A solar water heating system (solar thermal panels) uses the sun's natural heat to heat the water in your home. Solar thermal technology is an increasingly popular renewable alternative to traditional water heating systems, but is it the right choice for your home?
We've looked at the pros, cons and cost of installing a solar water heating system to help you decide.
NOTICE: Under the government's Green Home Grants scheme, between September 2020 and March 2021, you can apply for a grant to cover two-thirds of the cost of installing solar thermal panels.Click here for more info.
How does solar water heating work?
A solar water heating system uses solar thermal collectors, also known as solar thermal panels. These panels look a lot like photovoltaic solar panels and work in a similar way, that is, they capture energy from the sun, but instead of converting the heat into electricity, solar thermal collectors use the energy to produce hot water.
The process is very simple:
- Solar thermal collectors are panels that are (usually) installed on your roof. The panels contain small tubes of water that are heated by the sun.
- This heated water can reach up to 90 degrees C. It is transmitted to your home where the heat is transferred to the water in a storage tank or cylinder through a coil.
- Pipes carry this hot water for use in your home.
Most properties will need a boiler or electric immersion heater to provide a backup supply of hot water during peak demand times, but you should significantly reduce how often you need to use them to reduce heating costs and carbon emissions.
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Advantages of thermal solar panels
- By supplying up to 70% of a home's hot water using free energy from the sun, a solar water heating system can reduce your annual energy bills.
- Solar water heating systems can earn you money for every unit of renewable energy you generate under the government's Renewable Heat Incentive (RHI) scheme.
- Using more renewable energy from the sun instead of buying fossil fuels like gas or oil from a supplier will reduce your carbon footprint.
- Aside from the initial installation cost and some maintenance, there are no operating costs to be budgeted for with a solar water heating system as it is free energy.
- Solar thermal systems are very low maintenance. Aside from an annual self-checkup, your system only needs professional maintenance every 3-5 years.
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Cons of thermal solar panels
- A solar thermal system is not a complete solution; You will still need a boiler or immersion heater to provide hot water during the winter and supplement your supply on cloudy days.
- The cost of installing an average solar water heating system tends to fall between £3,000 and £5,000, which is a significant investment.
- Ideally, solar thermal collectors should be installed on a roof facing south at an angle of 20 to 50 degrees to the horizontal. However, they can work effectively when placed between southeast and southwest. They can also be installed on the ground in some circumstances, but any shade will reduce their effectiveness.
- Solar water heaters do not power electric showers or cold-fill washers/dishwashers.
- Solar water heating systems are not always compatible with Combi boilers, as they heat water directly from the mains on demand; You will need to check with the manufacturer whether your Combi boiler accepts preheated water.
- If you have a regular gravity fed heating system, you will need an additional valve or pump so that the system can work effectively in the winter when the heating is running at the same time.
- You will need to install a solar compatible water cylinder that is large enough to hold about 2 days of hot water.
Solar water heating costs and savings
The cost of installing a solar water heating system in a home for a family of 4 can cost between £3,700 and £4,200, but can rise to around £5,500 depending on the size of system required. Industry recommendations suggest that you will need about 1m2 of panel per person living in the house.
| system size | people at home | Average installation cost |
| 2m2 | 2 | £ 2.500 - £ 3.000 |
| 3m2 | 3 | £ 3.100 – £ 3.600 |
| 4m2 | 4 | £ 3.700 – £ 4.200 |
| 5m2 | 5 | £ 4.300 – £ 4.800 |
| 6m2 | 6 | £ 4.900 – £ 5.400 |
These costs will also be affected by the complexity of the installation, ie how easily the solar technology will be integrated into the existing pipeline and whether or not scaffolding is required. The size and brand of your solar water cylinder will also impact the cost of your system.
