Capturing Free Heat
The technical term "solar thermal" has two applications in the renewable energy field. One definition refers to concentrating the sun’s energy to super-heat water, creating steam to power turbines for the generation of electricity in commercial power plants. This large-scale application, also called concentrated solar power (CSP), is beyond the scope of the purpose of this site.
The other definition of solar thermal applies to the low temperature heating of water to be utilized for domestic hot water or radiant space heating. This simple renewable energy technology is well over a hundred years old and is the most efficient system for mechanically converting and storing solar energy. Modern off-the-shelf thermal panels are 75 to 80% efficient at converting solar energy into heat, while top PV panels are in the 15 to 20% range. Producing electricity provides versatility with how that electricity is used, but if you want to make water hot, solar thermal panels are far more efficient and cost effective.
Solar thermal systems are not complicated, have few moving parts and can last a lifetime. In cold climates, a collector or panel exposed to the sun heats the heat-transfer fluid (glycol/water mix) inside the panel. A small pump circulates this fluid from the panel though a heat exchanger to transfer the heat to water in a storage tank. The storage tank can be for domestic hot water or for radiant space heat, or for both.
The energy required to heat domestic hot water is significant, and is frequently underestimated. On an annual basis in a very well insulated home, the energy consumed to heat domestic water can actually exceed the energy required to heat the home. The simplicity, efficiency, low maintenance and life-expectancy of solar thermal systems can make them an excellent renewable energy source, even in Alaska. With appropriate storage capacity, they can also be utilized for space heating.
Recent advances in thermal storage designs have opened the door for space heating systems that are appropriate in Alaska. Imagine heating your home in January with stored June solar energy. Arctic Sun has several proven designs that can be tailored to fit many applications.
As with other solar energy systems, thermal potential is site specific as discussed in the “Solar Energy” section. Whether you are simply interested in reducing your domestic hot water heating load, or you want to heat all of your water and space heat your home, solar thermal can provide a broad variety of options.
Some hardcopy reading for more details on solar thermal include:
Heating water with the sun is a practice almost as old as humankind itself. Solar Water Heating, now completely revised and expanded, is the definitive guide to this clean and cost-effective technology. Beginning with a review of the history of solar water and space heating systems from prehistory to the present, Solar Water Heating presents an introduction to modern solar energy systems, energy conservation, and energy economics. Drawing on the authors’ experiences as designers and installers o…
Solar Domestic Water Heating is a comprehensive introduction to all aspects of solar domestic water heating systems. As fossil fuel prices continue to rise and awareness of climate change grows, interest in domestic solar water heating is expanding. Solar water heating technology is the most environmentally-friendly way to heat water. This fully-illustrated and easy-to-follow guide shows how domestic solar water heating systems work, the different types of systems, types of collectors, both flat…
Solar thermal systems available today offer efficiency and reliability. They can be applied in different conditions to meet various requirements in the residential, commercial and industrial building sectors. The potential for this technology and the associated environmental benefits are significant.This fully updated edition of 2004’s bestselling guide offers clear guidance on planning and installing a solar thermal system, crucial to the successful uptake of this technology. All major topics f…
The development of systems to provide both domestic hot water and space heating (solar combisystems) resulted in a diverse range of different designs that were not carefully optimized to reflect local climate and practice. Application of energy-efficient building strategies such as improved thermal insulation and use of low temperature heat supply systems is becoming increasingly common. This trend, combined with growing environmental awareness and the subsidies available in certain countries, f…
Tom Lane discusses particle approaches to high performance low maintenance systems and reality checks using current technologies.