2025-08-28
Choosing a more efficient hot water solution is a big decision for any home or business. Whether you want to cut energy bills, reduce carbon emissions, or guarantee reliable hot water, the comparison between heat pumps, solar, gas, and electric resistance is front and centre. At Econova, we’ve been helping Australians make the right call since 2018. Some models in our range achieve a COP of up to 5.7, meaning up to 5.7 kW of heat from every 1 kW of electricity, while solar hot water leverages free sunshine. Below we explain how each technology works, what it costs, and which is likely to suit your property.
Solar hot water uses rooftop collectors to absorb sunlight and warm a storage tank. Performance is excellent in clear conditions but drops under cloud or shade. A booster is often required in dull periods.
Heat pumps extract low-grade heat from ambient air using a refrigeration cycle and transfer that heat into water. Because they harvest heat from air, they work day and night, in all seasons, not just when the sun is shining.
Gas systems combust natural gas or LPG to heat water. Instantaneous (continuous-flow) models heat on demand; storage models maintain a tank at set temperature.
Electric resistance systems use an electric element to heat a storage tank. They are simple but energy-intensive compared to heat pumps.
Solar often has higher upfront costs due to panels, plumbing runs, roof penetrations, and potential structural considerations. Ongoing energy is largely free on sunny days, but a booster may add costs in extended cloudy periods.
Heat pumps typically cost less to install than solar thermal and can access federal and state incentives. With a high COP (up to 5.7 on selected models), electricity use is far lower than standard electric storage.
Gas systems can have moderate upfront costs. Running costs depend on gas prices, usage patterns, and whether the unit is instantaneous or storage. Continuous-flow gas avoids tank losses but still pays for every megajoule burned.
Electric resistance generally has the lowest upfront cost but the highest running cost because every kilowatt of electricity becomes only one kilowatt of heat.
Heat pumps are designed for consistent output across seasons, operating in overcast conditions and overnight. Built-in controls maintain your set temperature.
Solar hot water output depends on solar gain. Reliability is excellent in sunny climates but may need boosting in winter or overcast periods.
Gas instantaneous can deliver “endless” hot water at rated flow, provided gas supply and water flow are adequate. Gas storage offers good recovery but can still be depleted during heavy demand.
Electric resistance provides stable set-point control but recovers more slowly than gas instantaneous and consumes more energy than heat pumps for the same result.
Solar hot water has zero direct emissions once installed. Life-cycle impact is mainly embodied energy in panels and tanks.
Heat pumps, especially those using R290 refrigerant, have low global warming potential and deliver significant emissions reductions compared with electric resistance. Pairing a heat pump with onsite solar PV can further cut carbon.
Gas systems produce combustion emissions and rely on fossil fuels. They may also face future policy or pricing shifts as businesses decarbonise.
Electric resistance has the highest operational emissions where the grid mix is carbon-intensive. Emissions can be reduced if powered by onsite solar or renewable electricity.
Solar requires periodic inspection of panels, roof penetrations, valves, glycol (if applicable), and pipe insulation; occasional cleaning may be needed.
Heat pumps benefit from simple periodic checks such as airflow clearance, condensate drain inspection, and filter or coil cleaning depending on model.
Gas systems require licensed servicing to maintain combustion safety and efficiency, including flue checks where applicable.
Electric resistance systems are straightforward but can suffer from higher scaling on elements in hard-water areas and may need more frequent anode checks to protect the tank.
Solar needs an unshaded, structurally suitable roof with good northern exposure and adequate space for panels and pipe runs. Heritage overlays or shading can limit viability.
Heat pumps install on the ground or wall, need good airflow, and are flexible where roof space is constrained or shaded. They are often ideal for tight urban sites.
Gas needs compliant flueing or ventilation and must be sited away from ignition hazards such as LPG cylinders within defined exclusion zones.
Electric resistance has minimal siting constraints but requires adequate electrical supply capacity.
Both heat pumps and solar hot water can qualify for federal small-scale technology certificates and various state-based incentives such as VEU in Victoria and ESS in NSW, subject to scheme rules and product eligibility. Always confirm current incentives and compliance requirements at the time of purchase and installation.
Choose heat pumps when your roof is shaded or limited, you need reliable year-round performance, or you want strong savings without major roof works. Choose solar thermal when your site has ample unshaded roof, you prefer minimal ongoing energy use in sunny seasons, and you can accommodate a booster for low-sun periods. Many businesses choose both: solar thermal or PV with a heat pump for maximum resilience.
Heat pumps deliver excellent efficiency without combustion on site, reducing emissions and avoiding gas price exposure. Gas instantaneous can suit very high, short-burst demands but adds fossil-fuel dependency and safety considerations. For most commercial and light-commercial applications aiming to decarbonise and control costs, a modern heat pump is the forward-looking choice.
Heat pumps can cut electricity use by roughly 60 to 75 percent compared to like-for-like electric storage, thanks to the high COP. Unless there is a specific constraint that forces an element-only solution, heat pumps are the clear winner on operating cost and emissions.
The simplest, highest-ROI setup is to run your heat pump on your own rooftop solar (PV). Schedule the main heating cycle for late morning to mid-afternoon so the unit draws power while your panels are producing. Think of the tank as a “thermal battery”: raise the setpoint slightly during sunny hours so you store extra heat for the evening, then let the unit idle overnight. A basic timer, smart relay, or your inverter’s load-control feature can automate this. The result is lower grid imports, better self-consumption of solar, and noticeably lower bills without adding complexity. If you later add a home battery, keep the same daytime-first strategy use sunshine to heat water, and reserve the battery for night-time essentials.
Technology fit depends on budget, roof and site constraints, climate, tariffs, and hot water demand profiles. Heat pumps provide consistent performance day and night, strong running-cost savings, and low emissions, especially when paired with solar PV. Solar hot water shines in sunny locations but typically needs boosting. Gas can meet peak flow but carries emissions and safety considerations. Electric resistance is simple but costly to run. For many Australian businesses, a modern heat pump is the smartest blend of cost, carbon, and reliability.
Econova can assess your home or business, model demand, and recommend the right configuration, including rebate guidance and turnkey installation. Contact us for a tailored proposal and see how a high-efficiency heat pump can deliver reliable hot water, lower bills, and a smaller footprint.
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