mangocrazy
Italian V-twin nutjob
- Messages
- 1,164
- Location
- Sheffield, UK
I have a holiday home (fixer-upper) in the south of France and last year I completed the installation of a solar thermal system on the roof facing Southwest. The solar thermal array consists of 30 x 58mm diameter evacuated tubes
The tubes, mounting frame and hot water cylinder came as a kit which also contained a 230v pump, pressure vessel and control station. I really wasn't that enamoured of a mains voltage pump and all the attendant programming involved, so searched for a low voltage pump that could be driven by a small solar panel, and that is what is fitted now. I'm currently in France and last weekend we had some really warm, sunny conditions and the control station indicated a maximum of 67 degrees C for the water in the cylinder. I haven't used the thermostat in the DHW cylinder since the solar thermal has been operational.
I'm not sure how many other people use a low voltage, solar-driven pump for their solar thermal array, but I was hoping to tap into people's knowledge and experience. I'v noticed that in the morning the temperature of the water in the DHW cylinder decreases quite noticeably and only recovers when the sun has worked its way round by about midday. This is because the pump is active from quite early but the tubes don't produce much heat until later in the day, so I'm effectively pumping cool water into the cylinder and reducing the heat of the stored water.
Is there any way to delay the start of the solar-powered pump until such time as it will be feeding hot (or at least warm) water into the cylinder's indirect coils? I was wondering if there was a way of only passing DC electricity to the pump once it passed a certain voltage threshold? Would this be an option or would it be better to do it on water temperature using some kind of thermostat arrangement? I really want to keep the simplicity of the solar-powered pump but would like to tweak it to improve its overall efficiency.
Thanks in advance.
The tubes, mounting frame and hot water cylinder came as a kit which also contained a 230v pump, pressure vessel and control station. I really wasn't that enamoured of a mains voltage pump and all the attendant programming involved, so searched for a low voltage pump that could be driven by a small solar panel, and that is what is fitted now. I'm currently in France and last weekend we had some really warm, sunny conditions and the control station indicated a maximum of 67 degrees C for the water in the cylinder. I haven't used the thermostat in the DHW cylinder since the solar thermal has been operational.
I'm not sure how many other people use a low voltage, solar-driven pump for their solar thermal array, but I was hoping to tap into people's knowledge and experience. I'v noticed that in the morning the temperature of the water in the DHW cylinder decreases quite noticeably and only recovers when the sun has worked its way round by about midday. This is because the pump is active from quite early but the tubes don't produce much heat until later in the day, so I'm effectively pumping cool water into the cylinder and reducing the heat of the stored water.
Is there any way to delay the start of the solar-powered pump until such time as it will be feeding hot (or at least warm) water into the cylinder's indirect coils? I was wondering if there was a way of only passing DC electricity to the pump once it passed a certain voltage threshold? Would this be an option or would it be better to do it on water temperature using some kind of thermostat arrangement? I really want to keep the simplicity of the solar-powered pump but would like to tweak it to improve its overall efficiency.
Thanks in advance.