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Solar Thermal Panels: Everything You Need to Know

There are greener ways to get hot water for your home. Using a renewable energy source can help you with that.

Here's everything you need to know about installing solar thermal panels and their pros and cons.

What Are Solar Thermal Panels and How Do They Work?

Solar thermal panels work by using solar thermal energy to heat water. Installation and the price would usually depend on your home.

 Special panels absorb heat from the sun. These are called solar collectors. They trap the wavelength of sunlight and produce heat.

The heat captured is then transferred to a hot water cylinder. This storage contains antifreeze, which is a water and glycol mix.

This fluid is used when indirectly heating the water in your home.

The water is then stored in a hot water tank or a storage cylinder until you're ready to use it. Its main job is to prevent heat loss so you can enjoy regular hot water.

This process is only applicable to the domestic setting.

The manufacturer may design the panels slightly differently to accommodate central heating needs if you're running a thermal store.

Solar Water Heating Systems vs Solar PV Panels

It's important to remember that solar thermal panels and solar PV panels are different. While they both function as solar thermal systems, their end products are different.

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    People use solar PV panels to generate electricity and central heating for their homes. They're able to provide more energy compared to solar thermal panels.

    On the other hand, thermal panels only use solar thermal energy to heat water.

    The flat plate thermal panels closely resemble the PV ones, which could confuse some people.

    However, their functions are distinct. Knowing the difference between the two is important so that you invest in the right panel.

    How Long Do Solar Thermal Panels Last?

    Solar thermal panels typically last for more than 25 years. They require little maintenance, so you wouldn’t have to worry about them giving up on you.

    This system is seen as the most efficient and long-lasting in the solar industry.

    Most of these panels also come with a 5-10 year warranty to ensure quality.

    What Are the Different Types of Solar Thermal Panels?

    Solar thermal panels come in different types, each with pros and cons. However, they all have the same goal: to provide domestic hot water.

    Here are the different types of panels you can get for your solar water heating system.

    1: Flat Plate Collectors

    Flat plate collectors are the most common solar thermal panels on the market. They resemble PV panels, making them more familiar to the public.

    Flat panels contain a series of grid or serpentine-like pipes. The flat plate is made of metal. It is fixed and coated with a highly absorbent selective coating.

    Its flat plate covering prevents the heat from escaping before it can work.

    They also include an absorber panel which is attached to multiple copper pipes.

    Much like any other thermal panel, a flat plate would collect the wavelength of sunlight. Then, it would convert that energy into heat.

    These are usually installed on the roof in a landscape or portrait configuration.

    2: Evacuated Tube Collectors

    Evacuated tube collectors feature 10 to 30 glass tubes with copper tubes inside them. Each glass tube is connected to a header to shape the solar panel.

    The evacuated tubes also have a vacuum that serves as the panel's insulation.

    It makes them more efficient than flat plate panels for making and retaining heat. Their ability to retain more heat is especially useful during the colder months.

    Its direct flow design allows it to be discreetly installed onto a flat roof. The liquid inside the evacuated tubes would still circulate through the pipes.

    You can also use your evacuated tube collectors in sensitive areas, like conservation areas.

    3: Hybrid Solar Thermal System

    Hybrid solar panels are also known as PTVs. They combine solar PV and solar thermal technology into one system.

    These solar panels can convert the sun's energy into electricity and make hot water.

    While ideal, these solar panels are more expensive than the other two. As of now, it still hasn't entered the mainstream market and can be difficult to find for a home setting.

    How Do Various Types of Solar Water Heating Systems Differ?

    Besides the different types of panels, each solar water heating system functions differently.

    These are the different ways your solar thermal panels can heat water:

    • Active: Electric power is needed to activate the solar panels' pumps.
    • Passive: It relies on natural convection rather than electricity to circulate hot water.
    • Direct: Potable water is directly heated in the collector.
    • Indirect: After being heated up in the collector, the heat transfer fluid passes the heat to potable water.

    Which Is the Best Type of Solar Thermal Panel?

    Flat plate collectors tend to look good on your home. Their familiar appearance also makes them easier to like.

    Yet, evacuated tube collectors perform better because they have higher year-round efficiency. They also perform better than flat plate collectors during winter.

    Its all-around insulation helps them to produce heat, even in the cold.

    How to Know if Solar Panels Are Suitable for the House

    Before investing in solar water heating, it's best to see if your house is prepared for it. It can be disappointing to spend a lot of money and not get the best results from your investment.

