Everything you need to know about solar water heaters

A solar water heater is a sustainable installation that uses solar heat to heat tap water. The costs of a solar water heater including installation can vary based on several factors such as system size, collector type, and complexity of the installation. Below you will find an overview of the average costs.

1. Cost components

2. Average total costs per system size

• Small system (1 to 2 collectors, 100–150 liter tank): €3,000 – €5,000
• Medium-sized system (2 collectors, 150–200 liter tank): €4,500 – €6,500
• Large system (3 collectors, 200–300 liter tank): €5,500 – €7,500

3. Influential factors

• Roof type and accessibility: Difficult to reach roofs can incur extra costs.
• Collector type: Vacuum tube collectors are more expensive but more efficient than flat plate collectors.
• Heating system adjustments: Integration with existing systems such as underfloor heating can cause extra costs .
• Regional price differences: Labor costs and material costs vary by region.

4. Subsidies and payback period

• The ISDE subsidy can reduce costs by several hundred to thousands of euros.
• The payback period is on average between 10 and 15 years, depending on usage and energy prices.

Conclusion

The investment in a solar water heater including installation varies between approximately €3,000 and €7,500, depending on system size and technical requirements. By taking advantage of subsidies and a careful choice of the system, you can achieve both financial and ecological benefits.

When purchasing a solar water heater, it is useful to know the cost per liter of water storage, as this provides insight into the system's price-performance ratio. These costs include the solar collectors, installation, and VAT.

Average Cost per Liter of Water Storage

Explanation

• Storage tank: Larger tanks provide more hot water and increase initial costs, but often lower the cost per liter due to economies of scale.
• Solar collectors: The number and type of collectors affect the total cost. Evacuated tube collectors are more expensive than flat plate collectors, but often offer better performance.
• Installation: The complexity of the installation, such as roof type and accessibility, can increase costs.
• VAT: Included in the stated prices; VAT for private individuals is usually 21%, unless a specific arrangement applies.

Importance of this cost ratio

• A lower cost per liter value may indicate a more efficient investment system.
• Depending on your hot water needs, you can better assess which system suits your budget and usage.

Conclusion

The cost per liter of water storage in solar thermal systems varies between approximately €16 and €30, depending on the size of the system and installation requirements. Larger systems often offer a more favorable cost per liter, but require a higher total investment.

Purchasing a solar water heater is a smart investment in sustainability and energy savings. However, it is important to carefully consider beforehand which system best suits your situation and which factors are decisive for the success of your investment. Below you will find a comprehensive explanation of the most important considerations.

1. Type of Solar Water Heater

There are two main types of solar water heaters:

• Direct acting systems: In these systems, the water circulates directly through the solar collector. This system is simpler, but less suitable for areas where frost occurs, as the water can freeze.
• Indirect acting systems (with antifreeze): In these systems, an antifreeze circulates through the collector, which heats the water in the storage tank via a heat exchanger. This is more expensive, but offers protection against frost and is more reliable in colder climates.

Consideration: In the Netherlands, an indirect acting system is often recommended due to frost sensitivity.

2. Storage Capacity of the Buffer Tank

• The buffer tank determines how much hot water can be stored.
• Typical volumes range between 100 and 300 liters.
• A tank that is too small means the solar collector will regularly overheat or there will be insufficient hot water.
• A tank that is too large increases costs and can lead to heat loss.

Consideration: Adjust the size to the number of residents and the average hot water consumption.

3. Number and Type of Solar Collectors

• More collectors mean more heat output, but also higher costs.
• Flat-plate collectors are cheaper and suitable for temperate climates.
• Evacuated tube collectors are more efficient, especially in low sunlight and cold conditions, but more expensive.

Consideration: Choose a collector that suits your roof, budget, and climate.

4. Integration with Heating System

• Consider how the solar water heater connects to your existing heating system (e.g., central heating boiler, heat pump, underfloor heating).
• Low-temperature systems, such as underfloor heating, increase the efficiency of a solar water heater.

Consideration: Good integration prevents heat loss and increases efficiency.

5. Roof Suitability and Placement

• The roof must offer sufficient load-bearing capacity and space.
• Solar collectors work best on a roof with a pitch of approximately 30 degrees and facing south.
• Shading from trees, chimneys, or other buildings reduces efficiency.

Consideration: Have a shade scan and roof inspection performed for optimal placement.

6. Costs and Subsidies

• The total investment varies greatly, depending on system size, type of collector, and installation complexity.
• Inquire about available subsidies, such as the ISDE, which can reduce costs.
• Consider the payback period of 10 to 15 years.

Consideration: Perform a cost-benefit analysis to understand the financial benefit.

7. Quality and Warranty

• Choose reputable brands and ask about warranties on the system, collector, and storage tank.
• Also check the warranty for installation and service.

Consideration: Good warranties are a sign of reliability and quality.

8. Maintenance and Lifespan

• Solar water heaters require relatively little maintenance, but periodic inspection and cleaning are recommended.
• The lifespan of a solar water heater is often between 15 and 25 years.

Consideration: Schedule regular maintenance to maximize efficiency and lifespan.

9. Installer and Certification

• Choose a recognized and experienced installer who can advise you and guarantee a professional installation.
• Check certifications and customer reviews.

Consideration: A good installer prevents problems and ensures optimal performance.

10. Future-proofing

• Consider the possibility of expanding the system in the future or combining it with other sustainable installations, such as solar panels or a heat pump.
• Also think about technological developments and changing regulations.

Consideration: A flexible system offers more long-term certainty.

Summary

When purchasing a solar water heater, it is essential to consider the system type, storage capacity, collector type, roof suitability, integration with the heating system, costs and subsidies, warranties, maintenance, and the quality of the installer. By carefully weighing these factors, you will maximize energy savings and the return on your investment.