The cost of a 6.6 kW solar system with a 5 kW inverter and battery varies depending on factors such as location, brand of components, installation complexity, and local incentives. On average, you can expect the total cost to be the sum of the solar panels, the 5 kW inverter, the battery, and installation expenses. Solar batteries increase the initial investment but provide energy storage and backup, which may increase your long-term savings.