Pool owners often consider the combination of pool heat pumps and photovoltaic (PV) panels to heat their pools efficiently and sustainably. Heat pumps are a great solution for those who need to swim every day. But for other pool owners, while this may seem like a perfect match, there are important factors to consider before investing in such a system. To lower the heating cost and move towards a more sustainable future, it is important to understand that heat pumps are a big-ticket item compared to other household electrical appliances and their relationship with the PV panels affects the load balance of electricity use at home. The common belief is that running a heat pump with PV Panels is cost-effective year-round. In reality, the actual efficiency and cost-effectiveness of running a heat pump with PV panels depend on various factors, including climate, pool usage, and system design. 
Photo: a 17 kW pool heat pump can quickly consume most of the generated capacity of a 7 kW PV system, leaving minimum power for household use or battery storage. The heat pump will also consume electricity from the grid when the solar production is not enough in the morning or later in the afternoon.
Considerations
Impact of Shoulder Months:
In shoulder month (Oct-Nov and Mar-Apr in Melbourne) when the air temperature is lower, the heat pump’s heating capacity can be reduced by up to 80%. For example, a 21 kW heat pump will only provide 17 kW of heating. This means the heat pump needs to work at full capacity and lower COPs especially in the morning when recovering from the 2-degree overnight heat loss.
Solar Panel Efficiency:
PV panels themselves operate at around 67% of their capacity during this time, which limits the electricity generation available for the heat pump. The combined effect of lower PV electricity generation and higher electricity use of the heat pump in colder months changes the ideal idea of running a heat pump just using the PV panels and for free. Heat pumps need to run at their maximum capacity in the morning to recover from overnight heat loss, often consuming all the generated solar electricity, leaving little or none for other household needs.
Pool Usage:
Pool owners should question whether they intend to swim on days that are not sunny. If not, a dedicated solar pool heating system will be more cost-effective. Integrating a heat pump with house’s PV panels is a complex and expensive alternative compared to a dedicated solar pool heating system. Correctly sized solar pool heating systems are fast and can raise pool temperatures by as much as 10 degrees in just a few hours on sunny days. If the north facing roof space is needed for installation of PV panels, solar pool heaters can still be installed even on the southern roof with a slight adjustment for reduced solar exposure.
Recommendations
To minimise the impact of the pool heat pump on the electricity generation of PV panels, here is what we recommend:
- Use a pool cover to minimise the heat loss and electricity consumption of the heat pump. Use our online pool heat pump calculator to see how a pool cover can lower the heating cost.
- Use full-inverter heat pumps with highest COP possible. Inverter technology used in our heat pumps can provide up to 20x more heating using less electricity.
- Consider hybrid solar pool heating and heat pumps similar to our recent project for an off-grid property in Blue Mountains.
- Use direct DC heat pumps with dedicated PV panels. Our SunVolt ACDC heat pump is our new addition that can heat your pool for free and without affecting your existing PV electricity generation.