Morning, My advice would be
Morning, my advice on this if you is if you have the budget install solar geyser as your primary source of heating and have the heat pump as your auxiliary back up. In the warmer months of the year your solar will 90 % of the work and in winter when the sun is weaker the heat pump will pick up the slack.
Hello Everyone
I thought this might be worth a read for you - https://itssolar.co.za/water-heating/a-comparison-of-pv-solar-thermal-gas-and-heat-pump-water-heating-systems/