# The Naked Scientists Forum

### Author Topic: If every roof of every building was made of solar panels how much electricity?  (Read 17485 times)

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« on: 31/03/2011 15:47:42 »
If every roof of every building was covered in Solar panels, potentially how much electricity could that generate?

For a given country?

For the whole planet?

For a town?
« Last Edit: 31/03/2011 15:49:43 by Wiybit »

#### Pumblechook

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #1 on: 31/03/2011 16:09:21 »
I think average energy yeald per day per sq metre over a full year is of the order 250 to 500 Watt-hours.  They say roof panels can generate 1/3 to 1/2 of a home's demand.

The problem is the huge cost of the panels, batteries and electronics.  Without hefty subsidies (which the UK is likely to pull the plug on soon...excuse the pun) they never pay for themselves.

Even on an industrial scale Solar Power produces a very small proportion of our elec' needs.

A real system to study is that of St James's Church, Piccadilly London.

http://www.simondawson.com/sjpenv/sjppv1.htm

« Last Edit: 31/03/2011 16:11:21 by Pumblechook »

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #2 on: 31/03/2011 16:18:41 »
I think average energy yeald per day per sq metre over a full year is of the order 250 to 500 Watt-hours.  They say roof panels can generate 1/3 to 1/2 of a home's demand.

Relative to how many a home uses.

The problem is the huge cost of the panels, batteries and electronics.  Without hefty subsidies (which the UK is likely to pull the plug on soon...excuse the pun) they never pay for themselves.

No they will always pay for themselves eventually.

Even on an industrial scale Solar Power produces a very small proportion of our elec' needs.

A real system to study is that of St James's Church, Piccadilly London.

http://www.simondawson.com/sjpenv/sjppv1.htm

#### peppercorn

• Neilep Level Member
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##### If every roof of every building was made of solar panels how much electricity?
« Reply #3 on: 31/03/2011 16:36:27 »
No they will always pay for themselves eventually.
Panels do degrade over their lifetime - causing lower and lower Kw's available at a rate depending on the technology used.  For that reason their ability to 'pay for themselves' is not necessarily a given (ie. it depends on other economic factors also).

#### Pumblechook

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #4 on: 31/03/2011 16:53:01 »
You could say that if every domestic UK roof was covered that the equiv of about 8+ million homes could be supplied out of 25....Not that it would be possible to supply the 8 million 100% of the time.

Even if the panels remained as good as on the first day and no batteries etc had to be replaced the payback time is of the order of 40++ years...  In practice it means never as they will not remain as on day one and batteries certainly will have to be replaced several times in 40++ years.

You can spend as much as  £20,000 and save as little as £200 a year = 100 years.  No sense at all economically.  Again no replacement costs considered.

You would need a 5+ fold increase in elec prices or a 5+ fold decrease in the cost of panels.   Panels may drop in price but the reduction of subsidies in the UK and other countries will kill demand and economies of scale can't kick in.  Batteries are actually going up steeply in price.  I used to buy small lead acid at £5 a go.  Now they are £13!

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #5 on: 31/03/2011 19:56:13 »
No they will always pay for themselves eventually.
Panels do degrade over their lifetime - causing lower and lower Kw's available at a rate depending on the technology used.  For that reason their ability to 'pay for themselves' is not necessarily a given (ie. it depends on other economic factors also).

That could be a design flaw. Sounds like we need to make longer lasting panels, that will come over time, I'm sure.

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #6 on: 31/03/2011 20:07:11 »
You could say that if every domestic UK roof was covered that the equiv of about 8+ million homes could be supplied out of 25....Not that it would be possible to supply the 8 million 100% of the time.

On what do you base that statement? If they can supply now upto a half of a houses energy, and normally they simply use a few panels on a house, they never cover the whole roof, or use systems to assist the panels in recieving more light, or have panels that follow the sunlight.
Even today they potencially could give electricity to 12.5 million homes, not 8.

Industry isn't interested, and industry will rubbish renewable tech where ever it can but still, there is a lot more potencial avaliable.

Even if the panels remained as good as on the first day and no batteries etc had to be replaced the payback time is of the order of 40++ years...  In practice it means never as they will not remain as on day one and batteries certainly will have to be replaced several times in 40++ years.

You can spend as much as  £20,000 and save as little as £200 a year = 100 years.  No sense at all economically.  Again no replacement costs considered.

That should change over time as technology improves esp if there is a good market out there, the newest stuff will be expensive and the older very cheep, just like with computer technology.

You would need a 5+ fold increase in elec prices or a 5+ fold decrease in the cost of panels.

