Solar Water Heater Problems and Repair Guide (5 most common issues)

Solar water heaters are an important component in a house. They provide a constant supply of hot water for domestic or commercial use efficiently and in a cost-effective way, using free solar energy. The system works by collecting solar energy using collectors (tubes or flat panels) that are strategically positioned on the roof of a building and oriented for the best performance.

Today, solar water heaters have gained traction across the world due to its reliability and durability, including great ideas, available designs and kits, and advanced controllers.

Having basic knowledge about solar water heater repair is necessary if your water heater breaks down, and you want to keep the expenses low. Just like other solar-powered devices, solar water heaters develop issues as time passes, and elements start to deteriorate. If you are a homeowner and want to know about the common problems that are usually associated with solar water heaters, including troubleshoot them, then you are in the right place.

If your solar water heater was recently installed, keep in mind that periodic inspection and regular maintenance is needed to keep the system efficient and operational for many years to come.

But before we dive deeper, let's quickly take a look at what solar water heaters are and how they work.

Solar water heater

What are solar water heaters?

Simply put, a solar-powered water heater is an assemblage of solar collectors or panels, pumps, controllers, insulated storage tanks, and connecting pipes. The solar collectors are positioned to trap the maximum solar energy and convert it to heat – for free. The heat is then absorbed by water and then stored in storage tanks for use in the shower, dishwashing and clothes washing application

They are perfectly safe as they are equipped with solar panels made of tempered glass and temperature and pressure relief valves to control the water temperature and pressure. Plus, the system comes with a circulating pump to help circulate water in the system, from the solar panel to the storage tanks. Since some parts of the solar water heater are usually exposed to the elements, it is vital to protect these parts from overheating and freezing.

Commonly used types of solar water heaters

Solar water heaters are categorized into several popular types:

  • Thermosiphon Systems: Thermosiphon systems are used to produce hot water by heating water directly, or indirectly by heating the antifreeze fluid like glycol first and then using the heat exchanger to transfer the heat to the water. The system uses the water storage tank installed above the collector so the fluid can rise by natural convection to the storage tank, without using the pump. This type of solar-powered water heaters is very efficient in areas with high solar energy.
  • Integral system (ICS or batch) is, with the thermosiphon, another passive system which is used in regions with a lot of sunny days and where the demand for hot water is high. They are simply built utilizing one or more tanks painted in black, installed inside the box, and well insulated.
  • Direct-Circulation Systems: This type of solar-powered water heater works by pumping water from the storage tanks to the panels during sunny hours, thus increasing the use of energy. 
  • Drain-Down or Drainback Systems: In these systems, untreated or treated water is usually circulated via a loop. A heat exchanger is used to transfer heat to potable water. The system uses controllers, sensors, and pumps to turn the system off or on. In the evenings or nights, the water would drain by gravity to prevent convection loops and freezing.
  • Indirect Water-Heating Systems: These systems work by circulating freeze-protected water through a closed-loop. A heat exchanger is then used to transfer heat to the water in the storage tank. Water-ethylene glycol and water-propylene glycol solutions are an excellent example of freeze-protected fluid to use.

Now, let's take a look at the five most common problems associated with solar water heaters and how to fix them:

Solar water heater commons problems

As with any other devices, solar water heaters are also prone to problems, element failures that cannot be avoided, and situations that would lead to costly repairs.

The most common issues with solar water heaters are the sediment build-up, corrosion of the metal parts, deterioration (aging, wear and tear) of the non-metallic, freezing (in cold climates), fluid leakage and insufficient hot water supply or no hot water at all.

Some of the problems can be prevented with regular maintenance, so as the smooth operation and expected performance.

Preventing the problems and what to check

Clean the collector glazing from the soil, dust, leaves, vegetation, and other foreign materials that can affect the performance or damage the components.

Make sure the seals are not cracked and damaged, and there is no fluid leakage.

Ensure that bolts and nuts of the supporting structure are not loose.

Repair any crack on the collector glazing or replace if needed.

Check the storage tank for leaks and make sure the valves are operating especially the temperature and pressure relief valve.

If the sediment build-up frequently occurs, replace the heat transfer fluid if it is rich in minerals (hard water), or install a water softener.

