Adding Solar Tubes

ChrisR1818

I currently have 18 solar tubes installed on my roof and due to the home becoming occupied by more people in the past few years I'm wondering can I add tubes to this current system. There is plenty of room to do so but i'm wondering is it possible. Any feedback would be greatly appreciated.

air

If you have space alongside it should be relatively straightforward to add an additional panel to one side and put the two in series.

unkel

Welcome to boards, ChrisR1818

Don't mean to be rude, but I can't help wonder why you had an 18 tube system installed. Your use of hot water back then must have been modest and a small system like that relatively expensive to put in place. Those two mean a horrific ROI / pay back time. Probably 30-50 years. Who made the decision to put that system in and why?

Gumbo

unkel wrote: »

Welcome to boards, ChrisR1818

Don't mean to be rude, but I can't help wonder why you had an 18 tube system installed. Your use of hot water back then must have been modest and a small system like that relatively expensive to put in place. Those two mean a horrific ROI / pay back time. Probably 30-50 years. Who made the decision to put that system in and why?

Could have been a house built to comply with the early stages of the renewable requirements of Part L?
It’s only since 2011 that renewables had to take on more of a demand to comply with the building regulations.

quentingargan

The number of tubes you have might be matched to your cylinder size. If your existing tubes are getting a cylinder full of cold water up to temperature during the day, putting more tubes on might only do this earlier. To cope with larger water use you need both heat generation and storage. Some tube manufacturer warranties are limited to a ratio between cylinder size and number of tubes.

TomOnBoard

quentingargan wrote: »

The number of tubes you have might be matched to your cylinder size. If your existing tubes are getting a cylinder full of cold water up to temperature during the day, putting more tubes on might only do this earlier. To cope with larger water use you need both heat generation and storage. Some tube manufacturer warranties are limited to a ratio between cylinder size and number of tubes.

That makes sense. Just proving yet again that one component of any system should never be judged in isolation of all the others.

The O.P. did imply that his usage has increased since the install as more ppl are living there. Hence, it is likely that the current storage which was grand at the time, is proving to be insufficient. So maybe the systems needs more storage or more solar thermal generation or both? Generating more heat may give a full cylinder earlier and if the hot water usage is staged appropriately during the day, it may heat twice as much water even within the existing storage. If it cant be staged (e.g. most daily hot water usage is concentrated within a relatively short time-frame, then more storage will likely be needed as well.

rolion

My supplier recommended 10 tubes per 100l of cylinder capacity.
You can increase the number of tubes but as mentioned by above posters,you may need to look at tubes and / or cylinder.
Also,piping may need to be changed ,from the roof down to pump, to accomodate the extra length of the roof mounted mixer.

unkel

quentingargan wrote: »

The number of tubes you have might be matched to your cylinder size. If your existing tubes are getting a cylinder full of cold water up to temperature during the day, putting more tubes on might only do this earlier. To cope with larger water use you need both heat generation and storage. Some tube manufacturer warranties are limited to a ratio between cylinder size and number of tubes.

Indeed. Kingspan quite strongly insists their accredited installers to do a 1:10 as in 30 tubes, 300l etc. As a 400l cylinder did not fit in my hot press, the installer wanted to do a 30 tube, 300l system. I wasn't happy with that so they agreed to install a 360l slimline cylinder and a 40 tube system. Slightly "oversized" they call it

unkel

TomOnBoard wrote: »

The O.P. did imply that his usage has increased since the install as more ppl are living there. Hence, it is likely that the current storage which was grand at the time

Yes that's clear from the OP. What I don't understand is why he had solar tubes installed in the first place. It's an expensive system and if you don't use a lot of hot water, payback time is terrible (even though you do get a nice fat subsidy). Maybe what kceire suggested, it was some sort of compliance solution at the time?