House fitted with 4KW of solar panels

In brilliant sunshine, such as we have had over the past couple of days,
what prevents solar panels producing the full permitted 4KW. Down to 2KW
now.

A few days earlier, when not as hot, solar panels were producing 3.73KW.

Kindest regards,

Jim G

In article ,
"the_constructor" writes:
House fitted with 4KW of solar panels

In brilliant sunshine, such as we have had over the past couple of days,
what prevents solar panels producing the full permitted 4KW. Down to 2KW
now.

A few days earlier, when not as hot, solar panels were producing 3.73KW.

Angle of the sun (time of day).

Dust on the panels (my car seems to have a thick layer of yellow
pollen or sand which has built up over a few hot days of non-use).

Of course, there's also the possibility of a fault.

Also, it's light, not heat, which generates electricity.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 24/05/2012 23:42 the_constructor wrote:

In brilliant sunshine, such as we have had over the past couple of days,
what prevents solar panels producing the full permitted 4KW. Down to 2KW
now.

Temperature. The hotter they get, the less efficient they are.

I got peaks of over 4kW out of our 3.99kW system a few weeks ago when
the sky was clear but the temperature low. On similarly bright but warm
days now, the peaks are around 3kW.

Overall, with the longer days, I'm getting in excess of 25kWh each day.

--
F

the_constructor wrote:
House fitted with 4KW of solar panels

In brilliant sunshine, such as we have had over the past couple of days,
what prevents solar panels producing the full permitted 4KW. Down to 2KW
now.


lack of pixie dusrt.

A few days earlier, when not as hot, solar panels were producing 3.73KW.


sun angle.

And lack of cloud cover. They work on sunlight, not air temperature
..
You may have noticed they produce nothing at night.

Even when its a warm one.


Kindest regards,

Jim G




--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

F wrote:
On 24/05/2012 23:42 the_constructor wrote:

In brilliant sunshine, such as we have had over the past couple of days,
what prevents solar panels producing the full permitted 4KW. Down to 2KW
now.

Temperature. The hotter they get, the less efficient they are.

I got peaks of over 4kW out of our 3.99kW system a few weeks ago when
the sky was clear but the temperature low. On similarly bright but warm
days now, the peaks are around 3kW.

Overall, with the longer days, I'm getting in excess of 25kWh each day.


Oh and the other thing is the SPIV factor.

spiv stands for "Solar Power 'Investment' Vendor".

where an average of 100 watts becomes 'up to 4KW'
etc. etc.


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

On May 24, 11:42*pm, "the_constructor"
wrote:
House fitted with 4KW of solar panels

In brilliant sunshine, such as we have had over the past couple of days,
what prevents solar panels producing the full permitted 4KW. Down to 2KW
now.

A few days earlier, when not as hot, solar panels were producing 3.73KW.

Kindest regards,

Jim G

Though we have sunshine it is not "brilliant". To get the full
output, the sky need to be intensely blue, it has been quite hazy
actually, the sky has had a "milky" appeareance.

Also the panels run more efficiently when it t's cold, ideally with a
breeze.

This is all very common when we have high pressure. We have the best
weather for PV when we get very cold dry arctic air from the North and
sunshine. The panels can actually produce more then rated output in
these conditions.

So don't worry this is normal.
Water vapout in the air and high air temperatures are your enemies.

On May 25, 2:51*am, The Natural Philosopher
wrote:
F wrote:
On 24/05/2012 23:42 the_constructor wrote:

In brilliant sunshine, such as we have had over the past couple of days,
what prevents solar panels producing the full permitted 4KW. Down to 2KW
now.

Temperature. The hotter they get, the less efficient they are.

I got peaks of over 4kW out of our 3.99kW system a few weeks ago when
the sky was clear but the temperature low. On similarly bright but warm
days now, the peaks are around 3kW.

Overall, with the longer days, I'm getting in excess of 25kWh each day.

Oh and the other thing is the SPIV factor.

spiv stands for "Solar Power 'Investment' Vendor".

where an average of 100 watts becomes 'up to 4KW'
* etc. etc.

--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

Drivelling on again about things you have no clue about eh?

BTW, I have had a 3.88 Kwp arrray for 13 months now. Last year I had
4013Kwh of electricity. I cut my electric bill by 25% but we are at
home to make use of free electricity.

Production this year is so far around 200Kwh less than this time last
year. But in a week will have caught up going on the weather forecast.

Absolute max production in one day was 30Kwh. (May last year)
Min production was 0.3 Kwh (rain all day December)

But I have ideal orientation.

On Fri, 25 May 2012 00:35:38 +0100, F news@nowhere wrote:

On 24/05/2012 23:42 the_constructor wrote:

In brilliant sunshine, such as we have had over the past couple of days,
what prevents solar panels producing the full permitted 4KW. Down to 2KW
now.

Temperature. The hotter they get, the less efficient they are.

Is the right answer. Panels have power TC of about -0.4 to 0.5% per
degree C, and the panels will get hot, maybe 45-50 C hence, on a hot
day, peak output can be 20-25% below peak output on a cool day wit
sunny spells.

There's even a specification for it, NOCT - nominal operating cell
temperature.

I got peaks of over 4kW out of our 3.99kW system a few weeks ago when
the sky was clear but the temperature low. On similarly bright but warm
days now, the peaks are around 3kW.

Overall, with the longer days, I'm getting in excess of 25kWh each day.

On 25/05/2012 00:20, Andrew Gabriel wrote:
In articleiKidnQeYlsPqJCPSnZ2dnUVZ8vudnZ2d@brightvie w.co.uk,
.uk writes:
House fitted with 4KW of solar panels

In brilliant sunshine, such as we have had over the past couple of days,
what prevents solar panels producing the full permitted 4KW. Down to 2KW
now.

A few days earlier, when not as hot, solar panels were producing 3.73KW.

Angle of the sun (time of day).

