Insulate First
Before investing in a solar heating system, the building should be made energy efficient. This will reduce the size (and hence cost) of the heating system needed. The roof should be insulated to R38, the walls to R25 and heat leaks from inside the building to the attic should be closed. Drafts should be dealt with by using caulking or repairing walls. Replace single-pane windows with double-pane and/or seal drafts around window frames. For a building that is broader than it is tall, insulating the roof will have maximum impact on lowering heat loss. For a building that is taller than it is broad, good windows and insulated walls will have the largest impact.
Solar heating, passive
The most common method is by passive solar heating. This can be as simple as having many south- facing windows and few windows on other sides of the building. Building an over-hang or installing awnings on the south side will prevent unwanted heating in the summer. Variations on passive heating include:
* installing brick in front of windows which is heated during the day and re-radiates the heat at night,
* installing a wax-filled half-height wall in front of the windows which melts during the day and solidifies at night giving its heat to the inside of the building.
* building a porch or sun-room with a south-facing glass front.
* building a glass wall over a south-facing brick wall and circulating the heated air into the building. (The Visions Credit Union on McKinley Dr. in Endicott has one of these)
* Installing Solar-Wall siding on the south side of the building. This siding has small holes so that air is drawn into it and heated. The hot air is then circulated into the building. Solar-Wall siding is manufactured in Buffalo NY.
Solar heating, Active
The most effective active solar heating method is to heat a fluid in solar collectors. To prevent freezing at night, the fluid that is circulated to the collectors is generally a mixture of water and (non- toxic-type) antifreeze. A large tank of water is then heated, with a heat-exchanger taking the heat from the water-antifreeze mix and transferring the heat to the water in the tank. The water from the tank is then circulated to radiant floor elements. Solar hot water collectors consist of an array of copper tubes inside a box. A glass cover on the box prevents the winter wind from robbing heat from the collector. These collectors are now mass produced and standardized. The Florida Solar Energy Center certifies each type for a certain BTU output per sun hour. There are also many used (some only slightly) collectors for sale.
Solar collectors can heat the fluid to 160 degrees F. This will keep the tank at about 130 to 140 degrees F. Radiant floor heating elements work best since they heat evenly and don’t require water hotter than 120 degrees F. Base-board heaters will also work, but may require boosting the water temp from the solar tank
Heat is difficult to store for very long, but easy to store overnight. Heating a large tank (800 gallon) is one way to store heat. One can also heat a rock pile, sand pile or a concrete slab. Heating a slate floor also works well. Radiant floor heating is the most pleasant and comfortable way to heat. This increases the value of the building in which it is installed. Both radiant floor and base-board hot water heating systems can be zoned so that one can heat the only occupied rooms.
An effective solar heating system will require about 200 sq. ft. of collector area for every 1000 square feet. of building area to be heated. Therefore a 2000 square feet. house requires 400 square feet. of collector area or 10 collectors 4 x 10 ft. in size. Used collectors cost about $250/ea. (while new ones are $600/ea.). The cost of a solar hot water heating system is roughly equal to the cost of any other type of hot water heating system plus the cost of solar collectors and storage tank. (800 gallon storage tanks are about $1000). Storing heat in an existing concrete slab or slate floor eliminates the need for a large storage tank. Keep in mind that the solar hot water system may cost more to install, but will greatly reduce the fuel bills. The cost of fuel over 10 or 20 years can really add up, and the price of fuel is not constant.
A solar hot water heating system can be supplemented with a wood-stove or small propane or oil fired boiler. Every solar heating system should have some back-up system with it, since there are days with little or no sun.
Weather note
In some areas, there can be many days in the winter with no sun. However, cloudy days in the winter are generally warmer than clear days in the winter. So while a solar heating system won’t give much heat on those cloudy December days, less heat is needed on those days anyway. While on cold, clear days in January, the solar heating system will provide all the heat you need.
About Used Collectors and Repair
There are quite a number of used collectors on the market. Some of these are only 5 years old. The used collectors we deal in are mainly copper tubes with aluminum or copper absorber plates and glass fronts. Like other copper plumbing, these collectors rarely need repair. Even used ones are likely to last 15 to 20 years without need of repair. If repair is ever needed, they can be brazed, a simple procedure any plumber knows how to do.