Panel Positioning

I'm

Folks,

Apologies if these are noddy questions, but I'd appreciate any help you can give -

I would like to position my solar panels on a garage at the rear of a south facing two storey house, leading to the problem of shade during some winters months - I've been using Google SketchUp to figure out the shade and unless I change the position of the garage radically there doesn't appear to be a solution.

I don't particular want to place the panels on the roof of the house - but I can't think of any other options - anybody have any suggestions ?

Also, I'll be talking to my plumber next week, but I now assume that the garage is a bad idea in terms of having to pump to the hot press on the first floor rather than just relying on gravity ?

Thanks in advance for any advice

quentingargan

I'm wrote: »

Folks,

Apologies if these are noddy questions, but I'd appreciate any help you can give -

I would like to position my solar panels on a garage at the rear of a south facing two storey house, leading to the problem of shade during some winters months - I've been using Google SketchUp to figure out the shade and unless I change the position of the garage radically there doesn't appear to be a solution.

I don't particular want to place the panels on the roof of the house - but I can't think of any other options - anybody have any suggestions ?

Also, I'll be talking to my plumber next week, but I now assume that the garage is a bad idea in terms of having to pump to the hot press on the first floor rather than just relying on gravity ?

Thanks in advance for any advice

I wouldn't worry about winter shading. To be honest, the real gain in solar water heating is in the summer. At this time, the heating is off and your hot water is coming from more expensive sources, such as an immersion, or running a boiler very inefficiently just to heat the cylinder. In the winter, the boiler heats the water on its way to the radiators so to speak, at a cost less than half of electricity.

Also, the solar gains to be made a very much lower, particularly if you are looking at suffering shading for December and January only, for example.

However, I would be concerned that you will lose efficiency by having the panels a long distance from your cylinder. What length will the pipe run be? You start to lose quite a bit of efficiency if the run is over 10m, particularly at the fringes of the season.

By the way, strictly speaking, if your garage has a flat roof, the installation will probably need planning permission.

Your system is going to be pumped either way, there are very few installations that rely on thermosyphoning to bring the heat from the panel to the cylinder - it can only be done if the panel is below the cylinder and close to it. And even at that, there are quite a few issues about controls to prevent the cylinder boiling.

morning delight

quentingargan wrote: »

However, I would be concerned that you will lose efficiency by having the panels a long distance from your cylinder. What length will the pipe run be? You start to lose quite a bit of efficiency if the run is over 10m, particularly at the fringes of the season.

Hi Quentin

Can this inefficiency be overcome by use of insulated pipes? What if the distance is ~20m?
A

quentingargan

morning delight wrote: »

Hi Quentin

Can this inefficiency be overcome by use of insulated pipes? What if the distance is ~20m?
A

It is assumed that you would be using insulated pipes in any event. The pipes should be insulated with a high-temperature insulation the thickness of which is the same as the diameter of the pipe used (usually 13-15mm). There are still heat losses caused by the thermal mass of both fluid and pipes, but also, even with insulation, there is considerable heat loss.

However, the losses are of the order of 7 to 10% over that distance. This loss would be greater in spring and autumn (which unfortunately is the time when the system is struggling to meet your needs). However, it is often the only option available because of other considerations.

heinbloed

Get a professional in who is able to advise you on the many options you have to make use of ST energy.
Is there no unshaded part of your property?
ST collectors can be fixed flush to a wall as well. For optimum usage of limited space available the collectors can be made to meassure, every cm2 with potential can be made use of. Triangles can be manufactured as well.
For static reasons a limit is set at around 10m2 per collector.
There is usualy no reason why the winter's sun can't be used. Every PH building depends in it's energetic balance sheet on the gain from the winter sun. (Winter) sunshine MUST be integrated into the energetic calculation of any building.
Some ST installers don't understand this however.

homer911

heinbloed wrote: »

There is usualy no reason why the winter's sun can't be used.

Cost Vs Benefit?

heinbloed

Homer911 wrote:

" Cost Vs Benefit? "

There is no monetarian benefit in using collected ST energy in a standard situation for the individual.
It's a humanitarian question if the competing forms of energy should be prefered and their total costs are to be covered by society.
Crime pays the criminal. Not society.

I'm

Many thanks quentingargan

quentingargan wrote: »

I wouldn't worry about winter shading. To be honest, the real gain in solar water heating is in the summer

The shade seems to occur from early Dec from late Jan - I now understand the implications of the shade in these months better - thanks

quentingargan wrote: »

However, I would be concerned that you will lose efficiency by having the panels a long distance from your cylinder. What length will the pipe run be?

Unfortunately, as per the planning, its going to be approx 30m in total - down from 1st floor across yard and into garage - I'll see what I can do to limit this run.

heinbloed wrote: »

Get a professional in who is able to advise you on the many options you have to make use of ST energy.
Is there no unshaded part of your property?

