Maximizing Efficiency: The Ultimate Guide to Hot Water Solar System Installation and Maintenance

Are you considering a hot water solar system? This solution taps into solar energy to efficiently heat water in your home, leading to significant energy cost savings. Our guide explains the ins and outs of these systems, including how they work, how to install and maintain them, and the potential for reduced utility bills. Understand what makes a hot water solar system a smart choice for sustainable living and your pocketbook.

Key Takeaways

  • Hot water solar systems offer an eco-friendly solution to heating water by using solar collectors and storage tanks to harness and store the sun’s energy, reducing dependence on conventional heating systems.

  • Installation of hot water solar systems should be done by professionals, taking into account factors like roof orientation, shading, and system sizing, while adhering to local building codes and regulations for optimal efficiency and safety.

  • Although upfront costs for solar hot water systems can be significant, long-term savings on energy bills, coupled with potential government rebates and incentives, make these systems a financially viable and environmentally sustainable investment.

Understanding Hot Water Solar Systems

Solar collectors absorbing sunlight to heat water in a hot water solar system

Hot water solar systems, which harness the power of the sun, have dramatically changed our approach to hot water heating. No longer dependent on conventional hot water systems, these solar systems absorb sunlight and circulate water for heating, ensuring a constant supply of hot water for homes.

At the heart of this process are solar collectors, which capture solar radiation and transfer the accumulated heat to water. The natural thermosiphon process then comes into play, allowing hot water to rise into the storage cylinder from the solar collectors, with cooler water cycling down to the collectors for heating.

Solar Collectors

Acting as the core component of hot water solar systems, solar collectors absorb the sun’s energy and transfer the captured heat to water. You’ll find two types of solar collectors in most systems: flat plate collectors and evacuated tube collectors. Flat plate collectors utilize a flat panel to absorb solar energy and transfer the heat directly to water flowing through the system. On the other hand, evacuated tube collectors consist of transparent glass tubes forming a vacuum, providing increased efficiency in converting solar radiation into heat.

The water’s movement through these collectors can be explained by the principle of thermosiphon. In roof-mounted solar hot water systems, this natural convection of heated fluid rising displaces cooler fluid, ensuring consistent water heating. This process eliminates the need for mechanical pumps, making the system operation smooth and efficient.

Storage Tanks

Corrosion-resistant storage tank in a solar hot water system

Storage tanks are the unsung heroes of solar hot water systems. These tanks:

  • Maintain a consistent supply of hot water, ready for use whenever needed

  • Are typically made from stainless steel or other corrosion-resistant materials, ensuring longevity and reliability

  • Are connected to the solar collector and your home’s hot water pipes, acting as a thermal reservoir for the system.

Choosing the right size of storage tank is crucial for the system’s efficiency. The size of the tank is matched to your household’s hot water demand, with larger homes necessitating larger tanks. This means that whether you’re running a bath or washing dishes, you can trust your solar hot water system to keep the hot water flowing.

Electric or Gas Boosters

While solar energy is a reliable source of power, there are times when it might not be enough to heat your water. Enter electric or gas boosters. These boosters ensure a consistent hot water supply by providing backup heat during periods when solar energy is insufficient, such as on cloudy days or at night.

Boosters can either be electric, where an element inside the tank heats the water, or gas-powered, where a gas booster heats the water as it passes through the booster unit. While both are effective, gas boosters are more energy-efficient and can provide instantaneous water heating, heating the water only as it is needed, thus conserving energy.

Types of Hot Water Solar Systems

Roof-mounted hot water solar system with solar panels and collectors

Now that we have understood the basics of solar hot water systems, let’s explore the different types of systems at our disposal. Typically, solar hot water systems are categorized into collector-based systems and heat pump systems. Collector-based systems use solar collectors to absorb and transfer heat to water, while heat pump systems extract heat from the surrounding air. The main types of solar collectors in collector-based systems are flat plate collectors and evacuated tube collectors. Depending on the size of your home or building, different systems like the Slimline Roof Mount solar hot water system may be more suitable.

Roof-Mounted Systems

Roof-mounted solar hot water systems are a popular choice for many homeowners. These systems achieve high efficiency, converting about 80% of solar radiation into heat. The systems operate on principles like thermosiphon, which relies on natural water circulation, or active systems that use pumps for circulation.

