Please, can someone kindly elucidate how a domestic 240V house system maintains a stable voltage when connected to an FIT inverter fed from a pv panel?

One moment it's feeding amps into the local supply, the next it may be extracting them. To get a reversible current flow, there must be a pd (potential difference) between the 2 situations. How does it do this trick? (and avoid flickering lights etc).

Are mirrors involved?

TIA

jim wrote:
Please, can someone kindly elucidate how a domestic 240V house system maintains a stable voltage when connected to an FIT inverter fed from a pv panel?

One moment it's feeding amps into the local supply, the next it may be extracting them. To get a reversible current flow, there must be a pd (potential difference) between the 2 situations. How does it do this trick? (and avoid flickering lights etc).

Are mirrors involved?

It's all low impedance connections, so you need quite a large current
change to make a noticeable difference in the suply voltage. Anything
other than incandescent light bulbs or very old, non-stabilised power
supplies for TV sets won't really notice less than about a 10% change in
voltage anyway, which should need a current change of 100 amps or moreif
all is in order. As most domestic PV panel sets can't generate more than
about 16A, it's not a problem.

--
Tciao for Now!

John.

Far more of an issue is synchronising the frequencies and putting crap on
the local supply or even creating RFI from the inverter in my experience,
which is not much here, but from those who rushed out and got it, there have
been issues.. grin.

Brian

--
From the Sofa of Brian Gaff Reply address is active
"John Williamson" wrote in message
...
jim wrote:
Please, can someone kindly elucidate how a domestic 240V house system
maintains a stable voltage when connected to an FIT inverter fed from a
pv panel?

One moment it's feeding amps into the local supply, the next it may be
extracting them. To get a reversible current flow, there must be a pd
(potential difference) between the 2 situations. How does it do this
trick? (and avoid flickering lights etc).

Are mirrors involved?

It's all low impedance connections, so you need quite a large current
change to make a noticeable difference in the suply voltage. Anything
other than incandescent light bulbs or very old, non-stabilised power
supplies for TV sets won't really notice less than about a 10% change in
voltage anyway, which should need a current change of 100 amps or moreif
all is in order. As most domestic PV panel sets can't generate more than
about 16A, it's not a problem.

--
Tciao for Now!

John.

"Brian Gaff" wrote in message
...
Far more of an issue is synchronising the frequencies and putting crap on
the local supply or even creating RFI from the inverter in my experience,
which is not much here, but from those who rushed out and got it, there
have been issues.. grin.

Brian

Drivel.
Grid tie inverters are relatively cheap because they don't have to create
their own sine wave out of nothing.
They are more like an amplifier , input sinewave from the mains, so perfect
sine wave and perfectly sychronised.

In article , harryagain
scribeth thus

"Brian Gaff" wrote in message
...
Far more of an issue is synchronising the frequencies and putting crap on
the local supply or even creating RFI from the inverter in my experience,
which is not much here, but from those who rushed out and got it, there
have been issues.. grin.

Brian

Drivel.
Grid tie inverters are relatively cheap because they don't have to create
their own sine wave out of nothing.
They are more like an amplifier , input sinewave from the mains, so perfect
sine wave and perfectly sychronised.


Harry..

Obtain an Oscilloscope then connect that to the output of any
transformer or even direct to the mains and observe the mains waveform..

A Perfick sine wave is the one thing you will not see;!...
--
Tony Sayer

On 26/09/2013 08:54, tony sayer wrote:
In article , harryagain
scribeth thus

"Brian Gaff" wrote in message
...
Far more of an issue is synchronising the frequencies and putting crap on
the local supply or even creating RFI from the inverter in my experience,
which is not much here, but from those who rushed out and got it, there
have been issues.. grin.

Brian

Drivel.
Grid tie inverters are relatively cheap because they don't have to create
their own sine wave out of nothing.
They are more like an amplifier , input sinewave from the mains, so perfect
sine wave and perfectly sychronised.


Harry..

Obtain an Oscilloscope then connect that to the output of any
transformer or even direct to the mains and observe the mains waveform..

A Perfick sine wave is the one thing you will not see;!...

We might have to adjust harry's hit rate.... previously I worked on the
principle that 80% of what he posted would be wrong. Seems that might
have been over generous.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"tony sayer" wrote in message
...
In article , harryagain
scribeth thus

"Brian Gaff" wrote in message
...
Far more of an issue is synchronising the frequencies and putting crap
on
the local supply or even creating RFI from the inverter in my
experience,
which is not much here, but from those who rushed out and got it, there
have been issues.. grin.

Brian

Drivel.
Grid tie inverters are relatively cheap because they don't have to create
their own sine wave out of nothing.
They are more like an amplifier , input sinewave from the mains, so
perfect
sine wave and perfectly sychronised.


Harry..

Obtain an Oscilloscope then connect that to the output of any
transformer or even direct to the mains and observe the mains waveform..

A Perfick sine wave is the one thing you will not see;!...

And how exactly will you see how perfect or not perfect it is? Just eyeball
it?
Heh heh, You are as bad as TurNiP

The only way to be absolutely sure is to get a piece of graph paper and some
sine tables and draw your own.
And those tables were derived geometrically not by some stupid computer.
Similar geometry to that going on in an alternator.
And any non sinusiodal AC passed through inductors and capacitors, gradually
gets to look more and more like a sine wave interestingly.

On 22/09/2013 16:38, jim wrote:

Please, can someone kindly elucidate how a domestic 240V house system
maintains a stable voltage when connected to an FIT inverter fed from
a pv panel?

One moment it's feeding amps into the local supply, the next it may
be extracting them. To get a reversible current flow, there must be
a pd (potential difference) between the 2 situations. How does it do
this trick? (and avoid flickering lights etc).

The potential difference required actually comes from a phase shift in
the locally generated component. Depending on whether its leading or
lagging the waveform supplied via the grid as to whether its drawing or
feeding current. The RMS voltages of both grid and the output of the
local inverter could actually be the same. The local grid tie inverter
will adjust its generated phase relative to the grid voltage to achieve
the required direction of energy transfer.

Are mirrors involved?

Not usually, and hopefully no smoke either ;-)


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"John Rumm" wrote in message
o.uk...
On 22/09/2013 16:38, jim wrote:

Please, can someone kindly elucidate how a domestic 240V house system
maintains a stable voltage when connected to an FIT inverter fed from
a pv panel?

One moment it's feeding amps into the local supply, the next it may
be extracting them. To get a reversible current flow, there must be
a pd (potential difference) between the 2 situations. How does it do
this trick? (and avoid flickering lights etc).

The potential difference required actually comes from a phase shift in the
locally generated component. Depending on whether its leading or lagging
the waveform supplied via the grid as to whether its drawing or feeding
current. The RMS voltages of both grid and the output of the local
inverter could actually be the same. The local grid tie inverter will
adjust its generated phase relative to the grid voltage to achieve the
required direction of energy transfer.


What are you rambling on about?
The previous poster is entirely correct.
As the power output from PVpanels increases, the voltage at the AC output
terminal of the inverter rises.
So "stuffing the electricity back down the spout " so to speak.
My PV panels causes a rise of around 5volts when on full power.
There is no phase shift, the power factor is around unity at all outputs,
there is no transformer.

Of course a lot of these devices waste power when not a lot is being
generated, and over time I'd suspect this adds up to quite a high amount.
5v is nothing, in any day the mains goes up and down far more than that
amount.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"harryagain" wrote in message
...

"John Rumm" wrote in message
o.uk...
On 22/09/2013 16:38, jim wrote:

Please, can someone kindly elucidate how a domestic 240V house system
maintains a stable voltage when connected to an FIT inverter fed from
a pv panel?

One moment it's feeding amps into the local supply, the next it may
be extracting them. To get a reversible current flow, there must be
a pd (potential difference) between the 2 situations. How does it do
this trick? (and avoid flickering lights etc).

The potential difference required actually comes from a phase shift in
the locally generated component. Depending on whether its leading or
lagging the waveform supplied via the grid as to whether its drawing or
feeding current. The RMS voltages of both grid and the output of the
local inverter could actually be the same. The local grid tie inverter
will adjust its generated phase relative to the grid voltage to achieve
the required direction of energy transfer.


What are you rambling on about?
The previous poster is entirely correct.
As the power output from PVpanels increases, the voltage at the AC output
terminal of the inverter rises.
So "stuffing the electricity back down the spout " so to speak.
My PV panels causes a rise of around 5volts when on full power.
There is no phase shift, the power factor is around unity at all outputs,
there is no transformer.

