Confusion over PV connection to grid

[akaPABLO01]

Just think of voltage, like pressure in a water pipe, the water will always flow to the point of lowest pressure. The same is true of electricity, for current to flow the voltage must be higher than the the background voltage, its called potential difference. Turning on a switch lowers the voltage and current flows into the light/ motor whatever to correct the difference
Current comes from the mains but you can push it back up by raising your voltage, this will only be a very small amount as the grid can absorb an awful lot and you will be limited by the wires to your source. The lighter the wiring the higher you will have to push the voltage to force the current back.
I think you are confused by the alternating nature of DC where the power is indeed pulsating, but the current is actually only ever flowing in one direction

Ok, so, in order to export the voltage needs to be fractionally higher than network. We both agree on this.

Amps control the level of power, and these are fused. You draw more amps than you're aloud and you burn out the fuse. The network transmits in fluctuations which is why you have a transformer. The network can fluctuate between 240/266V.

The inverter measures this and live time alters the volts increasing its output slightly higher than the network. If this pushes export through higher voltage then this should fully push through at main board.

If it works on a pressure higher then this surely would push through stockpiling the network which back south England's full network capacity with the DNO not accepting grid connections for solar a year or so ago. That network couldn't handle anymore capacity whether it was on a business that would use all of this or in a field.

Concessions were then made if you applied limiters. Now, limiters work by shutting down inverters. You replace network capacity by drawing from the grid in equal measures, the capacity.

There was a rumour a few years ago that new metering would give DNO power to operate generation stations, solar, wind. They would switch them off when demand was low and switch them on when demand was high (wind farms) yes these are grid tied only but it was rumoured to eventually be ever generation station on the network with compensation for downtime.

I'm going to add this to my downtime research and I want to know exactly the behaviour of the inverter versus the network and need to find someone in metering to give me a run through as I'm not convinced. This could be the biggest rip off ever if you're not consuming more than half your generation then buying it back after selling it for 1/3 its value.

 

[jcb360]

Amps control the level of power, and these are fused. You draw more amps than you're aloud and you burn out the fuse. The network transmits in fluctuations which is why you have a transformer. The network can fluctuate between 240/266V.

What on earth are you on about?

 

[Exfarmer]

The network is allowed to fluctuate -10% to plus 6% from 240 volts
Ie 216 volts to 253 volts.
I am not sure that Pablo is quite what he claims to be.

 

[jcb360]

This could be the biggest rip off ever if you're not consuming more than half your generation then buying it back after selling it for 1/3 its value.

How many PV systems has your company sold?

And you're of the opinion that PV hasn't reduced any of your customers electricity bills?

Don't you have your own PV system installed?

 

[akaPABLO01]

It's a theory not a claim

I am of theory that the meter measures draw against export. Your generation meter accumulates the total generation and your incomer calculates usage versus export. You export 10kW and import 10kW your meter does not register usage. You use 6kW draw and export 4kW from the 10kW and this is calculated making savings on draw and export via the meter, the full 10kW.

I have about 6MW managed systems and 2kW personal, unfortunately I only profit from fit most is exported.

Pv does reduce billing but calculated by offsetting export versus usage.

Again, this is my opinion currently until I have hard fact, all you offer are opinions also. No one has presented hard evidence.

I'm not sure what you are insinuating @Exfarmer you have only discussed classroom explanation of current flow which offers no solid reply to my question/theory.

 

[Doing it for the kids]

Ok so in your view how does my system work?

Power leaves PV and then gets exported or 'goes the other side into the grid'. At this point it's been measured by the fit meter.

Power is called from the farm, are you saying it all comes via the Sse meter?

What I don't get is if your theory is true how do I and others benefit from PV other than the fit?

Further, if an export meter was fitted, would your theory still be true, it's just that I would know how much power I exported but never get to use it.

I think the most interesting thing from this thread how spectacularly incorrect someone is!?

 

[Highland Mule]

Pablo, can you clarify for me, do you have any qualifications in science, engineering or the likes?

I'm not an electrician or an electrical engineer, and I can clearly see that you are floundering over some pretty basic concepts.

As a professional engineer, I would say that the most important thing is to know what you don't know - I'd implore you to adopt that attitude and stick to giving advice on subjects that you are competent on. I suspect that this doesn't include any electrical installation above very simple systems.

 

[milkloss]

I'm green to all this so might have the wrong end of the stick.

What pablo doesn't get is that the higher voltage from the inverters will push onto the grid (which is a lower voltage) if it has to. That would be when there is no onsite demand.

If you turned a cooker on as an example this higher voltage (generated onsite) would rather push through the cooker than back to the grid. Therefore the leccy generated onsite is used in the cooker first before it is forced onto the wider grid for export.