Energy is about to start increasing in cost isnt it. Better technology is comming everyday, I would say that's a fore-gone-conclusion that over the next few years solar will be taking over.

Panels may drop in price but the reduction of subsidies in the UK and other countries will kill demand and economies of scale can't kick in.  Batteries are actually going up steeply in price.  I used to buy small lead acid at £5 a go.  Now they are £13!

It's a supply issue it sounds like lots of people want them, increased producers will come in to fill that gap, but also some of that might also be inflation.
« Last Edit: 31/03/2011 20:09:33 by Wiybit »

#### peppercorn

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #7 on: 31/03/2011 21:26:37 »
Sounds like we need to make longer lasting panels, that will come over time, I'm sure.

Hmmm. Well, we may have fusion reactors and flying cars over time. The problem is what we have now!
The many crises arising from humanities currently unsustainable approach to energy usage can't wait for what might be.
« Last Edit: 31/03/2011 21:49:16 by peppercorn »

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #8 on: 31/03/2011 21:40:35 »
Sounds like we need to make longer lasting panels, that will come over time, I'm sure.

Hmmm. Well, we may have fusion reactors and flying cars over time. The problem is what we have now!
The many crises arising from humanities currently unsustainable approach to energy usage can't wait for what might be.

No think you'll find there is lots of research going on in that field and it's improving rapidly.

#### peppercorn

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #9 on: 31/03/2011 21:50:10 »
You would need a 5+ fold increase in elec prices or a 5+ fold decrease in the cost of
panels.
Energy is about to start increasing in cost isnt it. Better technology is comming everyday, I would say that's a fore-gone-conclusion that over the next few years solar will be taking over.
It seems obvious that you are making a great number of assumptions/predictions about subjects that you clearly only have a outline understanding of.
Yes - traditional energy sources are increasing in cost.
Yes - New and better technologies are emerging.
But, what leads you to predict a five times (500%) increase in the economic effectiveness of solar panels will occur in a 'few' years?  -  This is no more than wishful thinking. - IOW extremely unlikely!
Further, there is such a thing as base-load power to take into account.

No think you'll find there is lots of research going on in that field and it's improving rapidly.

And?

#### Pumblechook

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #10 on: 01/04/2011 10:34:44 »
I am not predicting a 5 fold decrease in solar prices.  I am saying that is what you would need (at least).  Given poor economic conditions in many countries subsidies are likley to be reduced or removed.  This will kill demand and I think solar has no future really.  Similarly susidies for electric vehicles are likely to go and given the high cost of these vehicles they have no future either.

There is no rapid improvement in the technology on the horizon unless there a quantum leap breakthrough all of a sudden....unlikely.

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #11 on: 01/04/2011 12:07:10 »
I am not predicting a 5 fold decrease in solar prices.  I am saying that is what you would need (at least).  Given poor economic conditions in many countries subsidies are likley to be reduced or removed.  This will kill demand and I think solar has no future really.

I disgree those involved in solar will look to improve costs. But also subisides are not defiantely getting removed.

Similarly susidies for electric vehicles are likely to go and given the high cost of these vehicles they have no future either.

There is no rapid improvement in the technology on the horizon unless there a quantum leap breakthrough all of a sudden....unlikely.

There are planty of technologies out there. Big industry is more of an issue, than that the tech.

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #12 on: 01/04/2011 12:13:35 »
You would need a 5+ fold increase in elec prices or a 5+ fold decrease in the cost of
panels.
Energy is about to start increasing in cost isnt it. Better technology is comming everyday, I would say that's a fore-gone-conclusion that over the next few years solar will be taking over.
It seems obvious that you are making a great number of assumptions/predictions about subjects that you clearly only have a outline understanding of.
Yes - traditional energy sources are increasing in cost.
Yes - New and better technologies are emerging.
But, what leads you to predict a five times (500%) increase in the economic effectiveness of solar panels will occur in a 'few' years?  -  This is no more than wishful thinking. - IOW extremely unlikely!

Doesnt have to come in the next few years, but it will come eventually.

Further, there is such a thing as base-load power to take into account.

The base load will just change as more renewables are taken up by consumers, but again the industry doesnt want them, the coal plant owner wants you all using his energy, as does the nuclear plant owner.

No think you'll find there is lots of research going on in that field and it's improving rapidly.

And?

Have a little hope.

