Solar panel for use in the dark!

Question:

What is a copper microbore pipe? I assume it’s a small diameter pipe.

Correct. It is thick walled soft copper that comes in coils.  It can be bent by your fingers, although using a bender is the best and neatest way. I don’t know about your climate, but if it gets below freezing, won’t it expand and crack?

Yes.  However, you have a self draining solar system or one with ant-freeze in it. Let’s see if I understand your proposal. You are installing a ‘solar panel’ in your attic/loft, small pipes on the roof, and circulating water between them in the daytime.

No.  What he meant was that the whole dark tiled roof is the solar collector.  Microbore pipes are fixed under the tiles inside the attic/loft with insulation over the pipes.  This gives a very large area of tiled solar collector.  It is cheap to do and all can be done inside the attic/loft. The collected heat would be stored in a dedicated pre-heat cylinder or in a thermal store cylinder.

Response:

An attic is a habitable room a loft is not.   As I understand it, I may be wrong.

In Canada at least, but I suspect in much of the United States as well, an "attic" is generally not habitable, although if it was tall enough it might be made so, while a "loft" generally is part of the habitable space. For the purposes of this thread it appears that your loft and our attic are the same thing – non-habitable space. Kevin MacTavish

Response:

Hi peoples.

Greetings person!   :-) … a solar panel …nothing gets installed on the rooftop, this one is installed in the loft, …one could snake a copper microbore pipe up and down the slate roof to collect some of  the heat,

What is a copper microbore pipe? I assume it’s a small diameter pipe. I don’t know about your climate, but if it gets below freezing, won’t it expand and crack? (I have used 1/4" copper tubing in the desert for swamp coolers in the summer, but in the winter, there are short periods where it gets below freezing, and after 2 years of repairing leaky sections, I switched to those black poly tubing. Let’s see if I understand your proposal. You are installing a ‘solar panel’ in your attic/loft, small pipes on the roof, and circulating water between them in the daytime. Your solar collectors’ purpose, then, would not be to ‘collect heat’, rather, it would ‘store heat’ collected from your microbore pipe. Do I understand you? If so, then there are alot less costly heat storage containers. For instance, a hot water heater, an acquarium, a bathtub, 1000 foot of 1" diameter poly irrigation tubing. A heat storage device should be insulated. Most of my suggestions are much easier to insulate, due to their size; compared to a long, wide, narrow solar panel. I assume you’re pumping water through these microbore pipes, so won’t static pressure be fairly large due to a long small diameter pipe? …and won’t you need a fairly big pump (using lots of watts) to do such a thing? where there is no sunlight :)

yup… and now you lose heat out of it due to an affect called black-body radiation Toby

Response:

There’s the misunderstanding – in Canada, churches and mansions might have slate – very few others.

In England they also have concrete tiles that are the colour and look of slate.  My house has these and the south facing side gets quite hot even in November.  Slate is now expensive, and cheaper Spanish slate is now used a lot, which is actualy not the best, the best being Welsh slate, which is now rare.  Many older slate tiled rooves in North America are Welsh slate. Recycling slate and bricks is big business in England.  Old houses to demolish have a fare part of them recycled, even the old oak floorboards and beams. A friend of mine built a house using used bricks and roof tiles.  The tiles came from Wolverhampton and the bricks from Manchester, from houses that were built in the 1860-70s.  We demolish houses of such age here, in the USA they would put a preservation order on them.  In fact the houses were not really demolished, just re-incarnated in a different form. We tend to have shallow roofs with asphalt shingles that you can run around on. Inside the loft (or attic, as we call it)

An attic is a habitable room a loft is not.  As I understand it, I may be wrong.

Response:

I had an odd thought today, for a solar panel that might be practical. I am thinking it would be eaiser and cheaper to install – I guess the hope behind it would be to make solar more popular. It’s a nice idea – but how many people have slate roofs? (rooves?) Where I live almost everyone has. Same is true for a lot of British towns in fact.

