The Ultimate Guide to Solar Heating
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Although many homeowners use solar panels to power their homes, there are other ways to take advantage of solar energy. One option is solar heating, an alternative to traditional air and water heating systems. Solar heating improves your home’s energy efficiency and has a better return on investment (ROI) than traditional heating systems.
Our guide explores the benefits of solar heating, the types of systems available and how to choose the best solar heating system for your home.
Benefits of Solar Heating Systems
Solar heating helps reduce your carbon footprint and improves your home’s energy efficiency. These systems are easier to install than traditional options and work with most existing home systems. They also offer a range of other benefits:
- Early return on investment: According to the Solar Energy Industries Association (SEIA), homeowners could see an ROI in as little as three to six years.
- Increased home value: Data from Zillow shows that homes with solar panels sell for 4.1% more than comparable homes. Solar heating may give your home a similar boost.
- Low maintenance: Solar heating systems are simpler than other home heating systems. They require minimal maintenance, such as occasionally cleaning the panels, to maintain optimal efficiency.
- Increased energy independence: Solar technology reduces your reliance on conventional energy sources like electricity, natural gas, or propane. By generating your own heat, you become less susceptible to market fluctuations in fossil fuel prices.
- Lower energy bills: Solar heating systems tap into the sun’s free, abundant energy, which translates to lower energy bills and long-term cost savings.
You may also benefit from tax incentives and rebates. Many governments offer financial incentives, such as tax credits.
Solar Heating Technology
Similar to traditional panels, solar heating uses sunlight to generate energy for your home. However, solar heating transforms this energy into heat instead of electricity. Additionally, you can use a solar water heater for hot water. We’ll take a closer look at the types of solar heating technology available below.
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Types of Solar Heating Technology
Solar thermal energy systems use two types of heating technology:
- Passive: Passive solar heating doesn’t use an actual heating system. Instead, this type of heating relies on efficiency upgrades such as insulated blinds and drapes and sun-facing windows to warm your home naturally. The additional insulation seals in heat and reduces heat loss. Passive heating upgrades cost less than active systems and are often found in newer homes.
- Active: Active solar heating uses additional technology, such as heat pumps or storage tanks, to heat water or air and circulate it throughout your home. These systems cost more since they’re added to existing homes and replace traditional heating technology. Active solar heating also requires separate solar energy collection technology to function.
Choosing the Right Solar Collector
Active solar heating uses a collector to capture and absorb solar radiation. Here are the main types of solar collectors:
- Evacuated tube collectors: These collectors use copper tubes filled with liquid, such as water, contained in large vacuum-sealed containers. The evacuated tubes work more efficiently and generate higher temperatures than the more popular flat-plate collectors, but cost more. These collectors are used in space heating, cooling, and hot water heating appliances.
- Flat-plate collectors: These collectors use flat plates mounted in insulated frames covered with a special coating and a transparent cover to reduce heat loss. Flat-plate collectors are moderately priced with midrange efficiency and are the most popular option. Solar water heaters and space heaters use these collectors the most.
- Unglazed collectors: These collectors use a heat-conducting material to transfer the sun’s energy into a liquid. The liquid passes through a heat-conducting surface to its destination. These conductors don’t use protective covering (or glazing) to guard against heat loss, lowering their efficiency. Unglazed collectors are the least expensive of the collector options and are commonly found in solar pool systems.
We recommend calling an HVAC professional or solar company to select the best solar collector for your home heating system.
Heat Transfer and Distribution in Solar Heating
Once solar radiation is absorbed by a collector, it moves to a heat–transfer fluid. This liquid flows directly to a storage system or through a heat exchanger that separates the collected heat from the liquid and uses it to heat your air or water.
Some standard options for heat transfer include the following:
- Air: Some systems use air rather than a heat-transfer fluid. Although air won’t freeze or boil, it has a lower heat capacity and often leaks out of collectors and ducts. You’ll need a larger heat exchanger to increase the efficiency.
- Glycol: This antifreeze is popular for solar water heating. The liquid flows between the heat exchanger and solar collectors to prevent freezing.