#### peppercorn

• Neilep Level Member
• Posts: 1466
##### If every roof of every building was made of solar panels how much electricity?
« Reply #13 on: 01/04/2011 19:01:21 »
I would say that's a fore-gone-conclusion that over the next few years solar will be taking over.
It seems obvious that you are making a great number of assumptions/predictions...
then...
Doesn't have to come in the next few years, but it will come eventually.

The base load will just change as more renewable are taken up by consumers, but again the industry doesn't want them.

No think you'll find there is lots of research going on in that field and it's improving rapidly.
And?
Have a little hope.
I do, but mine is realistic.

#### Jolly- Joliver

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• Posts: 584
##### If every roof of every building was made of solar panels how much electricity?
« Reply #14 on: 01/04/2011 20:36:50 »
I would say that's a fore-gone-conclusion that over the next few years solar will be taking over.
It seems obvious that you are making a great number of assumptions/predictions...
then...
Doesn't have to come in the next few years, but it will come eventually.

The base load will just change as more renewable are taken up by consumers, but again the industry doesn't want them.

It's the minimum needed amount of energy, that is increasing, yet at the same time we are conserving also.

No think you'll find there is lots of research going on in that field and it's improving rapidly.
And?
Have a little hope.
I do, but mine is realistic.

Maybe but you seem pessimistic

#### peppercorn

• Neilep Level Member
• Posts: 1466
##### If every roof of every building was made of solar panels how much electricity?
« Reply #15 on: 02/04/2011 12:43:48 »
It's the minimum needed amount of energy, that is increasing, yet at the same time we are conserving also.
No.

Since you don't seem to want to take the initiative and spend time understanding base-load energy completely, the aspect I am talking about is this: http://en.wikipedia.org/wiki/Dispatchable_generation (referenced off the main article).  Note the separation between the defined of 'Dispatchable generation' and 'intermittent power sources' (like wind) and also with constrained base load generation (like nuclear).

Therefore, having pure wind generation is infeasibly impractical for the reasons outlined (as well as economically non-viable).
« Last Edit: 02/04/2011 12:47:51 by peppercorn »

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #16 on: 02/04/2011 21:22:59 »
It's the minimum needed amount of energy, that is increasing, yet at the same time we are conserving also.
No.

Since you don't seem to want to take the initiative and spend time understanding base-load energy completely, the aspect I am talking about is this: http://en.wikipedia.org/wiki/Dispatchable_generation (referenced off the main article).  Note the separation between the defined of 'Dispatchable generation' and 'intermittent power sources' (like wind) and also with constrained base load generation (like nuclear).

Therefore, having pure wind generation is infeasibly impractical for the reasons outlined (as well as economically non-viable).

Do not see your point base load power and base load plant are different things. But anyway I do not have an issue with coal and others base load forms of generation, I have an issue with nuclear, but Clean coal potencially can not only deal with base load issues it can also, be used to manufacture plastics, oil, diesel, and lots of other things, through feeding algie beds.

While there are issues we can address them, long term better answers are on there way.

I believe in many solutions to any problem. There is a lot of waste at the moment.

#### peppercorn

• Neilep Level Member
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##### If every roof of every building was made of solar panels how much electricity?
« Reply #17 on: 03/04/2011 09:23:14 »
Since you don't seem to want to take the initiative and spend time understanding base-load energy completely, the aspect I am talking about is this: http://en.wikipedia.org/wiki/Dispatchable_generation (referenced off the main article).  Note the separation between the defined of 'Dispatchable generation' and 'intermittent power sources' (like wind) and also with constrained base load generation (like nuclear).

Therefore, having pure wind generation is infeasibly impractical for the reasons outlined (as well as economically non-viable).

Do not see your point base load power and base load plant are different things. But anyway I do not have an issue with coal and others base load forms of generation, I have an issue with nuclear.

How quickly you forget your own arguments!
Trying to educate you about base-load power generation (requiring BL power plants - there's no other industry definition whether you like it or not) is done in the hope that you will finally understand why it is practically infeasible to solely use Intermittent energy sources (like wind and solar PV) for grid-scale power requirement, without the integration with base-load plants (one type of which is nuclear, even though you imply it's not).
Maybe if you stopped starting (ill-educated) arguments on so many fronts, you might keep a grip on the relevance of the responses you are getting. and learn a thing or two!

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #18 on: 03/04/2011 10:35:40 »
Since you don't seem to want to take the initiative and spend time understanding base-load energy completely, the aspect I am talking about is this: http://en.wikipedia.org/wiki/Dispatchable_generation (referenced off the main article).  Note the separation between the defined of 'Dispatchable generation' and 'intermittent power sources' (like wind) and also with constrained base load generation (like nuclear).

