According to a report by NI Energy, solar thermal panels, alternatively known as solar water heating collectors, are one of the UK’s most commonly used forms of solar energy. Further, the report stated that households across the country could save up to £40 every year on their hot water and energy bills by installing the panels.
So, what are solar thermal panels, and what makes them so popular? In this guide, you will find everything about solar panels, their installation, working principles, benefits, and more. Stay glued to our post till the end!
- 1 Key Takeaways
- 2 What are Solar Thermal Panels?
- 3 What are the Different Types of Solar Thermal Systems?
- 4 How Do Solar Thermal Panel Systems Work?
- 5 What are the Components Found in a Solar Water Heating System?
- 6 What is a Renewable Heat Incentive (RHI)?
- 7 How to Install a Solar Thermal System?
- 8 What are the Benefits of a Solar Thermal System?
- 9 What are the Disadvantages of a Solar Thermal System?
- 10 How to Choose the Right Type of Heating System?
- 11 Things to Keep in Mind Before Installing a Thermal System
- 12 Discover the Power of Solar with Solar Panels Network
- 13 Wrapping Up
- Solar thermal panels, also known as solar water heating collectors, are commonly used in the UK and can save households up to £40 annually on hot water and energy bills.
- There are two main types of solar thermal systems for heating water: flat plate collectors and evacuated tube collectors, each with advantages and limitations.
- Solar thermal systems offer benefits like reduced energy bills, year-round power supply, and environmental friendliness, but they are weather-dependent and have installation costs and limitations.
What are Solar Thermal Panels?
A solar thermal panel is not the same as a solar panel. While solar panels utilise the heat from the sun to generate electricity, the process is different in solar thermal technology. Here, sunlight is used to generate heat instead of electricity.
Usually, the heat energy produced by solar thermal panels is used for water heating purposes. In short, this is how solar thermal technologies operate: the solar panels installed on households’ rooftops function as sunlight collectors. The heat energy thus generated is then used to heat the water. Finally, the heated water is transported for daily use via connected tubes.
Solar thermal collectors are generally used for water heating but have other applications; for instance, these collectors function as solar parabolic troughs, towers, and air heaters.
However, in the UK, solar thermal collectors are predominantly used in residential buildings and large households with significant domestic hot water needs.
What are the Different Types of Solar Thermal Systems?
There are two solar thermal system types dedicated to heating water, and they are as follows:
Flat Plate Collectors
A flat plate collector is usually comprised of four main parts-
- An enclosure
- An absorber plate of dark shades
- A transparent cover
- Insulation on the front and back surfaces of the solar collector
The absorber plate’s function is to establish fluid circulation passageways. The absorbers can be made of polymers, copper, aluminium or steel. On the other hand, the purpose of the transparent cover is to facilitate optimum penetration of solar energy. Most flat plate collectors use a honeycomb structure to reduce the loss of heat energy.
In flat plate collectors, water is the ‘working fluid’. This type of thermal system works well in temperatures lower than 100 degrees Celsius. The average lifespan of a flat plate collector is pegged at 25 years.
Evacuated Tube Collectors
While evacuated tube collectors, also known as ETCs, are not very common in the UK, they are widely used in other parts of the globe.
An ETC is comprised of the following parts:
Glass evacuated tubes
- A heat pipe
- A condenser
- A collection tube
- Heat transfer fluid
- Insulation and aluminium casing
In ETCs, rows of evacuated glass tubes are arranged in parallel rows. Moreover, each inner glass tube usually comes with a heat pipe attached to it. By removing the air between two pipes, a vacuum is created. This vacuum is very effective in preventing heat loss. Due to their heat energy transfer efficiency, ETCs can function well in temperatures well above 200 degrees Celsius.
Depending on the life span of the vacuum, an evacuated tube collector’s lifespan can last anywhere between 5 to 15 years.
The commonly used solar collectors are through-pass air collectors and unglazed transpired solar collectors for air heating.
How Do Solar Thermal Panel Systems Work?
The working principle remains the same regardless of whether it’s a flat plate collector or an ETC. See for yourself:
- Depending on the purpose, the solar panels will be connected to a heater, collector or boiler
- The solar collector will utilise the sunlight to heat transfer fluid. Coated with an anti-freeze substance, the collector will prevent the liquid from getting cold.
- Once the water is heated, it gets transferred from the collector to a heat exchanger.
- The heat exchanger then heats the water once again
- The heated water gets delivered to households
- If there is any unused water, it will be circulated back to the collectors for reheating.
- The process is then repeated cyclically
What are the Components Found in a Solar Water Heating System?
