The cheapest way to generate electricity at home over the long term is through the installation of residential rooftop solar photovoltaic (PV) panels. While the upfront purchase and installation require a noticeable initial investment, federal tax incentives, net metering programs, and plummeting hardware costs allow homeowners to generate free electricity from sunlight for decades. Over time, the accumulated savings on monthly utility bills completely offset the initial capital outlay, providing a sustainable and highly cost-effective home energy solution.