PV Systems

Setting up a PV system

1. Total electrical energy consumption calculation

To determine energy consumption, the power required by each consumer (measured in Watts - W) has to be multiplied by it’s duration of use per day (measured in hours - h). Finally the figures for energy consumed by each consumer are added together and the total energy comsumption has been determined.
 

2. Battery storage requirements

Electrical consumers that must operate without sunshine require the supply of a rechargeable battery. The size of the battery is determined through the following calculation: the energy consumption plus losses (charge/discharge, electronics) plus the number of max. days without sunhsine (autonomy) plus the consideration of the max. discharge level required of the battery. This determines what lifetime can be expected of the battery.

3. Local irradiance

Local irradiance is determined via measurements onsite (best method) or with data from close by meteorological stations (if available), or via maps, tables and computer simulation programs. Determining the typical irradiance during the period (e.g. a month) when the year’s irradiation is at it’s lowest, is important as it will effect the system’s layout (4).

4. Layout of a PV generator

The layout of a PV generator is effected by it’s size and must enable the PV generator to effectively cover electrical energy requirements during the period of year with least irradiance. It must enable the generator to cover all of the energy losses within the system (including the inverter, and storage losses), and it must take into account the local irradiance including potential variability that may go on for several days.