 

[e3120]

Nope, I'm asking a valid question which probably needs someone with a higher understanding of physics coupled with electrical depth.

Not only do I have a working demonstration that your theory is wrong (see my clear figures on Sunday), but also a 1st class Oxford Physics degree. What I don't have is the time/patience to repeat the attempts of others to explain to you, as you don't seem to want to listen to logic. So please just take my theoretical and practical word for it.

 

[akaPABLO01]

This is real entertainment, I'm actually enjoying this.

Let's leave this thought and include energy suppliers now. These big 6 say, manage energy. They all purchase power auctions for energy on the network. Each will buy energy that is produced by nuclear, coal, gas,oil and renewables. They buy these auction capacities in advance. It is listed on your bill were the energy company has bought from. How do they auction off renewables in electricity and pre buy a capacity satellite generation capacity?

Production values are collected and estimations on future production at times of year and location are logged via the generation meter.

All deliverable solar capacity exits to buy.

The energy company buys your export and sells your generation to your neighbour for 15p and pays 4.8p now?? You are benefited buy no draw registered on the incomer, generation fit, and exported savings through using less then you needed calculated on your supply meter?

 

[Highland Mule]

I suspect that you're the only one who is enjoying this - the rest of the world is getting increasingly exasperated by your attempts to appear knowledgeable, when you clearly aren't.

I'm going to take your last message as confirmation that you aren't an engineer, purely on your inability to communicate effectively. Would you care to re-write your question coherently?

 

[akaPABLO01]

I suspect that you're the only one who is enjoying this - the rest of the world is getting increasingly exasperated by your attempts to appear knowledgeable, when you clearly aren't.

I'm going to take your last message as confirmation that you aren't an engineer, purely on your inability to communicate effectively. Would you care to re-write your question coherently?

Welcome @Highland Mule its nice to see a new face on this thread. I'm not entirely sure about your contribution but there's time.

So, you enter the thread and immediately target me, you offer no scientific practice that explains the crucial working of inverter and it's working in partnership with the local network. You don't explain how solar works in parallel to "offsetting" your electric supply and the savings you make.

Let me guess, you have nearly entered the thread to attack, lol

I think you need to crawl back into your cave troll. There is no benefit in you being in this thread if you have nothing to offer.

@Highland Mule please can you link me a thread in the renewable section where you've helped anyone? Lol

 

[milkloss]

@akaPABLO01 no point getting shirty with everyone. Did you get a chance to read my post above and, in your opinion, is it helpful/relevant to you?

 

[Exfarmer]

This is real entertainment, I'm actually enjoying this.

The energy company buys your export and sells your generation to your neighbour for 15p and pays 4.8p now?? You are benefited buy no draw registered on the incomer, generation fit, and exported savings through using less then you needed calculated on your supply meter?

You seem to suggest the energy companies are purchasing our surplus power for 4.8p then selling it to the neighbour for 15p
Firstly a lot of customers actually only pay about 8p .
Second the energy companies have to pay the DNO for shifting power from A-B and this will vary from a negative figure to 8+ p for this service
I have looked into exactly doing this for power supplied to a second meter where the power would not even have gone back to the transformer

 

[jcb360]

It's a theory not a claim

I am of theory that the meter measures draw against export. Your generation meter accumulates the total generation and your incomer calculates usage versus export. You export 10kW and import 10kW your meter does not register usage. You use 6kW draw and export 4kW from the 10kW and this is calculated making savings on draw and export via the meter, the full 10kW.

I have about 6MW managed systems and 2kW personal, unfortunately I only profit from fit most is exported.

Pv does reduce billing but calculated by offsetting export versus usage.

Again, this is my opinion currently until I have hard fact, all you offer are opinions also. No one has presented hard evidence.

I'm not sure what you are insinuating @Exfarmer you have only discussed classroom explanation of current flow which offers no solid reply to my question/theory.

Your theory doesn't explain how import kWhs are reduced when a non import/export meter i.e. an import meter only is used on a premises with PV connected via inverter?

Why don't you try my suggestion of measurement of current using a clamp meter/switchable load on your own 2kW system? The best way to prove a theory is through measurement surely?

My "opinion", while contrary to your theory, has been supported by hard evidence that PV reduces imported kWhs through demonstrations of examples of equipment which exploits this phenomenon by attempting to reduce export to zero. e.g. Cool Power Emma. Please explain why this equipment exists if your theory is correct.

 

[akaPABLO01]

I'm green to all this so might have the wrong end of the stick.

What pablo doesn't get is that the higher voltage from the inverters will push onto the grid (which is a lower voltage) if it has to. That would be when there is no onsite demand.

If you turned a cooker on as an example this higher voltage (generated onsite) would rather push through the cooker than back to the grid. Therefore the leccy generated onsite is used in the cooker first before it is forced onto the wider grid for export.

