Kees Verruijt wrote:

Admittedly, it is 30 degrees Celsius right now where I am typing this,
but that's not what we usually get. And with this steaming tropical
weather, hot water is not high on our priority list :-)

30C is "steaming tropical weather"? We've hit 45C already, and summer is
just starting! Probably won't hit 50C this year (although we have a few
times). Enjoy the lovely winter you're having :=)

As for solar heating, I don't know what the suns' intensity is at your
latitude (when you see the sun, that is), but in the summer here (34°
latitude) it can be as high as 375 BTU/ft^2/hr (10WattHr/M^2/hr) with
the absorbing surface normal to the sunlight. So there's energy to be had.

Keith Hughes
(reclining in sunny Arizona)