On average, a 9 kW solar panel system costs $23,040, according to real-world quotes on the EnergySage Marketplace from 2025 data. But your actual price will depend on factors like your roof's. A 9kw solar system can generate 35 to 45kWh of electricity per day and requires 30 300W solar panels. After the tax credit, it costs approximately $15,750 and $22,050. As of 2024, the average cost of a 9kW solar system in the United States ranges from $19,000 to $27,000 before. Compare price and performance of the Top Brands to find the best 9 kW solar system with up to 30 year warranty. 00 per watt with the latest, most powerful solar panels, module optimizers, or micro-inverters.