Solar panel and water dilemmas

A couple of weeks ago the water in the solar panel began to boil. I could hear it from down in the courtyard. The panel went up last summer to provide us with hot water and it did. Scorchio hot water whenever there was even a small bit of sunshine. But now it was boiling. I checked the temperature on the device in the hot press and it was scary. Up to 120C. The water in the tank was only 40C so something was very badly wrong.

The panel was blocked somewhere along the way. We have very hard water and should have installed a water softener, but didn't. Thought it would be ok. With some difficulty Joe flushed through the pipes and solar panel and cleared the blockage. We got a water softener installed and a separate tap for the still-hard drinking water. But now the water is full of tiny floating bits of lime. The pressure tank was shaken up during the installation procedure, and it looks like the limescale has peeled off the sides. So do I drink the water from the drinking-water tap which has lots of bits and sometimes tastes metallic? Or from the softened-water tap that has less bits but more sodium? Or buy water? Ho hum.

More expense I suspect, whatever we do.