Dust on the panels (my car seems to have a thick layer of yellow
pollen or sand which has built up over a few hot days of non-use).

Of course, there's also the possibility of a fault.

Also, it's light, not heat, which generates electricity.

And crucially heat decreases their efficiency although not normally by
factors of two. You should measure peak output when the sun is aligned
with the axis of your collectors (roughly same time each day).

Then you have a comparable number. It is possible you have a dodgy panel
that is misbehaving under thermal stress or they are covered in pollen
and dust at the moment.

Any partial shading of the array severely compromises output.

--
Regards,
Martin Brown

harry wrote:
BTW, I have had a 3.88 Kwp arrray for 13 months now. Last year I had
4013Kwh of electricity. I cut my electric bill by 25% but we are at
home to make use of free electricity.

So thats and average of 457 watts .
From 3.88 KW capacity panels.

A capacity factor of 11.7%.


Production this year is so far around 200Kwh less than this time last
year. But in a week will have caught up going on the weather forecast.

Absolute max production in one day was 30Kwh. (May last year)
Min production was 0.3 Kwh (rain all day December)

But I have ideal orientation.

Yes that true, your head is stuck up your arse and your hand is in
someone else's pocket.

Spiv.


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

On Friday, 25 May 2012 09:51:24 UTC+1, The Natural Philosopher wrote:
harry wrote:
BTW, I have had a 3.88 Kwp arrray for 13 months now. Last year I had
4013Kwh of electricity. I cut my electric bill by 25% but we are at
home to make use of free electricity.

So thats and average of 457 watts .
From 3.88 KW capacity panels.

A capacity factor of 11.7%.

I'm surprised you believe that nocturnal generation was expected...

Matt

larkim wrote:
On Friday, 25 May 2012 09:51:24 UTC+1, The Natural Philosopher wrote:
harry wrote:
BTW, I have had a 3.88 Kwp arrray for 13 months now. Last year I had
4013Kwh of electricity. I cut my electric bill by 25% but we are at
home to make use of free electricity.

So thats and average of 457 watts .
From 3.88 KW capacity panels.

A capacity factor of 11.7%.

I'm surprised you believe that nocturnal generation was expected...


Now why would you ever believe that I expected that?

If I were to comment on the capacity factor of a wind turbine, would you
say "I'm surprised you believe that calm no wind generation was expected"?

I was making the point that even WITH nocturnal losses, you might
naively expect 40% or so,.


BUT teh real point is the peak to mean ratio of about 9:1 which means
that the inverter is 9 times bigger, more material intensive and
expensive than it needs to be simply because on average solar panels
produce feck all, but have to be sized to deal with the occasional sunny
day.

Oh, and in Spain, a significant amount of 'solar power' *was* generated
after dark..


http://www.theecologist.org/News/new...y_in_u k.html

I think harry had to emigrate smartly, after that one.



Matt


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

And crucially heat decreases their efficiency although not normally by
factors of two. You should measure peak output when the sun is aligned
with the axis of your collectors (roughly same time each day).

Then you have a comparable number. It is possible you have a dodgy panel
that is misbehaving under thermal stress or they are covered in pollen
and dust at the moment.

Any partial shading of the array severely compromises output.



Must post up a pix somewhere. A neighbour has had his roof adorned with
panels and a nearby tree casts a large shadow across them, be
interesting to see just how much that reduces the output..

Must ask the council if they would be permitted to take it down as it is
in a public road...

--
Tony Sayer

On May 25, 8:22*am, Martin Brown
wrote:
On 25/05/2012 00:20, Andrew Gabriel wrote:





In articleiKidnQeYlsPqJCPSnZ2dnUVZ8vudn...@brightvie w.co.uk,
* *writes:
House fitted with 4KW of solar panels

In brilliant sunshine, such as we have had over the past couple of days,
what prevents solar panels producing the full permitted 4KW. Down to 2KW
now.

A few days earlier, when not as hot, solar panels were producing 3.73KW.

Angle of the sun (time of day).

Dust on the panels (my car seems to have a thick layer of yellow
pollen or sand which has built up over a few hot days of non-use).

Of course, there's also the possibility of a fault.

Also, it's light, not heat, which generates electricity.

And crucially heat decreases their efficiency although not normally by
factors of two. You should measure peak output when the sun is aligned
with the axis of your collectors (roughly same time each day).

Then you have a comparable number. It is possible you have a dodgy panel
that is misbehaving under thermal stress or they are covered in pollen
and dust at the moment.

Any partial shading of the array severely compromises output.

--
Regards,
Martin Brown- Hide quoted text -

- Show quoted text -

The inclination of the PV panels deemed best is for maximum annual
production. If they were any steeper, ey might work better in Winter
but Summer /overall production would be reduced.

The inclination of solar thermal panels deemed best is that for
maximum Winter production.
Because any surplus in Summer cannot be exported as with electricity.

However I have seen them (PV) performing at max with sun quite low in
the sky when the sky has been very clear. (Eg, after heavy rain has
cleared all the atmospheric moisture.)

On May 25, 10:05*am, larkim wrote:
On Friday, 25 May 2012 09:51:24 UTC+1, The Natural Philosopher *wrote: harry wrote:
BTW, I have had a 3.88 Kwp arrray for 13 months now. Last year I had
4013Kwh of electricity. I cut my electric bill by 25% but we are at
home to make use of free electricity.

So thats and average of 457 watts .
*From 3.88 KW capacity panels.

A capacity factor of 11.7%.

I'm surprised you believe that nocturnal generation was expected...

Matt

He's very simple minded.
The production peak occurs when it's needed by commerce and industry.

I have a new game when out on the bus/train.
Spot the PV array. it's amazing how many you see.
They seem to occur in clusters. I counted six on one row of terrace
houses the other day.

My neighbour has just got a 4Kwp array.There are quite a few round our
village too, I have seen around ten, I expect there's more I've
missed.
Lots of retired people worried about their savings.

