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Oct 26, 2024

What Is Solar Heating? (2024 Guide)

Aniket Bhor is a contributing writer for USA TODAY Homefront specializing in solar power. He has a master’s in renewable energies, and he has spent the past decade working as a solar engineer,

Aniket Bhor is a contributing writer for USA TODAY Homefront specializing in solar power. He has a master’s in renewable energies, and he has spent the past decade working as a solar engineer, entrepreneurship trainer and writer for solar power businesses in different parts of the world. Based in Vancouver, Aniket spends his free time hiking, biking, and obsessing over hot sauces and new recipes.

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Solar heating uses thermal energy from the sun to heat fluids or spaces.

Active heating uses circulating pumps, while passive heating uses the thermosiphon effect.

Solar heating offers low-cost heating while also preventing harmful emissions.

As the name suggests, solar heating uses the sun’s thermal energy to heat air and fluids such as water. It does this by using solar heaters, which comprise parts including collectors and tanks. Some of the best solar companies offer both solar heating and power-generating setups.

Humans have used solar energy for thousands of years, but modern solar heaters offer highly efficient and durable heating solutions. “Solar heating offers long-term cost savings on energy bills, requires low maintenance and enhances energy independence,” said Jessica Chrisman, a marketing manager at SunEarth, a solar heating equipment manufacturer in Fontana, California.

On a higher level, how solar heaters work is similar to how solar panels work. However, the actual system construction involves principles of heat transfer instead of electronics. Solar heaters come in different types, and their design varies based on factors such as application type and flow requirements. This article looks at the types of solar heating systems, their benefits and how to save on solar heaters.

The two main types of solar heating are passive and active, which signifies how the fluid in the system circulates.

Passive solar heaters do not use special components to circulate water, air or another heat transfer fluid. Instead, these heaters rely on gravity and the thermosiphon effect. Simply, such a system uses natural convection to move fluid.

Warmer fluids rise due to decreased density, while colder ones sink. Passive solar heating uses this principle to heat fluid. A passive heater has an inlet for cold fluid at the bottom and an outlet at the top, where warm fluid rises. As warm fluid exits the collector, cold fluid from the tank replaces it, circulating in an open-loop or direct circulation system. The heated water is stored and directly used for applications.

“The advantages of passive solar water heaters are that they are much easier to install and have no moving parts, making them less expensive and more reliable. They are appropriate to use in the bottom half of the United States that experiences relatively mild freezing,” said James Richards, founder and CEO of Sunbank Solar, a solar heater manufacturer in Davis, California.

An active solar heating system uses a pump to circulate heating fluid. While not as cost-effective as a passive system, an active system’s forced circulation of fluids prevents them from freezing, providing optimum performance throughout all seasons. A passive system would hardly function in areas where winters see freezing temperatures.

“From an efficiency perspective, active systems, which use pumps and controls to circulate fluid, are generally more efficient as they can operate under a wider range of conditions and provide consistent performance,” Chrisman said.

Alternatively, by regulating the pump speed, active systems can heat small volumes of liquid to high temperatures instead of focusing on efficiency.

Active solar heating systems are mainly used for space heating and heating water for domestic use.

Solar radiation has been used for space heating for quite some time. About 2,000 years ago, the Romans used large, south-facing glass windows to heat their bathhouses. Today, we use solar air space heaters to heat spaces within our homes.

A solar air heating system can use liquids or air as the primary heat transfer fluid, but liquid-based systems are more common because of their higher efficiency. In an active air heating system, water or an antifreeze chemical solution such as glycol circulates through the collector using a pump and controller. This fluid is then stored in an insulated tank.

It is possible for a solar space heating system to not have a storage tank, but a storage tank offers flexibility of use and allows for temperature control.

Once the warm fluid is stored in the tank, its heat can be conveyed to the desired space through the following:

Solar liquid heating systems, particularly solar water heaters, are the most widely used application of solar thermal energy. Solar liquid heaters are similar in construction to solar space heaters. However, their final application is different: Space heaters heat air, while these systems heat liquid for use (such as hot water).

Solar liquid heaters — as well as most space heaters — can use different types of solar collectors. Here are the two most common collector types:

Glazed flat-plate collectors: These are rectangular boxes with a clear glass or plastic top and a number of dark, flat absorber plates that heat up through sunlight, subsequently heating the fluid. The absorber plates are made from a highly conductive material such as copper. These collectors are easier to manufacture and, therefore, relatively cheaper.

