“Going solar” no longer means that you have to invest tens of thousands of dollars to cover your roof with solar panels (though you can still do that if you’re really serious about renewable energy). There are now a variety of stand-alone solar-powered devices that serve essential practical purposes, as well as DIY- friendly solar panel kits let just about anyone create a small solar system for custom uses. However, if you want to get a little more high-tech, you can also install a full-fledged solar water heating system. This utilizes solar heating panels that are mounted on your roof to collect the sun’s heat, which is transmitted to the water through a series of tubes looping through the panels. As the water is slowly circulated from the pool up through the solar heating panels and back to the pool, the water temperature in the pool is gradually increased.
Active Water Heater Systems
There are two types of active solar water heating systems:
Direct circulation systems have a pump that circulates household water through solar collectors and into the home. These systems work well in climates where it never freezes.Indirect circulation systems make use of a non-freezing liquid that circulates through the solar collectors to a heat exchanger, where the energy is transferred to the water that then flows into the home. These systems are commonly used in climates where there are freezing temperatures.
Passive Water Heater Systems
Passive solar water heating systems are considerably cheaper than active systems, but they’re usually less efficient. There are two basic types of passive systems:
Integral collector-storage passive systems are used more often in regions that rarely see freezing temperatures. These systems work well in homes where hot water needs are substantial. In these systems, the solar collector is integrated right into the water storage tank. The sun heats the water storage tank much the way a room gets warmer when the sun shines directly on its windows.Thermosiphon systems use a design in which the solar collector is positioned lower than the storage tank. As the collector heats the water, it naturally rises into the storage tank. Installation must be careful since the heavy tanks are typically installed on the roof.
Obviously, there can be a substantial investment in installing a solar water heater. Yet doing the math may prove that it is a cost-effective idea when you calculate the energy costs of operating a standard water heater over 20 years or more.
Hot Water Solar Systems
Whole-house hot water systems are the big-scale version of the same kind of solar system that can replace the water heater providing hot water to faucets. Like that system, whole-house heating systems use solar collector panels to heat water that circulates through tubing lacing through the collector panels. But rather than being stored in a relatively small tank for use in plumbing fixtures, this hot water is also circulated through piping that provides warmth to radiators or radiant flooring tubing through the entire home. These systems often serve both purposes: heating water for use at faucets, as well as providing whole-house heating. These are big-scale systems that use quite large solar collector panels on the roof and sophisticated tanks and circulation technology. Solar hot water heating systems are more commonly used in businesses, but they are also an option for residential use.
Hot Air Solar Systems
There are also full-house heating systems that use hot air rather than water or another liquid as the medium for moving warmth around the house. These systems work by gathering the air that has been heated by the sun beating down on a roof or an exposed wall, and circulating it through the home. For example, clay roof tiles may have air channels built into them that allow the warmed air to circulate. Houses that use hot air solar heating often have roof or siding surfaces designed to absorb heat. Many systems have some form of a powered circulating fan to distribute warm air. These systems are often designed to heat single rooms only. You can see this type of system as a much more sophisticated version of the old-fashioned sunroom, which was kept warm by sunlight beating down through large windows and heating up a stone or ceramic tile floor. But for maximum energy-saving impact, you can also run those circulating pumps on solar power through the use of photo-electric panels, which will generate the power to run DC motors on the circulating pumps. While there is, of course, some investment in getting such a system set up, you have now reduced the operating costs of your hot water system to almost nothing. Like any photo-electric system, the sun’s energy can be stored in batteries so that you can still run the circulating pumps at night or on cloudy days. On a much larger scale, as we’ll soon see, a large bank of solar panels can charge a whole bank of storage batteries that can power nearly any 120-volt AC device—right up to serving your entire house. In most locations, the utility companies now will meter your home in a manner that keeps track of the energy you are generating yourself, giving you credit for that usage and even paying you back when the power grid is making use of the energy you generate. If you are entirely “off-the-grid,” you can install a large bank of batteries to store energy for use at night or on cloudy days or rig your system with a backup generator that kicks in when there is no sunlight to power your home. It is no small undertaking to install a whole-house photo-electric panel system, but looking at the roofs on a drive through most neighborhoods in the U.S. will show that it is no longer a rarity, either. Lining your roof with photo-electric solar panels is not cheap. The average installation cost for a 5 kW system is $25,000 to $35,000. However, subsidies and rebates can cut this cost by 50 percent. And statistics show that the average payback period necessary to recoup your investment through energy cost savings is only 6 to 8 years. After that point, your household electricity is utterly free. The essence of a solar cooker is to create a container lined with foil or another shiny substance to focus the sun’s rays into a cooking chamber. Dozens of plans for solar cookers are available online. Other systems are available that make use of a larger central solar panel that can power multiple landscape lights. There are also kits for seasonal lighting displays for holidays that make use of solar panels.
