Are you all pleased with your solar panels for hot water heating

murphaph

dr.fuzzenstein wrote: »

I am German and have never seen 3 phase in a domestic house over there. Only ever in industrial units

I'm Irish and I'm building a house in Brandenburg at the moment and we already have our (standard) 100A 3 phase connection from e.dis (mini pillar with temp dist board and meter attached). We could have ordered a monster 250A connection for something like €300 more but it would never be used.

3 phase in house supplies absolutely are the norm here. You possibly never noticed because of the way things were wired. Even our present apartment in Berlin has 3 phase-I know, I connected the oven to it when I moved in That's the only thing in this flat that "uses" the 3 phases, though a single phase would be just fine. It isn't unusual in apartment blocks however to send a single phase to each flat, but the building will get all 3, as will your detached house. There are small regional pockets where the local grid doesn't allow this and it's set up like Ireland /UK where every 3rd house is on the same phase or whatever, but this is not common.

The phases are unmarked, so electricians will connect different loads at random to each phase so overall it will be more or less balanced. AFAIK 3 phase domestic supplies are standard in several other European countries. Seems to be a continental thing.

dr.fuzzenstein

^^^
Funny, I never noticed and I am German :pac: It was never needed in our previous house and I was a teenager, so I never paid attention.
We did have it in our next house, but that was because it had a bakery in it along with a shop, of course that had 3 phase, as the machinery needed it.

John T Carroll

John T Carroll wrote: »

Flowrate isnt the problem for my mains shower, its the power available to heat the water and stay around 40 amps cable loading, I can get over 10 LPM from my shower but because of the 9.5 KW I can only have around 4 LPM but if I had a three phase supply I could have a 16.45 KW shower for the same amps (but not running cost obviously) which would give a comfortable flowrate of over 7 LPM. You wont see too many electric showers in the USA as they only have a domestic supply of 110V.

My point was though is the majority of people in Ireland have central heating and this meets most of their yearly water needs then why use 9 kw showers to heat water when there is loads of it in the tank ?

My shower is pumped and plenty powerful.

dr.fuzzenstein

Deleted User wrote: »

My point was though is the majority of people in Ireland have central heating and this meets most of their yearly water needs then why use 9 kw showers to heat water when there is loads of it in the tank ?

My shower is pumped and plenty powerful.

Oh yes, it is the height of silliness. We have a pellet burner and it does heat the tank, except when we get our 2 week summer twice a decade and for that we have a very rarely used electric shower downstairs. Plans for solar have been shelved for now due to financial constraints.
If I was going for solar, I would have a million questions. My system would be for hot water and it would be fairly small (only have a 200 liter tank). In most systems, a radiator is installed outside to vent heat, I would rather have that heat be dumped into my radiators, because of the stone floor the house is always cold. There would be two coils going into the water tank, one from the pellet burner and (in future) one from solar. Would it be possible to just install an additional pump that activates if the water in the tank is about to go over a certain temperature? It would then simply start circulating water through the radiators in the house. That way the water and radiators would both get heated (radiators to a much lesser degree, I know that), so the solar would contribute to space heating in a small but maybe not insignificant degree, so less pellets would have to be burned. it seems logical to me, but the one or two installers I mentioned it to seem to think it's some kind of crazy, outlandish idea.

dr.fuzzenstein

dr.fuzzenstein wrote: »

If I was going for solar, I would have a million questions. My system would be for hot water and it would be fairly small (only have a 200 liter tank). In most systems, a radiator is installed outside to vent heat, I would rather have that heat be dumped into my radiators, because of the stone floor the house is always cold. There would be two coils going into the water tank, one from the pellet burner and (in future) one from solar. Would it be possible to just install an additional pump that activates if the water in the tank is about to go over a certain temperature? It would then simply start circulating water through the radiators in the house. That way the water and radiators would both get heated (radiators to a much lesser degree, I know that), so the solar would contribute to space heating in a small but maybe not insignificant degree, so less pellets would have to be burned. it seems logical to me, but the one or two installers I mentioned it to seem to think it's some kind of crazy, outlandish idea.

I'd be more inclined to go with solar PV rather than hot water, you can do a lot more with electricity and heat water, use electric heating for heat etc. Though at that point I would use some kind of heat pump and a small storage battery.