Thanks heinbloed - I'll engage a professional as suggested.

In terms of absolutely no shade, the main house is an option, but I was keen to have them at more reasonable height for any maintenance etc.

quentingargan

I'm wrote: »

In terms of absolutely no shade, the main house is an option, but I was keen to have them at more reasonable height for any maintenance etc.

Systems in another building tend to be much less efficient. In some cases, if you have to do this, you can put a secondary storage into the shed and then pump from that to your cylinder. There are less losses in doing this, but there is some added expense.

I would think that the advantages of being on the roof outweigh the disadvantages. A well installed system doen't need maintenance. Flatplates are more robust than tubes in terms of footballs (though if you do manage to break them you're in bigger trouble) but maintenance shouldn't be an issue, and on a new house there is scaffolding there during the installation already. Q

I'm

Thanks quentingargan - If I can't get the distance to a reasonable length, I'll go with the main roof.

heinbloed

Quote:
" ..... , I'll go with the main roof."

In this case it might be possible to use non-pressurised flexible tanks. They are cheaper and can make use of every corner, wasting no space. And you'll have a warm, well insulated roof above your head.
Transport from collector to storage could be very short, the thermal losses and plumbing work accordingly.
Check the loadbearing capacity of the attik. Try google for dealers and installation manuals.

skooby

I'm wrote: »

Many thanks quentingargan





Unfortunately, as per the planning, its going to be approx 30m in total - down from 1st floor across yard and into garage - I'll see what I can do to limit this run.

I have solar fitted on my garage which has a run of 25mtrs between panels and cylinder. It was fitted with a stainless steel coil of 1/2" pipe which was pre-insulated. He then put this dual pipe into another type of insulation (armaflex i think) to help keep heat in. For the part that was crossing the yard (approx 7 metres) he got some 6" duct pipe and ran the pipe through this. He then pumped something into this pipe to save heat loss. I have not got a clue what it was he pumped in but it acted just like expanding foam when pumped in. Maybe somebody else has come across this and might be able to help you out. I am delighted with the way it turned out. Its fitted about three years and in summer months I have 60 gallons of water heated to 55 deg. In winter months its only getting to about 25-30 but my boiler is switched on anyway in these months so the solar just gives it that little bit of a top up.

quentingargan

skooby wrote: »

I have solar fitted on my garage which has a run of 25mtrs between panels and cylinder. ...in summer months I have 60 gallons of water heated to 55 deg.

Thanks for that Skooby. Just to put this in a context, can you let us know what size your panels and cylinder are? I assume the cylinder is 300L, but are you using tubes or flatplate, and what size?

Cheers, Quentin.

skooby

quentingargan wrote: »

Thanks for that Skooby. Just to put this in a context, can you let us know what size your panels and cylinder are? I assume the cylinder is 300L, but are you using tubes or flatplate, and what size?

Cheers, Quentin.

its not exactly the 300litre. Its about 270. I had to get a copper cylinder made for it as i was fitting solid fuel. i was told i couldnt use the standard 300 litre pressurised cylinder due to solid fuel been unstable on pressure. not a clue what that means but was told solid fuel should be open vented so i just went with the flow. we put 3 panels on it because the installer said the 2 might struggle on the distance and a 3rd would help it out. i stayed clear of the tubes at the time because i got better feedback about panels than tubes. apparently the tubes are weaker and they are filled with pressurised gas or something. i was warned that if this gas lost pressure you would be get less of a return. dont no how true that is but the panels seemed a simpler idea with less to go wrong

skooby

skooby wrote: »

I have solar fitted on my garage which has a run of 25mtrs between panels and cylinder. It was fitted with a stainless steel coil of 1/2" pipe which was pre-insulated. He then put this dual pipe into another type of insulation (armaflex i think) to help keep heat in. For the part that was crossing the yard (approx 7 metres) he got some 6" duct pipe and ran the pipe through this. He then pumped something into this pipe to save heat loss. I have not got a clue what it was he pumped in but it acted just like expanding foam when pumped in. Maybe somebody else has come across this and might be able to help you out. I am delighted with the way it turned out. Its fitted about three years and in summer months I have 60 gallons of water heated to 55 deg. In winter months its only getting to about 25-30 but my boiler is switched on anyway in these months so the solar just gives it that little bit of a top up.

I have a similar setup!

What I have is 12m2 home made flat panel collectors on the garage roof and a 100 litre cylinder in the garage. the cylinder is connected in parallel with a 1000 litre buffer tank for the wood burner.

The garage is connected to the house via 30m of insulated "district heating pipe". The oil boiler is also in the garage and uses the solar pre-heated water.

The cylinder has a couple of sensors on it that start to pump the heated water to the main 300 litre cylinder in the house when the bottom if the cylinder in the garage reaches 65C and stops when the water exiting the cylinder drops to 50C, this batching of heat transfer reduces the losses that could be expected on part cloudy days.

