Has Anyone Used Powersensor Solar Energy Monitor for a Solar System

I have an old system, fortunately still on the Victorian Premium Feed in Tariff.

Have an old Efergy monitor monitor on it, but it lacks the modern interface, etc. My inverter only has an old serial interface.

Would anyone have any suggestions of a monitor that I could install myself to to really monitor how the panels are performing and if efficiency is dropping off, with age.

I've seen the Powersensor Solar Energy Monitor for $299 and looks like it may do the job. Anyone had any experience with this monitor and if you can get them cheaper. Any other suggestions for others monitors?

Thanks