5 Common Problems with a Solar Hot Water System: How to Keep It Running

Solar hot water systems are a fantastic way to harness Australia’s sunny climate and cut down on energy bills. But like any home appliance, they’re not completely immune to problems.

Over time, parts can wear out, components may stop working properly, or weather conditions might reduce the system’s efficiency. The good news is, most of these issues can be spotted early and resolved with regular maintenance or a professional inspection.

In this blog, we’ll walk you through five of the most common problems people face with their solar hot water systems. From not getting enough hot water to dealing with leaks and sensor faults, understanding what can go wrong helps you take action fast.

Let’s get started and make sure your system keeps running efficiently all year round.

1. Insufficient Hot Water Output

Not getting enough hot water from your solar system? This is a common complaint, and there are several possible reasons behind it.

Here are a few to consider:

• Poor sunlight exposure – If your panels are shaded by trees or buildings, they may not be getting enough sun to heat the water effectively.
• Undersized system – Your system might be too small for your household’s needs, especially if your family or hot water usage has grown over time.
• Faulty booster – Many systems have an electric or gas booster to help on cloudy days. If it’s not working, you’ll notice cooler water.
• Cold weather – During winter, your system may need more time or booster support to maintain the right temperature.
• Circulation issues – Problems with the pump or valves can slow the flow of heated water to your tank.

A qualified technician can help pinpoint and fix the issue quickly.

2. Leaks in the Pipes or Storage Tank

Leaks are one of the most common issues in solar hot water systems, and they can develop in either the pipes or the storage tank.

These systems are constantly exposed to the elements, and over time, pipes can corrode, crack or loosen at the joints. If your system uses copper pipes, mineral buildup or corrosion may be the culprit. You might notice water pooling around the tank, damp spots, or a sudden drop in water pressure.

Storage tanks can also develop leaks due to rust or internal pressure problems, especially in older systems. A leaking tank can reduce hot water supply and drive up your water bills.

It’s best to turn off the system and call a licensed technician if you spot any signs of a leak. Early repairs can prevent further damage and save you from needing a full replacement down the track.

3. Faulty or Broken Circulation Pump

The circulation pump is a key part of many solar hot water systems, especially active (pumped) systems. It moves heated water from the solar collectors to the storage tank. If the pump stops working properly, the whole system can lose efficiency or stop heating altogether.

Here’s what to watch for:

• No hot water despite sunny weather – If the sun is out but your water is cold, the pump may not be circulating water between the panels and tank.
• Strange noises – Grinding or rattling sounds could signal a failing motor or worn-out bearings.
• Water temperature fluctuations – A pump that works intermittently can lead to inconsistent hot water delivery.
• Visible water leaks – If water is leaking around the pump area, internal seals may be damaged.

Pump issues usually require professional repair or replacement. Regular servicing helps catch early signs of trouble and keeps your system working efficiently.

4. Sensor or Controller Malfunctions

The sensor and controller are the brains of your solar hot water system. They work together to monitor water temperature and trigger the circulation of water between the panels and the storage tank. If either component fails, your system might not heat water efficiently – or at all.

Common signs of a sensor or controller issue include inconsistent water temperatures, no hot water during sunny days, or an error message on the display (if your system has one).

Sometimes the problem is as simple as a loose connection or a faulty wire, but in other cases, the sensor itself may need replacing.

Because these parts involve electrical components, it’s best to leave diagnosis and repairs to a licensed technician.

Regular servicing can help prevent these malfunctions and keep your system running smoothly. Catching issues early means better performance, lower energy bills and fewer surprises when you turn on the tap.

5. Buildup of Sediment or Scale

Over time, sediment and mineral scale can build up inside your solar hot water system, especially if you live in an area with hard water. This buildup can reduce efficiency and even damage components if left unchecked.

Here’s what to look out for:

• Reduced hot water flow – Scale buildup can clog pipes and restrict water movement, leading to weak pressure at taps.
• Strange noises – Rumbling or popping sounds from the tank may indicate sediment heating and shifting around.
• Increased energy use – The system has to work harder to heat water through scale, raising your power bills.
• Shortened system lifespan – Scale can cause wear and tear on heating elements and internal parts over time.

Flushing the tank and descaling components during routine maintenance can help prevent these issues. It’s a good idea to schedule professional servicing regularly to keep your system clean and running efficiently.

The Power of the Sun

Solar hot water systems are a great investment, but like any appliance, they can run into problems over time.

Whether it’s a leak, a faulty sensor, a circulation issue or just not enough hot water, these problems are often fixable – especially if caught early.

Regular servicing, especially before the cooler months, can help keep your system running smoothly and efficiently. If you notice changes in water temperature, strange noises or higher energy bills, it’s worth getting a professional plumber to take a look.

Don’t wait for a complete breakdown – small issues can turn into big repairs if ignored. With the right care and timely attention, your solar hot water system can continue to provide reliable, eco-friendly hot water for many years to come.

Stay informed, act quickly and your solar hot water system investment will continue to shine.

Please note: This information is provided for advice purposes only. Regulations differ from state to state, so please consult your local authorities or an industry professional before proceeding with any work. See our Terms & Conditions here.