Remember that you must weigh the cost of installation against the potential savings a solar water heating system can generate. The Energy Saving Trust provides the numbers below as an estimate, but specifies that savings vary from user to user.
| existing heating system | Potential fuel bill savings per year | Potential CO2 savings per year |
| Gas | £ 50 | 270kg |
| Oil | £ 55 | 350kg |
| Coal | £ 65 | 5450kg |
| Electricity | £ 80 | 390kg |
| GLP | £ 95 | 310kg |
Subsidies and incentives for heating water with solar energy
Subsidies for Ecological Homes
under the governmentEcological Housing Concession Scheme, between September 2020 and March 2021 you can apply for a subsidy to cover two thirds of the cost of installing thermal solar panels.
Many UK homeowners want to reduce their heating bills and carbon footprint by installing solar thermal panels, but most don't have the cash on hand to cover the start-up costs. To address this, the government is introducing the Green Homes Grants scheme, which will give UK homeowners up to £5,000 (£10,000 for the lowest income households) to cover the cost of installing a solar thermal heating system.
renewable heat incentive
In addition to potential fuel savings, if your solar water heating system is installed and used correctly, you can earn money through the government's Renewable Heat Incentive (RHI) program.
For every unit of energy generated through your solar water heating system, you receive a financial reward based on the current government rate. Payments are made to you quarterly for 7 years. The following table provides an indication of the type of payment available to solar water system owners based on the rate between January 1, 2018 and March 31, 2018. NOTE: The RHI scheme closes for new applications on March 31, 2018 2021.
| Family Size/Strong> | Family Size/Strong> | Renewable heat incentive payment per year |
| 2 personas | 2m2 | £ 200 |
| 3 personas | 3m2 | £ 270 |
| 4 personas | 4m2 | £ 345 |
| 5 personas | 5m2 | £ 445 |
| 6 personas | 6m2 | £ 485 |
Efficiency of solar water heating
In general, a solar water heating system can produce between 40 and 70% of the hot water needed by an average family of 4 people per year. However, it is difficult to estimate exactly how much hot water you will benefit from, as there are several factors to consider:
Types of thermal solar panels
There are 2 types of solar thermal collectors: flat plate or vacuum tubes.
Flat plate collectors:
Flat plate collectors are more like traditional solar panels. They have a flat absorber plate, with a dark, glassy surface, containing metal tubes. The plate covering the tube, which is usually copper or aluminum, absorbs solar energy and the housing prevents heat from escaping it. A fluid constantly passes through the tube which is heated by solar energy captured from the sun.
Evacuated tube collectors:
Evacuated tube collectors look very different. The panel is a collection of glass tubes in parallel row that have an absorber isolated by a partial vacuum. They are generally more expensive than flat plate collectors, but they offer an alternative aesthetic option and are considered the more efficient option.
There are two different types of evacuated tube solar panels:
direct flow, where the fluid flowing in the absorber also flows through the pipes to the hot water cylinder.
heat pipescontaining liquid that evaporates at low temperature. As the fluid evaporates, it travels up the tube and condenses, transferring the heat it carried and the latent heat of condensation through the pipes to the hot water cylinder. The fluid then travels back through the tube ready to be reheated.
The best solar thermal energy manufacturers
We've listed some of the best solar thermal power manufacturers on the market here, but you can find more information in ourThe best thermal solar panelsarticle.
| Manufacturer | flat plate panel collectors | Evacuated tube collectors |
| Viessmann | Vitosol 100FM or 200FM | Vitosol 200T, 300T, 200TM, 300TM |
| Worcester Forest | Greenskies Solar Lito ou Greenskies Solar Lifestyle | N / D |
| Wingspan | Kingspan flat board panels | Thermomax HP400/DF400 o Varisol |
Installation and maintenance of solar water heaters
In most cases, you do not need to apply for planning permission for a solar water heating system, as it is classified as "permitted development". Some owners in conservation areas or listed buildings may need to contact their local authority before proceeding.