Air to water heat pumps are getting a lot more efficient.

dr.fuzzenstein

Deleted User wrote: »

I'd be more inclined to go with solar PV rather than hot water, you can do a lot more with electricity and heat water, use electric heating for heat etc. Though at that point I would use some kind of heat pump and a small storage battery.

Air to water heat pumps are getting a lot more efficient.

Why not both? Or would PV supply enough power to heat water, run half the house (and in your case) charge an EV? I reckon you'd need both and wind on top of that to even partially cover all that. I'm a little sceptical about heat pumps, most of them seem to generate the kind of electricity bills you would get if you just installed night storage...

dr.fuzzenstein

dr.fuzzenstein wrote: »

Why not both? Or would PV supply enough power to heat water, run half the house (and in your case) charge an EV? I reckon you'd need both and wind on top of that to even partially cover all that. I'm a little sceptical about heat pumps, most of them seem to generate the kind of electricity bills you would get if you just installed night storage...

Solar PV can charge the car, power the house for the year, according to the solar calculator I would need 8-9 KwP, this won't work without a feed in tariff because all that excess in Summer i would buy back in winter and get paid for any excess.

Having a battery would mean you need to store too much to tie you over for winter.

Almost 53% of Ireland's total electricity today is coming from wind and about 40-45% the last week or so and if we had Solar PV on every roof in Ireland this would make a big difference. Electric cars can store the excess !

rolion

Back to solar panels for DHW !

Im looking at options here...i have a Joule 40 tubes and 300L cylinder.

Today,at the bottom of the cylinder i had 30ish while at top around 40ish.
Once i start using the water,temperatures dropped quick under 20".

Im insulating the tank,the pipes and the 2 x 60 litres expasion vessels on Saturday,so that i will bring warmer water in the cylinder.
Is it going to be better if i fit an extra 20 tubes,having a 60 tubes system !?
I know winter will be fine but im woried for sunny days or in the summer, when i may have to cover one panel...

Thanks.

rolion

Back to solar panels for DHW !

Im looking at options here...i have a Joule 40 tubes and 300L cylinder.

Today,at the bottom of the cylinder i had 30ish while at top around 40ish.
Once i start using the water,temperatures dropped quick under 20".

Im insulating the tank,the pipes and the 2 x 60 litres expasion vessels on Saturday,so that i will bring warmer water in the cylinder.
Is it going to be better if i fit an extra 20 tubes,having a 60 tubes system !?
I know winter will be fine but im woried for sunny days or in the summer, when i may have to cover one panel...

Thanks.

championc

Only you know how well your system performs so you'll have a better idea about the necessity to possibly cover some tubes. However, you should possibly just increase the maximum temperature threshold. What is it set to, and did you ever hit it in the past ?

As for your current values, it sounds like you're temp probes are picking up the room temp around them. Maybe they have been attached to pipes on the outside of the tank rather than in pockets in it. The 300l tank will have a fairly thick insulation layer so I can't see the point of insulating it further.

My tank is in the attic. I have no insulation around the roof space. I don't care how cold the attic gets. But I only lose 1 deg every two hours.

rolion

According to my system supplier( Joules ) the capacity of the tank that I have (300L) will service only 30 tubes (10 tubes by 100L).
So, as my house will not take more than a 300L cylinder, i am forced to stay within the current parameters.
To retain the benefits, insulating the pipes, tank and attic will keep the inlet temperature with few degrees higher, in the cylinder.

rolion

According to my system supplier( Joules ) the capacity of the tank that I have (300L) will service only 30 tubes (10 tubes by 100L).
So, as my house will not take more than a 300L cylinder, i am forced to stay within the current parameters.
To retain the benefits, insulating the pipes, tank and attic will keep the inlet temperature with few degrees higher, in the cylinder.

freddyuk

Just install a simple bypass and crank the temperature limit up to 80c and install a TMV if you do not have one. The 30 tubes will hardly ever use the bypass but is is an important addition if you go away in summer. A decent controller will have programmes to cool the system automatically. Once you realise you have plenty of thermal capacity you can add more tubes thus increasing your season production profile. Joules info is incomprehensible.

josip

+1 on the bypass. Expensive repair bills without one.

rolion

Thanks for reply.

System installed in autumn so I cant predict how it will perform in the summer. I have to wait maybe and then proceed with upgrade or cancel and keep current.
Joules said 10 tubes for 100L,according to current Legislation / recommendation.

