Geothermal systems are able to transfer heat to and from the ground with minimal use of electricity. When comparing a geothermal system to an ordinary system a homeowner can save anywhere from 30% to 70% annually on utilities. Even with the high initial costs of purchasing a geothermal system the payback period is relatively short, typically between three and five years. Geothermal systems are environmentally friendly; they are a renewable energy source, non-polluting, and recognized as one of the most efficient heating and cooling systems on the market. Technically, they are solar systems since ground source heat is trapped from the sun's rays.