"Brian Gaff" wrote in message
...
Of course a lot of these devices waste power when not a lot is being
generated, and over time I'd suspect this adds up to quite a high amount.
5v is nothing, in any day the mains goes up and down far more than that
amount.
Brian

The inverters in use these days are around 95% efficient. (No transformer)
I think mine uses around 3w on standby.

What are you rambling on about?
The previous poster is entirely correct.
As the power output from PVpanels increases, the voltage at the AC output
terminal of the inverter rises.
So "stuffing the electricity back down the spout " so to speak.
My PV panels causes a rise of around 5volts when on full power.
There is no phase shift, the power factor is around unity at all outputs,
there is no transformer.

On 23/09/13 07:52, harryagain wrote:
"Brian Gaff" wrote in message
...
Of course a lot of these devices waste power when not a lot is being
generated, and over time I'd suspect this adds up to quite a high amount.
5v is nothing, in any day the mains goes up and down far more than that
amount.
Brian

The inverters in use these days are around 95% efficient. (No transformer)
I think mine uses around 3w on standby.

Harry, the idiot who thnks inverters dont have any transformers.




--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

On Sunday 22 September 2013 16:38 jim wrote in uk.d-i-y:

Please, can someone kindly elucidate how a domestic 240V house system
maintains a stable voltage when connected to an FIT inverter fed from a pv
panel?

One moment it's feeding amps into the local supply, the next it may be
extracting them. To get a reversible current flow, there must be a pd
(potential difference) between the 2 situations. How does it do this
trick? (and avoid flickering lights etc).

Are mirrors involved?

TIA

Yes, there is a PD, probably in the form of a very slight phase lead/lag.

It is minute. The supply impedance will be less than 0.35ohms (L-N) so 10A
FIT feed would be 3.5V or an equivalent phase shift. Not enough to be
flickering lights.

--
Tim Watts Personal Blog: http://squiddy.blog.dionic.net/

http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage

Reading this on the web? See:
http://wiki.diyfaq.org.uk/index.php?title=Usenet

On Sun, 22 Sep 2013 08:38:38 -0700 (PDT), jim wrote:

One moment it's feeding amps into the local supply, the next it may be
extracting them. To get a reversible current flow, there must be a pd
(potential difference) between the 2 situations. How does it do this
trick? (and avoid flickering lights etc).

The volts do change but not enough to notice. The voltage here drops
by about 8 V when the E7 kicks in and 11 kW is instantly applied. A
domestic PV array in bright sunlight produces less than 4 kW, only a
bit above a rapid boil kettle...

Do your lights flicker when you switch on the kettle? We don't notice
the E7 coming on but then we don't have incandescent lights that
would show it far more than anything else.

--
Cheers
Dave.

In message o.uk, at
17:30:56 on Sun, 22 Sep 2013, Dave Liquorice
remarked:
A domestic PV array in bright sunlight produces less than 4 kW, only a
bit above a rapid boil kettle...

There's a big poster at my local Sainsbury's which says they generate
enough electricity to boil every kettle in the town. But not
simultaneously I suspect! And mine is a traditional one on gas hob, so
that's a neat trick (maybe my share is the electricity to ignite the
gas...)
--
Roland Perry

On Mon, 23 Sep 2013 07:45:01 +0100, Roland Perry wrote:

A domestic PV array in bright sunlight produces less than 4 kW,
only a
bit above a rapid boil kettle...

There's a big poster at my local Sainsbury's which says they generate
enough electricity to boil every kettle in the town. But not
simultaneously I suspect!

Greenwash... if they are that proud of their solar PV why don't they
have a big meter showing the total store consumption and what
percentage of that is coming from the PV, both instantaneous and
averaged over lets say a week.

--
Cheers
Dave.

In message o.uk, at
09:07:34 on Mon, 23 Sep 2013, Dave Liquorice
remarked:
A domestic PV array in bright sunlight produces less than 4 kW,
only a
bit above a rapid boil kettle...

There's a big poster at my local Sainsbury's which says they generate
enough electricity to boil every kettle in the town. But not
simultaneously I suspect!

Greenwash...

Not the only example, they also say they are using LED lights in their
(semi-underground) car park to save energy, but it's obvious they are
fluorescents.

if they are that proud of their solar PV why don't they
have a big meter showing the total store consumption and what
percentage of that is coming from the PV, both instantaneous and
averaged over lets say a week.