On May 25, 9:51*am, The Natural Philosopher
wrote:
harry wrote:
BTW, I have had a 3.88 Kwp arrray for 13 months now. Last year I had
4013Kwh of electricity. I cut my electric bill by 25% but we are at
home to make use of free electricity.

So thats and average of 457 watts .
*From 3.88 KW capacity panels.

A capacity factor of 11.7%.

Production this year is so far around 200Kwh less than this time last
year. But in a week will have caught up going on the weather forecast.

Absolute max production in one day was 30Kwh. (May last year)
Min production was 0.3 Kwh (rain all day December)

But I have ideal orientation.

Yes that true, your head is stuck up your arse and your hand is in
someone else's pocket.

Spiv.

I'll think about you when I'm on holiday in the Bahamas at your
expense.
I could even send a post card.

On May 25, 10:36*am, The Natural Philosopher
wrote:
larkim wrote:
On Friday, 25 May 2012 09:51:24 UTC+1, The Natural Philosopher *wrote:
harry wrote:
BTW, I have had a 3.88 Kwp arrray for 13 months now. Last year I had
4013Kwh of electricity. I cut my electric bill by 25% but we are at
home to make use of free electricity.

So thats and average of 457 watts .
*From 3.88 KW capacity panels.

A capacity factor of 11.7%.

I'm surprised you believe that nocturnal generation was expected...

Now why would you ever believe that I expected that?

If I were to comment on the capacity factor of a wind turbine, would you
say "I'm surprised you believe that calm no wind generation was expected"?

I was making the point that even WITH nocturnal losses, you might
naively expect 40% or so,.

BUT teh real point is the peak to mean ratio of about 9:1 which means
that the inverter is 9 times bigger, more material intensive and
expensive than it needs to be simply because on average solar panels
produce feck all, but have to be sized to deal with the occasional sunny
day.

If they actually produced "feck all", you'd have nothing to carp on
about then would you?

Oh, and in Spain, a significant amount of 'solar power' *was* generated
after dark..

http://www.theecologist.org/News/new...panish_nightti...


Everybody knew the Spanish were crooks. The (financial) birds have
come home to roost now for them.

On Friday, 25 May 2012 10:36:25 UTC+1, The Natural Philosopher wrote:
larkim wrote:
On Friday, 25 May 2012 09:51:24 UTC+1, The Natural Philosopher wrote:
harry wrote:
BTW, I have had a 3.88 Kwp arrray for 13 months now. Last year I had
4013Kwh of electricity. I cut my electric bill by 25% but we are at
home to make use of free electricity.

So thats and average of 457 watts .
From 3.88 KW capacity panels.

A capacity factor of 11.7%.

I'm surprised you believe that nocturnal generation was expected...


Now why would you ever believe that I expected that?

If I were to comment on the capacity factor of a wind turbine, would you
say "I'm surprised you believe that calm no wind generation was expected"?

I was making the point that even WITH nocturnal losses, you might
naively expect 40% or so,.


BUT teh real point is the peak to mean ratio of about 9:1 which means
that the inverter is 9 times bigger, more material intensive and
expensive than it needs to be simply because on average solar panels
produce feck all, but have to be sized to deal with the occasional sunny
day.

I was just making the point that your calcs implied capacity as being over 24 hour days, whereas clearly it should be over 12 hour days; and then you can rightly make the point that dawn / dusk can never been good generation periods, so even with bright skies every day of the year you'd never get near the rated output every hour of the day.

I don't think inverter "overhead" in the way that you describe it is too much of a problem - you can make the same argument with most household features. Most of the time my guttering is over-specc'd to deal with the one period of heavy downpour. My roof is just sat there waiting for a cold, windy day when it is functioning to its maximum. My amp can go up to 11 :-) but that doesn't mean I have a DJ-d club session going on all the time.

(My interest in this is that I do have a solar installation, but I aesthetically like it, I like the fact that my house now requires about 1/3 less carbon generated electricity to function, and it cost me nowt!)

Matt

On May 25, 10:37*am, tony sayer wrote:
And crucially heat decreases their efficiency although not normally by
factors of two. You should measure peak output when the sun is aligned
with the axis of your collectors (roughly same time each day).

Then you have a comparable number. It is possible you have a dodgy panel
that is misbehaving under thermal stress or they are covered in pollen
and dust at the moment.

Any partial shading of the array severely compromises output.

Must post up a pix somewhere. A neighbour has had his roof adorned with
panels and a nearby tree casts a large shadow across them, be
interesting to see just how much that reduces the output..

Must ask the council if they would be permitted to take it down as it is
in a public road...

It will reduce the output by lots. It only takes the shadow of a few
twigs to really cut the performance. I cut a few trees back last year
when I checked out what the effect was.

On 25/05/2012 11:09, harry wrote:
On May 25, 8:22 am, Martin
wrote:
On 25/05/2012 00:20, Andrew Gabriel wrote:

In articleiKidnQeYlsPqJCPSnZ2dnUVZ8vudn...@brightvie w.co.uk,
.uk writes:
House fitted with 4KW of solar panels

In brilliant sunshine, such as we have had over the past couple of days,
what prevents solar panels producing the full permitted 4KW. Down to 2KW
now.

A few days earlier, when not as hot, solar panels were producing 3.73KW.

Angle of the sun (time of day).

Dust on the panels (my car seems to have a thick layer of yellow
pollen or sand which has built up over a few hot days of non-use).

Of course, there's also the possibility of a fault.

Also, it's light, not heat, which generates electricity.

And crucially heat decreases their efficiency although not normally by
factors of two. You should measure peak output when the sun is aligned
with the axis of your collectors (roughly same time each day).

Then you have a comparable number. It is possible you have a dodgy panel
that is misbehaving under thermal stress or they are covered in pollen
and dust at the moment.

Any partial shading of the array severely compromises output.

The inclination of the PV panels deemed best is for maximum annual
production. If they were any steeper, ey might work better in Winter
but Summer /overall production would be reduced.