There’s the misunderstanding – in Canada, churches and mansions might have slate – very few others. We tend to have shallow roofs with asphalt shingles that you can run around on. Inside the loft (or attic, as we call it) there’s insulation that makes you itch just thinking about it. It would work in many houses here because it’s also often about the same temperature in there as the Sahara at noon – in the summer, anyway. So to get serious about your idea – the microbore has a lot of resistance – you might be better to use a larger pipe and circulate the water slowly – small pump, not working hard.  Also, if you are serious about it, how about going up there a few times, and taking inside and outside temperatures at different times of day. Maybe get an aquarium pump and some plastic or flexible copper tubing and just running 10 or 15 feet of it up the rafters and back. See how much a five gallon container of water heats up in an hour for example. Another option you might consider if, the first experiment seems productive is to run a cold water line up to the peak of the loft, and across the peak where it’s hottest, (inside) you put a few of the cooling coils out of discarded grocery store meat coolers. These can often be had for nothing or just scrap value. The one I used was 8 feet long with 4" sauare aluminum fins. The copper tubing ran back and forth about 10 times – so 80 feet of 1/2 inch copper tubing with fins to carry the heat into it. The output goes back down to the supply side of the hot water tank. Even if it only ran for 8 or 9 months a year and was bypassed and and drained in the coldest months, it should be worthwhile. Fairly easy to setup, very low cost, no pumps required, and only takes an hour or so 2ce a year to switch it on and off. Install the unit at a bit of an angle so that it drains completely, and with a couple of valves and taps it’s a very simple, low maintenance design. What do you think?  (I did something like this at the top of my 2 story greenhouse on the south side of my house.) Bob – Hide quoted text — Show quoted text – While we wait for Nick to tell us exactly how efficient, I think maybe a more productive  direction would be along the lines Nick has been talking about lately – trickling water down the roof – either open or covered with plexi, lexan, or whatever. I can see a few diehards going to the trouble of a Thomason, but most would be refused planning permission for that anyway. Then there’s the fact that you couldn’t connect that up to the hot water tank – the resulting infection problems would soon kill someone, and almost certainly be illegal here. And then the fact that most people would be far too concerned about the water damaging their roofs to do it. Bear in mind that slate roofs do leak, they’re not really watertight, so continuous water trickling would soon rot part of the timber structure. And soak patches of ceiling. I am looking for something that is simple enough, cheap enough, uncontroversial enough, and popularisable enough, for it to become the domain of the masses. Consider this: 1000 people installing highly efficient solar systems that save 100% of water heating bills would give you 100×1000 nominal vague units of energy saved = 1,000,000 Now 10,000,000 imstallations saving 30% of hot water bills would save 300,000,000 nominal vague units of energy. 300x as much!! Now do you see where I’m coming from here? It seems there is potential here for both heating the water AND cooling the house. Probably much cheaper than all those microbore pipes, and a lot easier to install. Thats one bit I don’t understand. How could it be simpler? With my inefficient collector one can stand in the loft and staple some tags holding the pipe up, then staple polythene / card sheet etc onto the rafters. Vastly easier than getting scaffolding to get on the roof, putting in roof penetrating connections and mounts etc. Most people I know wouldn’t even consider climbing onto their steeply pitched slate roof. Stand on a slate roof and one false move and you go straight through it anyway, and people know that, or rightly suspect it. The rest of the installation would be the same for either type – conncting to cylinder, pump, controller etc. (Except on a slate roof perhaps!) Also, the basic trickle down the roof would work at very low cost, and a person could add plastic glazing to it as time and money became available – increasing the efficiency slowly. Well, not here anyway. They’d soon be court ordered to pull it off. We have masses of pretty and ancient housing stock, and a lot of areas are subject to very tight planning regs designed to keep things looking old fashioned and pretty. Plastic roofing sheets would not be accepted unless they were well out of view. And most householders here would sneer at plastic roofing even if they could install it – rightly or wrongly. No offense meant – just couldn’t help kidding you about slate roofs. I’d love to have one, myself. Yeah, they’re nice and pretty. Of course they are also over 100 years old… so need a few slates replacing every year or two. Well, you might think this is not a good idea, but I think it may well be. I’d like to hear more input tho. It is after all an unglazed collector with a little insulation between collector surface and pipe… so certainly not efficient. But the available roof area to use would be huge compared to most practical solar collectors. I don’t give up easy :) Regards, NT I wrote… It would be inefficient, but would also be huge. The basic idea is this… nothing gets installed on the rooftop, this one is installed in the loft, where there is no sunlight :) Its OK, I havent lost it yet… see a black slate roof gets hot in sunlight, so one could snake a copper microbore pipe up and down the slate roof to collect some of the heat, pinning it in place here and there, and putting some form of very basic insulation behind it. Now efficiency would be poor, but the loft roof area would be huge. Big Qs: How efficient might this be? How could one control it… it would have to be actively emptied when it got too cold, but I didn’t figure out in one sitting a simple way to both pump the water round and empty it. I really want to keep it cheap and simple. We can all put something complex together, but I’m hoping for something simple and cheap enough to make it into mass market application. Any input would be good… Regards, NT

