It’s been over three months since the solar collector was installed. I decided to build a controller by myself. And it turned out that it stayed in the prototype stage. So I put it into the enclosure and left it like is. So far, it works fine – water is hot every day, so I have nothing more to expect. I did not capture enough pictures of the build, but I think I will share what I have. In the forum thread, you probably saw what type of system I was building. As I mentioned, the solar collector is cheaply made in China and is pressureless. They usually come with a unique controller which takes care of the refilling tank, ensuring protection from water freezing and other individual scheduled routines. A pressureless collector usually is first filled with water which heats, and then it is used (mixed with cold). The initial test shows that when the collector is in direct sun, it boils what leads to heater elements’ calcification. Overall lifetime reduces and so efficiency.