I don’t want to start a fundamental debate with technical comparisons here, but just ask a question that arises from my laziness … (researching is quite extensive—and the more you learn, the more complicated it gets).
I’ve already looked at the documentation from different companies and noticed that tube vacuum collectors tend to be in a higher price range than conventional flat-plate collectors.
Looking at the technical data, I feel like I need to study it all over again.
To explain: I want to start by trying out a collector that I install myself to see how much hot water I can generate. Then, multiplying that and implementing it on a larger scale in a professional installation should allow me to calculate in advance what the whole thing would cost, which shouldn’t be a problem.
So far, I am quite skeptical about the payback calculations I have seen. (–When thinking about photovoltaics, I already gave up for this reason.)
My problem is that the pitch of my gable roof faces DIRECTLY west.
Is that even enough to make the investment worthwhile?
The tube collector is supposed to perform better in this respect, as it can make better use of side radiation.
But when I look at the efficiency figures from the companies, I notice that for differences of around 7%, they act like one system is boiling the water and the other is almost cooling it ;-)
Has anyone had experience if the better sensitivity to side radiation really provides a significant advantage?
In the long run, the flat-plate collector is probably simpler than the tubes, since I see that spare parts are also offered for the tubes ?! – For me, this raises the question: does the vacuum degrade? After how long?
Even though this is a trial, I would prefer not to set up two test installations.
Thanks in advance for any tips,
a believer in the wisdom of the crowd. ;-)
I’ve already looked at the documentation from different companies and noticed that tube vacuum collectors tend to be in a higher price range than conventional flat-plate collectors.
Looking at the technical data, I feel like I need to study it all over again.
To explain: I want to start by trying out a collector that I install myself to see how much hot water I can generate. Then, multiplying that and implementing it on a larger scale in a professional installation should allow me to calculate in advance what the whole thing would cost, which shouldn’t be a problem.
So far, I am quite skeptical about the payback calculations I have seen. (–When thinking about photovoltaics, I already gave up for this reason.)
My problem is that the pitch of my gable roof faces DIRECTLY west.
Is that even enough to make the investment worthwhile?
The tube collector is supposed to perform better in this respect, as it can make better use of side radiation.
But when I look at the efficiency figures from the companies, I notice that for differences of around 7%, they act like one system is boiling the water and the other is almost cooling it ;-)
Has anyone had experience if the better sensitivity to side radiation really provides a significant advantage?
In the long run, the flat-plate collector is probably simpler than the tubes, since I see that spare parts are also offered for the tubes ?! – For me, this raises the question: does the vacuum degrade? After how long?
Even though this is a trial, I would prefer not to set up two test installations.
Thanks in advance for any tips,
a believer in the wisdom of the crowd. ;-)
B
boxandroof15 Feb 2019 13:20Höhlenmensch schrieb:
I determine the performance experimentally over different days (clear, cloudy, dull, cold) and observe which hot water temperatures I achieve. I can then scale this up to a larger system on the roof area to decide if I want to go through with it. This leads to the main question of the thread opening: flat plate or tube. To me, this sounds more like a hobby and a past-time. That’s fine, of course, but I wouldn’t argue based on profitability, since that often puts you at a disadvantage in discussions.
In the forum I mentioned, you will certainly find someone who is knowledgeable about the different tubes.
An alternative project suggestion for you: heat the water tank using electricity from a guerrilla photovoltaic setup (and install the proper photovoltaic system later ;-))
Höhlenmensch15 Feb 2019 20:17Okay, I did a photovoltaic system calculation a few years ago, but maybe things have changed since then.
One of the issues back then was that, for cost reasons, I only wanted to buy the parts and install them myself, which meant I didn’t qualify for any subsidies, so the estimated payback periods were no longer valid.
I will look into photovoltaic systems again.
Thanks for the tip about the water tank :-) I can already picture myself sitting in the garden in a clay pot, waiting for a thunderstorm to turn lightning amps into warm water using a kite string like Franklin once did. ;-)
My skepticism also comes from the experiences of other acquaintances who found that the promised results were not achieved.
For example, there were corrosion defects in the pipes, which are supposed to be prevented in the future by using electronic potential compensators (current). Oxygen-binding agents are also now added, which must be monitored analytically (additional maintenance effort). You can definitely get yourself into trouble.