Therefore, having pure wind generation is infeasibly impractical for the reasons outlined (as well as economically non-viable).

Do not see your point base load power and base load plant are different things. But anyway I do not have an issue with coal and others base load forms of generation, I have an issue with nuclear.

How quickly you forget your own arguments!

What arguement? You asked me to look into Base load power, I did then you moan I havent understood what you meant, I read what you sent me which was about base load plants and point out there is a difference. Then I said I don't have an issue with clean Coal which is a base load plant, no change at all on other threads I was talking about how we can use clean coal to feed algie beds I give you the reference if you want.

Trying to educate you about base-load power generation (requiring BL power plants - there's no other industry definition whether you like it or not) is done in the hope that you will finally understand why it is practically infeasible to solely use Intermittent energy sources (like wind and solar PV)

But I never suggested that anyway
Quote
I believe in many solutions to any problem. There is a lot of waste at the moment.

Sorry you presume to think I was just saying everything should be renewable, as much as possible should, but I never for a moment said everything should be renewable, eventually it could be possible, anything is possible.

for grid-scale power requirement, without the integration with base-load plants (one type of which is nuclear, even though you imply it's not).

No I never said or implied that Nuclear wasnt base load I said "I have an issue with nuclear", issues that include what's been happening in Japan.

Maybe if you stopped starting (ill-educated) arguments on so many fronts, you might keep a grip on the relevance of the responses you are getting. and learn a thing or two!

Maybe if you didnt make assumptions this conversation would be easier.

#### peppercorn

• Neilep Level Member
• Posts: 1466
##### If every roof of every building was made of solar panels how much electricity?
« Reply #19 on: 03/04/2011 13:27:27 »
Better technology is coming everyday, I would say that's a fore-gone-conclusion that over the next few years solar will be taking over [from unsustainable fossil-fuelled power stations.]
The overwhelming implication of your meaning in what I've already quoted you as writing (along with the context you were writing in) is that solar could (& will!) become the vast majority of all power generated.  Therefore it was necessary for me to go on to explain what base-load generation means and why it rules this view out.

No I never said or implied that Nuclear wasnt base load
but
I do not have an issue with coal and others base load forms of generation, I have an issue with nuclear.
This implies you don't view nuclear as a base-load source, as I said. Nothing more.

I read what you sent me which was about base load plants and point out there is a difference.
Okay - explain the difference.

Maybe if you didn't make assumptions this conversation would be easier.
The whole point is that I am not making assumptions. Your badly structured sentences lead to the confusion in the first place.

It sounds like you have finally grasped (more-or-less) what base-load is - thank goodness!
BTW, contrary to your last post, an all renewable mix of generation can balance providing it includes renewable base-load stations, like hydroelectric.
« Last Edit: 03/04/2011 13:29:29 by peppercorn »

#### Jolly- Joliver

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##### If every roof of every building was made of solar panels how much electricity?
« Reply #20 on: 03/04/2011 13:53:49 »
Better technology is coming everyday, I would say that's a fore-gone-conclusion that over the next few years solar will be taking over [from unsustainable fossil-fuelled power stations.]
The overwhelming implication of your meaning in what I've already quoted you as writing (along with the context you were writing in) is that solar could (& will!) become the vast majority of all power generated.

No it isnt a total assumption on your part, My question on this thread was how much could be generated, a desire to get as much as possible, but that in no way implies it replaces all other forms of power generation.

Therefore it was necessary for me to go on to explain what base-load generation means and why it rules this view out.

No I never said or implied that Nuclear wasnt base load
but
I do not have an issue with coal and others base load forms of generation, I have an issue with nuclear.
This implies you don't view nuclear as a base-load source, as I said. Nothing more.

No as I said, The "issue" I have is with it's dangers, nothing to do with it being a base load power generation plant, again you make leaps and assuming things. But I can see your point slightly, just slightly- to the point of hair spliting.

I read what you sent me which was about base load plants and point out there is a difference.
Okay - explain the difference.

That base load power is the minimal power people need, the plants that are 'base load' generate that power.

Hence why I said
Quote
It's the minimum needed amount of energy, that is increasing, yet at the same time we are conserving also

to say "the base load is increasing"(as people use more), but we are also saving on the energy we use at the same time.

Maybe if you didn't make assumptions this conversation would be easier.
The whole point is that I am not making assumptions. Your badly structured sentences lead to the confusion in the first place.

It sounds like you have finally grasped (more-or-less) what base-load is - thank goodness!
BTW, contrary to your last post, an all renewable mix of generation can balance providing it includes renewable base-load stations, like hydroelectric.