Once the system is installed, it must be covered by a warranty. Warranties typically cover a period of 5 or 10 years and require very little maintenance. In addition to noticing issues with system performance, other possible issues could be a faulty pump or antifreeze leak. However, if everything is working perfectly, you simply need to have your system repaired by a professional every 3-5 years.
Get Free Solar Water Heating Quotes
If you think a solar water heating system might be the right choice for your home, your next step is to get several quotes for the installation. This is the best way to compare prices and get professional advice to ensure you get the right size and type of system.
We can put you in touch with up to 3 of the UK's leading solar installation professionals for free, with no quotes required. Use our easy online form and get solar thermal quotes from trusted dealers in your area.
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FAQs
Is solar heated water worth it? ›
On average, if you install a solar water heater, your water heating bills should drop 50%–80%. Also, because the sun is free, you're protected from future fuel shortages and price hikes. If you're building a new home or refinancing, the economics are even more attractive.
What is the lifespan of a solar water heater? ›The average life expectancy of certified solar water heating systems is 20 years, much longer than standard gas or electric storage water heaters.
Will a solar water heater still work in the winter? ›The evacuated tube solar water heater is the king for weathering cold and wintry conditions. The technology used to warm up water is so efficient that your system could be pumping out hot water in subzero temps. These are resilient to cold temps, winds, and low light conditions.
What are the 2 main disadvantages to solar energy? ›- The high initial costs of installing panels. The most commonly cited solar energy disadvantage, cost, is declining as the industry expands. ...
- Solar energy storage is expensive. ...
- Solar doesn't work for every roof type. ...
- Solar panels are dependent on sunlight.
Does solar hot water work at night? Your solar hot water system works hard during the day to heat water that'll still be hot enough for use at night and all through to the next morning.
How many solar panels does it take to heat a hot water heater? ›As a rule of thumb, you'll need about 1 square metre per person to give enough hot water in summer. For flat panels this usually means one panel for a small household, or two panels for a large one. For tube collectors, perhaps 20 or 30 tubes depending on the household and your use of hot water.
How hot are solar water heaters in winter? ›Collectors come in two main types. The most popular are the so-called flat-plate collectors: insulated glass boxes with copper pipes attached to heat-trapping “absorber sheets.” Under ideal conditions, they can produce 150-degree water, well above the 125-degree water in a typical water heater.
Do solar water heating systems overheat? ›Solar water heating systems can and do overheat, creating both inconvenience and cost for the customer.
Why are solar water heaters not popular? ›Solar water heaters were a popular option until a few years ago. The current trend is for homeowners to just get a solar panel system installed instead. Why? Because the cost of solar panels has fallen so much in recent years.
Which day Cannot use hot water on solar water heater? ›a cloudy day. The explanation for correct answer: On a cloudy day, a solar water heater cannot be used to heat water because there is no Sun, which is required for the device to function.
Do solar hot water systems leak water? ›
Although we hate to use the word “common,” in terms of overall trends, leaks are one of the most common maintenance issue associated with solar hot water systems. They can range from minimal to severe, but should always be stopped as soon as possible.
Does solar hot water work on rainy days? ›A solar water heater will still deliver hot water on cloudy and wet days. Anyone who has ever been sunburnt on an overcast day knows that it takes more than a few clouds to block out the sun. While clouds may filter out some of the brightness, the majority of sunlight still gets through.
Do solar panels affect home insurance? ›You may not see an increase in your homeowners insurance premium after installing solar panels on your roof. However, you'll likely need to raise your coverage limits to account for the replacement cost of your solar panels, which will likely result in some increase to your premium.
What is the biggest problem with solar? ›One of the biggest problems that solar energy technology poses is that energy is only generated while the sun is shining. That means nighttime and overcast days can interrupt the supply.
What is the biggest downside to solar electricity? ›- High Cost of Solar Panels. ...
- Sunlight Dependent. ...
- Installation Can Be Difficult. ...
- Space Constraints. ...
- Solar Energy Storage Is Expensive. ...
