Can I improve the
performance by adjusting the solar panel?
No, it would be very dangerous to attempt to do this.
The panel is situated on the roof and there are no user serviceable parts
inside. The heat transfer pipe is filled with a glycol solution and reaches
a maximum working pressure of 600kPa. The heat transfer pipe reaches
temperatures in excess of boiling point so, for example touching it, will
cause severe burns. Treat it with the same caution as you would treat a pan
of boiling water.