Solar panel

[lucly]

hi, im from Romania and here all the pipe connections for solar panels for dhw are braze or press fitting , i hard that sum plumbers in Europe special on the petrol platforms use soft welding ([FONT=arial,sans-serif][SIZE=-1]Soldering)???IS IT POSSIBLE ? 😕


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[Alanka]

Of course it's possible! Why not? When done properly, a soldered joint with copper pipes will last many years.

 

[lucly]

ok tx for your comment

 

[buster]

Hi, Solar is mainly used in this county to heat domestic hot water (DHW) and most systems are supplied with most fittings because of the very, very high temperatures that can be created within a solar panel, after all the sun is the most powerful heat source in the universe. It is not recommended to use soft soldered joints because of this reason! If soft solder is used before the exchange coil there is a chance of the joint sweeting and becoming compromised or detached. But most systems are kit based so you should not have this problem! Nearly all kits are supplied with annealed pipe and not just because its easy to work with but because of 'linear expansion of materials' and the fact that most plumbers prefer not to work with low carbon steel pipe (LCS) in a domestic setting.
Buster

 

[Agile]

Of course it's possible! Why not? When done properly, a soldered joint with copper pipes will last many years.

Clearly Alanka has not attended a solar course otherwise he would not be giving the wrong answer!

Thats the trouble with these internet forums with anonymous posters, you have no way of knowing if they are qualified or not!

At least Buster realises the temperatures can get very high and he knows that soldered connections are not permissable but he then suggests that plastic and pushfit connections are better! I am sure that on reflection he will realise that plastic fails just over 100° whereas soldered copper can stand 300° !

Solar panels should only be connected with compression joints! Silver soldered or brazed joints would also be acceptable but are not usually practiced for heating in the UK.

Tony

 

[lucly]

mmmmmmmmmmmmm
I see, you are right,

 

[Alanka]

Thanks for your input, Agile! Apologies for misleading the forum -- indeed I have not attended a solar course, so I should not have made the comments I did.

I presumed that solar pipework, though able to get very hot indeed, would not reach anything like 300*C, and so would not affect a soft soldered joint. It is surprising isn't it!

 

[Paultheplumber]

Surely it would not get any hotter than the 82 degrees most boilers can reach i mean all the safety devices in terms of thermostats are there to make sure that the water in pipe work NEVER gets past 95 degrees celcius. This being because under pressure its possible for water not to turn to steam until way past 100 degrees celcius and if someone opened that temp water to atmophere they would probably die as it would instantly turn to steam. So it cannot be for temperature reasons there must be another reason for not using soft solder.

 

[Spirit]

The water in a solar hot water system can get a lot hotter than that. Soft solder can fail at the high temperatures and pressures. Only compression or hard solder joints should be used.

 

[david williams]

most of the big solar comps use soldered fittings but not within 3 meters of panel

 

[Jimbob]

Some companys say that you use compression fitting within a certain distance of the panels, then after that it is ok to solder. I have never tried this though and have always used compression and trac-pipe fittings.

 

[lenny]

Hey if you want european expertise on solar try New Page 3

 

[so-solar]

Hi Lads!

The golden rule for solar installing ' NO SOLDER ON SOLAR'

The systems that i install are tested up to 220'c so there is avery high chance of a solder joint failing!

I use stainless steel pipe right from the panel through the pump station and connect straight on to 'dn' 16 fittings on the cylinder! therefore i am eliminating any copper in my installation!

This is what i was taught on a solar course in germany!

I am not saying this is the right way but it has worked for me and i am only passing on what i believe to be valuable advice.

1 more piece of advice! Solar runs alot hotter than domestic heating systems and the liquid i use is a glycol based formula that boils at a far higher temperature than water allowing the solar to work far longer than a water based liquid. remember, the solar system will shut down at around 140'c so the panel could sit in the sun for a long period of time, therefore very high temperatures can be reached on the panel itself, meaning that solder joints close to the panel could be at risk of popping.

Hope this helps!

 

[Plucky]

We try to use solarflex when installing solar which is very similar to trac pipe.

 

[david williams]

solar fluid is also under presure when in use which raises boiling point.

 

[solarsavings]

You can use lead free solder of solar system in the UK> Solder has been used and will continue to be used for many years without failing due to high temperatures.

Systems in Germany and Austria tend to be very large, they run at 3-6 bar when cold to raise the boiling point. They have poor emptying behavior when stagnating,(u-pipe or serpentine collectors) produce large amounts of steam at high temperature. because of this, they need very large expansion vessels are plumbed in using stainless flexi pipe to massive thermal stores 2500-5000l. Our systems in the UK are very small by comparison typically 200-300l would be considered large here.
Unfortunately many have adopted the German pipe installation method here believing ti to be better while cutting installation times too. They cant explain why Flexi is better or how it is that so many systems installed using solder have survived for many years without problems they just state blindingly "solder cant be used".

We tend to use collector with good emptying behavior, heatpipe or riser rail collectors. Our systems run at 1-3bar so boiling temperatures are lower, steam volumes smaller so expansion vessel are smaller too. I have yet to see a system anywhere near the 300c Agile and others claim, I doubt I ever will. The highest system temperature I've seen is 170c, the highest collector temperature was 230c. I have installed Ritter, Thermomax and Chinese vacuum tube collectors along with very many European flatplates. Tony may know all there is to know about boilers but he knows very little about solar other than that he learnt on his BPEC course.

A solar installer near me with more than thirty years experience who was once the head of the solar trades association. Still uses solder, as does his son, so do I and very many others too.

 

[so-solar]

The growth mechanism of intermetallics between solders and metallized substrates, after thermal aging, are investigated. The solders used in this study are unleaded Sn-Cu-Ni solder and eutectic Pb-Sn solder. The Pt-Ag/Al2O3, Cu block and the electroless Cu/Pt-Ag/Al2O3 are employed as the metallized substrates. Microstructure evolution of the interfacial morphology, elemental, and phase distribution are probed with the aid of electron-probe microanalyzer (EPMA) and x-ray diffractometry. Two kinds of intermetallics, Cu3Sn and Cu6Sn5, are formed at the solder/Cu interface. However, for the solder/Pt-Ag system, only Ag3Sn is observed at the interface. The thickness of Cu3Sn, Cu6Sn5, and Ag3Sn compound layers for all solder/metallized substrate systems shows at t0.5 dependence at 100, 125, 150 and 170 C. According to the calculated activation energy and diffusion constant, the growth rate of Cu3Sn and Cu6Sn5 intermetallics in the electroless ***etallized substrate is relatively higher than that for Cu block one at the range of 100 C to 170 C. However, the growth rate of Cu6Sn5 and Ag3Sn is reduced in the Sn-Cu-Ni solder with respect to the eutectic Pb-Sn solder. On the other hand, the Sn-Cu-Ni solder system exhibits a thicker Cu3Sn intermetallic layer than the eutectic Pb-Sn solder after various aging times at 100 C. The thickness of Cu3Sn in the eutectic Pb-Sn solder is, however, thicker than that for Sn-Cu-Ni solder at 170 C.

Stick that in ya pipe and smoke it!

You have quite clearly stated that you have seen 170'c on a solar system which looks to be solder melting point!

 

[paulproject]

hi sorry it has nothing to do with your thread but i have just posted a thread but it hasnt shown up in the forums. does it take a while to show up??

 

[solarsavings]

The growth mechanism of intermetallics between solders and metallized substrates, after thermal aging, are investigated. The solders used in this study are unleaded Sn-Cu-Ni solder and eutectic Pb-Sn solder. The Pt-Ag/Al2O3, Cu block and the electroless Cu/Pt-Ag/Al2O3 are employed as the metallized substrates. Microstructure evolution of the interfacial morphology, elemental, and phase distribution are probed with the aid of electron-probe microanalyzer (EPMA) and x-ray diffractometry. Two kinds of intermetallics, Cu3Sn and Cu6Sn5, are formed at the solder/Cu interface. However, for the solder/Pt-Ag system, only Ag3Sn is observed at the interface. The thickness of Cu3Sn, Cu6Sn5, and Ag3Sn compound layers for all solder/metallized substrate systems shows at t0.5 dependence at 100, 125, 150 and 170 C. According to the calculated activation energy and diffusion constant, the growth rate of Cu3Sn and Cu6Sn5 intermetallics in the electroless ***etallized substrate is relatively higher than that for Cu block one at the range of 100 C to 170 C. However, the growth rate of Cu6Sn5 and Ag3Sn is reduced in the Sn-Cu-Ni solder with respect to the eutectic Pb-Sn solder. On the other hand, the Sn-Cu-Ni solder system exhibits a thicker Cu3Sn intermetallic layer than the eutectic Pb-Sn solder after various aging times at 100 C. The thickness of Cu3Sn in the eutectic Pb-Sn solder is, however, thicker than that for Sn-Cu-Ni solder at 170 C.



