solar panels

[The Natural Philosopher]

:-)

I don't think it follows though. If they are marginally economic that probably means the energy savings are marginal too.

Look at how CFL bulbs have taken off. Not because they represent huge savings in energy, but because they last longer as well.

Everyone knows that the two dominant domestic uses of energy are cars and central heating. The rest is trivial. Just a 10% improvement in house insualation here, would pay for three years of hot water in a year.

Cutting out one supermarket trip a month would save more than equipping all the rooms with CFLs..

Wer have a wonderful solar heating system here. Its called windows. In the winter daytime, we draw the curtains, and get what sun there is heating the house. At night, we draw the curtains, and it stays in.

We have another form of solar heating too. Its called a log burning fire. In summer the sunlight is converted into wood., In winter we burn it.

[meow2222]

This last sentence doesnt follow logically from what comes before. It doesnt even begin to, I'm sorry.

The science behind solar space heating is quite basic. You've got insolation and insulation. With enough insolation, which we have even in winter, and enough insulation, which is down to panel design, there is nothing difficult about getting space heating to work. Most house roofs and walls are big enough to capture a whole lot of heat, even in winter. Again, how much of the heating bill a real world system chops off is down to design of system (effectiveness, size) and the design/insulation of the house itself.

Of course there are countries with better solar heating prospects than Britain, but even here its perfectly workable _if_ you design a system that pays its way. And among the multitude of poor designs that fail to pay their way, there are also many that do.

Well... again its a question of how much you want to spend and how much you want to take off the heating bill. A simple system that will heat half the house directly and the rest indirectly is not a difficult proposition, either design wise or financially. A full house system is a bit more demanding, and a year round system more demanding again... take your pick.

I dont know if that was without any formal qualifications or with. I'm also aware the general level of solar design has come a fair way since then. Either way, I find your position hard to agree with, sometimes on fairly basic principles..

NT

[meow2222]

I daresay this may work. Mass produced panels would be significantly cheaper. The result of this nannyism would be widespread implementatoin of systems that barely pay their way, all too often paid for by people who have far more pressing things to spend on and far bigger issues to resolve in their lives. Most such systems would be neither appreciated nor cared for, and would not be maintained or repaired. Note that in this system, since everyone buys solar panels, there is no economic incentive to develop the technology, either for lower cost or higher return, so the payback stays poor for evermore.

Lets look at the other option, which is permitting private market forces to address the problem. In the short term we'll see few systems because they mostly dont pay and are expensive. Once a company comes up with a design that can be sold at a third the price, ie one with much better payback performance, interest will increase. The next generation of design, with lower cost nd more return, will see widespread interest, be implemented up and down the country, and give quite large savings to the country as a whole, both of money and energy. And whoever starts such a company should make some very nice money.

Which do you want? Nannied borderline systems, many of which will cease even functioninng, or to let the market develop the technology so that it has genuine and signifcant value?

NT

[Matt]

Absolutely. But insulation, passive solar gain and building occupancy/equipment gains are more useful, more efficient, more economical and more reliable over the long term than any panel based solar collector.

On a new build with freedom to change or incorporate design modifications of say a few thousand pounds (actually the spend is immaterial) there is no way I would even contemplate solar (hydronic) space heating. For the hot water a cautious yes, but the majority of my spend would be on insulation, controlled ventilation/heat recovery and most importantly quality assurance during the build.

[Stuart Noble]

I can't believe the Chinese aren't already making them.

[Mary Fisher]

How do you know they're not?

Mary

[Stuart Noble]

That's what I mean. I think the equipment is already available cheaply. It's all over the place in southern Europe, so mass production must be happening somewhere. I wonder about solar fence panels. Looking around here, fences represent a vast area, and no one much cares what they look like. The cat would approve I'm sure

[Andy Hall]

Even they need to see a worthwhile volume market.

