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Solar Hot Water Leaking on Roof

If you’re “fixing a hole where the rain gets in,” even a Beatles song is unlikely to make the job any more fun. Even worse, if the leak is coming from your solar hot water system, your roof and home could be at serious risk of damage. 

Although we hate to use the word “common,” in terms of overall trends, leaks are one of the most common maintenance issue associated with solar hot water systems. They can range from minimal to severe, but should always be stopped as soon as possible. 

In this complete guide, we will explore the common causes of solar hot water leaks before examining solutions and frequently asked questions. With this, we hope that our readers can safely repair their leaks, or know when it is time for a partial or complete system replacement. 

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Parts of a Solar Hot Water System 

But first, let’s take a look at the parts of a solar hot water system to help you understand the terminology in this article as it relates to your renewable energy water heating system. Rooftop tanks with thermal solar collectors have very few moving parts, so they are typically not prone to much maintenance or wear and tear over time. 

Thermal Solar Collector 

The thermal solar collector is the component of your system that physically harnesses the heat energy of the sun. There are two main types of thermal solar collectors for hot water systems: flat plate and evacuated tube collectors.

Flat plate solar collectors: With a flat plate collector, you likely do not need to worry about anything leaking directly from the panel. Flat plate collectors are less common than evacuated tube systems in modern installations, and more closely related in size, shape, and appearance to photovoltaic (PV) solar panels.

Evacuated tube solar collectors: In high-performance evacuated tube solar collectors, there is a special heat transfer fluid contained within the tubes used to heat a home’s water. Although very uncommon, heat transfer fluids have a small risk of leaking as well.  

If you suspect that your evacuated tube solar thermal energy collector is leaking heat transfer fluid, we recommend calling a professional immediately.

Pool and purely thermal transfers: Lastly, some solar pool water heaters and systems designed in hot areas do not use any special thermal collectors at all. Instead, water continuously circulates through a black tube, which increases in temperature when exposed directly to the sun or heat of the day. 

For solar hot water pool heaters and purely water-based systems, components have the disadvantage of potentially leaking anywhere. For flat plate and evacuated tube systems, the leaks are almost always sprung in or around the water tank, valves, and pipe fittings.  

The Water Tank 

Unfortunately, the worst and most common place to spring a leak in a solar hot water system is on the water tank. Whether mounted on the roof, positioned directly on the solar collector, or tucked deep into a basement, the tank holds all of the necessary hot water a home may need safely in one place.

Solar hot water tanks are typically well-insulated to keep heat in. They are built with very durable materials and may be warrantied for 10 years or more on high-quality systems. Leaks in a water tank are extremely time-sensitive and should be addressed as soon as possible. 

The Circulating Pump 

For the hot water to be circulated, a pump is used to propel heated liquid throughout a home.  Circulation pumps can be supplemented with electric or gas boosts so that a home’s water can be properly circulated whenever solar thermal energy is unavailable.

The circulating pump may also be known as the controller, and it is connected to the solar collectors and storage tanks via piping. As the heart of the system, the circulating pump and controller may also be directly linked to control valves, pressure gauges, and various other system components where a leak is sprung. 

4 Common Causes for Solar Hot Water Leaks 

If your roof is designed to handle a little bit of rain, then it is unlikely that a rooftop solar system leak will cause any serious damage to your home. However, if the leak were to occur in one of the system’s internal components, then you may have more trouble on your hands

Although crazy things happen every day, the following can be considered the most common causes for solar hot water leaking on a roof:

  1. Old or rusted-out parts and materials
  2. Holes in pipes or tank from various sources
  3. Loose valves and fittings
  4. Freezing or excessive pressure in the system

As a solar hot water system ages, the more likely it will be to leak due to any of the factors listed above. While some fixes are easy, many serious leaks require part replacements and occasional plumbing expertise. If you’re unsure about any aspect of your solar hot water fix, please consult an expert for the safest solution. 

How to Fix Solar Hot Water Leaking on a Roof 

Although it almost goes without saying, there are always different solutions to every different kind of solar hot water leak. If you have a loose valve or pipe fitting, fixing the leak may be as simple as tightening a few pieces of hardware.

No matter what the problem is, however, solar hot water leaking on any roof can be fixed by following the 5 simple steps we will outline below. 

Step #1: Identify the Problem 

Step number one: identify the problem and find the leak. If you’ve got a large pool of water hanging out below your solar thermal collector, then it will be relatively easy to find the culprit area. On the other hand, small leaks only detected by a water tank with a slowly lowering capacity may need some extra examination. 

Slowly work your way around your water tank, pipes, and other system components to look closely for potential water leakage. If water seems to only be leaking from an overflow valve, then the system may be protecting itself against internal damage.  

For major problems, such as a hole in the water tank, it may be necessary to drain the system entirely. Safe water removal methods include buckets, hoses, pumps, and other systems to quickly prevent pooling water from rotting your roof or causing other damage. 

Step #2: Turn off all Power Systems 

Next, to protect yourself and your home, turn off all of the connected power systems before attempting to perform any sort of maintenance on your solar hot water heater. This includes electric and gas-powered boosters as well as any of the connecting values to the rest of your home’s water infrastructure. 

If you do not know how to safely disconnect your solar hot water system from its power supplies, please call the original installer or consult other resources for the safe deactivation of a solar hot water system. With a quickly dwindling supply of water, it is also necessary to shut off water valves to prevent continuous flow, if possible. 

Step #3: Check the Valves for Leaks

More than anything, a solar hot water roof leak is likely going to occur near one of the valves. Closely examine all of the parts of your system in which valve, pipe fittings, and other hardware are installed to safely connect two components. 

