Solar Thermal Heating: Pros, Cons and Costs
Solar thermal heating systems capture the free, renewable energy from the sun and use it to heat water in your home.
These systems give homeowners 70% of their hot water for free. Taking the strain off their boiler or immersion heater.
But is a solar thermal system right for your home? We've taken a closer look at the pros, cons and costs of solar thermal.
Pros of solar thermal heating
Reduced heating bills
On average, a solar thermal heating system is capable of producing between 40 – 70% of the hot water needed by a family of 4 in a year. By heating water with free solar energy rather than your boiler you'll need to use your boiler or immersion heater significantly less and won't need to pay for as much fuel. And, while you're likely to still need your boiler in winter, the solar thermal panels will still generate some heat, raising the temperature of the water so the boiler doesn't need to work as hard.
Earn money with RHI scheme
Solar thermal systems (which meet certain criteria) are eligible for the government's Renewable Heat Incentive (RHI) scheme. The scheme is designed to incentivise UK homeowners to adopt renewable energy over fossil fuels to reduce the country's carbon emissions. For 7 years after installation, the government will pay you for every unit of energy your solar thermal panels generate.
Lower carbon footprint
Reducing how often you need to use your boiler will not only reduce your heating bills, but also cut your home's carbon emissions as you'll be burning less fossil fuels, so you can do your bit to help the environment.
Almost no running costs
Once the system is up and running there are almost no running costs to budget for. You will need a professional to check over the system every few years but other than that it will run on free energy.
Solar thermal systems only require professional servicing every 3-5 years. They tend to covered by manufacturer warranties between 5-10 years. In addition, the solar thermal system will reduce the strain your boiler as it won't be working as hard so this should lengthen its life with less likelihood of repairs.
Cons of solar thermal heating
Not a complete heating system
For most homes, a solar thermal system won't be able to provide the entire hot water supply. You will still need a boiler or immersion heater to boost the supply on cloudy days and meet the higher demand for heating in winter. A solar thermal system will also not power electric showers or cold-fill washing machines / dishwashers.
High upfront cost
A stumbling block for some homeowners can be the upfront cost of installing a solar thermal system of between £3,000 – £5,000 on average.
Specific installation needs
To work at optimum efficiency solar thermal panels need to be installed on a roof facing due south at a 20-50 degree angle from horizontal, although they can work effectively when positioned between south east and south west. In some cases it's possible to install them on the ground or on a wall but any shade will reduce their effectiveness. You will also need to have or install a solar compatible water cylinder which is large enough to hold around 2 days of hot water.
Not suitable for all heating systems
Solar thermal systems are often not compatible with Combi boilers as they are fed water directly from the mains and heat water demand; you will need to check with the manufacturer if your Combi boiler will water which has been pre-heated by solar thermal. If you have a Regular heating system which is gravity fed you will need an extra valve or pump so the system can work effectively in winter when the heating is running at the same time.
Interested in Solar Thermal Heating
Solar thermal installation costs
To install a solar thermal system tends to cost between £3,000 – £5,000 for an average home, i.e. a family of four. This is of course an estimate and in some cases larger systems may be needed if the demand for hot water is higher; in these instances costs could rise to £7,000.
Industry recommendations suggest that you will need around 1m² of panel per person living in the home. The installation cost will also depend on how complex the process and how easily it integrates into your existing heating system.
If your hot water cylinder is not solar compatible you may also need to invest in a new one which could cost between £600 – £1,000 on average.
However, when calculating the likely upfront costs of solar thermal it's important to keep in mind that it's highly likely you'll be saving money on cheaper heating bills. The Energy Saving Trust estimates that solar thermal panels could save you £50 a year if you have a gas boiler, £55 if you have an oil boiler, £65 if you use coal, £80 if you have an electric boiler and £95 if you use LPG (liquid petroleum gas).
In addition, you should also factor in the potential RHI payments from the government.
Earn with the Renewable Heat Incentive
The government's RHI scheme was set up to encourage homeowners to install more renewable technologies and reduce their reliance on fossil fuels like oil, gas, coal and LPG. If your solar thermal system is installed correctly and meets the scheme's criteria you'll receive payments for every unit of energy generated by your solar thermal panels.
The payments are made to you on a quarterly basis over 7 years. Based on figures from the Energy Saving Trust, this table gives compares the average installation costs with potential earnings from the RHI scheme*.
|People in the Home
||Size of System Required
||Average Cost of Installation
||Annual RHI Payments
||RHI Payments Over 7 Years
|2||2m²||£2,500 – £3,000||£200||£1,400|
|3||3m²||£3,500 – £4,000||£270||£1,890|
|4||4m²||£4,500 – £5,000||£345||£2,415|
|5||5m²||£5,500 – £6,000||£445||£3,115|
|6||6m²||£6,500 – £7,000||£485||£3,395|
*These figures are based on the RHI tariff between January 1st and March 31st 2018.
Get free solar quotes
Ready to power your home with solar?
Then visit our sister website Solar Guide today to get free quotes from solar installers near you.
Interested in Solar Thermal Heating?
What is a Solar Thermal Heating System?
Solar thermal means using free energy from the sun to heat your home's water.
Solar Thermal with an Immersion Heater
How to use solar thermal with your immersion heater to save energy.
Solar Thermal with a Boiler
How to reduce your heating bills with solar thermal AND keep your boiler.