Question/Help needed re proposed Solar Thermal Installation in Spain

[Hatty]

Hello, I am new to solar thermal but would like to install at my holiday house in the Alicante region of Spain, (I live in the UK)

The pitched roof faces due south.
The only hot water is a 100 litre electric tank which is insufficient for the existing two bathrooms let alone the two new ones my wife wants

Over the past 18 months or so I have acquired the following:-

5no WATT 3000 S flat plate panels approx. size 2.00 x 1.00
300 litre WATT HT-300 HRR tank
Gledhill 210 litre solar twin coil tank

I would like to set up two individual drain back systems at either end of the house, so that I can turn them both off when I am not there and there will be no risk of overheating, (each system would have a thermostatic control to start and stop the pump at a predetermined temp)

1. One with two flat plate panels and a 210 litre tank with a back up immersion for the existing bathrooms
2. One with three flat pate panels and either the 300 litre or another 210 litre tank to serve the new bathrooms and kitchen

Each system would be pumped by a 12v solar powered pump

If I need another 210 l tank do I need a dedicated solar not water cylinder or could I used a normal unvented indirect cylinder as there is no other heat sourse?

Will I get enough hot water in each tank, 210 and 300l, or would two 210l tanks be a better bet?

Any comments and advise would be most appreciated as I have to explain the entire system to a Spanish plumber at some point!

[LucMan]

Hello, I am new to solar thermal but would like to install at my holiday house in the Alicante region of Spain, (I live in the UK)

The pitched roof faces due south.
The only hot water is a 100 litre electric tank which is insufficient for the existing two bathrooms let alone the two new ones my wife wants

Over the past 18 months or so I have acquired the following:-

5no WATT 3000 S flat plate panels approx. size 2.00 x 1.00
300 litre WATT HT-300 HRR tank
Gledhill 210 litre solar twin coil tank

I would like to set up two individual drain back systems at either end of the house, so that I can turn them both off when I am not there and there will be no risk of overheating, (each system would have a thermostatic control to start and stop the pump at a predetermined temp)

1. One with two flat plate panels and a 210 litre tank with a back up immersion for the existing bathrooms
2. One with three flat pate panels and either the 300 litre or another 210 litre tank to serve the new bathrooms and kitchen

Each system would be pumped by a 12v solar powered pump

If I need another 210 l tank do I need a dedicated solar not water cylinder or could I used a normal unvented indirect cylinder as there is no other heat sourse?

Will I get enough hot water in each tank, 210 and 300l, or would two 210l tanks be a better bet?

Any comments and advise would be most appreciated as I have to explain the entire system to a Spanish plumber at some point!

Unfortunately you didn't come here for advice before you purchased the materials for your proposed HW system. A single 500 litre solar water heater would have been a better choice than 2 separate tanks.
A solar thermal contractor instead of a plumber would be a good investment at this time to get everything installed and advise you on the piping layout and controls.
I suggest that you pipe all your tanks in series with your existing electric tank. Differential controllers are available to control multiple tanks and arrays. Steca has several available.
Regarding the 12v pumps, they would be a poor choice for use with a drain back system as they usually have insufficient flow to initiate circulation or supply the proper flow rate to multiple panels.

[Yet another Yeti]

Alicante should have reasonable beach as located some harbour city ...

And though no dessert , wife wants 2+2 bathrooms ..


Suggesting to stay in England , where the need to "dust off" is less ....