For a 1kW solar system, you would need either 30 100-watt solar panels, 5 200-watt solar panels, 4 300-watt solar panels, or 3 400-watt solar panels. The mode changes what you provide (e., daily vs monthly load, or target kW vs usage-based sizing). By the end of this guide, you'll have the knowledge and tools to confidently calculate your solar requirements, understand the key factors that affect. Caution: Photovoltaic system performance predictions calculated by PVWatts ® include many inherent assumptions and uncertainties and do not reflect variations between PV technologies nor site-specific characteristics except as represented by PVWatts ® inputs. For example, PV modules with better. This solar panel wattage calculator allows you to calculate the recommended solar panel wattage according to the energy consumption of your household appliances. Usually, we use the most common 100W, 200W, 300W, and 400W PV panels for this kind of system.