Step 5 - Designing the PV System focuses on the seasonal and hourly variability of temperature and irradiance, two variables that drastically impact solar production, to reveal how these affect solar water production. Global solar irradiance and temperature data are available from online sources, such as PVGIS. Step 5 presents the methodology for estimating the number of solar panels and using the pump curve to check daily water production against the daily water demand from Step 1.