Add the insulation where it is needed to reduce the risk of freezing and low performance.

Check the pump, sensors, and controllers, clean and replace if needed so they can operate properly.

Problem #1. Solar water heater not producing hot water

Sometimes, your heating system will work but doesn’t produce hot water. The cause of this problem is not far-fetched. During cloudy days or if the solar panel glass is broken, it won’t trap enough solar energy; thus, the water in the storage tank won’t get hot, and especially if there is no backup heater. Another reason why your solar-powered water heater may not produce hot water is that the thermostat (in the heating element) may be faulty or set too low.


  • Ensure the solar panels are correctly positioned where they would receive maximum solar energy and check that the glazing is not broken, covered or in shade
  • Clean the panels with a rag to remove the dirt, leaves and other
  • Check the thermostat for appropriate settings. But if it is damaged, replace it
  • Check to ensure that the sensor wires are correctly connected

If there is not enough hot water, make sure that the solar collector is installed correctly, and there are no obstructions. Check the sizing, tilt, orientation, and obstacles (shading). Make sure that there is no thermosiphoning overnight, and there is no heat loss through the tank or plumbing.

Tip: Make sure all the components are working correctly (sensors, controllers, pump).

Problem #2. Fluid leakage

Fluid leakage is one of the major problems that your solar water heater can develop. In fact, it is one of the leading issues commonly associated with solar-powered water heaters. 

This problem is usually caused when a collector glazing or pipe is broken or when the pressure relieve valve in the solar panels is damaged and open. Another possible cause of water leakage in a solar-powered water heater can occur due to loose pipe fittings and thermal expansion. 


Before you call a technician, do the following;

  • Check the pipe fittings and tighten any loose connection or replace broken pipes
  • Replace the temperature or pressure valve with a new one or replace the seal
  • Replace the solar panels if the glass is found broken
  • Adjust the thermostat settings to reduce the system pressure

Note: Before you carry out any troubleshooting work, ensure you isolate the solar panel.

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Problem #3. Unusual noise in the pump

When you turn ON your solar-powered water heater, and you hear an unusual noise coming from the pump, chances are that there is a sediment build-up on the pump’s impeller, which might be obstructing the impeller from rotating. Another possible cause of unusual noise in the pump could develop due to bearing failure. Also, make sure air is trapped inside the system.


  • Access the pump and clean the impellers of any deposits or debris
  • If you suspect bearing failure, then lubricate the bearing with an appropriate lubricant
  • If the problem persists, you might need to replace the pump
  • Loosen the vent screw if one exists or bleed the air. The air locked in the system could also prevent any flow, especially if the pump is not sized well.

Problem #4. Open circuit or loose connections

The moment your solar water heater stops working, chances are that there are open circuits along the connection line. As with other wire connections, solar water heaters are also prone to loose connections with time.


  • Trace the wire connections to check for broken cables or loose connection
  • Use the appropriate tools to cut the defective part of the cable
  • Re-connect the cable

Problem #5. Solar panel problems

This is another problem that homeowners need to be aware of. Solar panels can develop problems, so the collectors are not able to trap the maximum solar energy. One of the leading issues of the solar panel is broken glass. Another cause of solar panel problems could be that the coating or absorber paint has deteriorated. Furthermore, if there is condensation on the glass, it can affect the panel’s performance and efficiency.


  • If the solar panel glass is broken, replace the glass or replace the entire solar panel
  • If you suspect that the coating or absorber paint has deteriorated, then repaint the panels with a heat resistant paint
  • Create a small hole at the bottom of the panel to handle the problem of condensation on the glass


A solar water heater is a technology that has come to stay. Whether you want to take a warm bath or clean the dishes, a solar water heater can guarantee a constant source of hot water all year round. When the system develops issues, the repair process should be on time and without spending too much money. It is good to know fundamentals so you can troubleshoot simple faults before engaging the services of a technician.

As it can be seen from the troubleshooting guide, some problems are easy to identify and fix, while others such as “no hot water” or “not enough hot water” require more work before figuring out what is going on.

What is your experience with repairing a solar water heater? Share your thoughts with us using the comment box below


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