Thermoelectric generator (TEG) with water heating system, which utilizes solar energy with a high total energy conversion efficiency, is promising environmental technology for eco-housing and factories to reduce their carbon footprints. In this study, a newly developed cylindrical TEG consisting of ring-disk thermoelectric material is proposed showing that the total energy conversion efficiency is higher than that of a conventional pillar-type TEG. The cylindrical TEG is implemented using high-performance CoSb3-based filled skutterudite thermoelectric materials and a unique 45Ni-55Fe electrode as the hot-side junction. The solar TEG performance is demonstrated under the real sunlight, which is concentrated by a Fresnel lens. The maximum thermoelectric efficiency of the presented solar TEG is 1.8%, with a water heating efficiency of 59% when the temperature difference across the TEG is 428 °C. Further improvement should be achieved by lowering the internal resistance of the TEG and increasing the average dimensionless figure of merit of the thermoelectric materials.