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Author Topic: solar thermal or not..  (Read 3753 times)
duke700
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« on: June 04, 2019, 06:57:08 PM »

Hi Folks

I installed a thermal store last year which is run by a back boiler stove and feeds 7 radiators.
The store itself has two immersiers fitted .
I got tappings fitted to take Solar thermal panels but after reading up on stuff I'm not sure which way to go?
Should it be solar thermal? Or do i fit Pv panels and they can run the immersiers and other stuff..

Any advice would be much appreciated.

Thanks
Andy
 
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Tinbum
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« Reply #1 on: June 04, 2019, 07:50:56 PM »

immersiers  Huh   extrahappy

I have both and both are good, to be honest, for simplicity if I were doing it now I would just go for PV.

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DonL
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« Reply #2 on: June 05, 2019, 05:56:27 AM »

Either system is unlikely to make a significant contribution to your heating needs in winter when sunshine is scarce. Either could provide most of your hot water needs in summer. Layout might be critical solar hot water is much more efficient at converting solar energy to heat so the collectors are physically much smaller. if you have a large south facing roof, PV would probably be simpler and give other benefits in reducing electricity consumption. If you only have a small area of south facing roof solar thermal would be more attractive.
Don
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duke700
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« Reply #3 on: June 05, 2019, 08:09:10 AM »

Thanks for the input,much appreciated.
Its to help with hot water in the summer months when fire isnt on..

Thanks again.
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todthedog
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« Reply #4 on: June 05, 2019, 11:52:15 AM »

I have had both, ST provided hot water for about 8 months without the need of electricity. 200L tank supplying 2 adults.
PV is just great and probably the one I would opt for if I had limited roof space.
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dimengineer
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« Reply #5 on: June 07, 2019, 02:13:00 PM »

I have had both, ST provided hot water for about 8 months without the need of electricity. 200L tank supplying 2 adults.
PV is just great and probably the one I would opt for if I had limited roof space.

I'm curious. I thought it might be the other way round. The heat collected per square metre is much better with ST than PV? So if you've only limited roof, then ST would be better surely?
Or am I missing something?
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Pile-o-stone
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« Reply #6 on: June 07, 2019, 02:41:46 PM »

Several years ago I was looking at installing Solar Thermal, until I read this article:

https://www.renewableenergyworld.com/articles/2013/09/solar-hot-water-which-is-better-pv-or-thermal.html

The sentence that had the biggest impact and stuck in my mind enough to help me find the article again on google was:

"The Achilles Heel of solar thermal is that if the system stops working, it does not just fail to produce energy: it sets about its own self-destruction."

I subsequently installed PV (attached to 2x immersiers in my thermal store) and I have never regretted that decision, especially when the tank is full of hot water but the panels still generate usable energy.

« Last Edit: June 07, 2019, 02:43:58 PM by Pile-o-stone » Logged

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kristen
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« Reply #7 on: June 07, 2019, 02:57:11 PM »

"The Achilles Heel of solar thermal is that if the system stops working, it does not just fail to produce energy: it sets about its own self-destruction."

This.

I have both. Solar Thermal has needed maintenance from time to time. Air gets in. But reading this forum I reckon that has only happened to 50% of people, the other 50% (including my Father in law, who had his fitted by the same people, at the same time as mine) have never had a problem

I also have a separate Solar Thermal system for Pool. I wish I had put in PV plus Heat Pump. That would have the benefit in Summer of PV-runs-HeatPump but also in Winter or when pool s hot enough PV-goes-into-House and, if I need it (e.g. beginning of season) Grid-runs-HeatPump

PV much more flexible than Solar Thermal and, I suspect, less chance of needing maintenance

If you have PV then only the excess needs to run Immersion ... for starters you will have zero electricity consumption during the day (although maybe house is empty, and you are out at work? in which case after Fridge/Freezer then Immersion will be on)

With Solar Thermal you need to consider what happens when Tank is hot as the solar heat has to go somewhere.

Solar Thermal works best if pipe runs from hot water tank to solar panels on roof are short. Electricity doesn't care ...
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biff
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« Reply #8 on: June 07, 2019, 03:53:09 PM »

PV wins hands down.
  No trouble with airlocks. Faulty tubes etc. You have absolutely no hassle with heights or trying to avoid unsightly pipe runs and like Pile O Stones says. Once the tanks are full of hot water  the surplus heat exchanges  into our central heating System. Or used to supply electricity.
           Biff
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Iain
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« Reply #9 on: June 07, 2019, 07:21:27 PM »

Hi
Quote
.PV wins hands down


only if you have the space.

I have both. The solar thermal is taking the space of 4 of my PV panels. My PV panels are 180w so the solar thermal takes the space of 720 w worth of panels but gives about 2 kw.
So for the same area I get nearly 3 times the energy.

There is a bit of maintenance to do on solar thermal. In 10 years I have changed the fluid once. That is all.
So if space is a factor solar thermal can have great advantages.

It also means you don't have to waste high quality easily transferable energy by transfering it into heat.

Iain
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dimengineer
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« Reply #10 on: June 07, 2019, 09:01:19 PM »

Hi
Quote
.PV wins hands down


only if you have the space.

I have both. The solar thermal is taking the space of 4 of my PV panels. My PV panels are 180w so the solar thermal takes the space of 720 w worth of panels but gives about 2 kw.
So for the same area I get nearly 3 times the energy.

There is a bit of maintenance to do on solar thermal. In 10 years I have changed the fluid once. That is all.
So if space is a factor solar thermal can have great advantages.

It also means you don't have to waste high quality easily transferable energy by transfering it into heat.

Iain

Thats kind of my take on it as well.
I've got both.
In the area I have my ST panel, i'd fit 2 PV panels - thats 500W only. I cant see how i'd ever get as much benefit from PV panels as from my ST.

However, I do get the idea that if you are starting from scratch, a pure PV install is going to be a better bet (if you have hte roof space - many of us don't)
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billi
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« Reply #11 on: June 07, 2019, 10:55:01 PM »

PV is my advice too , beside warm water it reduces the electricity bill   , as well  produces something on dull days ......
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duke700
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« Reply #12 on: June 08, 2019, 08:36:48 AM »

Many thanks for taking the time to share your views on it..
I've plenty room on the roofs and lucky enough to have some land so I'm  thinking log  store and use roof for the panels if need be..

Thanks again

Andy
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