Energy Options: Considering Solar Heating

Passive solar collectors come in a variety of shapes and configurations. Collectors are available that use liquid or air as the heat transfer medium.

In cold climates the liquid collector uses a combination water-antifreeze mix to prevent the system from freezing. They also use a closed loop system that keeps the mixture separate from the domestic water supply. Other types of liquid collectors have a trickle down system that empties the liquid after sundown to prevent damage. Still other types, use propietary evacuated tubes to carry the heat tranfer medium.


In the early days, some collectors suffered from leaks after a number of years but these problems were solved by changes in materials and construction. Passive collectors for swimming pool heating and space heating in hot climates have been around for many years. They have been time tested and improved over time, providing a reliable means of saving energy. Passive collectors have been used with good results in cold climates as well. Collectors designed for these areas have extra insulation, double glazing(glass sometimes triple!) and other features that protect them from the more extreme weather conditions.

Using this design as the basis for your system is a smart choice. These types of designs work well and allow for instant backup heat if the sun is not shining. It can easily be sized to whatever requirements that the homeowner may need and has room for expansion. Having forced air or radiator heating makes things a lot easier as most solar heating components can be integrated into the existing system.

The closed loop system is ideal for use in cold climates and the backup system ensures no one gets caught without heat. Note the direct up and down connections between collectors and heat tank. this ensures minimum stress on the pump and heat loss from pipes before reaching the tank. Additional collectors can be added later on to increase the efficiency of the system but the basics are there for you to build on.

A liquid solar collector system similar to this one can save you from 60-100% of you hot water needs and from 50-100% of you heating needs, depending on where you live and other factors. While ideally suited for new construction, there have been thousands of retrofits done in homes around the world. A good time to start thinking about solar heating is if you are going to replace a furnace. Choose a reputable dealer to install the most energy efficient model that is available. You are going to have to make sure that your homes insulation r-values have been brought up to date. Seal all leaks in doorways, windows and add insulation to attic crawl spaces and walls if necessary. Go on the internet and find a listing of suppliers and dealers in your area. there is a good selection of world wide dealers and distributors available on the resource pages of this site.

Read, read and read all you can about the different types of collectors available. learn about the various controls needed with the system, note prices and compare efficiencies. we will have some sample systems and typical pay back-amortisation charts in a future article. Ask to visit some of their previous installations. early collectors were around 15% efficient but modern collectors perform much better.

There are many steps to consider when buying systems. the amount of area that you intend to heat, the amount of hot water you and/or your family uses, where you live and the amount of average insolation available in your area, just to name a few items that need to be considered. You must size the system to be able to deliver the minimum daily requirement and you have to allow for sufficient storage for heat, when there is no sun. Designers use a rule of thumb that allows for one and a half gallons of water for storage for every foot of collector. Collectors are typically sold in sizes close to standard heating tanks. they are usually available in 100 gallon, 200 gallon and 300 gallon sizes. some manufacturers make other sizes as well.

You should not purchase collectors that use plastic for the front covering. uv ultra violet light from the sun, seriously clouds and yellows many plastics after a few years. Only purchase collectors that use tempered low e glass. low e glass is a type of glass that has a low iron content, there by increasing the flow of light through the glass and minimizing reflection. They cost more than regular glass but it is worth it in terms of durability and increased efficiencies.

author - keith anderson

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