Solar Panels and Roof

Reyman · 10-04-2006 2:35pm #1

Anyone know how they install solar panels on an existing tiled roof?

I'm thinking of getting the job done , but i'm wary of problems afterwards with leaks in the roof, etc.

CJhaughey · 10-04-2006 2:56pm

For flat panels they pull the tiles off and fit the panels the same as they fit a velux, there is a flashing around the panel.
Or if you go for tubes they just fit metal brackets to the rafters and come out and around the tiles.

Reyman · 10-04-2006 3:12pm

Thanks CJ, useful information.

The cylindrical water tank you see at the top of the panels on the roofs of the houses in Spain/Turkey are pretty unsightly. I'd even imagine you could need planning permission for them in the cities here, they're so awful looking

Do they mount them externally in the same way here or can they be put in the attic of the house out of the way

CJhaughey · 10-04-2006 3:30pm

Generally the small water tanks that are used in those countries are not used here, I have a 400l tank in my house.
It has an orange lagging jacket though!

Reyman · 10-04-2006 3:51pm

That's a big tank maybe 85 gallons and weighing 1/2 a ton. Have you got that in the attic cavity?

I'm not a roofing expert but 1/2 a ton is fair load on a roof

CJhaughey · 10-04-2006 3:56pm

No that what I mean, most tanks here are in the utility room or some other place on the ground floor where the weight isn't a problem.
Usually in Ireland it is better to have a big tank in case you have some cloudy days .

MorningStar · 10-04-2006 4:17pm

Don't forget their are grants avilable for them now from the minister for the environment.

CJhaughey · 10-04-2006 4:22pm

NOT from the minister for the environment, announced by him maybe but from the SEI

Reyman · 10-04-2006 7:52pm

Right I get you. For some reason I assumed it was a gravity type system.

So it's pumped and indirect (with a worm and some kind of temperature control ) and presumably doesn't interact with the existing cylinder?

I think I need to read up on this !

iplogger1 · 10-04-2006 10:53pm

CJ or others who understand hot water plumbing better than i do .. :

I very much like the idea of the solar collectors as an option for DHW in the warmer/sunnier months. However, I'm still trying to finalise our main central heating source for the cold months. I've looked at Ground source heat pumps such as the NIBE heat pump with horizontal ground collector system and UFH or I might go with a condensing oil boiler and UFH .. or conventional rads .. or a wood pellet boiler.

At the moment (considering the grant) I'm a little more tempted than I was last month to go with the GSHP solution. I know that the outlay on this is 26k+ although maybe 8-10k of that is costing on the UFH/materials/installation/screeding/insulation,etc.

Anyway.. I've seen at least 2 GSHP installations where the home owner has a much larger hot press water tank compared to your traditional immersion tank. I'm told it is a cylinder within a cylinder but never explained properly to me. It seems it is necessary in order to avail of DHW on demand from the heat pump based system. My question is.. say I also installed solar collectors for summer hot water (cut down on summer elec' bills for geothermal) would I require yet another large water tank or is that
supersized cylinder which is part of the DHW on-demand via geothermal something which could be switched over to solar heated water in the summer months ?

Anyone here done geothermal/gshp + solar ?

~ipl

CJhaughey · 11-04-2006 9:52am

The solar system is very simple.
The panels on the roof are connected to 2 pipes feed/return.
The pipes come down into the utility room and are connected to a small central heating type pump setup which is controlled by a small electronic unit.
they then enter the solar watertank and pass through a coil inside the tank.
The electronic control unit measures the temp at the top of the tank, and the bottom of the tank and the panel temps.
Once the panel reaches a suitable temp it starts the pump and circulates the fluid around the circuit, thereby heating the water.

dras · 11-04-2006 9:45pm

Back to the original question: I was talking to Heatmerchants today who are selling the Wikora roof mounted solar panels through their chain. From what I understand they are bolted and sealed through the existing tiles and so would be suitable for retro-fits as well as new fits.

Please correct me if you know otherwise.

rooferPete · 11-04-2006 10:12pm

Hi dras,

There are some systems that are nothing short of expensive roof repairs in waiting, the idea of drilling through concrete tiles to try and fix what will be a heavy panel in place defies logic what's worse is the idea that pipes can be brought through the tiles and sealed with silicone.

I don't care if a big company like Heat Merchants think it's ok, I know it's wrong to use a standard roof tile to fix through against the flow of water.

I also know that silicone is not a successfull waterproofing material when used on a concrete tile, it doesn't bond to the tiles.

Also take into account that tiles crack and usually helped by a weak point, drilling a tile in place and using the fixing methods I have seen on so many web sites should be banned, there is no way a heavy object can be expected to hang from a piece of metal through a tile without causing stress on the roof covering.

I'm typing fast now so that means I have come across one of my pet hates.

.

