC ampere-hours = 60 * 1.2 = 72 ampere-hours The effective sun-hours (ESH) = 6 Therefore Number of panels in parallel = 72 6 4.44 =2.72 Thus we must connect 3 panels in parallel. System nominal voltage = 24V Rated voltage from datasheet = 34V Thus, number of panels in series = 24/34 = 0.705 Thus we have one panel in series.

Example-2 Consider a solar pump (DC) with a wattage of 250W. It is operated 5 hours every day for 4 days in a week. The motor operates at 24V DC. Calculate the solar panel size (series and parallel panels) required to supply this load. Consider the following datasheet parameters: