Typically, the dish is coupled with a Stirling engine in a Dish-Stirling system, but also sometimes a steam engine is used.These create rotational kinetic energy that can be converted to electricity using an electric generator.The advantage of a dish system is that it can achieve much high temperatures due to higher concentration of light (as in tower designs). Higher temperatures lead to better conversion to electricity, and the dish system is very efficient on this point. However, there are also some disadvantages. Heat to electricity conversion requires moving parts and that result in maintenance. In general, a centralized approach for this conversion is better than the decentralized concept in dish design. Second, the heavy engine is part of the moving structure which requires a rigid frame and a strong tracking system. Furthermore, parabolic mirrors are used instead of flat mirrors and tracking must be dual-axis.