Reyman · 12-04-2006 8:58am

CJhaughey wrote:

The solar system is very simple.
The panels on the roof are connected to 2 pipes feed/return.
The pipes come down into the utility room and are connected to a small central heating type pump setup which is controlled by a small electronic unit.
they then enter the solar watertank and pass through a coil inside the tank.
The electronic control unit measures the temp at the top of the tank, and the bottom of the tank and the panel temps.
Once the panel reaches a suitable temp it starts the pump and circulates the fluid around the circuit, thereby heating the water.

I'm not clear how the interface is made with the existing hot water system? Are they just paralleled at some suitable pipe ? Or how is it done?

If the solar tank is fitted on the ground floor is it topped up from the attic open tank to give the pressure ?

By the way I agree with Roofer Pete. The last thing you want is this thing giving you grief with the integrity of your roof. That could be really expensive

CJhaughey · 12-04-2006 9:52am

In mine, there is no existing system, the whole thing is solar based with a 3kw immersion for backup.
I have no attic tank the whole system is mains pressure.
You cannot use a conventional water tank in a solar system, the tank has coils inside that heat the water, conventional tanks don't have this.
I also agree that you don't want grief with your roof either, thats why I got professionals to install mine, I will post a pic sometime when I get a chance.

rooferPete · 12-04-2006 9:28pm

Hi CJH,

Very good info, have you seen the attempt at system offered by Solartwin in the UK ?

Not only do they offer the the horrible fixing through the roof tiles but they have a cheap and cheerful method of connecting to the existing cylinder.

Actually that's wrong they connect to the top outlet of the cylinder above the hot water level in the cylinder, they have a very impressive thirty plus page web site but hate realistic questions.

They appear to have forgotten what they were in contact with me about because they sent me an email claiming they would be approved for the SEI grants and were looking for installers.

The way I see it they are looking for inexperienced installers who don't understand even basic plumbing, a further problem I see is they have a large quantity of B.S. to blind the average consumer with.

There are good systems available, they don't have to cost the earth but beware of the cheap and cheerful brigade, our grant system is only beginning and there will be a lot of junk available.

.

Reyman · 13-04-2006 8:02am

CJ: you were saying in one of your other posts that you have 6.3m(sq) of panel on the roof.

What's the approximate angle and orientation of your roof ?

In you experience how many months of the year are you getting hot water from this ?

towbar · 13-04-2006 10:49am

Whats are the best methods for installing tubes on slates?

I have been told that they use straps pushed under the slate piercing the felt and attached to the joice underneath? Is this sufficient to hold the frame and what are the implications of piercing the felt?

I know the grant system doesnt make it attractive to use tubes but I'd prefer to have a more efficienct and easier maintained system with less weight on roof.

CJhaughey · 13-04-2006 11:13am

Reyman wrote:

CJ: you were saying in one of your other posts that you have 6.3m(sq) of panel on the roof.

What's the approximate angle and orientation of your roof ?

In you experience how many months of the year are you getting hot water from this ?

Reyman
My roof is 45deg pitch and faces SW.
My experience is limited to the 2 weeks that the system has been running

and during that time the temp has rarely dropped below 40 deg C and usually runs around 70deg C
People who live in the surrounding area and have similar systems tell me that they get hot water from April to October, they also tell me that this time of the year is better because of little foliage blocking the light from the panels.
during this time they may have to use the immersion a few times to keep the system topped up if it has been cloudy.
Towbar.
I have no experience of tubes apart from one course that I attended.
AFAIK the tubes are just fixed on a light metal frame, they weigh very little and can get away with a system like this.
However they are not very suitable where flying debris may strike them; sticks etc, as they are rather fragile.
I guess it is horses for courses, I am not able to apply for the grant as I have already installed the system:( but I look at it like this I haven't lost anything either:)
I have stonewold concrete tiles on my roof 8 pallets worth, and my roof is sarked so I am not worried about the weight of three flat panels.

AJL · 13-04-2006 4:05pm

CJ

What are the advantages of tubes versus flat panels? I want to install panels as I will be putting them on a low roof and they will be very visible.

AJL

Alun · 13-04-2006 4:21pm

CJhaughey wrote:

You cannot use a conventional water tank in a solar system, the tank has coils inside that heat the water, conventional tanks don't have this.

I always thought normal hot water tanks, those that are heated indirectly by a CH boiler, had coils? Or are the ones in a solar boiler different somehow?

We live in a bungalow with a roof facing SSW that would be ideal for this kind of system I think, but it's proving a bit difficult finding anyone who can give some straight answers on this.

towbar · 13-04-2006 4:22pm

AJL,

The points that have been noted to me

Tubes are much lighter and need less area.
If a tube breaks replace tube, if panel breaks or leaks you have to replace whole panel.
Tubes are more efficient per sq meter and dont need to be directly south facing.
Tubes are less suceptible to dirt and grime build up than panels( not sure if this is true or sales speak!!!)

