Common Problems With Solar Hot Water

Solar hot water setups are highly regarded for their eco-friendliness and cost-effectiveness in warming water. However, like any technological solution, they come with potential issues and require thorough understanding and regular upkeep to ensure peak operation.

In this comprehensive guide, we delve into the common problems with solar hot water systems, their solutions, and the best practices for preventative maintenance to ensure optimal performance and longevity.

  • Common issues associated with solar hot water systems include sediment build-up, corrosion, material degradation, leaks in pipes and components.
  • Troubleshooting should be done systematically to identify any potential problems that may arise over time.
  • Regular preventative maintenance can help extend the life and efficiency of a system while avoiding costly repairs.

Understanding solar hot water systems

Solar water systems consist of multiple components, including solar collectors or panels, pumps, controllers, insulated storage tanks, and connecting pipes. These components work together to provide a steady supply of hot water for domestic or commercial use. The heart of the system is the water supply tank, which stores the heated water for later use.

Understanding the components of a solar hot water system helps you pinpoint where, why, and how the system may be encountering issues.

How do solar water systems work?

Here’s how solar water systems work.

Thermal solar collectors play a crucial role in capturing the sun’s heat and transferring it to the domestic hot water supply. There are two types of solar collectors available. These are flat plate panels and evacuated tube cylinders. Both provide good efficiency in absorbing the sun’s energy. A heat exchanger, another vital component, conveys hot antifreeze liquid through the water tank via a heat-emitting conduit.

Solar hot water heaters are designed to generate heat during the day and store it for later use, ensuring that hot water remains available throughout the night.

However, in cases where there isn’t enough solar energy to meet hot water requirements, an external boost from a gas or electric power source can be used to augment solar energy. Moreover, safety features like tempered glass solar panels and temperature and pressure relief valves regulate the water temperature and pressure, ensuring a secure and efficient system.

Top solar hot water issues and solutions

Despite the numerous benefits of solar hot water systems, they are not immune to problems. Some of the most common difficulties encountered with solar water heaters include:

  • Sediment accumulation and blockages
  • Corrosion and material deterioration
  • Leaks in pipes and components
  • Inadequate hot water provision
  • Noisy solar hot water heaters

In the following subsections, we delve into each of these issues, their causes, and the remedies to ensure a smoothly functioning solar hot water system.

Sediment build-up and blockages

Sediment build-up is the accumulation of dirt and debris in the pipes of a solar hot water system, which can lead to blockages and decreased efficiency. This build-up occurs due to the presence of minerals and other substances in water, such as calcium carbonate, which settles at the bottom of the tank and pipes over time, potentially causing clogging and blockages.


Regular maintenance, such as periodic flushing of the system, can help prevent sediment accumulation and keep the solar hot water system operating efficiently. Flushing the system removes floating sediment, ensuring that the hot water flows smoothly and blockages are minimised.

Corrosion and material degradation

Corrosion and material degradation in solar hot water systems can be attributed to various factors, including:

  • Chemical reactions
  • Exposure to adverse weather conditions
  • Inadequate maintenance
  • Sediment accumulation.

Moisture can also cause corrosion in metal conductors, resulting in diminished performance. Corrosion can lead to leaks in pipes and components, as well as decreased system efficiency.


To mitigate the risk of corrosion and material degradation, preventive measures can be taken, such as implementing plastic-lined pipe nipples and the annual inspection of the anode rod. Additionally, pumping a mild, acidic cleaning agent through the system’s pipes every 3 to 5 years can help prevent component damage and corrosion.

Another preventive measure is to use a water-softening solution, which can independently lower the home’s water hardness and further reduce the likelihood of corrosion. Avoiding components made of iron or steel can also help prevent rusting and prolong the lifespan of the solar hot water system.

Leaks in pipes and components

Leaks in pipes and components of a solar hot water system can cause significant damage if not detected and addressed promptly. Fluid leaks commonly occur in the piping, heat exchanger, water storage, and collectors on the roof. It is imperative to contact a professional to rectify the issue expeditiously and to disengage the system completely with the safety switch installed.


In most cases, it is feasible to repair components without requiring a full replacement. However, before summoning a technician to address fluid leakage in a solar-powered water heater, it is advisable to isolate the solar panel. This ensures that any further damage is minimised while the professional attends to the issue.

Regular maintenance checks and timely repair of solar hot water systems can prevent excessive expenditure and help identify and rectify minor issues before resorting to professional assistance.

Monitoring the system for any signs of leakage and addressing them promptly can extend the life of the solar hot water system and maintain its efficiency.

