Can Solar Heat Your Home?

With energy prices on the rise, more homeowners are looking to solar power as a way to reduce electricity costs. The share of homeowners who say they have installed solar panels has increased from 4% in 2016 to 8% in 2022, according to a Pew Research survey. Solar panels can significantly offset a home’s energy use, but they also come with upfront costs and aren’t right for every home. This article will examine how solar thermal systems work, ideal locations and home types, costs and incentives, energy savings potential, environmental benefits, maintenance requirements, compatibility with other systems, and challenges to be aware of before installing your own solar thermal system.

How Solar Thermal Systems Work

Solar thermal systems use panels or collectors with glass panels and dark-colored backing to absorb heat from sunlight. The glass allows sunlight to pass through and strike the dark surface, which absorbs the solar energy and converts it into heat. The heat is then transferred to a liquid such as water or antifreeze solution that circulates through the solar collector (https://www.eia.gov/energyexplained/solar/solar-thermal-power-plants.php).

As the heated fluid circulates through the collector, it flows through pipes or tubes that carry it away to exchange heat elsewhere. For example, the fluid might flow into a storage tank to be used later for domestic hot water, or flow into a heat exchanger that transfers the heat to water in a conventional hot water tank. In large power plant applications, the hot fluid is used to boil water to produce steam that drives a turbine to generate electricity (https://www.energy.gov/eere/solar/concentrating-solar-thermal-power-basics).

Ideal Locations and Home Types

The effectiveness of a solar thermal system relies heavily on the amount of direct sunlight exposure. According to research from WhatNextNow, the top locations are close to the equator in hot and dry climates, with the highest solar energy potential on Earth near the equator away from humidity and clouds (source). Within the United States, the southwest states like California, Nevada, Arizona, New Mexico and Texas have optimal conditions for solar.

Research from Transect shows the top places in the U.S. for solar energy are California, North Carolina, New Jersey, Colorado, Nevada, Florida, and Arizona. California tops the list with abundant sunshine and high electricity prices making solar power financially beneficial (source).

According to analysis from LinkedIn, solar systems perform best on south-facing roofs with no shading or obstructions. Homes with large south-facing roof space and high energy costs benefit the most from solar thermal systems. The system is compatible with most home types, though larger systems can be installed on bigger rooftops (source).

Costs and Incentives

The system and installation costs for a solar thermal system can vary quite a bit depending on your location, system size, and types of components. According to Modernize, a solar water heating system for a typical home costs $3,000 to $6,000 on average. The main system components like solar collectors and storage tanks range from $1,500 to $4,500. Installation costs are typically $1,500 to $3,000. The total costs per square foot for a solar thermal system are estimated at $70 to $250. Larger systems for whole home heating and hot water can cost $15,000 to $30,000.

There are several incentives available to help offset the upfront costs of a solar thermal system. The federal solar tax credit offers a 26% tax credit for systems installed in 2022-2023. Many states and utilities also offer additional rebates and incentives, which can cover 25-50% of the system costs. For example, California offers rebates up to $1,500 per household through the Solar Water Heating Pilot Program. Check Database of State Incentives for Renewables and Efficiency (DSIRE) for incentives available in your state.

Energy Savings Potential

Solar water heating systems can provide significant energy savings compared to conventional water heaters. According to the U.S. Department of Energy, on average, installing a solar water heater can reduce water heating bills by 50-80% [1]. This translates to average annual savings of $140 or $2,900 over the 20 year lifetime of a system [2].

Compared to heating water with electricity, solar water heaters can lower electricity use by 50-90%. Compared to natural gas water heating, solar can lower natural gas use by 30-80% [1]. The energy savings depend on factors like climate, hot water usage, and system size and design.

Environmental Benefits

Solar thermal systems provide significant environmental benefits compared to conventional heating systems that rely on the burning of fossil fuels. By using the sun’s energy rather than combusting fuel, solar thermal dramatically reduces carbon emissions and air pollution (source). Solar thermal systems produce no greenhouse gases or other pollutants when operating, unlike systems that burn natural gas, oil, or propane (source).