Partly true. The optimum angle is a function mostly of azimuth and
latitude with a tiny correction for ambient summer temperatures. The
array in the UK is better off pointed to get maximum capture cross
section in early May rather than mid June.

Pure S facing at mid summer suns elevation is 113.5-latitude
Pure S facing at mid winter suns elevation is 66.5-latitude

Take UK average latitude as 53.5 degrees and you get
summer elevation 60 degrees (30 degree pitched roof)
winter elevation 13 degrees (77 degree pitched roof aka leaning wall!)

In practice something around 40+/-5 degrees is close enough.

Geometrical losses scale as cos(angle) which roughly tranlates to
- (theta^2/66) % where theta is the angle between the sun and the
normal to the PV array. Eight degrees away from optimal you lose ~1%. It
isn't worth losing any sleep over minor alignment errors.

The inclination of solar thermal panels deemed best is that for
maximum Winter production.
Because any surplus in Summer cannot be exported as with electricity.

The optimum is when it can provide all required domestic hot water for
the largest proportion of the time. Steeper than for PV but by no means
as near to vertical as optimum for winter would imply. Somewhere between
45 and 60 degrees based on a quick back of the envelope job.

The FIT distortion for PV means that people do not install SHW anyway.

However I have seen them (PV) performing at max with sun quite low in
the sky when the sky has been very clear. (Eg, after heavy rain has
cleared all the atmospheric moisture.)

A PV on a fairly steep roof in mid winter on a clear day the cold
compensates somewhat for the low solar angle, but can do nothing at all
about the incredibly short period of useful daylight in winter.

We are too far north for solar to be anything other than a novelty toy
and tax dodge due to incompetent government market distorting FITs.

--
Regards,
Martin Brown

harry wrote:
On May 25, 10:05 am, larkim wrote:
On Friday, 25 May 2012 09:51:24 UTC+1, The Natural Philosopher wrote: harry wrote:
BTW, I have had a 3.88 Kwp arrray for 13 months now. Last year I had
4013Kwh of electricity. I cut my electric bill by 25% but we are at
home to make use of free electricity.
So thats and average of 457 watts .
From 3.88 KW capacity panels.
A capacity factor of 11.7%.
I'm surprised you believe that nocturnal generation was expected...

Matt

He's very simple minded.
The production peak occurs when it's needed by commerce and industry.


No, it isn't.

Why are you lying harry?

lighting is a big load, and goes up - when the sun doesn;t shine!

Winter heating is a big load...when the sun doesn't shine!



I have a new game when out on the bus/train.
Spot the PV array. it's amazing how many you see.
They seem to occur in clusters. I counted six on one row of terrace
houses the other day.


I know,. I;ve got my freinds 22 rifle saighted up at 22 yards.

Spivs the lot of them,. profiting out of the sweat of the working classes.

My neighbour has just got a 4Kwp array.There are quite a few round our
village too, I have seen around ten, I expect there's more I've
missed.
Lots of retired people worried about their savings.

That why they aren't installing solar panels, harry.

Anyway, the government has just about killed the industry off now.

To many spivs in it.
Costing the nation too much

http://www.telegraph.co.uk/finance/p...in-tariff.html





--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

On Fri, 25 May 2012 03:29:03 -0700 (PDT), larkim
wrote:


I was just making the point that your calcs implied capacity as being over 24 hour days, whereas clearly it should be over 12 hour days

We only have '12 hour days' sometime in March and September.

There are 16 hours or more of 'sunlight' in the UK right now.


--

On Friday, 25 May 2012 12:17:17 UTC+1, The Other Mike wrote:
On Fri, 25 May 2012 03:29:03 -0700 (PDT), larkim
wrote:


I was just making the point that your calcs implied capacity as being over 24 hour days, whereas clearly it should be over 12 hour days

We only have '12 hour days' sometime in March and September.

There are 16 hours or more of 'sunlight' in the UK right now.


--

I was averaging the year, and being simplistic! I am aware of lengthening / shortening days ;-)

Matt

On 25.05.2012 12:46, Martin Brown wrote:
....
We are too far north for solar to be anything other than a novelty toy
and tax dodge due to incompetent government market distorting FITs.

For more help on the subject look at this:
http://www.withouthotair.com/
The next logical step is this link:
http://www.youtube.com/watch?v=P9M__yYbsZ4
--
jo
There's an initial Eden, a paradise, a state of grace and unity
with nature, there's a fall from grace into a state of pollution
as a result of eating from the tree of knowledge, and as a
result of our actions there is a judgment day coming for us all.
We are all energy sinners, doomed to die, unless we seek
salvation, which is now called sustainability. Sustainability
is salvation in the church of the environment. Just as organic
food is its communion, that pesticide-free wafer that the
right people with the right beliefs, imbibe. -- Michael Crichton

harry wrote:
On May 25, 10:36 am, The Natural Philosopher
wrote:
larkim wrote:
On Friday, 25 May 2012 09:51:24 UTC+1, The Natural Philosopher wrote:
harry wrote:
BTW, I have had a 3.88 Kwp arrray for 13 months now. Last year I had
4013Kwh of electricity. I cut my electric bill by 25% but we are at
home to make use of free electricity.
So thats and average of 457 watts .
From 3.88 KW capacity panels.
A capacity factor of 11.7%.
I'm surprised you believe that nocturnal generation was expected...
Now why would you ever believe that I expected that?

If I were to comment on the capacity factor of a wind turbine, would you
say "I'm surprised you believe that calm no wind generation was expected"?

I was making the point that even WITH nocturnal losses, you might
naively expect 40% or so,.

BUT teh real point is the peak to mean ratio of about 9:1 which means
that the inverter is 9 times bigger, more material intensive and
expensive than it needs to be simply because on average solar panels
produce feck all, but have to be sized to deal with the occasional sunny
day.