There are two types of tube direct and indirect. With indirect if a tube breaks there are no leaks and system works normally without that tube. With direct fluid flows through tube and so a broken tube will disable system. Panels are all direct and so a broken or leaking panel disables whole system.

Indirect tubes wont freeze up. Panels and direct tubes subject to freezing depending on fluid used.

I think also indirect tubes are not affected by overheating whereas panels need to be protected against overheating - is this correct?

Tubes can easily be replaced whereas replacing a panel is a major effort although it should be pointed out tubes are more suceptible to breaking than panels. My thoughts however are that when a child throws a stone up on the rough panel or tube are likely to meet the same fate..

However in favour of panels asthetically more pleasing and significantly cheaper when you factor in grant. Probably getting extra €600 grant.

CJhaughey · 13-04-2006 4:49pm

Tubes are more efficient, by about 30%, but they are more fragile and crucially now aren't as well served by the grant system.
If you have a low roof I would try and raise the back of the panels in order to create a better angle for the sun especially at this time of the year it is still low in the horizon and you will not get full value with low pitch roof.
The panels look pretty nice, not at all awkward just like a giant velux actually.
One other thing the glass that the panels are made from is pretty thick and would be quite hard to break compared with tubes.
This is just an observation I made when inspecting some tubes while shopping around.
My system has a type of antifreeze in it called Tyfocor or something.
If the panels work in Germany they should have no troubles here!

rooferPete · 13-04-2006 9:59pm

towbar wrote:

Whats are the best methods for installing tubes on slates?

I have been told that they use straps pushed under the slate piercing the felt and attached to the joice underneath? Is this sufficient to hold the frame and what are the implications of piercing the felt?

I know the grant system doesnt make it attractive to use tubes but I'd prefer to have a more efficienct and easier maintained system with less weight on roof.

Hi towbar,

I do believe you are trying to ruin my whole weekend if you got that information from where I think you did

I have seen more than my share of cowboy work on what used to be quality roofs until I saw the way the pipes were brought in through the slates :eek:

If ever there was an advertisement for solar panels instead of tubes that fixing method is it.

Good quality panels or tubes are not cheap, even in China they have different standards of manufacturing both products, if you have a nice slate roof my advice would be to go with the panels.

They are not easy to break in fact the opposite, they are supposed to be tested to a high standard using hail (the Texas not the Irish type) as one of a number of standards.

.

towbar · 13-04-2006 11:08pm

Pete,

I was afraid there was a catch - sounded too simple. Dublin based company...
In fairness they did say there was a flashing kit for the pipes.

I agree everything points to panels been harder to break but when they do - harder to repair as panel has to come out.

Anyway so how do you fit panels on slate roof? Do you lift the slates and fit like a velux? My builder will be well pleased with my project management skills given that they just finished the roof this week!!!

rooferPete · 13-04-2006 11:19pm

Hi towbar,

I believe the best way (long term) is to use panels with slates, however all is not lost, it is possible to fit brackets by removing the slate and using a product similar to a roof vent to flash the detail properly.

A similar vent can be used to bring the pipes safely into the attic without compromising the roof covering or the solar system.

I expect the reason these systems are not used on slates may have something to do with the lack of roofing knowledge and tools by many solar installers.

.

AJL · 14-04-2006 3:09pm

Thanks CJ/Towbar

Great info!!

AJL

Gurgle · 14-04-2006 9:03pm

On a tangental question - Do you have to include the solar panels in your application for planning permission?

And is it a simple case of the bigger area the better?

Lex Luthor · 15-04-2006 9:22am

Just to jump in on this thread...I'll have a good read of it later, but my sister is getting a large extension to her house in Kinsale and part of it is having all the tiles removed on her existing dwelling and getting the complete dwelling with extension recovered with slate.

As the back of her house is south facing and gets a lot of sunlight, and she is now in the planning stage of getting her drawings done, the solar panel idea came up.

Are they just for hot water for taps or can they be used for the central heating system aswell? Can the energy also be stored for use as electricity.

Apologies for asking questions that may have already been answered here, but I thought I get the question in before I forgot for the weekend.

endplate · 15-04-2006 9:52am

Lex I read on this site www.surfacepower.com that the tubes they use can also generate electricity to power the pump for circulating the water in the system. You would need a different type for solar panel for generating electricity for your house these are also available from the same website

AJL · 15-04-2006 10:57am

From what i've read you need a tonne of solar panels to creat electricity and it takes a considerable time to payback. To me not a viable option for a private house.
With the other type of solar panels the most efficient are those that are used to heat water. You can use them to supplement your heating but I've only read this and to me in this country if it heats your hot water that's as much as I would expect. You can also get them to heat air if you install a heat recovery ventilation system.
I'm not an expert on this stuff just researching before my build. i would think with the proce of fossil fuels plus the grant it is definitely worth putting in solar panels.

Solar Panels and Roof

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