Based on your advice above...that means ignoring manufacturers advice, spend €1,500 so that I can have a bypass and dump the hot water, generated by the upgraded system !? Or, im I missing something...

rolion

Thanks for reply.

System installed in autumn so I cant predict how it will perform in the summer. I have to wait maybe and then proceed with upgrade or cancel and keep current.
Joules said 10 tubes for 100L,according to current Legislation / recommendation.

Based on your advice above...that means ignoring manufacturers advice, spend €1,500 so that I can have a bypass and dump the hot water, generated by the upgraded system !? Or, im I missing something...

josip

We got a system installed without a bypass (never suggested by the installer). It was a great setup. South Facing roof, pump directly (<1m) behind the panels, 250l cylinder directly (~2.5m) beneath the pump.
We used to get a full cylinder of 50 C on a clear day at the end of January.

The pump failed the first summer, nobody explained why. It was under warranty but had to pay labour and the plumber took a while to come out.
The pump failed the second summer also and no longer covered by warranty. Another plumber had a look at it and said that the problem was caused by not having any heat dump and that the panels got to such a high temp that the heat travelled via conduction along the pipe wall and burnt out the motor. His fix was to replace the 1m pipe between panels and pump with 5m of pipe. Another few hundred euro for a less efficient system. Our pump hasn't burned out since, but if we go away on holidays in the summer, I have to put sleeves on the tubes to prevent stagnation.

So I think that getting a heat dump put in at design time is a good idea, but I didn't realise it would cost €1500?

Read the first bit before the "sell".
http://www.greentherm.ie/stagnation-and-solar-panels/

championc

I have 30 tubes connected to a 180 litre store. I've only maxed out twice. It seems some installers "assume" things.

I've said it before and i"'ll say it again, you can't beat getting data logging on your system. You can see exactly what's happening, day or night.

You may get 50 deg on a good day during Jan on 250l store, but I wonder what the starting temperature was

josip

championc wrote: »

I have 30 tubes connected to a 180 litre store. I've only maxed out twice. It seems some installers "assume" things.

I've said it before and i"'ll say it again, you can't beat getting data logging on your system. You can see exactly what's happening, day or night.

You may get 50 deg on a good day during Jan on 250l store, but I wonder what the starting temperature was

T2 = 18C, T3 = 27C

Qualitymark

I was asking a friend about his solar panels and he was very very happy with them. Said he'd give me the name of the company, who'd been efficient and fast and did a great job installing.
Then I didn't hear from him for a while. Ran into him, and he said "I know I said I'd get back to you about that company, but my feelings about them have changed. I had a problem, called them, they came to fix it, then it broke down again a couple of days after they'd gone. Now I can't get hold of them. They're not answering calls or texts or emails."
One company that won't be getting me - or any other friend, acquaintance or customer of my friend - as a customer. What are they, idiots?

Qualitymark

I was asking a friend about his solar panels and he was very very happy with them. Said he'd give me the name of the company, who'd been efficient and fast and did a great job installing.
Then I didn't hear from him for a while. Ran into him, and he said "I know I said I'd get back to you about that company, but my feelings about them have changed. I had a problem, called them, they came to fix it, then it broke down again a couple of days after they'd gone. Now I can't get hold of them. They're not answering calls or texts or emails."
One company that won't be getting me - or any other friend, acquaintance or customer of my friend - as a customer. What are they, idiots?

freddyuk

Plenty of new blood so they not interested in fixing the poor installations already paid for.
For a major brand name with "contracted installers" to recommend 100litres per 10 tubes is all about undersizing so their inefficiencies are not quickly obvious. The installers are not allowed to mess with the system supplied or they will lose their lucrative contract so they install poor systems; poorly. Of course there is a warranty but good luck with that.
What you want is to collect as much solar as you can when it is there and store it. To do that you need a bigger cylinder and hotter water. Legally you are not allowed to install very hot water to save you from scalding however by fitting a Thermostatic mixing valve the water is safe at the taps. Then by fitting a bypass the solar system is protected against overheating when you are away. So it is all very simple to control a system and make it last years but it does not happen unless you arrange a decent installer not contracted to a major supplier.
A TMV is about €75 and a bypass kit about €150. Fitting is much easier at time of installation but retro fitting is simple too.
If you store very hot water you may have scaling issues so check your water supply.