That's right it's my sentence structure, clearly. I tell you what. Well say 50% is down to my "bad grammar" and the other 50% is down to you assuming things.

Lets just call it quits there.
« Last Edit: 03/04/2011 14:01:36 by Wiybit »

#### teragram

• Sr. Member
• Posts: 122
##### If every roof of every building was made of solar panels how much electricity?
« Reply #21 on: 04/04/2011 18:51:09 »
May I stick my oar in?:-

In answer to the original question:-
The average yield is about 500Wh per day in the U.K. (“Sustainable Energy - without the hot air”, by David MacKay. Incidentally, a very interesting book, the contents of which are available online, www.withouthotair.com). This book is “to those who will not have the benefit of two billion years’ accumulated energy reserves”.

The roof of my small house is about 16 square metres, so should collect about 8KWh per day, or nearly 3000KWh per year, maybe one quarter to one third of total (all electric).
Not an insignificant amount.
I don’t know how many houses there are, but there are also shops, offices, factories, shopping centres….., all of which have roofs.

“New Scientist”  2nd April 2011:-
The relevant article is “The Fantasy of Renewable Energy”. This suggests that the energy requirements of the human race, if fulfilled by wind and wave, may change the dynamics of the atmosphere, with uncertain consequences. The article states that with hydro-electric generation, only solar energy (including photosynthesis) can supply the necessary energy renewably without side-effects.
But then, perhaps we are happy to continue increasing our reliance on fossil and nuclear.

#### Pumblechook

• Hero Member
• Posts: 569
##### If every roof of every building was made of solar panels how much electricity?
« Reply #22 on: 04/04/2011 20:16:22 »

Solar was discussed on Radio 4 today with the usual pro / anti representative.   The feed in tarrif (FIT) is a ridiculous 40 p per kWh which is around 3 to 4 times more than the going domestic rate and maybe 8 - 10 times the wholesale price (from a gas powered station)... = A massive subsidy.

8 kWh is only about £1 worth of elec and on the Radio 4 prog they interviewed a bloke who had paid £11,000 for such a system.

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.

#### Jolly- Joliver

• Hero Member
• Posts: 584
##### If every roof of every building was made of solar panels how much electricity?
« Reply #23 on: 04/04/2011 20:27:38 »
May I stick my oar in?:-

You certainly may

In answer to the original question:-
The average yield is about 500Wh per day in the U.K. (“Sustainable Energy - without the hot air”, by David MacKay. Incidentally, a very interesting book, the contents of which are available online, www.withouthotair.com). This book is “to those who will not have the benefit of two billion years’ accumulated energy reserves”.

The roof of my small house is about 16 square metres, so should collect about 8KWh per day, or nearly 3000KWh per year, maybe one quarter to one third of total (all electric).
Not an insignificant amount.

No it isnt, that's pretty good.

I don’t know how many houses there are, but there are also shops, offices, factories, shopping centres….., all of which have roofs.

“New Scientist”  2nd April 2011:-
The relevant article is “The Fantasy of Renewable Energy”. This suggests that the energy requirements of the human race, if fulfilled by wind and wave, may change the dynamics of the atmosphere, with uncertain consequences. The article states that with hydro-electric generation, only solar energy (including photosynthesis) can supply the necessary energy renewably without side-effects.

That's windmills changing the wether. Tidal shouldn't have an impact either, that could come under hydro electric tho.

But then, perhaps we are happy to continue increasing our reliance on fossil and nuclear.

There are better fossil power generators comming, Nuclear I can't see continuing really not in the long-long term. We'll see, but some fossil power generation is hadly a big issue, it's too much of it, that's the real problem and as renewables get better, the fossils and others systems can deminish.

#### Jolly- Joliver

• Hero Member
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##### If every roof of every building was made of solar panels how much electricity?
« Reply #24 on: 04/04/2011 20:35:35 »

Solar was discussed on Radio 4 today with the usual pro / anti representative.   The feed in tarrif (FIT) is a ridiculous 40 p per kWh which is around 3 to 4 times more than the going domestic rate and maybe 8 - 10 times the wholesale price (from a gas powered station)... = A massive subsidy.

8 kWh is only about £1 worth of elec and on the Radio 4 prog they interviewed a bloke who had paid £11,000 for such a system.

11,000 for what system?

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.

#### The Naked Scientists Forum

##### If every roof of every building was made of solar panels how much electricity?
« Reply #24 on: 04/04/2011 20:35:35 »