With solar heating, a solar collector is used to heat either air or fluid (typically water or antifreeze solution), which is then used to heat the home, or in the case of fluid-based solar heating, can be stored first before being used to power a radiant heating system
Economics and Other Benefits of Active Solar Heating Systems
Active solar heating systems are most cost-effective when they can be used year-round in cold but sunny climates. Their cost-effectiveness is maximized when they replace costly heating fuels like propane or oil.
The installed cost of an active solar heating system will vary between $30 to $80 per square foot of collector area. Larger systems reduce the costs per unit of collector area. Commercially available collectors provide warranties of 10 years or more, and should easily last decades longer. The economics of an active space heating system improve if it also heats domestic water, used for laundry, washing and bathing giving it year-round value. An active solar energy system can significantly reduce home heating costs in the winter, as well as reduce air pollution and greenhouse gases.
Selecting and Sizing a Solar Heating System
Select a solar energy system based on your home's site, design, and heating needs. Local bylaws and covenants may restrict some options, though many homeowners have been successful in challenging unreasonably restrictive covenants.
The local climate and the type, size, and efficiency of the collector determine how much heat the solar heating system can provide. Solar heaters are most cost-effective when designed to provide 40%-80% of the home's heating needs. Under 40% provides too little energy substitution and over 80% may still require backup heating from traditional sources (building codes & mortgage lenders may require this) which can include a wood stove or a conventional central heating system.
Controls for Solar Heating Systems
Controls for solar heating systems use sensors, switches, and/or motors to operate the system, and incorporate certain controls to prevent freezing or extremely high temperatures in the collectors. The operation, performance, and cost of these controls vary. The key to the control system is a differential thermostat, which measures the difference in temperature between the collectors and storage unit.
When the collectors are 5°-10°C (10°-20°F) warmer than the storage unit, the thermostat turns on a pump or fan to circulate water or air through the collector to heat the storage medium or the house. The control systems monitor the temperature in different parts of the house and use microprocessors to control & optimize heat transfer and delivery to storage and around the house.
It is possible to use a solar panel to power low voltage, direct current (DC) blowers (for air collectors) or pumps (for liquid collectors) to optimize efficient solar gain.
Building Codes Covenants and Regulations for Solar Heating Systems
You should investigate local building codes, zoning ordinances, and subdivision covenants, as well as any special regulations pertaining to the site. You will probably need a building permit to install a solar energy system onto an existing building. Typical problems homeowners have encountered include:
zoning issues include:
Special area regulations include subdivision, or homeowner's association covenants, historic district regulations, and flood-plain provisions. Check with your local jurisdiction's zoning and building enforcement divisions and any appropriate homeowner's, subdivision, neighborhood, and/or community association(s).
Installing and Maintaining Your Solar Heating System
An active solar energy system's performance depends on effective siting, system design & installation, as well as component quality & durability. Find an experienced contractor who can properly design and install the system.
Once installed, preventative maintenance optimizes performance and avoid breakdowns. Expect about 8-16 hours of maintenance annually.
Check your homeowner's policy that your solar water heater is covered. Sometimes, damage from freezing is not covered. Even if your provider will cover your system, it is best to inform them in writing that you own a new system.