Well, hello milkloss, I gather a dairy farmer ?

ok where was I? We have established that all generation such as solar enters the grid and you do not use any of it BUT offset your meter to benefit. This is done by you generating 10kW solar and having a use of 6kW on site. All the 10kW enters the grid and your meter freezes and adds the 4kW to the bonus part, Export.

You collect a generation using your solar meter, this is paid by your energy company who owns the rights to your solar production in order to sell it to your neighbour at 15p if they don't have solar. You then also benefit by having your meter offset your usage at the time of generation, making your bills cheaper. Thirdly, you then get a little brucie bonus of export, the generation you don't use.

The only way you can actually use the solar generated on your site is if you have storage, this doesn't offset your meter as you are storing it and does however enter and is used within your farm circuit and does not enter the network grid. You will be paid a generation tariff and have the benefit of using 100%. You will have cheaper bills also but will not qualify for an export tariff.

That about sums up where we are at currently.

ENERGY COMPANIES

Our next step was to understand where the heck your power goes? This is where the energy company come in that owns the rights to sell your renewable energy produced on your site and sell it. In return they will pay you a generation feed in tariff 100% of your generation is compensated in the form of a subsidy for...doing your bit!

They will then pay you a bonus export if you don't use the energy. Independently from this company another company will own your supply meter and using a meter that conforms to generation this offsets your energy usage as detailed before and those pesky big six cannot bill you for this.

So, your energy company like EON (lets call ours: T.B.R.O.) then has its agreement with you and begin accumulating solar satellite farm to do its bit and peacock the fact you are receiving a position of your energy from renewables! Aren't they a good boy, doing there bit for the environment and using less coal fuelled power stations. So, T.B.R.O pay you a tariff and maybe export, some have very lucrative payment plans at 30 odd pence whilst others 9p. They pay you this and charge your neighbour 15p. They then add a little tax on everyone's bill to help them pay these tariffs. If you look on your bill it will either be titled ROCS or FIT or renewables.

Your energy company uses this generation data to understand its haul of renewable energy entering the grid and forecast next years productivity which helps them decide how much nuclear, coal and other energy sources they need to buy in advance. Let's keep this small for understanding purposes from now.

T.B.R.O we buy this energy to supply to YOU~!
Nuclear Coal Oil Renewables
34% 25% 20% 20%

Now, have I missed anything... Ah!

surplus and undersupply!

Have you every had an inverter go down in summer, lost an unusual amount of generation in this period then submitted your figures? If yes, then you should have received an email asking you why your production was low. They send this because they have banked on your production to deliver.

When an energy company has surplus energy at the end of the year they are able to offer discounts to new customers with lower tariffs which is how Uswitch works. This can backfire, once this surplus is depleted you will then receive an email telling you "Unfortunately, we need to increase your tariff" by some 20/30% midway through your 12 month contract. This is why everyone needs to switch annually.

The best time to switch? Summer, when renewable energy is plentiful and units are cheap.

Ok, that covers how your renewable energy enters the grid and how the energy company pays.

The next lesson we will discuss solar panels.


hehehe

 

[milkloss]

Well, hello milkloss, I gather a dairy farmer ?

ok where was I? We have established that all generation such as solar enters the grid (wrong, it only enters the grid once you have taken what you want to use first) and you do not use any of it BUT offset your meter to benefit (if you have any to export after using it onsite a smart meter would count export leccy and no import would occur) This is done by you generating 10kW solar and having a use of 6kW on site (this would result in 4kw export and no import at this time, a smart or export meter would measure your production for calculation of fits and for payment for your production to grid). All the 10kW enters the grid and your meter freezes and adds the 4kW to the bonus part, Export. (I'm not entirely clear what you mean by 'bonus part' , the 4kw is bought from you by the energy company and you get fits for the whole of your production which is 10kw. The meter measures your total production, 10kw, for which you get paid fits, it also measures export, 4kw, for which you get paid per unit, it also measures import, 0kw, for which you pay. It is cheaper to use your own leccy as it's costs less than the grid hopefully and you get fits for using it too, that is why you use your own production first BEFORE importing. Selling and buying back makes no sense at all because you sell for less than it costs to buy!)

You collect a generation using your solar meter, this is paid by your energy company who owns the rights to your solar production in order to sell it to your neighbour at 15p (only once you have taken what you want to use first because it is cheaper to use your own than buy theirs) if they don't have solar. You then also benefit by having your meter offset your usage at the time of generation, making your bills cheaper. Thirdly, you then get a little brucie bonus of export, the generation you don't use.

