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Solar Thermal Panels: Solar Water Heating
Hot water can be a significant expense for Irish households, with our high energy prices. Solar thermal panels can help you to lower your energy costs and carbon footprint by making free hot water from solar power.
Key Takeaways
- 1Solar Thermal Panels cover 50% – 60% of your hot water need
- 2The SEAI has a €1,200 grant for Solar Thermal Panels
- 3Households can save €100 – €200 on average each year
What are Solar Thermal Panels
Unlike solar PV panels, which convert the light from the sun into electricity, solar thermal panels convert the heat from sunlight into hot water for your home.
There are two different purposes for hot water in your home:
- 1
Water Usage: Hot water for cleaning, bathing, and other consumption.
- 2
Space Heating: The central heating system of your home.
Solar hot water systems are primarily designed for providing water for showers, taps, and other uses. This is instead of the central heating system, which doesn’t draw water from the hot water cylinder.
There are two types of solar thermal panels: Evacuated Tubes and Flat Plate Collectors. Both of these operated off the same principles, but have different designs.
How Do Solar Thermal Panels Work?
Solar thermal panels, regardless of how they are designed, follow the same basic steps in their operation.
1. Sunlight strikes the heat collectors, which make up the main part of the solar thermal panels.
2. That sunlight heats up a fluid contained within pipes inside or beneath the panels. This fluid is then transferred in a loop down to the hot water cylinder.
3. The fluid moves through pipes inside the hot water cylinder, transferring its stored heat to the water within.
4. The now-cooler fluid moves back to the panels for the process to continue.
Solar panels for hot water can produce 50% – 60% of your annual needs. This is seasonal, since it relies on heat from the sun. In summer it can reach up to 90% of total demand, and fall as low as 25% in winter.
Solar thermal system components
The components of a solar thermal panel system will depend on the design. Evacuated Tube and Flat Plate Collector thermal solar panels have many of the same features, but also some differences.
Cost of Thermal Solar Panels in Ireland?
Solar thermal panels generally cost between €800 and €1,200 per square metre. Prices will vary depending on:
What type of solar hot water system is being installed.
How easy or difficult it is to carry out the installation on your roof.
Whether or not you qualify for the SEAI grant for solar water heating.
Solar Thermal Panel Grants in Ireland
There is an SEAI grant of €1,200 available to help homeowners with the cost of installing solar thermal panels. This grant is subject to the following criteria:
- Availability: Available for all home built and occupied prior to 2021.
Grant Rate: This is a flat rate grant of €1,200 for all applicants.
Grant Approval: The grant must be approved before any works take place
Contractor: An SEAI registered installer must be used to qualify.
Product: The panels must be capable of supplying 10kWh/m²Yr.
Return on investment for solar thermal panels
The ROI of your solar hot water system will depend on the following key factors about the system itself and your hot water usage.
- 1System Capacity: What percentage of your hot water usage will be covered by the solar system?
- 2System Cost: How much did it cost to get the solar thermal system installed?
- 3Hot Water Usage: How much hot water is used in your household each year?
- 4Heating Fuel: The heating fuel you ordinarily use for hot water generation, and how much it costs.
Taking an average household, which uses ~15,000kWh of energy a year, about 15% of their total energy consumption is on hot water. This amounts to 2,250kWh of energy used for hot water each year.
If a solar thermal system replaced 50% of this you would be reducing your energy consumption by 1,125kWh per year. This could save €100 or more each year on your hot water bills.
Solar thermal panels have a far lower ROI than solar PV panels. Customers with oil or gas heating will struggle to recoup their full cost in their lifespans.
Solar Thermal vs. Solar PV: Which is Right for You?
Solar Thermal Panels
- Purpose: Heats water for taps/showers.
- Best For: High hot water demand, limited roof space.
- ROI: Lower return (longer payback period).
- Grant: €1,200 flat rate grant
- Verdict: A targeted solution for water heating needs.
Solar PV Panels
- Purpose: Generates electricity for household use and export
- Best For: Reducing overall electricity bills, EVs, heat pumps.
- ROI: Higher return (shorter payback period).
- Grant: €1,800 Max Grant, scales by system size
- Verdict: The recommended, versatile choice for most homes.
Overall, we would recommend solar PV panels as a far better option in the long run. Even small systems can deliver a far greater return on investment than solar hot water systems.
Frequently Asked Questions
Solar hot water systems typically have a lifespan of 20 – 25 years if properly maintained.
No. Planning permission is not needed for rooftop solar thermal panels.
No. Solar PV panels have a greater return on investment than solar water heating systems in their lifespan.
No. Most heating systems are not set up to allow solar thermal panels to work for space heating. This is due to the central heating system not drawing from the hot water cylinder.
No. Solar water heating systems only active when there is enough heat from the sun to make a difference in the hot water cylinder’s temperature. They also turn off when the water has reached a desired temp.
Yes. Solar thermal panels will need some infrequent maintenance. This may just amount to inspections to make sure nothing is leaking from the system.
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