Impact of solar PV on national grid

SallyKing

I have read on this forum, and others many comments along the lines of:

"PV will not prevent one drop of oil/coal/gas being burnt at power stations"

and

"PV doesn't generate electricity when we need it most, between 5-7pm in the winter"

I'll start with a question - If I reduce my daytime electricity consumption, does it reduce the amount of fuel burnt at the power station?

ColinFishwick

Good question and I am not sure of the answer but at a guess it may do if many others follow suit. I believe there always has to be some over capacity because they cant have an exact detail how much usage at any one time although I believe they have a good idea and monitor the news and tv schedules and have backup to get extra energy due to more usage

energysavingexp

SallyKing wrote: »

I have read on this forum, and others many comments along the lines of:

"PV will not prevent one drop of oil/coal/gas being burnt at power stations"

and

"PV doesn't generate electricity when we need it most, between 5-7pm in the winter"

I'll start with a question - If I reduce my daytime electricity consumption, does it reduce the amount of fuel burnt at the power station?

quick answer is no it does not reduce the amount of fuel burnt at the power station

SallyKing

ColinFishwick wrote: »

Good question and I am not sure of the answer but at a guess it may do if many others follow suit. I believe there always has to be some over capacity because they cant have an exact detail how much usage at any one time although I believe they have a good idea and monitor the news and tv schedules and have backup to get extra energy due to more usage

The point I am trying to make is that if solar pv does nothing to save energy, then there is no point trying to save energy during the day.

Lets take two houses as an example, house A has solar PV and house B doesn't.

House A - uses 5kWh of electric between 9am and 5pm (because some has been supplied by the PV)

House B - uses 10kWh of electric between 9am and 5pm (all its electric has to come from the grid)

So house A will save some money, but has no effect on the fuel burnt at the power station because the power stations can not be turned on and off.

So if lowering consumption during the day makes no difference, why are we bothering at all with energy saving devices?

SallyKing

energysavingexp wrote: »

quick answer is no it does not reduce the amount of fuel burnt at the power station

Yes, exactly - so why are we being told to buy energy efficient appliances and to save energy if it makes no difference?

If we were to all turn on electric heaters during the day would it increase the fuel burnt at the power station?

grahamc2003

SallyKing wrote: »

I have read on this forum, and others many comments along the lines of:

"PV will not prevent one drop of oil/coal/gas being burnt at power stations"

and

"PV doesn't generate electricity when we need it most, between 5-7pm in the winter"

I'll start with a question - If I reduce my daytime electricity consumption, does it reduce the amount of fuel burnt at the power station?

I've never read your first quote on these boards.

I, and others, have posted your second quote.

The answer to your question is, on average, yes. The 'on average' bit comes from the amount you personally save being such a tiny amount that it is just 'noise' in the system (i.e. tolerances and accuracies elsewhere just dwarf the amount you'd save, e.g. a station engineer ramping down the output of a genset a second earlier or later would dwarf the energy you saved.

If many cut down their daytime use, then sure, less would be generated (the demand and generation always match second by second), and less fuel would be burnt/less fissile material would be used.

grahamc2003

energysavingexp wrote: »

quick answer is no it does not reduce the amount of fuel burnt at the power station

I can assure you with 100% certainty that that is incorrect. Why do you think that?

SallyKing

grahamc2003 wrote: »

I've never read your first quote on these boards.

I, and others, have posted your second quote.

The answer to your question is, on average, yes. The 'on average' bit comes from the amount you personally save being such a tiny amount that it is just 'noise' in the system (i.e. tolerances and accuracies elsewhere just dwarf the amount you'd save, e.g. a station engineer ramping down the output of a genset a second earlier or later would dwarf the energy you saved.

If many cut down their daytime use, then sure, less would be generated (the demand and generation always match second by second), and less fuel would be burnt/less fissile material would be used.

Graham, thank you for your response - I'm not sure if you or energysavingexp is correct, but you have given some explanation to your reasoning, so lets take it that you are correct.

So, that means the simple answer is that solar PV does in fact reduce the amount of fuel being burnt at the power stations?

grahamc2003

SallyKing wrote: »

Graham, thank you for your response - I'm not sure if you or energysavingexp is correct, but you have given some explanation to your reasoning, so lets take it that you are correct.

So, that means the simple answer is that solar PV does in fact reduce the amount of fuel being burnt at the power stations?

Yes.

The amount saved by all the solar systems installed today (in England and Wales) will be pretty minimal though, at an extremely high cost relative to all other generation technologies now in use.

In addition, as you mentioned, solar contributes absolutely zero at the period of maximum demand, so we have to have other generation which does contribute (if we don't want power cuts).

So if we spend £5 billion on solar panels, we'd still need the same amount of conventional generation to meet the maximum demand - we can't close other power stations on the basis of spending billions on solar (or wind for that matter).

SallyKing

grahamc2003 wrote: »

Yes.

The amount saved by all the solar systems installed today (in England and Wales) will be pretty minimal though, at an extremely high cost relative to all other generation technologies now in use.

In addition, as you mentioned, solar contributes absolutely zero at the period of maximum demand, so we have to have other generation which does contribute (if we don't want power cuts).

So if we spend £5 billion on solar panels, we'd still need the same amount of conventional generation to meet the maximum demand - we can't close other power stations on the basis of spending billions on solar (or wind for that matter).

Graham, thanks again for another useful reply.

So the answer is that solar PV does save fuel from being burnt at the power stations, its just a question of ecomonics.

So what is the solution?

Our oil and gas are running out fast so we increasingly have to import expensive supplies from abroad.

Nuclear would be great if wasn't so expensive and being built by French companies who will stitch us up on price once they are built. There is also the risk and the waste issue.

Coal releases mercury and while we have a fair bit of coal left we have already mined the best stuff.

Wind is going nowhere due to the nimbys

PV works but is expensive


So is not just a case of we all need to use less energy? Would this not solve all of the issues we face?

larkim

SallyKing wrote: »

Graham, thank you for your response - I'm not sure if you or energysavingexp is correct, but you have given some explanation to your reasoning, so lets take it that you are correct.

So, that means the simple answer is that solar PV does in fact reduce the amount of fuel being burnt at the power stations?

Actually, when you are talking about coal, oil or gas powered power stations the answer is no it doesn't - on the day that you first start saving energy, the power station burns the amount of fuel it thinks it will need for that day. However, if your reduced usage is noticeable to the grid then they will plan to burn less on the next day.

So if we all (unexpectedly) switched off everything at 11.01am tomorrow for a couple of minutes then the amount of fuel being burned at that time would remain the same.

Matt