[Mary Fisher]

That's a thought! But they could be vulnerable to malicious damage. Some people think they're ugly - goodness knows why. Then there would be maintenance - keeping growth down without damaging the panels. And there could be a long way for the hot water to travel and there might be shade on the panels .. hmmm. It was a nice idea while it lasted :-)

Mary

[Stuart Noble]

Every hotel and holiday home in southern Europe isn't a bad start

[meow2222]

I was wondering why you said that until I read further

Space heating and hydronic are concepts that mix badly imho. Hot air systems are a fraction the material cost and installation cost of hydronics, much more reliable, and much more efficient.

You may be right if considering hydronic systems, which I dont hold in high regard, mainly due to excessive install cost and weak payback. But if we compare hot air panels with passive solar gain, the picture is somewhat different. Passive solar gain comes at the price of winter heat loss, or high dg/tg install cost, and large areas of glass are needed to get good gain. But the prime problem is poor control. External panels are easy to control, their output can be switched on or off at any time, simply by powering a fan or dampers. IOW a well designed system would normally be thermostatic. Another plus with separate panels is cheaper glazing can be used. Glass or plastic outer and mylar film inner glazing are practical with panels, but not really with building windows.

Its a curious thing that the lowest cost best payer version of solar power is so little known.

NT

[meow2222]

I think solar power is not acepted here yet, since commercial systems do not so far give enough payback to be considered worthwhile by most of the population. Hence it makes more sense to manufacture TVs than solar kit. Today anyway, I'm sure it'll change in time.

I like that one. But it would only work well for unobstructed south facing fences that run right upto the house. Not sure what size market that is. Plus rented accom would be generally unlikely to purchase.

Yes, but then so are shed windows, and they seem ok in most areas

yes, but again it depends on design. The only given with solar panels is they'll be a dark colour. They could be made to look like slates, or imitate any other dark stone, or be midnight blue. Even mid colours will work, if not as well, so looking like dark or even medium wood is perfectly workable.

I dont know what sort of glazing would be wanted, but this point would be a lot easier if the bottom foot of the panels were decorative only, and not used for solar gain.

Use hot air. A hydronic system would bring many downsides, especially on price.

limitation to south and unobstructed does limit things somewhat, but

2nd generation panels only need a couple of percent market penetration to succeed. And with respectable payback, commercial use would flourish.

Still many details to resolve though, and the market perception is a block.

NT

[The Natural Philosopher]

Wrong.

Yup. Its called a south facing picture window and plenty of thermal mass with heavy lined curtains that are drawn at night. Or in fact on hot summer days.

Its attractive, effective, and the control is so simple even my wife can do it.

[David Hansen]

On Wed, 27 Sep 2006 12:37:10 GMT someone who may be Stuart Noble wrote this:-

They already are. Try buying an evacuated tube that is not made in China. However, they are not making complete panels for the whole world.

[meow2222]

I prefer a system that controls itself thermostatically, and where one doesnt need to close the curtains during much of the summer days to control it. But you can have your prefered system if you want.

Before you say overhangs, there are many locations where they cant be installed, and when they are theyre not thermostatic..

NT

[Andy Hall]

Perhaps people have more taste though....

[The Natural Philosopher]

Well put a thermostat on the curtains then

No, but they work.

[Stuart Noble]

Part of the landscape in Greece. I doubt people will stop going there because every little bungalow has a shiny tank on the roof. "Taste" seems a rather quaint concept in the big scheme of things.

[Andy Hall]

It is, however, a major reason for buying or not buying something. People do buy (or not) on impression and appearance.

If one takes an economically marginal at best proposition and it is then also visually an eyesore, it is not a winning combination.

I am reminded of the dreadful solar hot water heating systems which adorn many rooftops in Tel Aviv. These consist of a metal canister to store some water plus a collection of tubes and pipes connected to a solar panel on an angled stand on the flat roof. They are absolutely hideous. Fortunately there it doesn't matter quite so much because it is customary not to complete construction but to leave steel reinforcing rods sticking out. I believe there is a tax dodge for doing this. There of course there is no question of lack of sun either.

Howver, try to transport the concept to a country where people do care more about aesthetics and where solar energy is substantially less and it is not going to sell. Fortunately.

[Doctor Drivel]

The Chinese invented them. Over 50% of all solar panels in the world are in China.