# The Naked Scientists Forum

### Author Topic: If every roof of every building was made of solar panels how much electricity?  (Read 17453 times)

#### Geezer

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #25 on: 04/04/2011 21:26:07 »

You could end up with the farcical situation of exporting all your solar elec for 40p a kwH and use elec for your own use via a cable from your neighbour at 12p a kWh. Even then payback would be about 11 years.

The point is you get 40p for each Kwh you give the grid, but then your system will still take energy from the grid at 12p a kwh, that in theory would seriuosly reduce you electricity bill, provided you actually didnt use all the solar you generated and did give some over to the grid.

No. You seem to be missing the point.

Pum is pointing out that the idiotically huge subsidy might encourage people to game the system by only supplying power through their meter to the grid, but even if they did, their investment in solar power has a very poor return.

#### Pumblechook

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #26 on: 04/04/2011 21:34:43 »
The £11,000 was for a domestic system..maybe of the order of 16 sq metres.  The man who had bought the system kept saying his elec was free???   Yeah right..having forked out 11 Grand and having battery replacement and other costs to come?

The point is that most of the 40p comes from tax payers.
That was the central point of the BBC item.

I suspect most of these systems cannot supply heavy loads like cookers, showers, kettles, heaters, washing machines (cold fill)  particularly when you use 2 or 3 of these on at once and you have to rely on the mains for those.

« Last Edit: 04/04/2011 21:45:31 by Pumblechook »

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #27 on: 05/04/2011 01:02:45 »

You could end up with the farcical situation of exporting all your solar elec for 40p a kwH and use elec for your own use via a cable from your neighbour at 12p a kWh. Even then payback would be about 11 years.

The point is you get 40p for each Kwh you give the grid, but then your system will still take energy from the grid at 12p a kwh, that in theory would seriuosly reduce you electricity bill, provided you actually didnt use all the solar you generated and did give some over to the grid.

No. You seem to be missing the point.

Pum is pointing out that the idiotically huge subsidy might encourage people to game the system by only supplying power through their meter to the grid, but even if they did, their investment in solar power has a very poor return.

A very small finacial return, but it's not about that, isnt the point to be using energy that is better for the enviroment, and getting cheaper bills. For each Kwh they give to the grid, they can use 3kwh from the grid and pay nothing for them, effectively and potecially they could end up not paying for electricity but actaully be paid by others for the energy they produce. That would be savings and money back on the investment.

It is a lot to buy but once paid for you have very low energy costs. I agree with the asisstence it will encourage others to take up solar.

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #28 on: 05/04/2011 01:09:45 »
The £11,000 was for a domestic system..maybe of the order of 16 sq metres.  The man who had bought the system kept saying his elec was free???   Yeah right..having forked out 11 Grand and having battery replacement and other costs to come?

The point is that most of the 40p comes from tax payers.
That was the central point of the BBC item.

Well there is a social benefit to using solar, minimally cleaner air etc, But at the same time the electrical companies I believe also have to pay something towards it, at least I saw somewhere that they did but that might not have been in England. I cannot agree with the idea that an energy company will take electricity you produce and sell it to someone else but get the state to pay you from the tax payer the 40p for each kWh. If that is what is happening then the energy companies are just ripping of the people.

I suspect most of these systems cannot supply heavy loads like cookers, showers, kettles, heaters, washing machines (cold fill)  particularly when you use 2 or 3 of these on at once and you have to rely on the mains for those.

Exactly which is why it's unlikely to become a scam for householders that have it, they will always need some grid power.
« Last Edit: 05/04/2011 01:11:50 by Wiybit »

#### Geezer

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #29 on: 05/04/2011 01:54:09 »
Unfortunately, at the moment, the economic benefits of solar energy, particularly in the UK, are negligible, if they even exist.

So, it comes down to the socio/political benefits. If that's the case, it requires taxpayer (voter) approval. Solar energy should be nationalized so that it can be operated at a loss. Pretending it is economically viable is only deception.

#### Pumblechook

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #30 on: 05/04/2011 10:22:42 »

However you look at it the financial return is very poor even negative.  Solar must be the most expensive source of elec we have.

If you want to argue about saving the planet that is another matter but even there the picture is not clear cut.

But why should the tax payer who maybe like me thinks solar is a waste of time subsidise it?