- Silicone fluid: This thicker liquid has low freezing and high boiling points but requires more energy to flow through your heating system effectively. Silicon can also leak from the system easily.
- Water: This is one of the most common options for solar water heating systems. However, water freezes in cold temperatures, so you must mix it with antifreeze to remain fluid.
You may not need a heat exchanger when using air or a natural liquid, such as water. With other substances, the heat exchanger helps keep the artificial liquid from contaminating your water supply. After passing through the heat exchanger, the heat is moved from the liquid to heat either the air or stored potable water. The heat transfer fluids begin another cycle, flowing back through the system for continued heat generation.
Solar Water Heating
Solar water heaters store warmed water in insulated tanks for your shower, laundry, kitchen, and other areas where hot water is needed. They’re cost-effective alternatives to traditional water heater systems, which rely on fossil fuels such as natural gas for power.
Solar water heaters are also more energy-efficient, resulting in more savings. According to the U.S. Department of Energy (DOE), homeowners can save 50%–80% on their water heating bill on average by switching to a solar water heater.
Types of Solar Water Heaters
Solar water heaters can use either active or passive technology. Active solar water systems use circulation to pump liquids for warming. They typically cost more than passive systems but are more efficient. Passive solar water systems don’t use active pumps. Instead, they use convection technology and gravity to circulate liquids through your system. These hot water systems are more affordable but less efficient than active system options.
The active and passive categories can be further broken down into four main types of solar water heaters:
- Direct circulation system (active): In a direct circulation system, household water flows through collectors without heat exchangers. Because they use water, these systems work well in warm climates where freezing is not an issue.
- Indirection circulation system (active): Indirect circulation systems use heat exchangers and nonwater liquids, such as antifreeze. These systems are ideal for colder climates and areas prone to freezing temperatures.
- Integral collector-storage system (passive): Integral collector-storage systems use tanks covered in a radiation-absorbing material to allow for direct solar heating. The heated water flows through your plumbing system once warmed. These systems are ideal for areas with limited freezing temperatures or homes with constant hot water needs.
- Thermosyphon system (passive): Thermosyphon systems use natural convection and gravity to circulate the water. Heated water remains at the top of the tank for use. Cooler water flows to the bottom of the storage tank and returns to the collectors for repeated heating.
To learn more about solar-powered water heaters and how to install one, check out this video featuring heating experts Richard Trethewey and Bob Dudley:
Solar Air Heating
Solar air heating works by drawing in fresh air and heating it with coated black aluminum panels. The warmed air then passes through your home’s ductwork using a solar-powered fan. These heating systems reduce carbon emissions and can work along your existing HVAC system. They cost less to install than heat pumps and can significantly reduce your fossil fuel use. As you might expect, they work most efficiently in sunny climates.
Types of Solar Air Heating Systems
Solar air systems come in active and passive options like other solar heating systems. There are several solar air heaters that function as stand-alone or complementary heating sources.
- Active systems: Active solar air heating uses collectors, storage tanks, and pumps to push warmed air through your home. Solar collectors absorb the thermal energy while fans push the heated air through your home. You’ll have access to dedicated controls to regulate fan operation and air temperature.
- Passive systems: Passive air heating relies on convection distribution rather than circulation. These systems use south-facing windows or surfaces to absorb as much sunlight as possible. Sunlight passes through thermal mass material designed to store heat and slowly release it later. Warm air rises and circulates throughout your home using convection currents. Vents are strategically placed throughout your living space to distribute warm air.
Active systems can work independently or with your current HVAC system. Homeowners can use their existing ductwork or install a separate system for the solar air heater. The effectiveness of passive air heating, meanwhile, depends heavily on your home’s insulation, design, and sunlight exposure.
Solar Pool Heating
Solar pool heating uses solar technology to warm outdoor swimming pools. This heating technology makes your pool usable throughout the year and warms the water more cost-effectively than traditional electric or gas pool heaters. Ground- or roof-mounted solar collectors heat the water and circulate it back to your pool. Solar pool heaters can work automatically and contain sensors that actively regulate the water temperature.
