Since becoming involved with clean renewable energy, I'm increasingly interested in promising technologies that seem to be begging for integration. I have been learning a new trade recently, and have found rewarding work installing residential solar PV, solar hot water, and geothermal heating systems. The more I have learned about evacuated-tube solar collector technology, and the more I learn about Stirling Cycle engines (yet to be produced as serious consumer products, but buildable nonetheless) the more I want to know. These technologies belong together: There may be a serious potential to integrate the two, and achieve over 300% more efficient conversion of solar energy into electricity than is possible using photovoltaics- PV is not full-spectrum conversion, and PV performance suffers dramatically with heat. Evacuated tubes, on the other hand, soak up nearly full-spectrum solar energy, and can be used in conjunction with inexpensive light and heat collectors. Stirling engines are also all about heat, and happen to be surprisingly good at converting thermal differential into torque; capable of efficiently driving generators. In further integrations of existing technology, large thermal masses and geothermal loops integrated with Stirling-cycle devices may offer energy storage exceeding the cost/performance of chemical batteries for fixed residential applications. The more I install and maintain off-grid battery systems, the more I am convinced that there has got to be a better way. I'm thinking of relatively small-scale integrations of already-developed technologies for home power on an average budget. It's possible that under the large-scale corporate energy paradigm, promising solutions are being overlooked. The implications of practical small-time distributed clean energy production are not small: If achieving renewable personal energy independence is possible applying only a modest intelligence and budget, the know-how will change the world. I'd like to discuss these and related potentials in this thread. Here are some introductory links: Evacuated Tube Solar Collectors - Navitron Stirling Enginess - Wikipedia Geothermal Heating and Cooling - Ground Loop Inc.