This gives a payback period of 66. 3 years, after which every kWh your panels produce is essentially free electricity. Over the typical 25-year warranty period of modern solar panels, the total net return on your investment would be approximately EUR -3,738. Generally, a solar power system pays for itself in 10-15 years. These include the total system cost (panels, inverters, installation, maintenance), the amount of power generated (influenced by. Read about solar power production, its costs and environmental effects and the project development of the solar power plant. The first is an annual statistic covering. LCOE assesment should take into account the whole lifetime of a solar plant which is 30 years on average.