The only way you can actually use the solar generated on your site is if you have storage (no, you can use it directly because your inverter converts the raw solar to a usable form which is slightly higher voltage than the grid so your equipment onsite uses it first and then forces it to grid. You import it from the grid if you are not producing enough solar), this doesn't offset your meter as you are storing it and does however enter and is used within your farm circuit and does not enter the network grid. You will be paid a generation tariff and have the benefit of using 100%. You will have cheaper bills also but will not qualify for an export tariff. You will get fits for all of your solar production if used onsite or exported regardless,





hehehe

Ex dairy farmer, now just suckler cows. I have added in red in the quote above where I think you are different to what I think happens to onsite generated leccy. I am presuming the solar output is on the consumer side of the meter to the Dno.

 

[akaPABLO01]

Ex dairy farmer, now just suckler cows. I have added in red in the quote above where I think you are different to what I think happens to onsite generated leccy. I am presuming the solar output is on the consumer side of the meter to the Dno.

I admire the work you have put in to debunk actual solar productivity and it's use on the grid acknowledging payment. Again ill try to answer your questions.

You should appreciate the work I am putting in to help you understand the dynamics with which this process tree works and can assure you that all of this is fact.

Well, hello milkloss, I gather a dairy farmer ?

ok where was I? We have established that all generation such as solar enters the grid (wrong, it only enters the grid once you have taken what you want to use first) (nope, your meter aggregates usage versus import and the meter freezes if your production is higher then your demand, anymore is recorded as an export, the export is your business side, the generation you are aloud to sell albeit, taxable) and you do not use any of it BUT offset your meter to benefit (if you have any to export after using it onsite a smart meter would count export leccy and no import would occur) (you have exported all of it, paid a generation subsidy and paid again for energy you have not used and exported, your meter credits you for usage by not adding kWh) This is done by you generating 10kW solar and having a use of 6kW on site (this would result in 4kw export and no import at this time, a smart or export meter would measure your production for calculation of fits and for payment for your production to grid) (Your generation meter (solar) measures total productivity which you give to your FiT partner who in turn accounts this as POWER STOCK to be sold on, your supply meter measures the amount of current productivity and offsets this with your demand and any surplus is added in the export). All the 10kW enters the grid and your meter freezes and adds the 4kW to the bonus part, Export. (I'm not entirely clear what you mean by 'bonus part' , the 4kw is bought from you by the energy company and you get fits for the whole of your production which is 10kw. The meter measures your total production, 10kw, for which you get paid fits, it also measures export, 4kw, for which you get paid per unit, it also measures import, 0kw, for which you pay. It is cheaper to use your own leccy as it's costs less than the grid hopefully and you get fits for using it too, that is why you use your own production first BEFORE importing. Selling and buying back makes no sense at all because you sell for less than it costs to buy!) (You offset you productivity with your demand through your supply meter, you receive 3 benefits which far out ways Mr Farmer next door who has no solar and buys directly from supplier. Export is a payment relief of power, in all reality a system should be designed for the end user. It takes into account your usage and a solar installation size is calculated to best suit your needs. Large system should really be exporting, this doesn't make sense to export at low demand only to import when solar is not in production. Small domestic systems are levied at 50% export because in reality a household will probably only use 25% of solar production unless say you have a new family and they are at home during daylight or elderly couple at house using appliances. This 50% is grace for a what...2kW standard domestic? This side of the transaction is surpluss to your installation and is available to sell, yes you earn the production (generation meter) export all of it, benefit by the production offset as well as surplus to requirement sales that being taxable on business)

You collect a generation using your solar meter, this is paid by your energy company who owns the rights to your solar production in order to sell it to your neighbour at 15p (only once you have taken what you want to use first because it is cheaper to use your own than buy theirs) (you never take it, your meter offsets your usage versus production, you save on your bills) if they don't have solar. You then also benefit by having your meter offset your usage at the time of generation, making your bills cheaper. Thirdly, you then get a little brucie bonus of export, the generation you don't use.

The only way you can actually use the solar generated on your site is if you have storage (no, you can use it directly because your inverter converts the raw solar to a usable form which is slightly higher voltage than the grid so your equipment onsite uses it first and then forces it to grid. You import it from the grid if you are not producing enough solar) (you always import the amount and replace it back on the grid thus neutralising your cost) , this doesn't offset your meter as you are storing it and does however enter and is used within your farm circuit and does not enter the network grid. You will be paid a generation tariff and have the benefit of using 100%. You will have cheaper bills also but will not qualify for an export tariff. You will get fits for all of your solar production if used onsite or exported regardless,

reet, getting tired now so ill await all queries and reply tomorrow, ciao

 

[akaPABLO01]

I forgot to add, received a phone call from Rob, he is one of the DNO @ ENWL who confirmed to me all production of renewable electricity goes onto the grid and is not used on site.

 

[goodevans]

out of interest if there was a power cut in high summer at noon where would ones solar electricity go