Caption: Thermal flat-plate collectors, such as these, are designed to produce most of the domestic hot water needs for an average family. Photo: Courtesy of Velux
Solar energy has long held promise as one of the answers to our dependence on dirty fuels and foreign dictators. Unfortunately, its acceptance is still not widespread.
Several things have held the solar industry back from gaining mainstream momentum.
1. Not Enough Incentives
Incentives come and go, depending upon political decisions by federal and state lawmakers. In recent years, incentives in the forms of tax credits and rebates have helped many homeowners pay for systems. Some of these very successful programs have recently been suspended due to lack of funding. To find out what incentives are available to you, visit the
Database for State Incentives for Renewables & Efficiency (DSIRE).
2. Location
The best place for solar panels is
on the roof: a ready-made support that usually has direct exposure to the sun. Panels may be ground-mounted, but that adds to the cost of an installation.
Unfortunately, the roof presents several problems. First, for maximum effectiveness, the panels should be oriented properly: facing south. You have a bit of wiggle room here, though; a little southeast or southwest is not bad either.
A bigger issue is the condition of the roof. Say it's 25 years old and you figure you have another 10 years of life left in it. Do you tear it off and install a new roof before installing the solar panels? Or do you install the panels on the old roof and pay to temporarily remove them when the day comes to replace the roof?
Another roof-related dilemma: aesthetics. While solar panels can sometimes be mounted in a way that does not adversely affect the look of a house, this is not always possible -- especially when retrofitting the panels onto an existing home.
3. Cost
Solar energy systems require a sizable upfront investment. They typically have an initial cost that's going to be higher than the conventional alternative. A gas-fired domestic
water heater, for instance, is initially going to be a lot less expensive to install than a
solar water heater. That a solar domestic water heater will recoup its extra cost after 5 to 7 years is not always enough to convince a homeowner take the plunge.
4. Newness
Being a relatively new industry also hinders solar power from going mainstream. Solar companies are often young companies, with all of the problems that go along with starting a business. Will the one you choose be around when you need servicing? Trained installers may also be scarce in some parts of the country. If you're going to invest in a solar system,
choosing the right solar installation company is imperative.
TOP 4 SOLAR APPLICATIONS FOR HOMEOWNERS
If you're thinking of incorporating solar energy into your home but are unsure of where to start, consider one (or more) of these domestic solar applications.
1. Solar Electricity, a.k.a. Photovoltaic Energy
When you think of solar electricity, you probably think of glassy blue or green
photovoltaic panels, called modules. Like other types of solar collectors, they too are typically installed on the roof -- but can also be ground-mounted on racks or poles. When sunlight strikes solar cells within the module, electrical current is produced. Put enough cells in a module and enough modules in an array, and you can generate a significant amount of electricity on your roof or in your back yard.
There are many types of solar electric modules, including monocrystalline and polycrystalline, both of which are made from silicone. A less efficient but also less expensive alternative to crystalline modules are thin film modules and laminates. Thin film is the least efficient type of solar electric collector, but it's also lighter in weight and less expensive than the others. In addition, can be incorporated in various building products -- primarily roofing and windows.
Electric solar modules installed on an old Colonial home in Connecticut. Photo: Joe Provey, Home & Garden Editorial Services
Note that solar electric systems may be either of the following:
Grid-tied: When the sun is out, the system produces most or all of the electricity needed. If you aren't using electricity during the day, it is fed into the grid, and you are credited for its production. At night or on cloudy days, the grid supplies whatever electricity you need. Essentially, you pay only for the net amount electricity that you use.
Off the grid: Your solar energy system produces electricity for immediate use. Excess production is stored in batteries for use at night and on cloudy days. Should the batteries run out, a generator may be used to tide you over.
Solar electric systems are expensive and the paybacks are lengthy, but there are programs that can help you with the financing. Leases and power purchase agreements, available in some states, allow homeowners to purchase grid-tied systems. Monthly payments exceed the cost of electricity at first but should be lower in the future as electricity rates rise.
2. Solar Pool Heating
Pool water is circulated in black plastic collectors that look like long mats. The lightweight mats can go on a roof or a rack on the ground. For above-ground pools, they are often laid flat on the ground beside the pool during the swimming season, and rolled up and stored in a shed or garage for the rest of the year. The system can typically use the same pump that circulates water through the pool's filter. Payback on such systems are typically a few years, assuming you're already using gas to heat your pool.
Solar panels can be used to heat in-ground, indoor, and above-ground pools, thereby lengthening the swimming season and eliminating fuel costs. Photo: Courtesy of Fafco
3. Solar Domestic Water Heating
There are
several types of solar water heating systems. The one you choose to install should depend upon your climate and budget. In general, water or a coolant is circulated through large flat-plate or evacuated-tube collectors, where it is heated. The heat is then stored in a
solar storage tank. When needed, the heated water is sometimes used directly. More often, the heat is transferred to potable water by means of a heat exchanger. Paybacks can range from 4 to 7 years, excluding incentives.
Flat-plate collectors for supplying a solar domestic water heating system. Photo: Courtesy of Velux
4. Solar Space Heating
There are many approaches to using the sun to heat a home, but all of them fall into two categories:
Passive solar space heating: This usually entails building a house in such a way that it can take full advantage of the sun. This goal defines the shape, glazed area, and orientation of the building. It also requires significant thermal mass to store the collected heat for use at night.
Active solar space heating: These systems are either liquid- or air-based.
With liquid-based systems, flat-plate thermal collectors absorb heat from the sun and transfer it to either water or coolant running through tubes in the collector. The heated liquid is pumped from the collectors directly to the home's heat distribution system, typically radiant flooring, or to a water-filled thermal storage tank. Heat from the storage tank can be used to heat the home when the sun is no longer shining.
Air-based systems work a similar way, except air is used to transport heat from the solar collectors to the home. The heated air may be ducted directly to the home's heat distribution system or, if it's not needed at the time, to a thermal storage device. Thermal storage for air-based systems often take the form of a pebble bin in the basement from which heat can be drawn off using a hot-air heat-distribution system. Active solar space heating systems may be combined with passive solar home designs.
Does your house rely on solar energy? Tell us about your experiences in the comments below!
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