    Here are some things to check on before doing your switch.

    The Sun's Rays

    Your solar panels must have direct sunlight for most of the day. You would normally see a solar panel on a roof instead rather than placed elsewhere.

    A south-facing roof is ideal for maximum efficiency. It's also best if you don't install it on a flat roof.

    Having the panels installed at a 30 to 60-degree angle helps them to better capture the sun's rays.

    It's also best to position them away from any shade. Trees, buildings, and even chimneys can prevent a solar panel from efficiently collecting energy.


    While your panels may belong on the roof, you will also need space for a solar cylinder.

    If you don't own one, you would need to replace your existing cylinder. You can also get a cylinder that has a solar heating coil.

    These cylinders are very big and heavy and enough space should be allocated for one on your roof. The cylinder should also be well-supported to prevent any dangerous accidents.

    What Are the Pros and Cons of Solar Thermal Panels?

    This next section will discuss the benefits and drawbacks of installing solar thermal panels in your home.

    Pros of Solar Thermal Panels

    There are many reasons why people choose to invest in solar thermal panels. Here is how they can benefit your home.

    1: Environment Friendly

    People switch to solar thermal systems because they want to use renewable resources to make hot water for the home. They also want to lower their energy bills.

    By switching to renewable energy sources, you'll reduce your carbon footprint.

    Most of the country's energy still comes from non-renewable or nuclear resources. This switch would help in reducing your use of these.

    The government also has the Renewable Heat Incentive (RHI). This compensation covers those who switch to using renewable energy technology at home.

    The government will pay you back for seven years based on how much hot water and energy your solar thermal panels make.

    2: Takes Up Less Space

    Solar water heating systems tend to be much smaller than solar PV panels. They won't take up a lot of space on your roof, and they could still fit your home’s aesthetic.

    They are also usually installed on the roof for optimal heat collection. This means they take up less space in your home.

    However, some people may prefer to have them installed in their yards. Given their size, the panels still won't take up much space.

    3: Minimal Running Costs

    Having a solar water heating system is a great investment. Once installed, you wouldn't need to spend more to keep it running.

    On most days, it only collects energy and requires very little maintenance. It even helps lessen your energy bills.

    You may need to have it maintained by a professional service. However, you only need to have this done every 3-5 years.

    Cons of Solar Thermal Panels

    Despite all its benefits, solar thermal panels also come with their drawbacks. Here are the negatives to consider when investing in them.

    1: Limited Use

    Since it can only generate hot water, your solar thermal panels are very limited. It also only provides about a third of your hot water needs.

    You would still need an immersion heater or a boiler to make your water hotter. These additional appliances also compensate during the months when there's less sunlight.

    Solar thermal panels are incompatible with most boilers and houses without a hot water tank. You need to make your household energy efficient to make the most of these panels.

    2: Weather Dependant

    A solar thermal system relies heavily on the sun to heat water. There will be days or months when it won't produce as much heat. This is more common during rainy days or winter.

    At these times, you would need a back-up system to fulfil the hot water demand in your home. For some households, this may be an additional cost for them.

    3: Initial Investment

    Investing in solar thermal technology is expensive, especially when your existing water heating system isn't compatible with your panels.

    There is support from the RHI for reducing your carbon footprint. However, it could still seem like a long time before you get the full incentive.

    It's an investment in the long run. However, you'll be spending a lot at first.

    You might have more questions about solar thermal panels and how they work.

    We've gathered the commonly asked questions to help you.


    Hot water is necessary, especially when the weather starts to get cold. However, it could get expensive when added to the rest of your energy consumption.

    Solar water heating is a great alternative for heating the water in your home. Consult a professional to explore if you can switch to this greener way of getting hot water.

    Did you know that Solar Panel Installation can match you with 3 local installers who will provide you with a free quote? Fill out our form today to get in touch with installers.

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    Mark McShane
    Content Writer
    Mark McShane is a seasoned professional in the solar industry and the owner of Skills Training Group, a leading provider of solar training and education. With years of experience in the field, Mark has developed a deep understanding of the latest trends, technologies and best practices in the industry. His expertise and passion for solar energy have helped countless professionals develop the skills and knowledge needed to succeed in the fast-growing field of solar energy. Whether you’re an aspiring solar professional or an experienced industry veteran, Mark is an excellent resource for anyone looking to enhance their skills and knowledge of the solar industry.
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