Those are not solar cells, those are water heaters.

In the interest of being honest.

No wonder they still work, those are literally water pipes embedded in a roof panel. No inverter, no battery, nothing. The only thing they have in common with solar cells people install today is the fact that they are powered by sun.

Worth noting that people do still install those today in addition to PV panels. PV panels seem to get 20-30 years of use, which isn’t bad at all. And I believe they usually still work after that time, just with reduced efficiency.

There's also some cool combo rooftop solar panels/water heaters. [1] By cooling the panels themselves they increase their efficiency by up to 15% (so an increase from ~20% to ~23% total efficiency) - while also heating water for the home.

[1] https://dualsun.com/en/product/hybrid-panel-spring/

It is my understanding that residential solar water heating is moving to PV + heat pump water heaters.