Insufficient hot water supply

Several factors may contribute to an insufficient hot water supply in solar hot water systems. These include:

  • Lack of sunlight
  • Blockages in the pressure system
  • Sediment buildup in the pipes
  • Inadequate insulation or collector glazing
  • Defective heating elements or thermostats
  • A system that is too small for the household


To address a lack of sunlight, additional solar collectors can be installed, or a backup heating system can be employed. For blockages in the pressure system, flushing the system with a cleaning solution or replacing the pipes can help alleviate the issue. In cases of sediment buildup in the pipes, flushing the system with a cleaning solution or replacing the pipes can also resolve the problem.

Rectifying inadequate insulation or collector glazing may require the installation of additional insulation or the replacement of the glazing. For malfunctioning heating elements or thermostats, replacement of the element or thermostat can resolve the issue.

If the solar hot water system is too small for the household, installing additional solar collectors or a backup heating system can ensure an adequate hot water supply.

Noisy solar hot water heaters

Noisy solar hot water heaters can be a nuisance and may indicate an underlying issue that needs to be addressed. Common causes of noise in solar hot water heaters include:

  • Sediment build-up
  • Limescale
  • Moisture build-up
  • Component corrosion
  • Contraction and expansion of the hot water tank during normal operation


When faced with a noisy solar hot water heater, a few remedies can be considered. Installing a tempering valve or a new solar hot water controller can help mitigate the noise. However, these solutions require professional installation and repair services to ensure proper functioning and safety.

Timely diagnosis and repair of the issue can prevent more severe damage to the system and ensure smooth operation.

Protecting your solar hot water system from freezing and infestations

Freezing temperatures and infestations are potential threats to the performance and longevity of solar hot water systems.

How to prevent freeze damage

To prevent freezing damage, antifreeze heat transfer fluid can be used in the system’s pipes. Some solar hot water systems are also equipped with automatic draining features, which drain the system when temperatures approach freezing to prevent damage. Regular inspections and maintenance can help identify potential issues caused by freezing temperatures and ensure that the system is protected.

How to prevent infestations

Infestations can be highly damaging to solar hot water systems and should be dealt with promptly. In the event of an ant infestation, it is recommended to contact a pest control service before addressing any issues with the solar hot water system. Keeping the area around the solar hot water system clean and clear of debris can help prevent infestations and ensure the system remains in optimal condition.

By taking preventive measures against freezing and infestations, you can protect your solar hot water system from potential damage and ensure it operates efficiently for years to come.

Troubleshooting and repairing solar hot water problems

When faced with solar hot water problems, it is essential to follow a systematic approach to troubleshooting.

  1. Start by inspecting the circuit breaker, reestablishing the water heater, assessing for water leakage around the tank, analysing the compartments on the water heater, and examining the pilot light. If the issue persists, verify the system’s switchboard and toggle the boost switch to “off”.
  2. Next, investigate the collector or heating system for any signs of damage or malfunction. In many cases, it is prudent to consult a professional when troubleshooting solar hot water problems. A certified solar hot water technician can identify the issue and provide a suitable resolution, ensuring the system is repaired safely and efficiently.

Regular maintenance and monitoring of your solar hot water system can help prevent issues from arising in the first place. By keeping an eye on system performance and addressing any potential problems early, you can ensure a smooth and efficient operation for years to come.

Preventative maintenance for solar hot water systems

Preventative maintenance is crucial for solar hot water systems’ optimal performance and longevity. Some examples of preventative maintenance include:

  • Monitoring the system for any signs of leakage
  • Scheduling annual servicing by a professional
  • Topping up glycol fluid
  • Keeping the area around the solar hot water system clean and clear of debris

By performing these tasks consistently, you can enhance system operations, augment efficiency, and decrease the likelihood of common issues such as leaks, corrosion, and material deterioration.

Investing time and effort into preventative maintenance for your solar hot water system can save you from potential headaches and costly repairs down the line. A well-maintained solar hot water system can provide a steady supply of hot water for years, contributing to a more sustainable and cost-effective lifestyle.


With proper care and maintenance, a solar water heater can provide you with decades of reliable service. Solar water heaters are estimated to last between 10 and 25 years on average, depending on the type and quality of installation, materials, and maintenance that is performed.

It appears that the lack of pressure in your solar hot water system could be due to several factors, such as improper panel orientation, blockages, inadequate insulation, or insufficient collector glazing.

I suggest starting by raising the thermostat setting, and if that does not work, then the thermostat may be faulty or the heater may be too small.

To fix a leaking solar water heater, it is best to identify what part has been damaged and then replace it with a new one. Once the part is changed, make sure to modify the system to avoid any further damage.

To ensure your solar hot water system is safely shut down, first unplug the system and switch off the booster. Then close the water supply and open all taps to purge the air from the system before finally switching it off.

Following these steps will ensure a safe shutdown of your solar hot water system.