With climate change an urgent threat, transitioning to clean renewable energy sources like solar is critical. Solar thermal can play an important role in mitigating greenhouse gas emissions and global warming. Experts estimate that replacing conventional heating systems with solar thermal could reduce carbon dioxide emissions by up to 2.7 billion tons per year globally (source). By installing a solar thermal system, homeowners can directly contribute to fighting climate change through clean energy use.

In addition to slashing carbon emissions, solar thermal also reduces air pollution that harms public health. Eliminating the smokestacks and furnaces needed for fossil fuel heating improves local air quality. Solar thermal allows for heating homes without emitting dangerous pollutants like nitrogen oxides, volatile organic compounds, particulate matter, and carbon monoxide into the atmosphere. The clean operation of solar thermal results in healthier communities.

Maintenance Requirements

Solar thermal systems require some routine maintenance to keep them operating efficiently. According to the U.S. Department of Energy, it’s recommended to inspect the system annually and repair or replace any worn or broken parts as needed (Source). This maintenance includes checking and replacing glycol fluid levels, inspecting collectors for leaks, checking insulation, and clearing any obstructions or debris.

The key system components that may need repairs or replacement over time are the circulating pump, valves, sensors, and heat exchanger. The system collectors typically have a lifespan of 15-30 years. With proper maintenance, the overall system can last 20 years or longer before needing full replacement. The maintenance costs are relatively minimal, often just the cost of a checkup service call plus any minor parts needing replacement.

Pairing with Other Systems

Solar thermal systems can be effectively paired with other renewable energy technologies to maximize efficiency and cost savings. One popular combination is pairing solar thermal with photovoltaic (PV) panels, which convert sunlight into electricity. While solar thermal heats water, PV panels generate electricity that can power the pumps and controls for the solar thermal system. According to the research, combining these two solar technologies can provide greater overall energy savings compared to using either on its own. The PV panels provide clean electricity to run the solar thermal system, reducing reliance on the grid.

Solar thermal systems can also be integrated with geothermal heat pumps. Geothermal heat pumps use underground pipes to transfer heat between the ground and the building. According to one analysis, the solar thermal system preheats water before it enters the geothermal system. This combination allows the geothermal system to operate more efficiently. The geothermal system can also store excess heat collected by the solar thermal system for use at night or on cloudy days. Together, these technologies provide a robust and reliable renewable heating solution.

Challenges and Drawbacks

While solar thermal systems offer many benefits, there are some challenges and drawbacks to be aware of:

Solar thermal systems rely on ample sunlight to effectively heat water. This makes solar thermal better suited for sunnier climates. Homes in cloudier regions may not receive enough solar radiation for the system to sufficiently heat water year-round (1).

The roof area needed for solar collector panels may be unattractive or impractical for some homes. Larger solar collector arrays can appear bulky and detract from a home’s aesthetics (2).

Peak solar energy collection occurs in the middle of the day. But peak hot water usage is often in the morning and evening when solar output is lower. This mismatch can lead to insufficient heated water when it’s needed most.

Heated water generally cannot be stored more than a day or two. Cloudy weather lasting multiple days can lead to a lack of hot water.

While costs have declined, purchasing and installing a system still requires a significant upfront investment. Payback periods of 5-10 years are common.

Conclusion

Solar thermal systems can be a viable option for heating water and spaces in many homes. The technology has improved greatly in recent years, with systems that are more efficient, affordable, and easier to maintain. Key factors to consider are your location, sunshine availability, home type, and goals for energy savings or environmental benefits. While costs are still high upfront, incentives can help offset 30-50% in many places. Ongoing maintenance is minimal for most systems.

Pairing solar thermal with other renewable systems can maximize efficiency and savings. However, solar thermal may not work well in some climates or home types. Carefully assess your specific situation. If solar thermal does not seem practical for you at this time, stay updated on advances, as the technology is rapidly evolving. Weigh the pros and cons presented here as you explore whether solar thermal could be right for your home.

To learn more about residential solar thermal systems and get quotes from installers near you, check out unbiased resources like the Department of Energy, EnergySage, and the Solar Energy Industries Association.