Solar hot water systems have been around for almost as long as solar PV systems have been gracing our rooftops. Heat pump hot water systems are a relatively newer technology. With both hot water systems being eligible for federal incentives, and fantastic ways to lower electricity bills and home emissions, which is the better choice? Let’s look at the two different technologies and find out which one you should choose for your home.
The pros and cons of solar hot water
Unlike gas or electric hot water systems, solar hot water utilises solar panels or evacuated tubes on your roof to generate electricity to heat your water. Solar hot water systems are generally electric boosted, meaning that the water will be heated by electricity from the grid when there’s not enough solar-generated electricity available. Because water heated by a solar hot water system primarily uses the renewable resource of the sun, it is highly sustainable and great for the environment.
The systems usually comprise two components; the panels or evacuated tubes installed on the roof and the water tank which stores and heats the water. Solar hot water systems come with either a roof-mounted tank or a split system where the tank is installed on the ground outside your home.
There are many pros and cons of a solar hot water system.
Pros of solar hot water
- Energy efficiency: Uses renewable solar energy, reducing reliance on grid electricity or gas.
- Lower energy bills: Can significantly reduce energy costs over time by using free sunlight.
- Environmentally friendly: Reduces carbon footprint, as solar energy produces no greenhouse gas emissions.
- Government incentives: Qualifies for small-scale technology certificates (STCs) and may be eligible for other state rebates or incentives, lowering the upfront cost.
- Long lifespan: Solar hot water systems generally last longer than conventional heaters with proper maintenance. Many systems can last 20 or more years.
- Energy independence: Reduces dependence on fossil fuels and energy providers.
- Ongoing savings: Solar hot water systems typically save the average Australian household between $300 and $1,000 each year.
Cons of solar hot water
- High initial cost: Upfront costs can be expensive, even with government incentives. Prices for a system range from $3,000 to $7,000 before rebates and incentives.
- Weather dependence: Effectiveness can drop during cloudy or rainy days, requiring backup heating systems.
- Night-time use: As the system requires sunlight to operate, your hot water system will effectively become electric at night time – drawing electricity from the grid.
- Maintenance: Requires regular maintenance to ensure efficient operation, particularly for storage tanks and solar panels.
- Space requirements: Needs adequate roof space for solar collectors, which may not be ideal for smaller properties or properties with existing solar panels.
- Installation complexity: Installation is generally more complex due to the installation of rooftop solar panels or evacuation tubes, increasing costs.
This system is highly suited to sunny regions but may not be as efficient in areas with less sunlight.
The pros and cons of heat pump hot water systems
You’d be hard-pressed to find a home without a refrigerator, and owning one means you already have experience with a heat pump – though in reverse! Heat pump hot water systems use the air surrounding the system to heat the water. Fans within the heat pump draw air from the outside through an evaporator and heat from this air is absorbed by a refrigerant. The refrigerant vapourises which raises the temperature and creates pressure. The refrigerant vapour heats the water through a heat exchanger. This simultaneously cools down the vapour, turning it back into liquid refrigerant. The cycle then repeats.
Heat pumps are available in two variations; split-system or integrated system. A split system has the water tank separate from the fan, compressor, and evaporator (one unit). An integrated system is a single unit comprising the tank, fan, compressor, and evaporator. Most heat pumps are electric-boosted; cold temperatures below the system’s operational limits may require boosting for the system to effectively heat the water.
As with solar hot water systems, there are pros and cons to heat pump hot water systems.
Pros of heat pump hot water systems
- Energy efficiency: Heat pumps use ambient air to heat water, consuming much less electricity compared to conventional electric water heaters, leading to lower running costs.
- Suitable for various climates: They can operate in a wide range of temperatures, making them versatile in both warmer and cooler climates across Australia.
- Environmentally friendly: Since they rely on air rather than fossil fuels, heat pump systems produce fewer greenhouse gas emissions, contributing to a lower carbon footprint.
- Government incentives: In Australia, heat pump systems qualify for rebates and incentives under programs like the Small-scale Renewable Energy Scheme (SRES), reducing upfront costs.
- No roof space required: Unlike solar hot water systems, heat pumps don’t need panels or roof space, which is beneficial for homes where roof space is limited or shaded.
- Long lifespan: A typical heat pump hot water system will last around 10 to 15 years – extending to 20 years and beyond with regular maintenance.
- Works day and night: Heat pumps are not reliant on sunlight, so they can provide hot water consistently, even at night or on cloudy days.
- Ongoing savings: Heat pump hot water systems save the average Australian home $300 to $900 per year on their bills.