#### Pumblechook

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #31 on: 05/04/2011 10:24:52 »

However you look at it the financial return is very poor even negative.  Solar must be the most expensive source of elec we have.

If you want to argue about saving the planet that is another matter but even there the picture is not clear cut.

But why should the tax payer who maybe like me thinks solar is a waste of time subsidise it?

Even the much more financially viable nuclear is essentially a nationalised business.

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #32 on: 05/04/2011 15:42:12 »
Unfortunately, at the moment, the economic benefits of solar energy, particularly in the UK, are negligible, if they even exist.

So, it comes down to the socio/political benefits. If that's the case, it requires taxpayer (voter) approval. Solar energy should be nationalized so that it can be operated at a loss. Pretending it is economically viable is only deception.

Nationalising pushes all the costs on to the tax payer. Yet these system are for indiviudal private houses, the house holder does get a benefit for them, in the case of the mains grid going down they will still have access to eletricity for example, but there is also a benefit to the society in general also, the subsidy should reflect that social benefit and work to encourage it's promotion.
How could you nationalise them anyway? Hardly going to replace the base loads generating plants, or be put onto every house? so you would then have to decide whic houses got them and which didn't, at least this way people that are prepared to spend money on a solar system get some assistence.
As I said before the power companies that buy the solar kWh off of the people that have these systems, should be paying for that purcase, the extra money should come from tax, but as always business' see government as a way to make money extra profits- hopefully that isnt happening.

But it is also possible that people could install a wind system on there land, or if they had a river running through, some form of hydo-electric also, sub pumps for heating, where possible I think that should be encouraged and assisted, for the benefits it does provide the society at large.

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #33 on: 05/04/2011 15:50:16 »

However you look at it the financial return is very poor even negative.  Solar must be the most expensive source of elec we have.

If you want to argue about saving the planet that is another matter

In some ways it's the whole matter, we would not be having this conversation if the other base load forms of power generation, were not poluting and using resourses unsustainably.

but even there the picture is not clear cut.

But why should the tax payer who maybe like me thinks solar is a waste of time subsidise it?

Because of the social benefits it does provide for us all, but if you want to start down that path there are lots of things government subsised people have issue with. Big business being one of them.

Even the much more financially viable nuclear is essentially a nationalised business.

Apparently Japan is looking to or talking about taking TEPCO national also, considering that private corporate business always seeks profit over it's safety reponsibilities, it kinda understandable, business can't be trusted to run some things safely and we are all potencially effected when it goes wrong.

#### peppercorn

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #34 on: 05/04/2011 17:45:27 »
Solar must be the most expensive source of elec we have.
We would not be having this conversation if the other base load forms of power generation, were not polluting and using resources unsustainably.
For the fifth time, solar can not be used as a form of base-load generation. This is critical to the discussion.

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #35 on: 05/04/2011 17:53:43 »
Solar must be the most expensive source of elec we have.
We would not be having this conversation if the other base load forms of power generation, were not polluting and using resources unsustainably.
For the fifth time, solar can not be used as a form of base-load generation. This is critical to the discussion.

I was saying the "other" forms of power generation, that are base load cause polution ect.

You wanna split hairs go for it, I was not suggesting that solar was a base load form of generation.

However:- if your house only needed the amount of electricity that the solar system you bought provided it, it would be base load for your house, As it would meet the base needs of your home.

#### teragram

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #36 on: 05/04/2011 18:08:31 »
Pumblechook:-
I also heard the Radio 4 (BBC) program. It seemed to say that other countries, notably Germany, are embracing solar energy technology with much greater enthusiasm than the U.K. It also said that solar p.v. is about the only technology whose price is falling rapidly.

The statement “even the much more financially viable nuclear industry….” made me smile. I heard on T.V not long ago that this industry in the U.K. is still subsidized to the level of around £1 billion per annum. It is still a nationalised business in that the U.K. taxpayer still has to underwrite the risks of accidents, the decommissioning of retired plants, and the storage and disposal of waste. But I remember a few years ago, when energy prices were quite low and the shareholders returns had fallen, the government had to fork out, to make up the difference.

Peppercorn:-
The question of baseload is extremely important, and a problem. How about broadening the discussion to include proposals for industrial scale energy storage, to better cope with the variability of supplies from renewables?