Evacuated tube collectors: Instead of housing multiple plates and tubes in a single large box, an evacuated tube collector uses multiple tubes with an absorber plate inside each tube. The tube is vacuum-insulated, meaning that in colder temperatures, heat loss from the absorber or tube will be less compared to flat-plate collectors. The round tube design allows more sunlight to enter each tube, resulting in improved heating. Their complex construction means they are more expensive than flat-plate collectors.

Compared to space heating or heating water using natural gas, wood or other fossil fuels, solar heating offers several benefits.

Solar heaters have little to no operating costs because they use free energy from the sun. “Water heating accounts for 15% to 30% of the average home’s energy bill,” Richards said. “What most people don’t realize is that the cost of operating a water heater (the cost of electricity or gas) over 20 to 30 years is much greater than the initial cost of a solar heater.”

Solar heating offers long-term cost savings on energy bills, requires low maintenance and enhances energy independence.

Solar heaters may not be able to offset your heating expenses entirely, but they can offset most of your heating costs. “An appropriately sized solar water heater will reduce your energy cost to heat water by 80% per year,” Richards added.

Solar heaters can help mitigate the effects of climate change. “Solar heating provides significant environmental benefits by reducing greenhouse gas emissions and reliance on fossil fuels,” Chrisman said.

Fossil sources, including wood, coal or even natural gas, can emit large amounts of carbon dioxide and carbon monoxide over decades, contributing to climate change. Solar heaters can help prevent these emissions. “Solar heaters reduce your personal carbon footprint by roughly 4,400 pounds of CO2 per year,” Richards said.

Unlike a gas or electrical grid connection, solar heaters do not depend on utility providers to provide thermal energy.

From 2001 to 2011, the number of weather-related power outages in the U.S. increased by roughly 78%, according to Climate Central. Such outages, along with gas pipe damage, can lead to a lack of water or space heating for multiple hours and sometimes multiple days. This can be extremely inconvenient, especially in colder areas. Solar heaters operate effortlessly in such events, constantly providing hot water or space heat.

Solar heating systems are more affordable than solar electric systems. And you can save on the upfront cost of solar heaters by keeping a few things in mind. For example, “Properly sizing and installing the system to match your specific needs can also maximize efficiency and reduce costs,” Chrisman said. “Consider taking advantage of government incentives and tax credits,” she added.

“Solar water heaters are eligible for the 30% federal tax credit, which applies to the cost of the installation and equipment,” Richards said. “So, you get 30% of the total cost back after installing a solar water heater. It’s a good time to go solar.”

If you are unsure whether solar panels are worth it for you, solar heating systems are an excellent alternative. “Relative to solar photovoltaic panels, it is a more affordable first step toward making your home energy-efficient,” Richards said.

If you are exploring solar hot water systems or space heaters for your home, the first step is to research reputable solar heater manufacturers and installers. Request multiple quotes from companies providing hassle-free warranties and customer support. To save money, consider providers that offer discounts or bundle multiple services, such as HVAC maintenance, lawn care or pest control.

Editorial note: The name “Homefront” refers to the alliance between USA TODAY and Home Solutions that publishes review, comparison, and informational articles designed to help USA TODAY readers make smarter purchasing and investment decisions about their home. Under the alliance, Homefront provides and publishes research and articles about home service and home improvement topics.

Homefront has an affiliate disclosure policy. The opinions, analyses, reviews or recommendations expressed in this article are those of the Homefront editorial staff alone (see About Homefront). Homefront adheres to strict editorial integrity standards. The information is believed to be accurate as of the publish date, but always check the provider’s website for the most current information.

Aniket Bhor is a contributing writer for USA TODAY Homefront specializing in solar power. He has a master’s in renewable energies, and he has spent the past decade working as a solar engineer, entrepreneurship trainer and writer for solar power businesses in different parts of the world. Based in Vancouver, Aniket spends his free time hiking, biking, and obsessing over hot sauces and new recipes.

Erika Skorstad is a senior editor for USA TODAY Homefront. She covers topics ranging from home warranties to lawn care. Previously, Erika edited content about venture capital, marketing and cloud computing. She has a BS in professional writing with a minor in interactive narrative. Her fiction has been published in Marathon Literary Review, Levitate Literary Magazine and the Burlington Writers Workshop Cold Lake Anthology. Outside of work, Erika enjoys reading psychological thrillers, doing yoga, going on nature walks and spending time with her sassy black cat, Cassie. She lives in Washington.

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