If they actually produced "feck all", you'd have nothing to carp on
about then would you?

Id have even more to carp on abput as then they would double the FIT again.


Oh, and in Spain, a significant amount of 'solar power' *was* generated
after dark..

http://www.theecologist.org/News/new...panish_nightti...


Everybody knew the Spanish were crooks. The (financial) birds have
come home to roost now for them.

Everyone knows you are a spiv harry.



--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

harry wrote:
On May 25, 10:37 am, tony sayer wrote:
And crucially heat decreases their efficiency although not normally by
factors of two. You should measure peak output when the sun is aligned
with the axis of your collectors (roughly same time each day).
Then you have a comparable number. It is possible you have a dodgy panel
that is misbehaving under thermal stress or they are covered in pollen
and dust at the moment.
Any partial shading of the array severely compromises output.
Must post up a pix somewhere. A neighbour has had his roof adorned with
panels and a nearby tree casts a large shadow across them, be
interesting to see just how much that reduces the output..

Must ask the council if they would be permitted to take it down as it is
in a public road...

It will reduce the output by lots. It only takes the shadow of a few
twigs to really cut the performance. I cut a few trees back last year
when I checked out what the effect was.


You only need to have a basic knowledge of photography to know that open
shade will give you 1/4 the light of full sun.

As will light cloud. Deep cloud reduces it anther 2-4 times, and you can
halve the output again within an hour of sunset.


But basic knowledge isn't your strong point, is it harry?


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

larkim wrote:
On Friday, 25 May 2012 10:36:25 UTC+1, The Natural Philosopher wrote:
larkim wrote:
On Friday, 25 May 2012 09:51:24 UTC+1, The Natural Philosopher wrote:
harry wrote:
BTW, I have had a 3.88 Kwp arrray for 13 months now. Last year I had
4013Kwh of electricity. I cut my electric bill by 25% but we are at
home to make use of free electricity.

So thats and average of 457 watts .
From 3.88 KW capacity panels.

A capacity factor of 11.7%.

I'm surprised you believe that nocturnal generation was expected...

Now why would you ever believe that I expected that?

If I were to comment on the capacity factor of a wind turbine, would you
say "I'm surprised you believe that calm no wind generation was expected"?

I was making the point that even WITH nocturnal losses, you might
naively expect 40% or so,.


BUT teh real point is the peak to mean ratio of about 9:1 which means
that the inverter is 9 times bigger, more material intensive and
expensive than it needs to be simply because on average solar panels
produce feck all, but have to be sized to deal with the occasional sunny
day.

I was just making the point that your calcs implied capacity as being over 24 hour days,
whereas clearly it should be over 12 hour days;

I am sorry. You cannot change the way measurements are done by the
industry just to fit your prejudices, and sell crap to gullible citizens.

Capacity factor is defined as the (generally annualised or lifetime)
annualised average power divided by the nameplate capacity of the
technology.

In the case of non dispatchable generation like renewables, it is a
measure of the uselessness of the technology or in fact the energy
source itself in terms of the overcapacity that has to be built in, and
especially with wind, of how often it is in fact out of service and broken.


..


and then you can rightly make the point that dawn / dusk can never been good generation periods,
so even with bright skies every day of the year you'd never get near the rated output every hour of the day.

That still ********. Capacity factor is what its defined to be.



I don't think inverter "overhead" in the way that you describe it is too much of a problem -
you can make the same argument with most household features.
Most of the time my guttering is over-specc'd to deal with the one period of heavy downpour.
My roof is just sat there waiting for a cold, windy day when it is functioning to its maximum.
My amp can go up to 11 :-) but that doesn't mean I have a DJ-d club session going on all the time.

Yes, to all of those, but *I* am not expected to pay for them, am I?

Whereas *I* have to pay for every single solar panel on any roof in the
UK and not a few abroad.

Solar lets you down when you need it most - dark cold winter mights.

You don't need electricity much on bright clear summer days.


(My interest in this is that I do have a solar installation,
but I aesthetically like it,

Theres nowt as queer as folk...

I like the fact that my house now requires about 1/3 less carbon generated electricity to function, and it cost me nowt!)

It costs you in the increased bills you pay on the electricity it does
NOT provide, and if you think its carbon free or has even reduced the
UKs carbon footprint you don't understand anything at all.

Its a really bad job creation scam with green stripes that's all.




Matt


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

Martin Brown wrote:
On 25/05/2012 11:09, harry wrote:
On May 25, 8:22 am, Martin
wrote:
On 25/05/2012 00:20, Andrew Gabriel wrote:

In articleiKidnQeYlsPqJCPSnZ2dnUVZ8vudn...@brightvie w.co.uk,
.uk writes:
House fitted with 4KW of solar panels

In brilliant sunshine, such as we have had over the past couple of
days,
what prevents solar panels producing the full permitted 4KW. Down
to 2KW
now.

A few days earlier, when not as hot, solar panels were producing
3.73KW.

Angle of the sun (time of day).

Dust on the panels (my car seems to have a thick layer of yellow
pollen or sand which has built up over a few hot days of non-use).

Of course, there's also the possibility of a fault.

Also, it's light, not heat, which generates electricity.

And crucially heat decreases their efficiency although not normally by
factors of two. You should measure peak output when the sun is aligned
with the axis of your collectors (roughly same time each day).

Then you have a comparable number. It is possible you have a dodgy panel
that is misbehaving under thermal stress or they are covered in pollen
and dust at the moment.

Any partial shading of the array severely compromises output.

The inclination of the PV panels deemed best is for maximum annual
production. If they were any steeper, ey might work better in Winter
but Summer /overall production would be reduced.

Partly true. The optimum angle is a function mostly of azimuth and
latitude with a tiny correction for ambient summer temperatures. The
array in the UK is better off pointed to get maximum capture cross
section in early May rather than mid June.