A solar water heating system’s structure differs slightly from the flat plate or tube collector. Here are the components that play a significant role in the overall functioning of a solar water heating system:
- Solar Thermal Panels: Usually, these panels are fixed on the roof or the ground
- Heat Transfer Fluid: Like the two types of collectors, even a solar water heating system uses a heat transfer fluid
- Heat Exchanger Coil: The dual coil plays a significant role, as it allows the heating system to provide extra hot water when required
- Pump: The pump’s function is to circulate the transfer fluid from the panels to the cylinder
- Piping: The flow piping and the return piping are involved in maintaining insulation between the panels.
- Control Panel: Displays all the information related to the water heating system’s performance
- Heat Flow Generation Meter: This measures the overall output of the system. The reading can then be used to claim renewable heat incentive payments.
What is a Renewable Heat Incentive (RHI)?
The RHI scheme by the UK government was introduced to promote a switch to renewable heat energy sources. This scheme targets households and businesses and incentivises them to switch to renewable energy.
The RHI is paid every quarter, with payments spread across seven years. The incentive rate is 20.66p/kWh for energy generated by solar thermal panels and water heating systems.
How to Install a Solar Thermal System?
The installation of solar thermal systems involves elaborate steps and procedures:
- In the UK, it is recommended that all households, before the installation, need to get their property inspected by personnel with MCS accreditation.
- Ideally, your property will be inspected for the roof’s orientation, inclination and other related factors.
- Depending on their findings, the surveyors will give you an estimate of the output of energy you can expect after installing solar thermal systems.
- Likewise, the surveyor will also try to determine the domestic water needs of your household.
Solar Thermal Collector
- The collector frames will be installed on the flat roof using stainless steel brackets.
- The brackets will be fixed directly to the roof to create a tight structure.
- Your roof tiles might have to be removed but will be replaced once the solar thermal installation is complete.
- If you have opted for an ETS, a transfer unit will be juxtaposed atop the frames.
Hot Water Cylinder
- A dual coil water cylinder will be installed first, followed by a pump and system control panel.
- The installers will then install a hot water tank, which is required for solar energy storage purposes.
- The tank will be connected to various equipment like cold water mains, auxiliary heating, immersion heater, temperature sensors and an expansion vessel.
Solar Thermal System Plumbing
- The installers will first place a pumping station to fix the pump.
- An expansion tank will be fitted in to monitor pressure changes as a preventive measure.
- Insulated pipes will go in next, creating the flow and returning the piping channel for fluid transfer.
- The installers will ensure enough distance between all the plumbing components.
Controls and Display System
- Finally, the solar thermal system’s display components will be setup
- The installer will begin by fitting a heat generation meter, essential for RHI
- Automatic control equipment will also be installed
Pumping of Transfer Liquid
- The installer will pump the transfer and anti-freeze liquid into the fully assembled solar thermal heating system as a final step.
- The liquid will be subjected to pressure, according to specifications
If you want to be eligible for RHI, an extra step will be involved. Your installer will register your household’s solar thermal system with the MCS. You will receive all the necessary documentation to apply for the RHI.
Sometimes, you might need planning permission before installing solar heating systems.
Planning Permission and When It’s Needed
In most cases, domestic and residential solar water heating systems can be installed without planning permission. However, permission will be required in the following cases:
- If the panels are installed on the walls of a building containing flats
- If the panels protrude from the edges of a flat roof
- If the panels project upwards, i.e. if their height exceeds the limit
- If the house or building is situated at a World Heritage Site
- Solar panels should be installed without compromising the aesthetics of the building
What are the Benefits of a Solar Thermal System?
There are many benefits of installing a solar thermal system, and they include:
- Less space: To install solar heating systems, you require less space, making it a convenient option for many households
- Simple: The technology and processes involved are straightforward. As a result, the system is easy to understand and operate.
- Limitless Energy: Since solar energy is renewable and available in abundance, there’s no limit to the amount of energy that a solar thermal system can generate
- Seamless Integration: Solar thermal systems can be easily paired with existing power sources
- Increased Savings: It is a lot cheaper to heat water using a solar water heating system, leading to considerable savings in the electricity bills
- Year-round Power Supply: With advancements in solar technologies, most solar thermal systems can work efficiently during the winter months as well, powering households and commercial establishments throughout the year
- Environment Friendly: Using a renewable energy source for heating water and power generation means no fuss about using fossil fuels.
- Reduced Carbon Footprint: There are no CO2 emissions with solar heating technologies. Besides, a solar hot water cylinder significantly reduces the carbon footprint. It is estimated that, on average, a UK household can reduce its carbon emissions by over 400 kg each year.
What are the Disadvantages of a Solar Thermal System?
