With the consequences of a hurricane and other catastrophes, many families are evaluating their disaster preparedness plans. One important aspect to purchasing a generator is looking at and understanding the cost. The Kohler generator comes in a variety of sizes, from an energy storage of 6 kilowatts (kW) to 150 kW depending on the size of your home. The 20kW model, which is the most commonly installed size of Freedom Solar customers, has a retail price of just under $5,000 and costs between $11,000 and $15,000 fully installed.