On 13/12/2022 13:41, Tweed wrote:
>
> Java Jive <java@evij.com.invalid> wrote:
>>
>> IIRC, solar panels were integrated into more or less the entire outer
>> surfaces of the car, and its light weight and aero-dynamic styling means
>> that it can go a long way on not much electricity.
>>
>> Perhaps you ought to watch the programme before claiming to have done
>> the science?
>
> Short day lengths and clouds are killers for solar power. I know from
> direct experience of my 10 panels on my roof.

But how long ago were yours installed? Solar panels are a still an
evolving and improving technology, and, though I can't remember details
now, I know that I have heard programmes over the last year or so
concerning significant improvements to it, and this is borne out by the
fact that a quick count of references to it in my download history finds
about 15 science programmes.

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On 13/12/2022 14:09, Java Jive wrote:
> But how long ago were yours installed?  Solar panels are a still an
> evolving and improving technology, and, though I can't remember
Day lengths and cloud cover are multipliers. Efficiency may have
improved, but the ability to extract energy when there is no solar input
hasn't.
I think current efficiencies are around 25% for silicon cells (which
incidentally means the maximum output is around 250 watts/square metre,
not 1kW).
You can get a bit better by using two layers, with different materials,
to extract energy from a wider range of wavelengths, but even silicon is
within about a factor of four of the conservation of energy limit, and
there may be thermodynamic or other considerations, that mean total
conversion is impossible.
<https://www.sciencedirect.com/science/article/pii/S136403211401048X>
suggests (in the conclusion) that single layer systems cannot go better
than 33.3% at room temperature. This is also backed up by
<https://en.wikipedia.org/wiki/Shockley%E2%80%93Queisser_limit>, which
notes that even an ideal multi-layer device is limited to 68.7%. Both
assume the capture area is the same as the array area.
<https://en.wikipedia.org/wiki/Solar-cell_efficiency#/media/File:Best-research-cell-efficiencies-rev220126_pages-to-jpg-0001.jpg>
gives efficiencies over time and technology. Silicon cells have roughly
doubled in efficiency since first introduced.

Java Jive <java@evij.com.invalid> wrote:
> On 13/12/2022 13:41, Tweed wrote:
>>
>> Java Jive <java@evij.com.invalid> wrote:
>>>
>>> IIRC, solar panels were integrated into more or less the entire outer
>>> surfaces of the car, and its light weight and aero-dynamic styling means
>>> that it can go a long way on not much electricity.
>>>
>>> Perhaps you ought to watch the programme before claiming to have done
>>> the science?
>>
>> Short day lengths and clouds are killers for solar power. I know from
>> direct experience of my 10 panels on my roof.
>
> But how long ago were yours installed? Solar panels are a still an
> evolving and improving technology, and, though I can't remember details
> now, I know that I have heard programmes over the last year or so
> concerning significant improvements to it, and this is borne out by the
> fact that a quick count of references to it in my download history finds
> about 15 science programmes.
>

They were installed in October this year. You can’t really improve over
short days, low sun angle and clouds.

On 13/12/2022 16:00, David Woolley wrote:
>
> On 13/12/2022 14:09, Java Jive wrote:
>>
>> But how long ago were yours installed?  Solar panels are a still an
>> evolving and improving technology, and, though I can't remember
>
> Day lengths and cloud cover are multipliers.  Efficiency may have
> improved, but the ability to extract energy when there is no solar input
> hasn't.
>
> I think current efficiencies are around 25% for silicon cells (which
> incidentally means the maximum output is around 250 watts/square metre,
> not 1kW).
>
> You can get a bit better by using two layers, with different materials,
> to extract energy from a wider range of wavelengths, but even silicon is
> within about a factor of four of the conservation of energy limit, and
> there may be thermodynamic or other considerations, that mean total
> conversion is impossible.
>
> <https://www.sciencedirect.com/science/article/pii/S136403211401048X>
> suggests (in the conclusion) that single layer systems cannot go better
> than 33.3% at room temperature.  This is also backed up by
> <https://en.wikipedia.org/wiki/Shockley%E2%80%93Queisser_limit>, which
> notes that even an ideal multi-layer device is limited to 68.7%.  Both
> assume the capture area is the same as the array area.
>
> <https://en.wikipedia.org/wiki/Solar-cell_efficiency#/media/File:Best-research-cell-efficiencies-rev220126_pages-to-jpg-0001.jpg>
> gives efficiencies over time and technology.  Silicon cells have roughly
> doubled in efficiency since first introduced.

Thanks for the info. I think it was the multi-layer devices that I
remember hearing about, and the doubling figure sounds familiar too.