Cons of heat pump hot water systems
- Higher upfront costs than traditional systems: While cheaper than solar hot water systems, heat pumps still have a higher initial cost compared to standard electric or gas water heaters. Typical systems cost between $3,000 to $5,000 before rebates and incentives.
- Lower efficiency in cold climates: In colder regions (especially below 5°C), heat pump efficiency can decrease, meaning the system may need to work harder, slightly increasing energy usage.
- Noisy operation: Heat pumps can generate noise during operation due to the compressor, which might be bothersome if installed near living spaces. Systems generally operate between 40 and 60 dB.
- Slower heating time: Heat pumps generally take longer to heat water compared to instant electric or gas heaters, which might be inconvenient during periods of high hot water demand.
- Maintenance needs: The system requires occasional maintenance to ensure optimal performance. This includes cleaning the air filters and servicing the compressor.
- Installation location restrictions: Heat pumps need to be installed outdoors in a well-ventilated area to access ambient air. This might be a limitation for homes with limited outdoor space.
Should I install solar hot water or a heat pump?
When exploring your hot water options for your home, it is important to consider a few factors:
Climate
Solar hot water: Works best in areas with abundant sunlight (e.g., Queensland, Western Australia). It may be less efficient in regions with more cloudy days or colder temperatures, requiring a backup booster system.
Heat pump: Suitable for a wide range of climates, including cooler regions, as it extracts heat from the air. However, its efficiency can drop in extremely cold conditions.
Energy efficiency and savings
Solar hot water: Can reduce energy consumption by 50–90% depending on sunlight availability, making it highly efficient in sunny areas. It has low operating costs once installed but might need a booster in low sunlight. Requires electric boosting at night.
Heat pump: Typically reduces electricity use by 60–75% compared to conventional electric systems, making it very efficient in both warm and cooler areas. It may be more consistent in areas with less sunlight.
Upfront costs
Solar hot water: Higher initial cost, typically ranging from $3,000 to $7,000, including installation. Government rebates under the Small-scale Renewable Energy Scheme (SRES) can help reduce this, along with applicable state rebates.
Heat pump: Generally cheaper than solar, with average costs ranging from $3,000 to $5,000, including installation. Rebates can also reduce the upfront price.
Roof space
Solar hot water: Requires adequate roof space for the solar collectors/panels. If your roof is shaded or unsuitable, this could limit efficiency.
Heat pump: Doesn’t need roof space, as it only requires ground space for the unit. This is ideal for homes where roof space is limited or shaded.
Reliability
Solar hot water: Performance is highly dependent on sunlight. During cloudy periods, boosting (electric or gas) is needed to ensure consistent hot water.
Heat pump: Provides reliable hot water regardless of weather conditions, as it operates by extracting heat from the air, making it more dependable in areas with less sunlight.
Maintenance
Solar hot water: Requires regular cleaning of panels and maintenance of the system to ensure optimal performance, especially in dusty or dirty environments.
Heat pump: Needs occasional servicing, particularly to ensure the compressor and fan are working efficiently, but generally involves less maintenance than solar systems.
Environmental impact
Solar hot water: Generates zero emissions when powered by solar energy, making it the most environmentally friendly option, especially if combined with a solar PV system.
Heat pump: More energy-efficient than traditional electric heaters and reduces carbon emissions, but still relies on electricity (though much less than traditional systems).
Household size and water usage
Solar hot water: Larger households with higher hot water demand may benefit more from solar, as they can take full advantage of solar energy during the day.
Heat pump: More consistent and efficient for households with moderate to high water usage, especially where sunlight may not be enough to meet demand.
Long-term costs
Solar hot water: Higher upfront costs but potentially greater savings in sunny areas over the long term due to lower running costs.
Heat pump: Lower upfront costs with consistent savings on electricity bills, especially in areas without optimal sunlight.
Aesthetics and space
Solar hot water: Requires visible solar panels on your roof, which may affect the look of your home.
Heat pump: Requires an outdoor unit, which might take up space and generate noise, although it can be placed in less visible areas.
The verdict
While there’s no hard and fast rule for which to pick, selecting the hot water system that best suits your budget, usage, and ongoing needs will keep you in good stead. Solar hot water is best for areas with abundant sunlight, larger households, and those looking for minimal environmental impact. Heat pump hot water systems are more versatile across climates, more affordable upfront, and suitable for homes with less roof space or consistent energy needs.
We recommend speaking with professionals who will discuss your needs and suggest a system to best suit them. Energy Matters can connect you with local installers who will provide you with FREE no-obligation quotes. Click the button below and get your free quotes today!