I also have a diverter valve that switches the warm water from the panels to the buffer tank if the temperature of the returned water is cooler than that in the top of the cylinder.

quentingargan

skooby wrote: »

its not exactly the 300litre. Its about 270. I had to get a copper cylinder made for it as i was fitting solid fuel. i was told i couldnt use the standard 300 litre pressurised cylinder due to solid fuel been unstable on pressure. not a clue what that means but was told solid fuel should be open vented so i just went with the flow. we put 3 panels on it because the installer said the 2 might struggle on the distance and a 3rd would help it out. i stayed clear of the tubes at the time because i got better feedback about panels than tubes. apparently the tubes are weaker and they are filled with pressurised gas or something. i was warned that if this gas lost pressure you would be get less of a return. dont no how true that is but the panels seemed a simpler idea with less to go wrong

That all makes sense, though there is a touch of the Chinese whispers about some of it:) Normally if you put 6 sq m on onto a 270L cylinder, your water would be going well above 55 degrees, so you do have a fair bit of loss, which is what I would expect, and this loss is greater as a percentage of the energy available in winter.

You are right about not using a pressurised cylinder with solid fuel. You can't stop the heat in the event of a power cut or pump failuer, and what can go wrong with that is shown here

The bit about tubes versus flatplates is, hopefully, something that happened with earlier tubes - they do eventually lose their vacuum, but that should be after 15 or 20 years, and the more common tubes are very cheap and easy to replace. But that might not have been the situation at the time. Q

skooby

quentingargan wrote: »

That all makes sense, though there is a touch of the Chinese whispers about some of it:) Normally if you put 6 sq m on onto a 270L cylinder, your water would be going well above 55


Q

The solar controls were set to stop at 55 deg as i have a booster pump after the cylinder for the showers which is only covered to 60 deg. I checked with the supplier and monsoon which is meant to be one of the better makes have specified that the warranty will be void over 60 deg as the rubber washers will perish. He has a blending valve before the pump anyway due to the solid fuel so there is never anymore than 55 deg going through the pump but there was no point heating the cylinder any further just to mix it back down again. I thought it might make sense to overheat it so it would stay warmer longer but i got 80mm foam on my cylinder instead of the standard 30mm so it retains heat for ages

quentingargan

skooby wrote: »

The solar controls were set to stop at 55 deg as i have a booster pump after the cylinder for the showers which is only covered to 60 deg. I checked with the supplier and monsoon which is meant to be one of the better makes have specified that the warranty will be void over 60 deg as the rubber washers will perish. He has a blending valve before the pump anyway due to the solid fuel so there is never anymore than 55 deg going through the pump but there was no point heating the cylinder any further just to mix it back down again. I thought it might make sense to overheat it so it would stay warmer longer but i got 80mm foam on my cylinder instead of the standard 30mm so it retains heat for ages

It is a condition of the SEI grant (and rightly so) that your cylinder must be brought to at least 60 degrees to prevent legionnaires disease. The plumber who installed this setup should have known this.

Your instincts about allowing the system to overheat are quite correct, provided you don't have hard water. If there is limescale in your kettle, then allowing the system to go up to, say, 85 degrees, would cause limescale on the coil of your cylinder. However, if it isn't a hard water area, raising the maximum temperature of your cylinder will not only give you more hot water storage, it will also extend the life of your panel by reducing the amount of time it spends in stagnation with the pump switched off (unless you have a heat dump).

skooby

quentingargan wrote: »

The plumber who installed this setup should have known this.

.

thanks for that quentin. i will be on the phone today to get this resolved. never went with the grant. i didnt have time to wait for all the paperwork to go through as i was tight for time on the build and just wanted to get it done. im guessin you have some sort of professional background in this as your suggestions are not just pie in the sky. if so is there anything else with that system that sounded a bit dodgy

quentingargan

skooby wrote: »

thanks for that quentin. i will be on the phone today to get this resolved. never went with the grant. i didnt have time to wait for all the paperwork to go through as i was tight for time on the build and just wanted to get it done. im guessin you have some sort of professional background in this as your suggestions are not just pie in the sky. if so is there anything else with that system that sounded a bit dodgy

Thanks. Its hard to tell on the net, but there wasn't anything else in your system that stood out. If your system has been shutting down (which causes the panel to overheat) you may well have damaged your anti-freeze. We usually use a heat dump to prevent this from happening. You can retrofit a heat dump in your situation perhaps by getting the controller or a stat to run a pump on one of the heating coils to cool the cylinder, but this would depend on the layout of your system, zoning etc. Q

skooby

as far as i know i have had no problems. i got a lad to change the antifreeze over the xmas. it was in 3 years. i was told should be done bout every 6 years but i wanted to be safe rather than sorry. heard stories about air in systems and all that sort of going on so i thought it would be no harm to do the service early