Buyer beware! Any company that uses lies and pressure to achieve sales, walk away from them. Legionaires cannot survive above 55C, therefore by heating your water within your cylinder to temperatures above this will automatically kill legionaires. This is why cylinder thermostats should be set to minimum 60C. Where legionaires is more likely to occur is within a shower head, where temperatures are normaly lower and shower heads break water into a mist. This is easier for us to breath in the legionaires. Solar cannot kill legionaires at the shower head and normal heating systems heat water within the cylinder to 60C or above. You should not install solar on the basis that is is safer and €8,000 is a monstrous amount!
Evacuated tubes overall perform better than flat plate collectors. They both perform fairly equally in summer, but have different performances in winter and in shoulder seasons.
Evacuated tubes have their absorbers surrounded by a vacuum, therefore very little heat loss and also ambient temperatures do not cool the absorbers. Flat plate collectors have no vacuum. Therefore in cold temperatures, but sunny days, evacuated tubes will absorb the sun's radiant heat without being cooled by the surrounding low temperatures.
Flat plate collectors also lose some efficiency from solar radiation being reflected off the glass as it is flat. The sun is a moving target being higher in the sky in summer and lower in winter. Radiation from the sun is reflected when is not at ideal angles and therefore not all is absorbed by the absorber. Evacuated tubes loose much less from reflection as they are round and can absorb from a much greater range of angles.
Also with heat pipe evacuated tubes, the water within the heat pipe itself is within a vacuum. Water under normal atmospheric pressure boils as we know at 100C. In a vacuum, the boiling point is lowered, depending on the strength of the vacuum, to on average 15C. Therefore, for heat to be transferred from the absorber to the heat transfer fluid heating the coil in the cylinder, only 15C has to be achieved. This, of course, does not happen with direct flow tubes as the heat transfer fluid (glycol) is pumped through the absorber itself and is not contained within a vacuum.
This is a fine post, one of the best I have seen in a while.
I have a small query about the sentence underlined.
If the temp in the cylinder is > than 15 degrees then what heat gets transferred.
In terms of energy transfer, I know from my mountaineering days that while the water might 'boil' on the side of K2, it took much longer to cook the egg as the water was boiling at 50 or so C
Am a bit puzzled here, have no issue with the post, just on the science in the last piece
Flat plate panels are easier to keep clean especially if u are in an area prone to lots of leaves.
I believe easier to replace a broken tube in the evac tube ones
Having said that neither make sense $$$ wise in the standard configuration 'sold' in Ireland.
Thanks for this.
what is the liquid used that boils and condenses as the energy transfer is related to the vapourisation/condensing of this liquid.?
We have 3 panels installed since 2016 . I don't understand the technical issues but I do know that they don't work as we get very little hot water even on bright summer days. These panels are the worst investment on our house that we have made. Active 8 have so far provided no back up servicing despite efforts to make a booking . The only contact from active8 is when they try to sell us new panels.(no chance)
What company did you go with and when did you install the panels?Do you have a timing switch?
Our solar panels work brilliantly.
I also had a visit from Activ8 and I agree with you but the final price they gave me was 7,5k not 25k for a normal system that would cover well our needs. How did the cost of your system come out to 25k????Like others I found the Activ8 sales tatics extremely aggressive and frankly predatory. The sales guy didn't leave our house until 10pm after spending hours trying to persuade us to sign there-and-then or we'd lose out on this deal or that deal. Secret codes that you have to pass from your first contact with them to your sales guy. Proposal that started out near to €25k for a very basic system. Deals that expire that night etc etc.
They are part-owned by SSE Airtricity, no idea how they are letting these practices take place under their name to be honest.
Avoid like the plague, there are plenty of really good companies out there.
Who knows. Maybe they've corrected their ways, this was early last year. Maybe they thought I was a sucker so tried it on. To be fair I think the final quote after I gave the secret code, agreed to put a sign in my garden and did the secret hand shake (only this part is made up) was €15k, but that was for a small system with no battery - ie. it is in excess of 200% above the price it should be.I also had a visit from Activ8 and I agree with you but the final price they gave me was 7,5k not 25k for a normal system that would cover well our needs. How did the cost of your system come out to 25k????
ah, so you don't know who did the job. Are they still good?They were installed when we bought the house.
Do you know what size battery you were being quoted? Also the power output of the panels?Can anyone advise on the best type of Solar Panels to install. I was told that Badger Power Electronics (BPE) are reliable. I was quoted by an installer for 12 panels with battery and immersion diverter at a cost of €14,500 - grant €3,500 - cost to me €11,000
What's the power output output of those panels? Sounds expensive. boards.ie has huge threads on what people are being quoted and paying for solar panels here, you'll see a lot of examples of what you'd expect to pay there.Can anyone advise on the best type of Solar Panels to install. I was told that Badger Power Electronics (BPE) are reliable. I was quoted by an installer for 12 panels with battery and immersion diverter at a cost of €14,500 - grant €3,500 - cost to me €11,000
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