Pure S facing at mid summer suns elevation is 113.5-latitude
Pure S facing at mid winter suns elevation is 66.5-latitude

Take UK average latitude as 53.5 degrees and you get
summer elevation 60 degrees (30 degree pitched roof)
winter elevation 13 degrees (77 degree pitched roof aka leaning wall!)

In practice something around 40+/-5 degrees is close enough.

in reality you are nest to optimise for summer sun as they produce so
little in winter you might as well not have them at all.

Well really you might as well not have them, at all from a UK
perspective anyway...



Geometrical losses scale as cos(angle) which roughly tranlates to
- (theta^2/66) % where theta is the angle between the sun and the
normal to the PV array. Eight degrees away from optimal you lose ~1%. It
isn't worth losing any sleep over minor alignment errors.

The inclination of solar thermal panels deemed best is that for
maximum Winter production.
Because any surplus in Summer cannot be exported as with electricity.

The optimum is when it can provide all required domestic hot water for
the largest proportion of the time. Steeper than for PV but by no means
as near to vertical as optimum for winter would imply. Somewhere between
45 and 60 degrees based on a quick back of the envelope job.

The FIT distortion for PV means that people do not install SHW anyway.

However I have seen them (PV) performing at max with sun quite low in
the sky when the sky has been very clear. (Eg, after heavy rain has
cleared all the atmospheric moisture.)

A PV on a fairly steep roof in mid winter on a clear day the cold
compensates somewhat for the low solar angle, but can do nothing at all
about the incredibly short period of useful daylight in winter.

We are too far north for solar to be anything other than a novelty toy
and tax dodge due to incompetent government market distorting FITs.


Well you got that bit right. Its all about Germany creating solar panel
jobs. That's all going tits up now anyway as they solar companies are
going bust and being undercut by cheap Chinese imports.

I bet you see accusations of dumping and an EU trade barrier erected
shortly. Or a scrapping of renewables in Germany.

Mind you the new Germann minister of power is a big fat balding ex lawyer.

http://www.world-nuclear-news.org/up...12_250x167.jpg


So we are bound to get really clueful policy right?




--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

Jo Stein wrote:
On 25.05.2012 12:46, Martin Brown wrote:
...
We are too far north for solar to be anything other than a novelty toy
and tax dodge due to incompetent government market distorting FITs.

For more help on the subject look at this:
http://www.withouthotair.com/
The next logical step is this link:
http://www.youtube.com/watch?v=P9M__yYbsZ4

We discussed both those at least a year ago.

Do keep up.


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

On Fri, 25 May 2012 13:18:22 +0100, The Natural Philosopher wrote:

A neighbour has had his roof adorned with panels and a nearby
tree
casts a large shadow across them, be interesting to see just how
much
that reduces the output..

It will reduce the output by lots. It only takes the shadow of a
few
twigs to really cut the performance. I cut a few trees back last
year
when I checked out what the effect was.

You only need to have a basic knowledge of photography to know that open
shade will give you 1/4 the light of full sun.

As will light cloud. Deep cloud reduces it anther 2-4 times, and you can
halve the output again within an hour of sunset.

But basic knowledge isn't your strong point, is it harry?

But it's not simply the amount of light being reduced the panels are
series connected and a shaded one reduces the terminal voltage and
possibly increases the source impedance so the panels that are fully
illuminated can't deliver their energy to the invertor.


--
Cheers
Dave.

On Fri, 25 May 2012 03:29:03 -0700 (PDT), larkim wrote:

If I were to comment on the capacity factor of a wind turbine,
would
you say "I'm surprised you believe that calm no wind generation
was
expected"?

I was just making the point that your calcs implied capacity as being
over 24 hour days, whereas clearly it should be over 12 hour days;

Only to bias the capacity factor in favour of the solar PV. Unless
you say that nuke stations can also work on a 12 hour basis thus have
capacity factors of around 160%.

Capcity or load factor is damn good measure at how well a particular
generation method actaully performs in the real world. None of this
"enough power for 10,000 homes" (when the sun shines but not too
strong) greenwash.

--
Cheers
Dave.

On 25/05/2012 13:34, The Natural Philosopher wrote:
Martin Brown wrote:
On 25/05/2012 11:09, harry wrote:
On May 25, 8:22 am, Martin
wrote:

Any partial shading of the array severely compromises output.

The inclination of the PV panels deemed best is for maximum annual
production. If they were any steeper, ey might work better in Winter
but Summer /overall production would be reduced.

Partly true. The optimum angle is a function mostly of azimuth and
latitude with a tiny correction for ambient summer temperatures. The
array in the UK is better off pointed to get maximum capture cross
section in early May rather than mid June.

Pure S facing at mid summer suns elevation is 113.5-latitude
Pure S facing at mid winter suns elevation is 66.5-latitude

Take UK average latitude as 53.5 degrees and you get
summer elevation 60 degrees (30 degree pitched roof)
winter elevation 13 degrees (77 degree pitched roof aka leaning wall!)

In practice something around 40+/-5 degrees is close enough.

in reality you are nest to optimise for summer sun as they produce so
little in winter you might as well not have them at all.

Well really you might as well not have them, at all from a UK
perspective anyway...

On that at least we are agreed. If the price eventually falls enough
then they will become truly cost effective but that will happen first in
sunnier equatorial and sub tropical climates. We in the UK and in
Germany for that matter live to far north to be worthwhile.

Solar panels or better small wind turbines make sense for some remote
off grid applications where modest power is required. Please go round
the bend signs in the UK are a notable failure since they are all
completely stone dead on frosty winter mornings (when they are needed).

They don't work. Last year in mid summer someone went straight on:

http://www.gazettelive.co.uk/news/te...4229-26955401/

The bend sign was almost certainly working properly at the time.

Geometrical losses scale as cos(angle) which roughly tranlates to
- (theta^2/66) % where theta is the angle between the sun and the
normal to the PV array. Eight degrees away from optimal you lose ~1%.
It isn't worth losing any sleep over minor alignment errors.