Choosing the right model for your roof-mounted system is dictated by your regional climate conditions. Various options like the Rheem 52L Series for non-frost areas or the Rheem Premier Hiline® for frost-prone areas, employ strategies like anti-freeze fluid for heat exchange and protection to -7°C. While installation might present certain challenges due to the weight of the storage tank, these systems are typically less expensive than split systems and require less space than photovoltaic panels for heating water.

Ground-Mounted Systems

Not all homes have the luxury of ample or suitable roof space, and that’s where ground-mounted solar hot water systems come in. These systems offer flexibility in system placement, allowing homeowners to optimize sun exposure regardless of their roof’s condition or orientation.

The benefits of ground-mounted solar hot water systems include:

  • Flexibility in system placement

  • Ability to optimize sun exposure

  • Reduced roof load

  • Potential for future upgrades to solar by adding collectors and a controller

Ground-mounted systems offer easier access for maintenance or repairs and are less complex to install as they do not require working at heights or reinforcing roof structures. However, these systems do require inbuilt pumps to circulate the fluid and careful site selection to avoid shading.

Heat Pump Systems

If you’re living in a less sunny climate, heat pump hot water systems might be your best bet. These systems:

  • Extract heat from the surrounding air to heat water

  • Function akin to an air conditioner in reverse mode

  • Use technology that pulls heat from the air to increase water temperature

  • Use 75% less electricity than conventional electric water heaters

Models like the Solahart Atmos Heat Pump Water Heater efficiently convert ambient air warmth into heat, which is then used to warm the water in the tank. When it comes to sizing heat pump water heaters, the first hour rating is considered, which measures the heater’s capacity to supply hot water over an hour from a full tank.

Despite the upfront costs, which typically range from $3000 to $4000, the long-term savings in electricity usage make heat pump systems a cost-effective option for many households.

Installation Process

Expert conducting site assessment for hot water solar system installation

The process of installing a hot water solar system involves:

  1. Mounting solar collectors

  2. Setting up storage tanks

  3. Installing heat exchangers

  4. Establishing a robust piping system

  5. Configuring control systems for efficient operation

  6. Insulating all components to minimize energy loss

Please note that this process is intricate and necessitates professional expertise. It is not recommended as a DIY endeavor.

Physical installation might necessitate removing roof shingles, creating holes for piping, and the attachment of temperature sensors for both collectors and storage tanks.

Site Assessment

Prior to any installations, a thorough site assessment is imperative for identifying the optimal locations for solar panels and storage tanks, thereby maximizing the efficiency of hot water solar systems. Factors like ensuring there is good access to sunlight, panels are facing north for maximum sun exposure, and that the area is free of shading from trees or other structures are considered.

During an on-site assessment, assessors evaluate the home’s energy needs, roof size and orientation, and identify any shading issues that could impede solar collector performance. Trained and accredited solar assessors adhere to strict protocols to ensure their assessments are safe and provide accurate recommendations for solar collector placement.

System Sizing

Following the site assessment, the subsequent step involves system sizing. This involves selecting the appropriate collector area and storage tank size based on the household’s hot water needs. For a small family of one to two people, a collector area of approximately 20 square feet and a small storage tank of 50-60 gallons are recommended.

For each additional person beyond the initial two, an additional collector area of 8 square feet in the U.S. Sun Belt or 12-14 square feet in the northern United States is needed. The size of the storage tank should be about 1.5 gallons per square foot of collector area, with considerations for increasing this ratio in very sunny climates.

Compliance with Regulations

Compliance with regulations is an essential facet of the installation process. In Victoria, Australia, for instance, the installation of a solar hot water system must adhere to the National Construction Code (NCC) and the Plumbing Regulations 2019. Certain variations to the NCC require that new dwellings must have either a solar water heater or a rainwater tank connected to all sanitary flushing systems.

Plumbing Regulations mandate that solar water heaters with solar collectors include a booster powered by conventional gas or electricity, and if reticulated gas is available, it must be used for the booster. It’s worth noting that upcoming amendments in NCC 2022 will introduce new ‘Whole of Home’ energy efficiency standards for hot water systems.