freddyuk

Plenty of new blood so they not interested in fixing the poor installations already paid for.
For a major brand name with "contracted installers" to recommend 100litres per 10 tubes is all about undersizing so their inefficiencies are not quickly obvious. The installers are not allowed to mess with the system supplied or they will lose their lucrative contract so they install poor systems; poorly. Of course there is a warranty but good luck with that.
What you want is to collect as much solar as you can when it is there and store it. To do that you need a bigger cylinder and hotter water. Legally you are not allowed to install very hot water to save you from scalding however by fitting a Thermostatic mixing valve the water is safe at the taps. Then by fitting a bypass the solar system is protected against overheating when you are away. So it is all very simple to control a system and make it last years but it does not happen unless you arrange a decent installer not contracted to a major supplier.
A TMV is about €75 and a bypass kit about €150. Fitting is much easier at time of installation but retro fitting is simple too.
If you store very hot water you may have scaling issues so check your water supply.

rolion

HiFreddy.

So you are saying tat I should ignore the spplier's recommendation and /r industry standards and just follow the practical aspects of the solution !?

I will be very worried I I over size the sytem to accommodate me in the cold day of the winter AND to creatmajor troubles in theHOT days of the summer,for which I have to invest something to "dump" free generated hot water.
I meant,here im I supposed t install the dumping unit / radiator,for usage in te summer !?

Can you clarify,please.
Thanks.

rolion

Hi Freddy.

So you are saying that I should ignore the supplier's recommendation and /or industry standards and just follow the practical aspects of the solution !?

I will be very worried if I over sized the sytem to accommodate me in the cold day of the winter AND to create major troubles in the HOT days of the summer,for which I have to invest something to "dump" free generated hot water.
I meant,where im I supposed to install the dumping unit / radiator,for usage in the summer !?

Can you clarify,please.
Thanks.

This is where I say Solar PV is far more practical, you can use the electricity to heat water , run the house and I think this year there will be a feed-in-tariff to sell the excess.

josip

rolion wrote: »

Hi Freddy.

So you are saying tat I should ignore the supplier's recommendation and /or industry standards and just follow the practical aspects of the solution !?

I will be very worried if I over sized the sytem to accommodate me in the cold day of the winter AND to create major troubles in the HOT days of the summer,for which I have to invest something to "dump" free generated hot water.
I meant,where im I supposed to install the dumping unit / radiator,for usage in the summer !?

Can you clarify,please.
Thanks.

The name heat dump doesn't do it any favours but you must understand that this dump is protecting you overall system.
If your cylinder reaches max temp, you're not going to be capturing any of that extra energy anyway, it will just be superheating your fluid and reducing its life expectancy.
Most dumps that I've heard of are a radiator installed in the attic space.

championc

Hi @rolion,

I have 30 Kingspan tubes into 180 litre store. The only main difference I might have to other people is that I have a combined boiler and so I don't heat my water any other way other than via solar, and the incoming water comes straight off the rising main so it's quite cold.

I have only twice maxed out the system. I'd need about 3 or 4 days of continuous stone splitting sunshine to Max it out. I would expect others to be the same.

josip

championc wrote: »

Hi @rolion,

I have 30 Kingspan tubes into 180 litre store. The only main difference I might have to other people is that I have a combined boiler and so I don't heat my water any other way other than via solar, and the incoming water comes straight off the rising main so it's quite cold.

I have only twice maxed out the system. I'd need about 3 or 4 days of continuous stone splitting sunshine to Max it out. I would expect others to be the same.

Are they due south facing champion? If so, what angle are they at?
Our 36 are dues south at an angel of 35 degrees (off horizontal)
Our 250l cylinder is set to 70C
During the summer it would mac out on the 2nd of 2 consecutive good days if it stared from a base of 21/22C at both bottom and mid point int he cylinder.

championc

Yes, absolutely due south at around 23 deg slope. However, once they get sunshine, they produce much the same amount of heat throughout the day, so the slope angle doesn't hugely come into play. My system gains 1 deg about every 10 mins. So yes, I think I can match your gains alright. I log my system, by the minute, to Xively. Not only could I validate how well it worked, John Carroll did too, so it was great to get feedback from an expert

Data logging is king. It takes away all guesswork and dismisses bullsh1tters