--
Roland Perry

On Monday, September 23, 2013 9:42:59 AM UTC+1, Roland Perry wrote:
In message o.uk, at
09:07:34 on Mon, 23 Sep 2013, Dave Liquorice
remarked:

There's a big poster at my local Sainsbury's which says they generate
enough electricity to boil every kettle in the town. But not
simultaneously I suspect!

Greenwash...
Not the only example, they also say they are using LED lights in their
(semi-underground) car park to save energy, but it's obvious they are
fluorescents.

2 Leds in an emergency exit sign

if they are that proud of their solar PV why don't they
have a big meter showing the total store consumption and what
percentage of that is coming from the PV, both instantaneous and
averaged over lets say a week.

weird how thats seen as a good thing

On Mon, 23 Sep 2013 09:42:59 +0100, Roland Perry wrote:

Not the only example, they also say they are using LED lights in their
(semi-underground) car park to save energy, but it's obvious they are
fluorescents.

Are you sure? There are LED strip lights that fit standard florry
fittings, not sure it would be very easy to tell what the light
source is behind a diffuser...

--
Cheers
Dave.

"Roland Perry" wrote in message
...
In message o.uk, at
09:07:34 on Mon, 23 Sep 2013, Dave Liquorice
remarked:
A domestic PV array in bright sunlight produces less than 4 kW,
only a
bit above a rapid boil kettle...

There's a big poster at my local Sainsbury's which says they generate
enough electricity to boil every kettle in the town. But not
simultaneously I suspect!

Greenwash...

Not the only example, they also say they are using LED lights in their
(semi-underground) car park to save energy, but it's obvious they are
fluorescents.


Why is it obvious?
Some LED tubes fit into fluorescent light bodies.
http://www.earlsmann.co.uk/sections/product/id/15
It could be just you is thick?

"Dave Liquorice" wrote in message
ll.co.uk...
On Mon, 23 Sep 2013 07:45:01 +0100, Roland Perry wrote:

A domestic PV array in bright sunlight produces less than 4 kW,
only a
bit above a rapid boil kettle...

There's a big poster at my local Sainsbury's which says they generate
enough electricity to boil every kettle in the town. But not
simultaneously I suspect!

Greenwash... if they are that proud of their solar PV why don't they
have a big meter showing the total store consumption and what
percentage of that is coming from the PV, both instantaneous and
averaged over lets say a week.

No reason at all why not. But the average Saintsbury shopper won't
understand the numbers.

"Dave Liquorice" wrote in message
ll.co.uk...
On Sun, 22 Sep 2013 08:38:38 -0700 (PDT), jim wrote:

One moment it's feeding amps into the local supply, the next it may be
extracting them. To get a reversible current flow, there must be a pd
(potential difference) between the 2 situations. How does it do this
trick? (and avoid flickering lights etc).

The volts do change but not enough to notice. The voltage here drops
by about 8 V when the E7 kicks in and 11 kW is instantly applied. A
domestic PV array in bright sunlight produces less than 4 kW, only a
bit above a rapid boil kettle...

Arrays cab be as big as you like/can fit in/afford.

The reason many are sub4Kw is that the smallest charge (money) band is
0-4Kw.
The next is 4-10Kw, too big to fir on most domestic house roofs.

harryagain wrote:

Arrays cab be as big as you like/can fit in/afford.

The reason many are sub4Kw is that the smallest charge (money) band is
0-4Kw.

I think you mean highest, in that above 4 kWp the FIT is lower.

The next is 4-10Kw, too big to fir on most domestic house roofs.

and requiring specific acceptance by your DNO.

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.

On 24/09/2013 09:00, harryagain wrote:

The reason many are sub4Kw is that the smallest charge (money) band is
0-4Kw.
The next is 4-10Kw, too big to fir on most domestic house roofs.

More to the point, 16 A per phase is the maximum current you're allowed
to back-feed into the LV mains without elaborate protection
arrangements and approval of the DNO. (See ENA Engineering
Recommendation G83/2.) This limits you to about 3.8 kVA on a
single-phase connection.