Nonetheless, there are a couple of disadvantages of solar thermal systems that you need to consider:
- Weather-dependent: Poor local weather conditions can hamper the hot water supply in households. During winter, the solar water heating cylinder’s efficiency will be reduced.
- Singular Function: If you opt for thermal systems meant exclusively for water heating, that’s the only function it can perform. This singularity can be a dampener for many.
- Costs: It can take up to 20 years or so to see visible returns on investment. Nevertheless, schemes like the RHI make up for the long payback period.
- Expensive and Long-drawn Installation: The installation process takes time, and the cost is also high
- Limited Availability of Installers: It’s hard to find installers for water heating systems that are solar-powered in the UK
- Limited Storage Capacity: While all solar water heating systems do come with storage facilities, the hot water cannot be stored for long
Solar PV Panels vs Thermal Heating Systems
Many struggle to understand the difference between solar PV panels and thermal heating systems. However, the differences are distinct and cannot be ignored:
- Technology: Solar PV panels’ working principle is driven by the photovoltaic effect, while in a solar water heating cylinder, sunlight is used directly to heat the water
- Complexity: In solar panels, the energy conversion process is rather complicated when compared with the procedures in a solar immersion heater or other thermal energy appliances
- Use: While households use solar PV panels mainly for electricity generation, solar heating systems are used for domestic and industrial hot water supply and storage.
- Design: In terms of design and building solar PV panels have a more straightforward structure and assembly procedure than solar heating systems
- Lifespan: Domestic solar PV systems last longer than their thermal counterparts
Solar Thermal Systems and Energy Bills: The Equation
How much could a household in the UK save by installing a solar system? Here is what to expect.
To begin with, the savings will be directly influenced by daily hot water usage. Further, your savings will also depend, to a considerable extent, on the existing energy system you have installed.
However, it is estimated that a solar thermal system installation can save a household around £50 in a gas system, £55 in an oil system, £65 in a coal system, and £95 in an LPG system per year. Now, that’s a lot of savings in a year.
How to Choose the Right Type of Heating System?
While solar heating systems can be classified depending on the collector type, another classification is also possible. Here, the systems are classified according to how they use the collectors. They are as follows:
- Active: In this type, you’ll need electricity to power the pumps
- Passive: Passive systems usually make use of natural heating methods, like convection, to get the job done
- Direct: The water is heated directly in the collector
- Indirect: A two-step process is involved here. First, the transfer liquid is heated in the collector, and then the heat is automatically transferred to the water.
- While choosing a heating system for your household, keep in mind the two classifications: the collector type and how it’s being used.
Things to Keep in Mind Before Installing a Thermal System
If you plan to install a thermal system, it will help if you ensure the availability of three things: a spot that receives plenty of sunshine, sufficient space, and a boiler. A sunshine spot is essential, as thermal power generation relies heavily on the availability of the sun’s energy.
Similarly, thermal systems require space for installation and maintenance. Moreover, the solar cylinder that’s a prerequisite will also take up some space.
At times, the existing boiler at home might not be compatible with a thermal system. In this case, you will need to install a new one and the system.
Discover the Power of Solar with Solar Panels Network
Are you navigating the world of solar installations? Look no further than Solar Panels Network, the UK’s trusted partner in harnessing the sun’s potential. Our dedication goes beyond just installations; we’re on a mission to transform how homeowners and businesses across the UK perceive and utilise energy. By choosing us, you’re reducing your carbon footprint and making a smart financial move that promises savings for years ahead. Contact us today and embark on your solar journey.
Solar thermal power generation systems bring a host of benefits to the table. With the UK government introducing the RHI scheme, many households and commercial establishments have switched to solar thermal heating systems. There are different solar thermal systems, depending on the collector type and how it is being used.
A unique working mechanism powers them. In keeping with the same, every solar water heating system has components that play a crucial role in daily functioning and operation. Installing a thermal system is often elaborate and involves plumbing and pumping thermal transfer liquid.
The RHI scheme is a benefit that all UK households can take advantage of upon switching to a thermal system. While there are downsides to solar systems, they still hold an edge over solar PV panels. You can save a lot on your energy bills by choosing the right system for your household. To read more about solar thermal systems, please reach out to us.
About the Author
Solar Panels Network stands at the forefront of solar energy solutions, driven by a team of seasoned solar engineers and energy consultants. With over decades of experience in delivering high-quality solar installations and maintenance, we are committed to promoting sustainable energy through customer-centric, tailored solutions. Our articles reflect this commitment, crafted collaboratively by experts to provide accurate, up-to-date insights into solar technology, ensuring our readers are well-informed and empowered in their solar energy decisions.