Solar Thermal Evacuated vs Wagner Panel

rdwarf12

I came across this product while doing some research and I am wonder if its to good to be true. I would like a solar thermal installation but I already have 12 PV's installed. I have always consider evacuated tubes to be the best option for the UK. However its likely I may need to have direct-flow tubes fitted horizontally, rather then the heat pipe type.
The Wagner L20 AR Flat Plate product seems to have very good specifications, that seem comparable to tube performance figures. Any comments welcomes on these panels or Tubes to Flat discussions in general.

rdwarf12

web link : http://www.barillasolar.co.uk/collectors.aspx

Cardew

If you look back on old threads I posted a long detailed government sponsored trial of 8 systems(2 evacuated tube).

http://webarchive.nationalarchives.gov.uk/+/http://www.berr.gov.uk/files/file16826.pdf

The report wouldn't get much publicity as it showed the poor output of these systems.

For those not conversant with the units used!
For the 8 systems tested(evacuated Tube and Flat plate) the annual output ranged from 3440 MJ(megajoules) equal to 955kWh to 4,820MJ(1,339kWh)
However from that total had to be deducted the ‘parasitic’ energy to run the pump and electronics. This ranged between zero and 390MJ(108kWh) pa. This of course is daytime rate electricity.
The average for the 8 systems was just over 1,000kWh per year.