The inclination of solar thermal panels deemed best is that for
maximum Winter production.
Because any surplus in Summer cannot be exported as with electricity.

The optimum is when it can provide all required domestic hot water for
the largest proportion of the time. Steeper than for PV but by no
means as near to vertical as optimum for winter would imply. Somewhere
between 45 and 60 degrees based on a quick back of the envelope job.

The FIT distortion for PV means that people do not install SHW anyway.

However I have seen them (PV) performing at max with sun quite low in
the sky when the sky has been very clear. (Eg, after heavy rain has
cleared all the atmospheric moisture.)

A PV on a fairly steep roof in mid winter on a clear day the cold
compensates somewhat for the low solar angle, but can do nothing at
all about the incredibly short period of useful daylight in winter.

We are too far north for solar to be anything other than a novelty toy
and tax dodge due to incompetent government market distorting FITs.

Well you got that bit right. Its all about Germany creating solar panel
jobs. That's all going tits up now anyway as they solar companies are
going bust and being undercut by cheap Chinese imports.

Same with the immense amount of oilseed rape planted this year which
seems to be a result of the German biofuels scam driving prices up.

I bet you see accusations of dumping and an EU trade barrier erected
shortly. Or a scrapping of renewables in Germany.

I bet on the former. YMMV

Mind you the new Germann minister of power is a big fat balding ex lawyer.

http://www.world-nuclear-news.org/up...12_250x167.jpg

So we are bound to get really clueful policy right?

More likely some very complicated laws that keep lawyers in business

--
Regards,
Martin Brown

Martin Brown wrote:
On 25/05/2012 13:34, The Natural Philosopher wrote:
Martin Brown wrote:
On 25/05/2012 11:09, harry wrote:
On May 25, 8:22 am, Martin
wrote:

Any partial shading of the array severely compromises output.

The inclination of the PV panels deemed best is for maximum annual
production. If they were any steeper, ey might work better in Winter
but Summer /overall production would be reduced.

Partly true. The optimum angle is a function mostly of azimuth and
latitude with a tiny correction for ambient summer temperatures. The
array in the UK is better off pointed to get maximum capture cross
section in early May rather than mid June.

Pure S facing at mid summer suns elevation is 113.5-latitude
Pure S facing at mid winter suns elevation is 66.5-latitude

Take UK average latitude as 53.5 degrees and you get
summer elevation 60 degrees (30 degree pitched roof)
winter elevation 13 degrees (77 degree pitched roof aka leaning wall!)

In practice something around 40+/-5 degrees is close enough.

in reality you are nest to optimise for summer sun as they produce so
little in winter you might as well not have them at all.

Well really you might as well not have them, at all from a UK
perspective anyway...

On that at least we are agreed. If the price eventually falls enough

It wont.

then they will become truly cost effective

Not even then.

but that will happen first in
sunnier equatorial and sub tropical climates. We in the UK and in
Germany for that matter live to far north to be worthwhile.

Solar panels or better small wind turbines make sense for some remote
off grid applications where modest power is required. Please go round
the bend signs in the UK are a notable failure since they are all
completely stone dead on frosty winter mornings (when they are needed).


They are all completely dead here even when powered by windmills as well.

They don't work. Last year in mid summer someone went straight on:


No intermittent renweable 'works'

http://www.gazettelive.co.uk/news/te...4229-26955401/


The bend sign was almost certainly working properly at the time.

Geometrical losses scale as cos(angle) which roughly tranlates to
- (theta^2/66) % where theta is the angle between the sun and the
normal to the PV array. Eight degrees away from optimal you lose ~1%.
It isn't worth losing any sleep over minor alignment errors.

The inclination of solar thermal panels deemed best is that for
maximum Winter production.
Because any surplus in Summer cannot be exported as with electricity.

The optimum is when it can provide all required domestic hot water for
the largest proportion of the time. Steeper than for PV but by no
means as near to vertical as optimum for winter would imply. Somewhere
between 45 and 60 degrees based on a quick back of the envelope job.

The FIT distortion for PV means that people do not install SHW anyway.

However I have seen them (PV) performing at max with sun quite low in
the sky when the sky has been very clear. (Eg, after heavy rain has
cleared all the atmospheric moisture.)

A PV on a fairly steep roof in mid winter on a clear day the cold
compensates somewhat for the low solar angle, but can do nothing at
all about the incredibly short period of useful daylight in winter.

We are too far north for solar to be anything other than a novelty toy
and tax dodge due to incompetent government market distorting FITs.

Well you got that bit right. Its all about Germany creating solar panel
jobs. That's all going tits up now anyway as they solar companies are
going bust and being undercut by cheap Chinese imports.

Same with the immense amount of oilseed rape planted this year which
seems to be a result of the German biofuels scam driving prices up.

yup. Our farmer chuckles all the way to the bank.
His gain, your loss in terms of increased wheat prices.



I bet you see accusations of dumping and an EU trade barrier erected
shortly. Or a scrapping of renewables in Germany.

I bet on the former. YMMV

Depends if the Euro survives the summer.
The Germans have made a total utter balls up of everything they have got
politically involved in since forever.




Mind you the new Germann minister of power is a big fat balding ex
lawyer.

http://www.world-nuclear-news.org/up...12_250x167.jpg


So we are bound to get really clueful policy right?

More likely some very complicated laws that keep lawyers in business

well, yes.


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

On Fri, 25 May 2012 14:21:46 +0100, Martin Brown wrote:

olar panels or better small wind turbines make sense for some remote
off grid applications where modest power is required. Please go round
the bend signs in the UK are a notable failure since they are all
completely stone dead on frosty winter mornings (when they are needed).

They don't work. Last year in mid summer someone went straight on:

http://www.gazettelive.co.uk/news/te...4229-26955401/

The bend sign was almost certainly working properly at the time.