- Environmental Impact of Manufacturing. ...
- Difficulty With Relocation. ...
- Scarcity of Materials.
If you are running out of hot water it could be because you are using more hot water than you expected or because the storage tank is too small for your household needs. Assess your household use of hot water. For example, consider having shorter hot showers and using the cold cycle on your washing machine.
How long does it take for solar hot water to pay for itself? ›As the purchase and installation price of a solar hot water system is generally a few thousand dollars more expensive than a traditional water heater, it may take 5-10 years before you start seeing real savings.
How do you get hot water from solar in the winter? ›Yes,The solar water heater in winter works well because of efficient insulation that means when the temperature remains cold during winters,radiator fluid technology gets used in solar water heaters. you get hot water all the time even in extremely cold weather.
Which type of solar water heater is best? ›- Supreme Solar 200 LPD Solar Water Heaters (SS-003)
- Racold Alpha Pro Solar 100LPD Domestic Water Heaters.
- Solarizer Spring AV 200L Solar Water Heaters.
- Mandhata Inventions 200 LPD Solar Heaters.
- Gold Model Solar Water Heaters by Green Energy Systems.
As a rule of thumb, a relatively water efficient household is looking at a system size of 75 litres per person. A typical solar hot water panel is 2 square metres and will supply 150 litres. So a typical 4 person family will need a system sized at 300 litres which has 2 panels.
Is 120 degrees hot enough for water heater? ›
120 degrees Fahrenheit is the safety recommendation against scalding, but 140° is the common default setting. Most experts agree that anything below 120 degrees creates a risk for bacteria to develop inside your water heater from stagnant water, such as legionella that causes Legionnaire's disease.
Do solar panels freeze in winter? ›In colder climates, however, the cold temperatures can help boost solar production as panels operate more efficiently at lower temperatures. Can solar panels freeze? Yes, solar panels can freeze depending on the environmental conditions of the area.
Which is better heat pump or solar hot water? ›What's right for you? While both options will help you heat water at a lower cost to you and the planet, heat pumps are generally the most efficient way to go. The upfront cost of buying and installing a heat pump system is usually less (sometimes significantly less) than a solar hot water system.
Why are the pipes in a solar water heater black? ›black colour absorbs heat.it does not allow heat to escape.
Can tap water damage solar panels? ›Filter (or 'soften') hard water (tap water that contains a lot of minerals) before you use it to clean your solar panels. Untreated hard water can leave a film of calcium on the panels that, over time, can cause them permanent damage.
Which water heater is best solar or electric? ›Although the initial cost of both the systems is relatively the same, the solar hot water system performs much better in terms of operational cost. Another downside of installing conventional geysers is the huge carbon footprint on the environment.
Is solar water heater better than electric? ›With the one-time investment in the solar water heater, you will be saving money and energy for your entire life. Therefore, investing in a solar water heater will be the best decision. The solar water heater is energy efficient than an electric water heater in many ways.
How hot can solar water heater get in winter? ›Collectors come in two main types. The most popular are the so-called flat-plate collectors: insulated glass boxes with copper pipes attached to heat-trapping “absorber sheets.” Under ideal conditions, they can produce 150-degree water, well above the 125-degree water in a typical water heater.
Why is my solar hot water cold? ›If your solar hot water system is too small, it might not be able to generate enough heat to properly heat your water, which could produce lukewarm/cold water. Conversely, if your system is too large, it might overheat your water, producing scalding hot water.
What water heaters do plumbers recommend? ›...a gas tankless water heater or heat pump water heater could work well for you. Both gas tankless water heaters and heat pump water heaters work well for households who don't have a high demand for hot water at any given time. And both can provide considerable savings on water heating bills.
What is the most efficient way to heat water for a home? ›
Heat pump water heaters move heat from one place to another instead of generating heat directly for providing hot water, resulting in high efficiencies and significant cost savings. Solar water heaters use the sun's heat to provide hot water and also save money on energy bills.