Solar Thermal Systems for Energy Savings

Solar thermal systems are one of my favorite energy-efficiency topics. They are simple, affordable, green and save money. As energy costs continue to soar and sustainable building goes mainstream, many homeowners are turning an enthusiastic eye to solar thermal systems for energy savings.

Solar thermal gained in popularity during the oil crisis in the early 1970s, when fuel for hot water was scarce and expensive. The industry boomed for a short time, in part due to government incentives and subsidies. It lost momentum when oil became cheap again but the technology continued to evolve. Today, consumers can benefit from a wide range of applications that are suitable to nearly any region and building type.

The systems operate on a simple natural process that captures the sun’s warmth and transfers it to mediums that can be used for heating in the home. We experience this process regularly but too often fail to use it effectively.

Think about swimming in a natural water body like the ocean or a lake. These are cooler in the morning and at the beginning of warm seasons. This is because water stores absorbs and stores heat. When it’s cool or dark outside, this heat escapes making water cooler at these times. When the sun is shining or the weather has been warm for a longer time, the water retains this heat.

By coupling the sun’s energy with modern technology, solar thermal systems provide a cost effective way to heat hot water and reduce the need for non-renewable fuels. While simple in principle, there are a few different techniques used depending on the region and situation.

Passive solar thermal systems simply collect solar heat in stored water. They operate passively, without pumps or complex controls. Cold water flows in and warm water flows out through a drain valve to a hot water storage tank. These systems basically work like a siphon. Hot water rises within the collector and is siphoned off to the storage tank. As the hot water is drawn off for storage and use, the cold water replaces it and lines up to be heated by the sun. Depending on the siting of the collector and tank, these systems aren’t always applicable to homes where the collector is planned for a roof mount.

A little different are active solar thermal systems. These use water or, in colder climates, an antifreeze solution to collect the sun’s heat. The heat is dispersed through the medium and circulated with pumps which drive the medium through the collector. These systems require electricity and are a little more complicated than passive, direct systems but still provide an energy-efficient means to heat hot water and reduce energy use. Both of these systems can be coupled with an auxiliary heat source to bring and maintain stored water to a higher, usable temperature.

Solar thermal systems can be used to heat water for residential hot water or swimming pools. They can also disperse heat to living spaces when integrated with radiant underfloor heating. Even though they may not provide complete hot water needs, they are a cost-effective way to reduce fuel use and costs. Systems usually come with 5-10 year warranties and require little maintenance. They are definitely worth a look for anyone interested in renewable, clean energy for their domestic hot water needs.