From my own experience with electricity here in Berlin, meters are being digitally upgraded so operators can soon read them remotely via telephone lines. As part of this, not only is the meter replaced, but the electrical distribution must be updated to new DIN standards. Additional surge protectors for network protection, adaptations for the digital meter’s future internet connection, and if earth current values are off, extra grounding mats have to be installed. That’s a lot of unexpected costs when connecting to the power grid. (Costs, costs, …)
… and I have to do all that if I want to sell the electricity I generate myself.
Of course, I don’t want to change my daily routine and have the washing machine run at noon on a timer, just because that’s when the sun is at its highest. I only run the machine when I’m home! … ever had a water damage?
Thanks for the forum recommendation; I’ll check it out for my DIY project.
If it helps, I’ll report back.
Right now, my heating is still running and I shower without thinking about it.
If it gets warmer soon (climate change? We’ve never had it this warm before), I’ll turn it off and then the electricity meter will start spinning. It would be nice if the sun could help with that.
Is showering less actually advisable from a payback perspective? ;-)
Greetings from the still showering “Clean Freak”
One of the issues back then was that, for cost reasons, I only wanted to buy the parts and install them myself, which meant I didn’t qualify for any subsidies, so the estimated payback periods were no longer valid.
I will look into photovoltaic systems again.
Thanks for the tip about the water tank :-) I can already picture myself sitting in the garden in a clay pot, waiting for a thunderstorm to turn lightning amps into warm water using a kite string like Franklin once did. ;-)
My skepticism also comes from the experiences of other acquaintances who found that the promised results were not achieved.
For example, there were corrosion defects in the pipes, which are supposed to be prevented in the future by using electronic potential compensators (current). Oxygen-binding agents are also now added, which must be monitored analytically (additional maintenance effort). You can definitely get yourself into trouble.
From my own experience with electricity here in Berlin, meters are being digitally upgraded so operators can soon read them remotely via telephone lines. As part of this, not only is the meter replaced, but the electrical distribution must be updated to new DIN standards. Additional surge protectors for network protection, adaptations for the digital meter’s future internet connection, and if earth current values are off, extra grounding mats have to be installed. That’s a lot of unexpected costs when connecting to the power grid. (Costs, costs, …)
… and I have to do all that if I want to sell the electricity I generate myself.
Of course, I don’t want to change my daily routine and have the washing machine run at noon on a timer, just because that’s when the sun is at its highest. I only run the machine when I’m home! … ever had a water damage?
Thanks for the forum recommendation; I’ll check it out for my DIY project.
If it helps, I’ll report back.
Right now, my heating is still running and I shower without thinking about it.
If it gets warmer soon (climate change? We’ve never had it this warm before), I’ll turn it off and then the electricity meter will start spinning. It would be nice if the sun could help with that.
Is showering less actually advisable from a payback perspective? ;-)
Greetings from the still showering “Clean Freak”
B
boxandroof15 Feb 2019 21:14Yes, take another look at photovoltaic systems; the opinions shared here are well-founded, unbiased, and come from critical homeowners with personal experience – collective intelligence and all that.
By the way, my reference to guerrilla photovoltaics was serious, less about heating water, but you should look it up. Meant as a DIY project, like solar thermal but smaller and with electricity 🙂
And please keep us updated; we’re curious.
By the way, my reference to guerrilla photovoltaics was serious, less about heating water, but you should look it up. Meant as a DIY project, like solar thermal but smaller and with electricity 🙂
And please keep us updated; we’re curious.
B
boxandroof16 Feb 2019 00:02Höhlenmensch schrieb:
Is showering less often actually advisable from a cost-recovery perspective? ;-) That was good 🙂
I have no knowledge about photovoltaics. But I can honestly say that since February 14th, our solar thermal system alone has been producing hot water without any additional heating. I have turned off the hot water heating system. The sun’s position is sufficient and will be enough until about mid-October. Hot water for two people. Not so bad at all. Karsten
N
nordanney17 Feb 2019 17:26Nordlys schrieb:
Since February 14th, our solar thermal system has been producing hot water entirely without additional heating The solar thermal system is already sufficient. You won’t get any more yield in summer when the sun is really shining.
With photovoltaics, however, you do get more (even some in winter), which you can then sell.
The original poster doesn’t understand this.
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