Response:

I had an odd thought today, for a solar panel that might be practical. I am thinking it would be eaiser and cheaper to install – I guess the hope behind it would be to make solar more popular. It’s a nice idea – but how many people have slate roofs? (rooves?)

Where I live almost everyone has. Same is true for a lot of British towns in fact. While we wait for Nick to tell us exactly how efficient, I think maybe a more productive  direction would be along the lines Nick has been talking about lately – trickling water down the roof – either open or covered with plexi, lexan, or whatever.

I can see a few diehards going to the trouble of a Thomason, but most would be refused planning permission for that anyway. Then there’s the fact that you couldn’t connect that up to the hot water tank – the resulting infection problems would soon kill someone, and almost certainly be illegal here. And then the fact that most people would be far too concerned about the water damaging their roofs to do it. Bear in mind that slate roofs do leak, they’re not really watertight, so continuous water trickling would soon rot part of the timber structure. And soak patches of ceiling. I am looking for something that is simple enough, cheap enough, uncontroversial enough, and popularisable enough, for it to become the domain of the masses. Consider this: 1000 people installing highly efficient solar systems that save 100% of water heating bills would give you 100×1000 nominal vague units of energy saved = 1,000,000 Now 10,000,000 imstallations saving 30% of hot water bills would save 300,000,000 nominal vague units of energy. 300x as much!! Now do you see where I’m coming from here? It seems there is potential here for both heating the water AND cooling the house. Probably much cheaper than all those microbore pipes, and a lot easier to install.

Thats one bit I don’t understand. How could it be simpler? With my inefficient collector one can stand in the loft and staple some tags holding the pipe up, then staple polythene / card sheet etc onto the rafters. Vastly easier than getting scaffolding to get on the roof, putting in roof penetrating connections and mounts etc. Most people I know wouldn’t even consider climbing onto their steeply pitched slate roof. Stand on a slate roof and one false move and you go straight through it anyway, and people know that, or rightly suspect it. The rest of the installation would be the same for either type – conncting to cylinder, pump, controller etc. (Except on a slate roof perhaps!) Also, the basic trickle down the roof would work at very low cost, and a person could add plastic glazing to it as time and money became available – increasing the efficiency slowly.

Well, not here anyway. They’d soon be court ordered to pull it off. We have masses of pretty and ancient housing stock, and a lot of areas are subject to very tight planning regs designed to keep things looking old fashioned and pretty. Plastic roofing sheets would not be accepted unless they were well out of view. And most householders here would sneer at plastic roofing even if they could install it – rightly or wrongly. No offense meant – just couldn’t help kidding you about slate roofs. I’d love to have one, myself.

