Is a passive solar heat coil worth it?

I have a heat pump that works well - when I turn it on. Since our yard surrounding the pool gets a lot of southern exposure, I'm thinking about installing a couple of these black solar pipe heaters in line with the return jets. My thinking is that the black pipes would passively capture solar

Heat Pump vs Solar: Which is More Cost-Effective for Hot Water

How solar heating system is made - material, manufacture, history, used, parts, components, History, Raw Materials

Solar Thermal water heater that will not overheat - Ecohome

How solar heating system is made - material, manufacture, history, used, parts, components, History, Raw Materials

How to Build a Passive Solar Water Heater – Mother Earth News

Passive Solar Homes Department of Energy

Solar water heating - Wikipedia

ENGINEERING.com Passive Solar Systems & Solar Hot Water

Solar Water Heaters - MEP Academy

Tankless Coil and Indirect Water Heaters

Solar Heating Systems: Are They a Good Idea?

Passive Solar Heating System (Everything to Know) - ShopSolar.com

Active vs Passive Solar Water Heaters - Sunbank Solar

Active vs Passive Solar Water Heaters - Sunbank Solar