--
Andy

On Tue, 24 Sep 2013 09:00:30 +0100, "harryagain"
wrote:


"Dave Liquorice" wrote in message
ill.co.uk...
On Sun, 22 Sep 2013 08:38:38 -0700 (PDT), jim wrote:

One moment it's feeding amps into the local supply, the next it may be
extracting them. To get a reversible current flow, there must be a pd
(potential difference) between the 2 situations. How does it do this
trick? (and avoid flickering lights etc).

The volts do change but not enough to notice. The voltage here drops
by about 8 V when the E7 kicks in and 11 kW is instantly applied. A
domestic PV array in bright sunlight produces less than 4 kW, only a
bit above a rapid boil kettle...

Arrays cab be as big as you like/can fit in/afford.

The reason many are sub4Kw is that the smallest charge (money) band is
0-4Kw.
The next is 4-10Kw, too big to fir on most domestic house roofs.


1) Solar panels don't need to be fitted to roofs

2) More than one supply and corresponding solar installation receiving a FIT
payment per property was permitted

3)With a property having space for an array of more than 4kW you could size each
'installation' to be sub 4kW and optimise the return.

What do you mean you didn't have the common sense all those years back to
request another metered conneciton from the DNO and could have got, in cash
terms twice as much as you extort now from all those in fuel poverty?

--

On 22/09/13 16:38, jim wrote:
Please, can someone kindly elucidate how a domestic 240V house system maintains a stable voltage when connected to an FIT inverter fed from a pv panel?

One moment it's feeding amps into the local supply, the next it may be extracting them. To get a reversible current flow, there must be a pd (potential difference) between the 2 situations. How does it do this trick? (and avoid flickering lights etc).

Are mirrors involved?


smoke, and mirrors. :-)


however the imdeance of the mains supply is pretty low...
TIA



--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

"jim" wrote in message
...
Please, can someone kindly elucidate how a domestic 240V house system
maintains a stable voltage when connected to an FIT inverter fed from a pv
panel?

One moment it's feeding amps into the local supply, the next it may be
extracting them. To get a reversible current flow, there must be a pd
(potential difference) between the 2 situations. How does it do this
trick? (and avoid flickering lights etc).

Are mirrors involved?

You take say four Kw out of the system and the voltage drops by a small
amount.
You stuff four Kw back into the sytem and the voltage rises by the same
amount.
(Everything else being equal).

Most of the energy stuffed back intot the sytem is used by nieghbours so in
fact reducing the load on the system and making it more efficient.

As long as the PV systems are small sytems, dispersed and there are not too
many of them there are no problems.
Large system can present problems and as they become common the problems
will increase.

This is another possible use for smart meters, the remote control of such
systems.

On 22/09/2013 18:07, harryagain wrote:
Most of the energy stuffed back intot the sytem is used by nieghbours so in
fact reducing the load on the system and making it more efficient.

Locally perhaps, nationally unlikely. The big generators can't be easily
throttled up and down, and lose efficiency when this has to be done.

Andy

On Mon, 23 Sep 2013 08:33:24 +0100, Vir Campestris
wrote:

On 22/09/2013 18:07, harryagain wrote:
Most of the energy stuffed back intot the sytem is used by nieghbours so in
fact reducing the load on the system and making it more efficient.

Locally perhaps, nationally unlikely. The big generators can't be easily
throttled up and down, and lose efficiency when this has to be done.

Because of where it is metered, that is beyond the location of bulk supply
points, all UK domestic solar is viewed as reduced demand. Currently it is of
such a low level that it is operationally lost in the noise.


--

On 23/09/13 20:56, The Other Mike wrote:
On Mon, 23 Sep 2013 08:33:24 +0100, Vir Campestris
wrote:

On 22/09/2013 18:07, harryagain wrote:
Most of the energy stuffed back intot the sytem is used by nieghbours so in
fact reducing the load on the system and making it more efficient.

Locally perhaps, nationally unlikely. The big generators can't be easily
throttled up and down, and lose efficiency when this has to be done.

Because of where it is metered, that is beyond the location of bulk supply
points, all UK domestic solar is viewed as reduced demand. Currently it is of
such a low level that it is operationally lost in the noise.


Exactly so. A cosmetic solution to a non-existent problem and if wind is
anything to go by, one that's being pretty much abused by the FIT/ROC
claimants.

Its odd how wind that isn't centrally metered seems to operate at a much
higher capacity factor than wind that IS centrally metered...

--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.