Stick that in ya pipe and smoke it!

You have quite clearly stated that you have seen 170'c on a solar system which looks to be solder melting point!

Yes I've seen 170c on solar loops several times most have melted the AAV several times but never the solder. so stick that in pipe! BEPC boy
Here's a cut and paste for you.
SnSb5, tin with 5% of antimony, is the plumbing industry standard. Its melting point is 232-240 °C. It displays good resistance to thermal fatigue and good shear strength.

Here's another for you
Main article: Solder
Soldering filler materials are available in many different alloys for differing applications. In electronics assembly, the eutectic alloy of 63% tin and 37% lead (or 60/40, which is almost identical in performance to the eutectic) has been the alloy of choice. Other alloys are used for plumbing, mechanical assembly, and other applications.
A eutectic formulation has several advantages for soldering; chief among these is the coincidence of the liquidus and solidus temperatures, i.e. the absence of a plastic phase. This allows for quicker wetting out as the solder heats up, and quicker setup as the solder cools. A non-eutectic formulation must remain still as the temperature drops through the liquidus and solidus temperatures. Any differential movement during the plastic phase may result in cracks, giving an unreliable joint. Additionally, a eutectic formulation has the lowest possible melting point, which minimizes heat stress on electronic components during soldering.
Common solder alloys are mixtures of tin and lead, respectively:

• 63/37: melts at 183 °C (361.4 °F) (eutectic: the only mixture that melts at a point, instead of over a range)
• 60/40: melts between 183–190 °C (361–374 °F)
• 50/50: melts between 185–215 °C (365–419 °F)

Lead-free solders are suggested anywhere children may come into contact with (since children are likely to place things into their mouths), or for outdoor use where rain and other precipitation may wash the lead into the groundwater.
Lead-free solder alloys melt around 250 °C (482 °F), depending on their composition.
For environmental reasons, 'no-lead' solders are becoming more widely used. Unfortunately most 'no-lead' solders are not eutectic formulations, making it more difficult to create reliable joints with them. See complete discussion below; see also RoHS.
Other common solders include low-temperature formulations (often containing bismuth), which are often used to join previously-soldered assemblies without un-soldering earlier connections, and high-temperature formulations (usually containing silver) which are used for high-temperature operation or for first assembly of items which must not become unsoldered during subsequent operations.
Alloying silver with other metals changes the melting point, adhesion and wetting characteristics, and tensile strength. Of all the brazing alloys, the silver solders have the greatest strength and the broadest applications. [4]
Specialty alloys are available with properties such as higher strength, better electrical conductivity and higher corrosion resistance.

Oh and one final thing, Fernox technical told me their lead free solders melting point is 258c

 

[Agile]

Surely it would not get any hotter than the 82 degrees most boilers can reach i mean all the safety devices in terms of thermostats are there to make sure that the water in pipe work NEVER gets past 95 degrees celcius.

Another person who needs to go on a Solar Course!

Its not a gas boiler! You cannot just turn off the sun when it gets too hot !

Steam can be at any temperature and expands by about 500 times the volume when opened to atmosphere from pressure.

Go on the course!

Tony

 

[holedoctor]

listen to agile he knows what he is talking about. safest and easiest option is compression unless your good at brazing, silver solder is not as easy as soft solder to use or just use flexable stainless steel pipe more expensive but takes the skill out of pipe work.

best of luck

 

[Plucky]

flexible pipe here. Can normally hide it down the back of a cylinder cupboards. Easier to weater through the roof as well ans I put my slate behind tubes and pull the pipes out underneath and straight onto connections so you barely see any pipe.

 

[kirkgas]

i was advised if using compression fittings to use brass olives rather than copper for solar

 

[solarsavings]

Another person who needs to go on a Solar Course!

Its not a gas boiler! You cannot just turn off the sun when it gets too hot !

Steam can be at any temperature and expands by about 500 times the volume when opened to atmosphere from pressure.

Go on the course!

Tony

Another great post from you with regards solar Tony.
What course would you recommend. Bpec perhaps?.

You may not be able to "turn off the sun" but you turn off your solar thermal system or re-cool it depending on the installation method cant you.

Steam 500 times volume really? at what point and in what system is that likely to happen?

Tony Stone

 

[ecowarm]

at what point and in what system is that likely to happen?

It can and does happen at stagnation and the excess pressure taken up by the expansion vessel. But it all returns to liquid again as the collectors cool down.

Eco