Maintenance and Troubleshooting

Ensuring the efficiency and durability of your hot water solar system necessitates consistent maintenance and troubleshooting, encompassing appropriate insulation of solar thermal systems and storage tanks. The glycol-water mixture used in indirect solar thermal systems circulates through the solar modules to the storage tank and back, requiring well-insulated pipes to minimize heat loss.

Regular Inspections

Consistent maintenance and periodic inspections are paramount for maintaining the system’s durability and efficiency. Issues like scaling caused by minerals in the water and corrosion can be detected early and rectified before they lead to larger problems.

Regular visual inspections help identify any imminent issues with the solar hot water system, which can be rectified before they lead to larger problems. It’s recommended that professionals be engaged for these inspections and repairs, as homeowner repairs could void warranties and potentially lead to greater expenses.

Cleaning Solar Collectors

Manual cleaning of solar collectors in a hot water solar system

As for the solar collectors, they may not require frequent cleaning if rainwater is sufficient to keep them clean. However, in hot and dusty periods, manual cleaning becomes necessary. For manual cleaning, solar collectors can be cleaned using:

  • a hose

  • a soft cloth

  • a soft-bristled brush

  • a broom

Warm soapy water or a glass cleaning agent can be used for removing tougher dirt.

Dealing with Frost and Cold Weather

Lastly, dealing with frost and cold weather is an essential part of maintaining the efficiency of solar hot water systems. Systems can be equipped with Drain Back heat exchange technology or include elements such as a 3.6kW mid tank electric booster and a 1.0kW bottom frost element for frost protection.

Circulation systems or ‘Hotlogic’ controllers activate to prevent water freezing by keeping it moving, and anti-frost valves release water when temperatures drop near freezing to mitigate freezing risk. Insulating outdoor pipes with heat-resistant materials like elastomer insulators helps to retain heat and prevent freezing within solar hot water systems.

Financial Considerations

Despite the evident benefits of hot water solar systems, it’s fundamental to account for the financial implications. Collector systems cost between $3,000 to $8,000 and heat pump systems cost between $3,000 to $4,000, with the final cost influenced by factors such as system and installation costs, and available rebates and STC prices.

Upfront Costs

Depending on the type of system you choose, solar power hot water systems typically cost between $4000 and $8000 when fully installed. Electric-boosted solar hot water systems are generally less expensive to purchase than gas-boosted systems.

Savings on Energy Bills

Although the initial costs might appear intimidating, it’s worth noting the potential savings on energy expenditure. Replacing an electric hot water system with a solar or heat pump hot water system can save a household at least 50%, and often much more, on their hot water costs, especially when using a hot water tap.

In fact, upgrading from an electric storage water heater to solar can result in annual energy bill savings of $500-$700 for a household, significantly reducing water heating bills.

Rebates and Incentives

Furthermore, the purchase cost of solar hot water systems can be offset with government rebates and incentives like STCs. Federal Government rebates are available for hot water systems under the Federal Government’s Renewable Energy (Electricity) Act 2000. Some states also offer additional incentives like the ACT’s energy-efficient electric water heater upgrade and South Australia’s Retailer Energy Productivity Scheme (REPS).


In conclusion, hot water solar systems are a sustainable and cost-effective solution for your home’s hot water needs. By understanding the different components and types of systems, as well as considering the installation process, maintenance needs, and financial implications, you’re well-equipped to make an informed decision about your home’s hot water system. Remember, the sun is a powerful resource, and harnessing its energy efficiently is a step towards a greener and more sustainable future.

Frequently Asked Questions

Are solar hot water systems worth it?

Yes, solar hot water systems are definitely worth it. Despite the higher upfront cost, they will save you money in the long run and are better for the environment. So, investing in one is a wise decision for the future.

How many solar panels do I need for hot water?

You only need 3 solar panels that produce 15300-watts to run a water heater that uses up to 1500-watts. This will save you roof space and be easier to install.

What are the disadvantages of solar hot water?

Solar hot water systems can have higher upfront costs and may not be suitable for all climates. However, they can significantly reduce energy bills and greenhouse gas emissions.

What does a solar hot water system cost?

Solar hot water systems can cost anywhere from $3000 to $7000 fully installed, depending on the type of system you choose.

What are solar hot water systems?

Solar hot water systems are designed to absorb sunlight and circulate water for heating, providing hot water for homes. They are an eco-friendly and cost-effective alternative to traditional water heating methods.

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