Solar hot water systems heat water using the sun’s energy. Solar hot water is generated by heat from the sun which thermally heats the water within either flat collector panels or evacuated tubes attached to a circulating header manifold. Roof-mounted storage tanks with close-coupled solar collectors utilise a natural thermosiphon and cause heated water to rise in the storage tank in proportion to the roof pitch percentage. The steeper the pitch, the faster the thermal rise.
Other styles of solar water heating consist of the storage tank located on the ground connected to the solar collectors on the roof by flow and return piping. Heated water is circulated by a pump attached to the storage tank and the thermostat controller determines when to circulate heated water down to the storage tank by way of a sensor lead that is connected to both the collectors on the roof and the return pipe line at the storage tank’s position.
These two types of solar hot water systems can be classified as either active or passive. Active systems use a system of pumps to transfer fluid between a heating component and the storage tank. In contrast, passive systems use gravity to move fluid between the heating component and storage tank. Solar panels often make use of antifreeze fluid called glycol or ‘heat transfer fluid’ in this regard. This replaces water so the system doesn’t freeze in cold climates. The fluid doesn’t mix with the water contained in the storage tank, but instead resides in a separate jacket located around the portable water tank.
A solar hot water system contains solar collectors, storage tanks and controls. Solar collectors are positioned in a location that receives abundant sunlight: usually the roof of a home. As mentioned above, solar panels heat fluid that is used to increase the temperature of water that is stored in insulated storage tanks. These tanks maintain their temperature throughout the day and night – even when there isn’t enough sunlight to properly heat water. Solar hot water system controls operate autonomously and record the heat of the fluid contained in the system. They will transfer fluid from the collector to the tank when the temperature of the tank has dipped; to ensure the hot water temperature remains consistent.
Solar Hot Water Problems and Their Causes
There are a range of problems which affect the operational efficiency of solar hot water systems. Collector efficiency issues, freezing and overheating, corrosion and scaling, pump or circulation problems, system leaks and control or sensor failures can all result in water temperatures decreasing to a temperature less than desirable.
Collector Efficiency Issues
Issues with the solar collector can become present when there are obstructions in the environment that block sunlight from reaching the photovoltaic cells. Dust, debris from trees or bird droppings can all affect energy absorption and make it difficult for the solar system to heat water to the desired temperature. Shade from trees can affect the same drop in solar efficiency.
Freezing and Overheating
In cold climates, frozen pipes or collectors can cease to function properly. This can prevent heating fluid from warming up water stored in the solar storage tank or photovoltaic collectors from collecting enough energy to heat up the heating fluid at all. On the other hand, overheating in hot climates can cause pressure build-up within solar hot water systems and damage the system’s components.
Corrosion and Scaling
Over time, corrosion of metal components due to poor water quality or lack of maintenance can block pipes or cause hot water to become cloudy or even rusty in colour. Scaling inside pipes and collectors reduces their efficiency and makes it harder for hot water systems to pump water between collectors and storage units. This can result in solar hot water systems improperly heating water or not heating it at all!
Pump and Circulation Problems
In active solar hot water systems, pump failure can lead to inadequate water circulation. Other problems related to circulation in solar hot water systems include airlocks preventing proper water flow. This problem is usually related to the climate causing internal pressure to spike, preventing movement of heating fluid and water throughout the system.
Solar Hot Water System Leaking
One of the most common problems present in solar hot water systems is leaks from pipes, connections or storage tanks. This causes a loss of the system’s potential energy which makes it hard to heat water properly. Leaks can also cause water to leak directly into the surrounding environment which can cause damage to the structure of a house and additional problems with the solar hot water system. Poor installation or ageing components are the most prevalent causes of leaks.
Control and Sensor Failures
If temperature sensors that regulate operation of a solar hot water system malfunction, it can cause water to come out of taps and showers at a different temperature than is expected. Malfunctioning temperature sensors or glitching electronic control systems can cause water to be heated too much or not enough.
Solar Hot Water Troubleshooting and Solutions
If your solar hot water system is experiencing any of the issues listed above, you can troubleshoot your unit by following the guidelines below. Keep in mind it’s better to employ a professional to maintain your solar hot water heater over doing it yourself, yet the following techniques may be achievable depending on your situation.
Preventative maintenance is by far the best way to ensure your solar hot water heater remains operating at optimum capacity. Regular cleaning, visual inspection and operational maintenance should be performed to make sure your unit is working properly. You can clean your solar panels gently with a brush and warm, soapy water. You can also physically remove any obstructions preventing sunlight from reaching the panels. Check for leaks regularly and check the water quality produced by your unit regularly too.
If you are experiencing trees in your backyard or front yard throwing shadows onto your solar collectors, you must trim them back in order to allow maximum sunlight to fall onto the panels. If the problem persists, it can be worth hiring a professional to reposition your collectors so that they can enjoy the sun’s full potential. Tracking devices can be bought from your local hardware store in order to determine the best position for your solar hot water collectors.
Antifreeze and Overheating Prevention
In colder regions where heating fluid can become frozen due to the temperature, homeowners can add antifreeze solution to their heating fluid to ensure it remains in a liquid state. Furthermore, temperature and pressure release valves should be installed as a failsafe mechanism for the purposes of relieving high temperatures and high pressure. High temperature and high pressures can cause system components to burst.
Water softening and filtration can be used in your solar hot water system to reduce scaling and corrosion. Water softening involves removing minerals from water that can form deposits and clog pipes and storage units. Water softening uses a process called ionisation to replace harder minerals within the water with softer minerals like sodium. In addition to water softening, water filtration can be used to remove sediment particles from the water supply. Microfibre filters can be installed externally to your solar hot water unit to capture particulate matter that would otherwise penetrate and cause damage to the system over time.
Pump and Control Maintenance
If you use an active solar hot water system, regular inspection and testing of pumps and controls is needed to maintain your unit. A visual inspection should reveal any severe problems with your pumps and control systems, however, we recommend you also employ a professional serviceman to check pump housing, connections and electrical components for signs of wear, corrosion and damage as well as controller calibration, electrical connections and backup power units for operational capacity. If a component is operating at less capacity than is desired, a professional will replace it.
Leak Detection and Repair
Detecting and addressing leaks in a solar hot water system is crucial to prevent water and energy loss, as well as potential damage to the system components. Leaks can occur in various parts of the system, including pipes, connections, valves, and the storage tank. Visual inspection, evidence of pressure loss and monitoring the water metre should all give indication of leaks if they are present. A professional serviceman will be able to perform these tasks when you call Australian Hot Water and schedule maintenance on your unit.
Call Australian Hot Water For Professional Assistance Today!
While you can always attempt do-it-yourself repairs on your solar hot water heater, it is best practice to employ a professional to do the job for you. Australian Hot Water can schedule maintenance or repairs on your solar hot water system when you call us today! Our team of experienced professionals can perform preventative maintenance, install antifreeze and overheating protection as well as water treatment solutions, maintain your solar heater pumps and controls and easily detect and repair any leaks to your system. Call us today!