Yeah, they’re nice and pretty. Of course they are also over 100 years old… so need a few slates replacing every year or two. Well, you might think this is not a good idea, but I think it may well be. I’d like to hear more input tho. It is after all an unglazed collector with a little insulation between collector surface and pipe… so certainly not efficient. But the available roof area to use would be huge compared to most practical solar collectors. I don’t give up easy :) Regards, NT – Hide quoted text — Show quoted text -I wrote… It would be inefficient, but would also be huge. The basic idea is this… nothing gets installed on the rooftop, this one is installed in the loft, where there is no sunlight :) Its OK, I havent lost it yet… see a black slate roof gets hot in sunlight, so one could snake a copper microbore pipe up and down the slate roof to collect some of the heat, pinning it in place here and there, and putting some form of very basic insulation behind it. Now efficiency would be poor, but the loft roof area would be huge. Big Qs: How efficient might this be? How could one control it… it would have to be actively emptied when it got too cold, but I didn’t figure out in one sitting a simple way to both pump the water round and empty it. I really want to keep it cheap and simple. We can all put something complex together, but I’m hoping for something simple and cheap enough to make it into mass market application. Any input would be good… Regards, NT

Response:

- Hide quoted text — Show quoted text —— Original Message —– Newsgroups: alt.solar.thermal Sent: Saturday, August 10, 2002 9:08 PM Hi peoples. I had an odd thought today, for a solar panel that might be practical. I am thinking it would be eaiser and cheaper to install – I guess the hope behind it would be to make solar more popular. It’s a nice idea – but how many people have slate roofs? (rooves?) While we wait for Nick to tell us exactly how efficient, I think maybe a more productive  direction would be along the lines Nick has been talking about lately – trickling water down the roof – either open or covered with plexi, lexan, or whatever. It seems there is potential here for both heating the water AND cooling the house. Probably much cheaper than all those microbore pipes, and a lot easier to install. (Except on a slate roof perhaps!) Also, the basic trickle down the roof would work at very low cost, and a person could add plastic glazing to it as time and money became available – increasing the efficiency slowly. The nice thing about the glazing – the snow doesn’t stick for nearly as much as it does on the asphalt shingles – especially on a shallow roof. Of course, slate roofs (rooves) tend to be much steeper and it’s very difficult to nail into it. A shame to glaze over a nice slate roof anyway. No offense meant – just couldn’t help kidding you about slate roofs. I’d love to have one, myself. Bob It would be inefficient, but would also be huge. The basic idea is this… nothing gets installed on the rooftop, this one is installed in the loft, where there is no sunlight :) Its OK, I havent lost it yet… see a black slate roof gets hot in sunlight, so one could snake a copper microbore pipe up and down the slate roof to collect some of the heat, pinning it in place here and there, and putting some form of very basic insulation behind it. Now efficiency would be poor, but the loft roof area would be huge. Big Qs: How efficient might this be? How could one control it… it would have to be actively emptied when it got too cold, but I didn’t figure out in one sitting a simple way to both pump the water round and empty it. I really want to keep it cheap and simple. We can all put something complex together, but I’m hoping for something simple and cheap enough to make it into mass market application. Any input would be good… Regards, NT

Response:

Hi peoples. I had an odd thought today, for a solar panel that might be practical. I am thinking it would be eaiser and cheaper to install – I guess the hope behind it would be to make solar more popular. It would be inefficient, but would also be huge. The basic idea is this… nothing gets installed on the rooftop, this one is installed in the loft, where there is no sunlight :) Its OK, I havent lost it yet… see a black slate roof gets hot in sunlight, so one could snake a copper microbore pipe up and down the slate roof to collect some of the heat, pinning it in place here and there, and putting some form of very basic insulation behind it. Now efficiency would be poor, but the loft roof area would be huge. Big Qs: How efficient might this be? How could one control it… it would have to be actively emptied when it got too cold, but I didn’t figure out in one sitting a simple way to both pump the water round and empty it. I really want to keep it cheap and simple. We can all put something complex together, but I’m hoping for something simple and cheap enough to make it into mass market application. Any input would be good… Regards, NT

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