Types of Pool Heating Systems
Solar pool heaters differ in the type of collector they use. The best option for your pool depends primarily on climate, budget, and intended use. Here are the typical residential solar pool collector options:
- Glazed solar collectors: Also known as flat-plate solar collectors, these collectors include an iron-tempered glass covering over a metal surface. They work well year-round, offer better efficiency, and reach higher temperatures than unglazed options. However, they cost more.
- Unglazed solar collectors: These collectors typically use heavy-duty rubber or black plastic. They’re less efficient and work best in warmer areas that don’t experience freezing temperatures. Unglazed collectors are less expensive than glazed alternatives.
Additional factors, such as pool size and collector efficiency, may also affect your choice. The DOE advises that your solar collector’s surface area should equal 50%–100% of your pool’s surface area. For example, a 12-by-24-foot pool will need 144–288 feet of solar collectors to provide ample heating. We suggest consulting a professional pool installer to determine the best heating options for your needs.
Choosing the Right Solar Heating System for Your Home
Your home heating needs, local climate, and budget can affect your solar heating options. Consider the following factors before installing a solar heating system.
- Climate: Solar heating system options depend heavily on your local weather. If your area is susceptible to freezing temperatures, choose equipment suited for your environment. Systems will perform better in areas with ample sunlight than those with cloudy conditions.
- Cost: Investing in high-quality solar collectors will improve efficiency but increase your investment. You can opt for cheaper unglazed options, but your system won’t be as efficient. Choose the option that work best for your estimated budget.
- Heating needs: Choose heating systems that provide plenty of heat throughout your home. Larger homes will need more powerful systems. Work with professional installers to determine the right system size and type for your needs.
- Home design: Most existing homes won’t benefit from passive solar heating, as these systems require south-facing windows for optimal performance. If your home lacks the design features needed for a passive system, you should select active options instead.
- Price comparisons: We recommend getting quotes from multiple installers to find the best equipment and pricing for your project.
How To Save on Residential Solar Heating Systems
Federal and state lawmakers offer incentives, rebates, and credits to make solar heating more affordable and encourage homeowners to use it. Here are a few ways to save money on your system:
- Federal tax credit: The federal tax credit allows you to claim 30% of your system costs on your federal taxes to reduce your owed amount. This incentive doesn’t apply to solar pool heating systems.
- State incentives: Some states offer sales or property tax exemptions and tax credits for upgrading to a solar-powered heating system.
- Carbon reduction incentives: Some areas offer incentives to encourage renewable energy use. These include credits and rebates for upgrading to solar-powered systems.
Additional programs could include utility company incentives or local programs for low-income households. We recommend checking the Database of State Incentives for Renewables & Efficiency (DSIRE) for a complete list of solar heating incentives in your state.
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Our Conclusion
Converting to a solar heating system can lower your energy costs, improve your home’s energy efficiency, and provide a cleaner alternative to traditional heating systems. Your climate, chosen solar collector, and specific home needs can all impact your system’s overall efficiency. We recommend consulting a professional solar heating installer before installing a new system. Request multiple quotes to compare system details and costs before making a decision.
FAQ About Solar Heating
Can I use passive solar heating on an existing home?
Yes, you can use passive solar heating on an existing home. However, you may need to make several upgrades to improve performance, such as installing energy-efficient windows, building a sunroom, adding thermal mass material, and improving insulation. Adding an active solar heating system is often a more cost-effective option for existing homes.
What is the difference between using solar heating and solar power?
The difference between solar heating and solar power is that solar panels convert sunlight into electricity while solar heating turns it into thermal energy to warm your home. You can use solar heating equipment to heat your home, but you can’t use it to generate electricity. Solar panels, on the other hand, can provide the electricity needed to power a solar heating system as well as the rest of your home.
What are the best ways to use solar heating?
There are several ways to use solar heating, including water, pool, floorboards, and air. Homeowners can use solar heating systems as stand-alone options or supplement existing installations such as an HVAC system. Several factors, including home heating needs, local climate, and system equipment, will impact the overall heating system efficiency.
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