Generally, it's recommended to size the inverter to 80-100% of the DC system's rated capacity. Before determine the inverter size, the most important thing is to calculate your average daily power consumption (kWh) and calculate your solar panel array size to match your power. . Choosing the right solar inverter size is critical—and one of the most common questions: what solar inverter size do I need? Whether you are installing a rooftop system in California, powering a remote cabin in Alberta, or sizing for a community center in Rajasthan, getting it right means. . A properly sized solar inverter typically lasts 10‑15 years, though premium or microinverter units can reach 20‑25 years with good maintenance. Think of inverter sizing like choosing the right-sized engine for your car. What Size Solar Inverter Do I Need? A solar inverter should closely match your solar system's output in kW—typically within 80% to 120% of your total panel capacity.