Transcape Plumber

Nice installation!

Update: I've just returned from a site visit and instead of 50 people using the system, there are now 90 people using it daily. They have used 244000l of hot water in just over a month (no water restrictions there!) so we are pretty chuffed that the system has held up with the added demand.

Update: I've just returned from a site visit and instead of 50 people using the system, there are now 90 people using it daily. They have used 244000l of hot water in just over a month (no water restrictions there!) so we are pretty chuffed that the system has held up with the added demand.

Update: I've just returned from a site visit and instead of 50 people using the system, there are now 90 people using it daily. They have used 244000l of hot water in just over a month (no water restrictions there!) so we are pretty chuffed that the system has held up with the added demand.

Update: I've just returned from a site visit and instead of 50 people using the system, there are now 90 people using it daily. They have used 244000l of hot water in just over a month (no water restrictions there!) so we are pretty chuffed that the system has held up with the added demand.

Update: I've just returned from a site visit and instead of 50 people using the system, there are now 90 people using it daily. They have used 244000l of hot water in just over a month (no water restrictions there!) so we are pretty chuffed that the system has held up with the added demand.

Some might find this interesting. We've just completed a hot water system in the Delta for the staff village of a guest lodge. 4500l Thermocube Tank with heat exchangers. Heat supplied by 2 x 24kw ITS heat pumps and 12 x 20 tube evac solar tubes in series. A 300m ring main feeds 24 tap off points supplying hot water for about 50 staff at a time and their kitchen and the camp laundry. 

I believe Stellenbosch University has a similar setup for feeding hot water to residences. Sometimes a number of nearby residences even share a heat source in this manner. The heat is circulated to keep it hot at the point of use.
When I was there so many years ago, I remember how our residence NEVER ran out of hot water. My girlfriend (now wife) on the other end of campus wasn't as lucky though: They had geysers, and being girls and all, they ran out of hot water frequently :-)

Aah! So that is where I get my cross-trade cock up skills from... Being a farmers son! I remember being taught to change the plug before being able to tie my shoe laces. I still can't tie my laces properly.  

Aah! So that is where I get my cross-trade cock up skills from... Being a farmers son! I remember being taught to change the plug before being able to tie my shoe laces. I still can't tie my laces properly.  

Aah! So that is where I get my cross-trade cock up skills from... Being a farmers son! I remember being taught to change the plug before being able to tie my shoe laces. I still can't tie my laces properly.  

Spot on @Janma the efficiency is dominated by the radiation losses for both types of collectors.
See below for a comparison of collectors and how they compare in efficiency. (Picture copied from Soltrain Training Manual)
As expected the Evacuated Tube Collector performs very well and outperforms even a selective coated flat plate collector in most applications. 
But if you look a bit closer you will notice that for domestic hot water systems we are more interested in the left hand side of this graph where their isn't a huge difference between a vacuum tube and good selective coated flat panel.
The fact that the flat plate collector gets less efficient the hotter it gets means that it naturally cools itself down as it heats up and therefore reduces the chances of overheating. 
In my opinion, for our Climate in South Africa, a simple flat plate panel that is painted black is good enough. It is cheap, will not overheat, and will do the job for most of the year.