If anything seems loose, it is safe to assume that tightening components to an appropriate level is a good way to get started, especially if the leak’s origins seem obvious. In most cases, it is best to first loosen a valve to inspect it for any damages or debris build-up and then tighten the hardware back securely once it seems safe to do so. 

Occasionally, leaky valves may erode existing parts, so you may need to replace the seat washer, nut, or entire valve if pieces are damaged. If the damage was caused in the winter, added freeze protection may be necessary to safely keep the system running. 

Step #4: Run the Water Taps 

Once you have determined that all valves and fittings are on as tightly as possible, then it is time to test your system. Simply reactivate all of your power and run the taps in your home to activate your solar hot water. If the leak persists, please turn all of the systems back off and continue on to step 5. 

Step #5: If Necessary, Call a Professional

Last but not least, a serious water leak may make it necessary to swallow your pride and call a professional. Although there are some instances in which solar hot water leaking on a roof can be easily solved with a few quick adjustments, consulting a repairman is almost always going to be the safer and quicker option.

If your system is still under warranty, then you will want to contact the installer or original manufacturer to see what can be done about the leak. In some cases, repairs can be made without any additional payments, though most service calls will require at least a little bit of spending to get your system back where it needs to be. 

How to Avoid Leaks on Your Rooftop Solar Hot Water System 

Ready to hear a secret?  The best way to stop solar hot water from leaking on your roof is to prevent it from happening in the first place. Although it is probably too late for many people, there are a few great things you can do to prevent future leaks at any stage in your solar hot water system ownership. 

To get ahead of the ball, we suggest performing regular system checks and maintenance every 1-2 years. Although this may not be much more than getting up on your roof and ensuring everything is running smoothly, a quick spot check could save you tons of money and hassle down the road. 

If you’re worried another leak may spring, then it is best to consult a local thermal solar specialist for long-term solutions.  In some cases, extra hardware, such as a thermosiphon arrestor valve, can help prevent further damage. 

Look a Little Closer With Visual Case Studies

If you’re a visual learner, we will now switch over to your side of the brain to help better paint the image of what happens when solar hot water is leaking on a roof. Below, we will showcase a few visuals from around the web to help you further understand the nature and solution of your potential solar hot water problem.

For the absolute worst-case scenario, please turn your attention to this video on YouTube, of which a screenshot is taken above. In this video, a property owner examines a pool of water leaking underneath his solar hot water collector, likely stemming from a loose valve or hole in the rooftop water tank. 

In this instance, we hope that the expert is on their way and that the building owner simply isn’t biding his time and taking a video for the fun of it. Hopefully he will:

  1. Shut off the water supply and tighten all system valves, and
  2. Form a plan to safely remove the water from his roof. 

Image source:

Next, in this image, you can see a rooftop leak in a solar hot water pool heating system. In the water-filled tubes above, the piping is placed on top of a roof in full sun exposure so that the heat from the sun is directly transferred to the water supply.

In the photo, you can see that a leak has sprung, which has most likely been caused by falling or floating debris. Here, a quick fix from plastic or duct tape could be used after the water supply is turned off before a professional would be able to probably patch the tubing for safe, continuous use. 

Image source:×1833/smart/filters:no_upscale()/close-up-of-drain-pipe-leaking-water-157376761-5800e1ba5f9b5805c2b568a1.jpg

Finally, the leak in the image above occurs in a pipe, near the fitting above the water tank in a modular solar water heating thermal system. Here, the water should be shut off immediately so that there is no longer continuous flow through the system’s pipes. 

In this instance, the pipe will likely have to be replaced. Of course, the sooner a leak is detected, the better, as a pipe replacement is going to be a lot cheaper than a new basement on every occasion. 

Rooftop Leaking Solar Hot Water FAQ

Before we wrap things up, here are a few answers to some of the most commonly asked questions regarding solar hot water leaking on a roof. 

Why is my solar hot water leaking?

If your solar hot water system is leaking, then nine times out of ten it is going to be from a loose or faulty valve. Leaks can be sprung from the inputs and outputs of your tanks, controllers, and other systems components where hot water travels continuously.

How do you fix a leaking solar water heater?

More often than not, a leaking solar water heater is fixed with a part replacement. If something has become damaged (i.e. the tank, a valve, a pipe, etc.), then it is almost always safer to replace the part and modify the system so that potential breaks will not occur.

Can I shower if my hot water heater is leaking?

Yes, if your solar hot water system is leaking at a less than critical rate, it is still safe to shower or use the hot water in your home. Of course, small leaks can lead to serious spills if you are not careful, and the problem should be handled as soon as possible. 

Should I replace my solar hot water system if it’s leaking? 

If your solar hot water leaking on the roof was caused by old and worn system components, then it may be time for an upgrade. While we highly encourage you to replace small parts before doing an entire overhaul, a solar hot water system past its prime may be more trouble than it’s worth (remember that in some situations, a heat pump hot water system may actually be more efficient and cost-effective).

Why does my solar hot water system overflow?

If your solar hot water system is overflowing, then it is likely that your PTR valve has failed. Although some overflow can be expected, excessive spills can be prevented with a standard system inspection and part replacement. 

Do solar hot water systems need servicing?

Yes, in addition to semi-annual inspections, solar hot water systems should be serviced at least once every 5 years. Experienced technicians may be able to stop serious leaks before they occur, which can provide a prolonged system lifespan and increased return on investment. 

Should I turn off my hot water heater if it is leaking?

Yes, if your solar hot water heater is leaking, then you should turn off all of the water and energy sources connected to your system. Not only may this immediately stop the leak, but it also allows for you or a hired technician to safely work on your system. 

Final Thoughts 

At the end of the day, we hope that your solar hot water system is able to live a long, maintenance-free life without any serious leaks or issues. If it does spring a leak, however, we hope that this guide has helped you identify the problems, solutions, and information necessary to fix or replace the problem.