"He was asked if speed was a key factor in the crash, but declined to
comment."
Of course it wasn't a factor - the car was in collision with a house (cue
Betjeman).
--
Peter.
The gods will stay away
whilst religions hold sway

We are too far north for solar to be anything other than a novelty toy
and tax dodge due to incompetent government market distorting FITs.

Well you got that bit right. Its all about Germany creating solar panel
jobs. That's all going tits up now anyway as they solar companies are
going bust and being undercut by cheap Chinese imports.

I bet you see accusations of dumping and an EU trade barrier erected
shortly. Or a scrapping of renewables in Germany.

Mind you the new Germann minister of power is a big fat balding ex lawyer.

http://www.world-nuclear-news.org/up...ages/Merkel_Ga...

So we are bound to get really clueful policy right?

--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

So tell us how much energy a PV panel produces in winter o great
oracle.

On May 25, 2:08*pm, "Dave Liquorice"
wrote:
On Fri, 25 May 2012 13:18:22 +0100, The Natural Philosopher wrote:
A neighbour has had his roof adorned with panels and a nearby
tree
casts a large shadow across them, be interesting to see just how
much
that reduces the output..

It will reduce the output by lots. It only takes the shadow of a
few
twigs to really cut the performance. I cut a few trees back last
year
when I checked out what the effect was.

You only need to have a basic knowledge of photography to know that open
shade will give you 1/4 the light of full sun.

As will light cloud. Deep cloud reduces it anther 2-4 times, and you can
halve the output again within an hour of sunset.

But basic knowledge isn't your strong point, is it harry?

But it's not simply the amount of light being reduced the panels are
series connected and a shaded one reduces the terminal voltage and
possibly increases the source impedance so the panels that are fully
illuminated can't deliver their energy to the invertor.

--
Cheers
Dave.- Hide quoted text -

- Show quoted text -

He doesn't understand such things Dave. You can't educate pork.

harry wrote:
We are too far north for solar to be anything other than a novelty toy
and tax dodge due to incompetent government market distorting FITs.
Well you got that bit right. Its all about Germany creating solar panel
jobs. That's all going tits up now anyway as they solar companies are
going bust and being undercut by cheap Chinese imports.

I bet you see accusations of dumping and an EU trade barrier erected
shortly. Or a scrapping of renewables in Germany.

Mind you the new Germann minister of power is a big fat balding ex lawyer.

http://www.world-nuclear-news.org/up...ages/Merkel_Ga...

So we are bound to get really clueful policy right?

--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

So tell us how much energy a PV panel produces in winter o great
oracle.

I will, when you tell me how long a piece of string is.

however for those more intelligent than you, the following link may be
of interest:

http://www.contemporaryenergy.co.uk/solarmap.htm

which shows that summer power production averages out at ten times (Jun)
what winter does (Dec).

Average power per unit area is around 900kwh per year per sq meter,.
which at an efficiency of about 30% means you will get 300 units of
electricity per year per square meter of panel more or less.

At a market price of about 10p per unit retail, that's an income of £30
a year. Per square meter.

Of course with a 40p subsidy like spiv* harry has, that's about £150 a
year per square meter.

Compared with actual wholesale power like gas coal or nuclear of around
6p a unit, you can see its pathetic. £18 a year fuel saved, if that.


*Solar Panel Installation Vendor.

--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

"harry" wrote in message
...
On May 25, 10:05 am, larkim wrote:
On Friday, 25 May 2012 09:51:24 UTC+1, The Natural Philosopher wrote:
harry wrote:
BTW, I have had a 3.88 Kwp arrray for 13 months now. Last year I had
4013Kwh of electricity. I cut my electric bill by 25% but we are at
home to make use of free electricity.

So thats and average of 457 watts .
From 3.88 KW capacity panels.

A capacity factor of 11.7%.

I'm surprised you believe that nocturnal generation was expected...

He's very simple minded.

Your problem is ear to ear dog ****.

The production peak occurs when it's needed by commerce and industry.

Wrong, as always. Particularly in winter.

And it isnt commerce and industry that matters
anyway, it's the total grid load that matters.

On May 25, 9:33*pm, The Natural Philosopher
wrote:
harry wrote:
We are too far north for solar to be anything other than a novelty toy
and tax dodge due to incompetent government market distorting FITs.
Well you got that bit right. Its all about Germany creating solar panel
jobs. That's all going tits up now anyway as they solar companies are
going bust and being undercut by cheap Chinese imports.

I bet you see accusations of dumping and an EU trade barrier erected
shortly. Or a scrapping of renewables in Germany.

Mind you the new Germann minister of power is a big fat balding ex lawyer.

http://www.world-nuclear-news.org/up...ages/Merkel_Ga....

So we are bound to get really clueful policy right?

--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

So tell us how much energy a PV panel produces in winter o great
oracle.

I will, when you tell me how long a piece of string is.

however for those more intelligent than you, the following link may be
of interest:

http://www.contemporaryenergy.co.uk/solarmap.htm

which shows that summer power production averages out at ten times (Jun)
what winter does (Dec).

Average power per unit area is around 900kwh per year per sq meter,.
which at an efficiency of about 30% means you will get 300 units of
electricity per year per square meter of panel more or less.

At a market price of about 10p per unit retail, that's an income of £30
a year. Per square meter.

Of course with a 40p subsidy like spiv* harry has, that's about £150 a
year per square meter.

Compared with actual wholesale power like gas coal or nuclear of around
6p a unit, you can see its pathetic. £18 a year fuel saved, if that.

*Solar Panel Installation Vendor.

--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.- Hide quoted text -

- Show quoted text -

My June production was 510 Kwh.
My December production was 103 Kwh
So your source is wrong by 100% in this case

June was actually exceptionally low last year too, nearer 550 would
have been typical, May production was 530 Kwh.

So as usual you are full of ****. Rambling on about stuff you have no
first hand knowledge of. A qualification in janatorial servises is no
help.

Oh, I don't have to buy any coal, gas or oil to make electricity.