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #37 on: 05/04/2011 18:20:08 »
Pumblechook:-
I also heard the Radio 4 (BBC) program. It seemed to say that other countries, notably Germany, are embracing solar energy technology with much greater enthusiasm than the U.K. It also said that solar p.v. is about the only technology whose price is falling rapidly.

The statement “even the much more financially viable nuclear industry….” made me smile. I heard on T.V not long ago that this industry in the U.K. is still subsidized to the level of around £1 billion per annum. It is still a nationalised business in that the U.K. taxpayer still has to underwrite the risks of accidents, the decommissioning of retired plants, and the storage and disposal of waste. But I remember a few years ago, when energy prices were quite low and the shareholders returns had fallen, the government had to fork out, to make up the difference.

Yeah the real costs of nuclear are huge.

Peppercorn:-
The question of baseload is extremely important, and a problem. How about broadening the discussion to include proposals for industrial scale energy storage, to better cope with the variability of supplies from renewables?

Industrail batteries, that can be called upon when sun, wind are low. I'm pretty sure Hydro from tidal and dams is fairly consistent although rain fall could play a part.

On another thread we did talk about solar farms in the desert charging batteries then selling the batteries on.

#### peppercorn

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #38 on: 06/04/2011 10:49:54 »
You wanna split hairs go for it, I was not suggesting that solar was a base load form of generation.
I don't. I want to make it clear for anyone following the thread. What you persistently write (in, what I assume is your second language) gives the impression (and more importantly could lead others to think) that solar or wind or other intermittent-sources can be included in the base-load definition; which could cause problems later on. That is all!

The question of baseload is extremely important, and a problem. How about broadening the discussion to include proposals for industrial scale energy storage, to better cope with the variability of supplies from renewables?
Good idea!
As a start: Some of the pressures on renewables can be lessened where super-grids (continent-wide ultra-high-voltage electricity networks) can be implemented.
So, for instance, Germany's solar output can help even out the fluctuations of the UK's wind (at the not insignificant cost of having a seriously heavy-duty under-sea-cable), whilst being backed-up by Scandinavian hydro.  NB. this is a theoretical energy model only - no guarantees!

#### teragram

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #39 on: 07/04/2011 16:06:59 »
I believe that plans are already afoot for  the said super-grid in Europe, interestingly it will be a DC grid. One or two smaller scale (but still industrial size) DC grid systems are already in place I think. It has even been suggested that such a grid could carry power from the desert areas of North Africa.

Chemical means of electricity storage-:

Another method of storage already in use in the U.K is hydro pumped storage, but there are too few suitable sites to build a lot of these.  A similar method, also in use on small scales in parts of Europe and I think the U.S.A. is energy storage by underground compressed air. Excess power on the grid is used to pump air into old mines etc., to be released via turbines when the grid cannot be supplied by renewables (or nuclear). This is rather inefficient of course, unless the heat caused by compression can be retained and re-used. Experimental plant has been built to achieve this.
This seems to me a better use of underground spaces than carbon capture and storage, which I think is a bad idea.

#### peppercorn

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #40 on: 07/04/2011 16:48:55 »
Teragram,

A DC grid! That sounds like a contradiction in terms!  - I'd love to see the thyristors used for stepping voltage on that!

As for Carbon capture and storage, I'm not sure I'm particularly keen on it as a 'band-aid' solution to climate change, but the very fact that the 'caves' are chosen for adsorbing CO2 might make them unsuited to air-storage.  In any case I think we could be a lot more inventive with our energy storing/balancing technologies.

#### Pumblechook

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #41 on: 07/04/2011 17:14:15 »
The UK - France interconnector is DC.   In any case the UK is not phased locked to France.  They use lots of IGBT devices.

#### Geezer

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #42 on: 07/04/2011 19:53:24 »
I think there are several DC links already in operation in the US, although I suppose you could say that, in a sense, they are not really part of a grid because they interconnect grids, but I don't want to start another fight about semantics

Anyway, DC transmission does solve a lot of problems. I seem to remember being taught that it was not possible to use an AC transmission line that went from one end of Russia to the other simply because of the wavelength.

#### teragram

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #43 on: 08/04/2011 00:28:45 »

Anyway, DC transmission does solve a lot of problems. I seem to remember being taught that it was not possible to use an AC transmission line that went from one end of Russia to the other simply because of the wavelength.

i remember also being told by  an instructor that a particular section of A.C. grid in the U.S.A. was extremely efficient because it was just the right length for (almost) resonance. I cannot verify that. Generally A.C. systems lose energy because of capacitance and inductance.

PC:-
I didn't know that the cross channel cable was DC. I've learned something.

#### Geezer

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #44 on: 08/04/2011 02:53:10 »

Anyway, DC transmission does solve a lot of problems. I seem to remember being taught that it was not possible to use an AC transmission line that went from one end of Russia to the other simply because of the wavelength.

i remember also being told by  an instructor that a particular section of A.C. grid in the U.S.A. was extremely efficient because it was just the right length for (almost) resonance. I cannot verify that. Generally A.C. systems lose energy because of capacitance and inductance.

The capacitance and inductance in the line don't directly result in lost power, but the capacitance and inductance of the loads can lead to lost power. Power losses are mainly due to resistance of the line, but if the voltage and current on the line are not in phase because the load is reactive (inductive or capacitive), the reactive current increases and that increases the power dissipated in the line's resistance (P=i²R). To minimize that loss, the tranmission companies add power factor correction equipment to keep the current and voltage in phase.

Of course, you don't have that problem at all on a DC line, but you do have a lot of fancy kit to convert to and from AC, which is why DC lines are only used in certain situations.

#### SeanB

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #45 on: 08/04/2011 20:28:25 »
Geezer, you are wrong about the capacitance and inductance of the line not resulting in loss of power, as the current capacity of the line is fixed ( It is a rating that is limited by the amount the wires sag down due to heating, and is limited both by the lowest temperature the line will experience, giving the shortest line that can be supported without breaking, and the highest summer temperature causing sagging, which is added to the sag caused by heat from the current carried), generally to around 1000A for most 66kV or higher lines. If the line is long the capacitive charging current becomes a significant part of the total current, limiting the power it can carry, and the inductance increases the impedance of the supply, causing a load dependent voltage drop. The capacitive losses can be high, as the voltage drop can be up to 1000V/km for highly loaded lines.

DC lines can run at full load current irrespective of line length, and the longer the line the more the capacitance helps to stabilise the line voltage. The power carried on a DC link is 40% more than what the same line can carry at AC, and you only need 1 conductor instead of 3 if you use an earth return. While you do need thousands of semiconductor switches at each end for the conversion, they are generally quite reliable, and are assembled in field replaceable modules that are quick to change out in case of problems. Interestingly the links are generally 2 way, as power can flow either way depending on generating and load variations without any switching of mode by each end.

#### Geezer

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #46 on: 08/04/2011 21:27:52 »
Ah! I see what you mean. I stand corrected. Thank you Sean.

Ultimately, don't all those losses just end up as i²R losses in the line?

#### NewYork

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #47 on: 18/04/2011 15:29:48 »
There will enough electricity to power the basic gadgets in the house. But the problem is that solar panel is very costly. Compare the price of a solar panel and the price of a rooftop and you will see huge different.

#### techmind

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #48 on: 18/04/2011 23:52:26 »
I think that to ignore the financial and economic cost of PV panels and claim that you are doing your bit for the environment by using PV is naive in the extreme. I believe that a fair bit of the initial cost of PV is related to the energy required to make them - you have an energy-payback time to consider as well as an economic payback time.
If you've invested the energy in making a PV cell, it is best to then use it somewhere very sunny - and not on some north-facing roof in the Outer Hebrides because "every little helps"! It doesn't.

Although the technology is far more mundane, I believe that solar hot-water panels should have a far faster (energy) payback time than PV. Their efficiency is a whole lot better for starters.

I'm also mystified as to why "green" energy seems to be synomymous with microgeneration in the governments' eyes. For everything else, we have economies of scale and have a modest number of "serious" power stations.

#### Geezer

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #49 on: 19/04/2011 00:09:06 »

- and not on some north-facing roof in the Outer Hebrides because

LOL!

Another highly dodgy location would be Greenock!

I'd never heard about a connection with "green" and microgeneration before. Is it because they are running recovered methane or something? One of those systems going in a few miles from here.

I suppose you might make an argument that they save power because the transmission losses might be lower, but I'm not sure that would offset the economy of scale of a large plant.

#### The Naked Scientists Forum

##### If every roof of every building was made of solar panels how much electricity?
« Reply #49 on: 19/04/2011 00:09:06 »