--

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I may be contacted via the contact address given on my website:
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On 13/12/2022 16:14, Tweed wrote:
>
> Java Jive <java@evij.com.invalid> wrote:
>>
>> On 13/12/2022 13:41, Tweed wrote:
>>>
>>> Java Jive <java@evij.com.invalid> wrote:
>>>>
>>>> IIRC, solar panels were integrated into more or less the entire outer
>>>> surfaces of the car, and its light weight and aero-dynamic styling means
>>>> that it can go a long way on not much electricity.
>>>>
>>>> Perhaps you ought to watch the programme before claiming to have done
>>>> the science?
>>>
>>> Short day lengths and clouds are killers for solar power. I know from
>>> direct experience of my 10 panels on my roof.
>>
>> But how long ago were yours installed? Solar panels are a still an
>> evolving and improving technology, and, though I can't remember details
>> now, I know that I have heard programmes over the last year or so
>> concerning significant improvements to it, and this is borne out by the
>> fact that a quick count of references to it in my download history finds
>> about 15 science programmes.
>
> They were installed in October this year.

Hopefully then they are higher efficiency than they might have been if
installed, say, five or more years ago, though, of course, they could
still be of an older and less efficient design. Nevertheless, I'm happy
to accept your opinion based on them.

> You can’t really improve over
> short days, low sun angle and clouds.

No.

Perhaps when I have time I'll try to see if I can find out any hard
figures on the car's performance.

BTW, if you didn't watch it, the program I linked is still worth
watching, aside from this debating point.

--

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I may be contacted via the contact address given on my website:
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I know hat we need a clockwork car.
Brian

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"Bob Latham" <bob@sick-of-spam.invalid> wrote in message
news:5a55abcb25bob@sick-of-spam.invalid...
> In article <tn7bn9$282bc$1@dont-email.me>,
> NY <me@privacy.invalid> wrote:
>> "Bob Latham" <bob@sick-of-spam.invalid> wrote in message
>> news:5a55a55a62bob@sick-of-spam.invalid...
>> > https://youtu.be/vyS9uqRLbB8
>> >
>> > I'd not seen this until today, I think it was a while back but...
>> >
>> > Heaven help us all. :-(
>
>> Giving him the benefit of the doubt, maybe he's means solar panels
>> that have a storage battery, so the daytime sun charges the
>> storage battery that then charges the car overnight. That allows
>> the car to be charged at a time when there is no sun.
>
> I love optimists. ;-)
>
> Bob.
>

Java Jive <java@evij.com.invalid> wrote:
> On 13/12/2022 16:14, Tweed wrote:
>>
>> Java Jive <java@evij.com.invalid> wrote:
>>>
>>> On 13/12/2022 13:41, Tweed wrote:
>>>>
>>>> Java Jive <java@evij.com.invalid> wrote:
>>>>>
>>>>> IIRC, solar panels were integrated into more or less the entire outer
>>>>> surfaces of the car, and its light weight and aero-dynamic styling means
>>>>> that it can go a long way on not much electricity.
>>>>>
>>>>> Perhaps you ought to watch the programme before claiming to have done
>>>>> the science?
>>>>
>>>> Short day lengths and clouds are killers for solar power. I know from
>>>> direct experience of my 10 panels on my roof.
>>>
>>> But how long ago were yours installed? Solar panels are a still an
>>> evolving and improving technology, and, though I can't remember details
>>> now, I know that I have heard programmes over the last year or so
>>> concerning significant improvements to it, and this is borne out by the
>>> fact that a quick count of references to it in my download history finds
>>> about 15 science programmes.
>>
>> They were installed in October this year.
>
> Hopefully then they are higher efficiency than they might have been if
> installed, say, five or more years ago, though, of course, they could
> still be of an older and less efficient design. Nevertheless, I'm happy
> to accept your opinion based on them.
>
>> You can’t really improve over
>> short days, low sun angle and clouds.
>
> No.
>
> Perhaps when I have time I'll try to see if I can find out any hard
> figures on the car's performance.
>
> BTW, if you didn't watch it, the program I linked is still worth
> watching, aside from this debating point.
>

Just to give an idea, assuming a bright sunny day at noon is full power,
light high altitude clouds can easily halve output. The miserable grey days
we are having (here at least) at the moment can bring it down to a tenth
output.

On Tue, 13 Dec 2022 13:29:20 +0000, Java Jive <java@evij.com.invalid>
wrote:

>On 13/12/2022 09:07, charles wrote:
>>
>> In article <mrbgphdrev7sc2kfb90cr552175i7k8bhk@4ax.com>,
>> Roderick Stewart <rjfs@escapetime.myzen.co.uk> wrote:
>>>
>>> A 60kWh battery would take 60 hours to charge at 1kW, which is
>>> rreckoned to be about the rate at which we receive energy from the Sun
>>> over an area of 1 square metre. Therefore if the solar panel has an
>>> area of 1 suare metre (probably a reasonable estimate for a car roof),
>>> and is 100% efficient, and is always facing squarely towards the Sun,
>>> and the Sun is shining, then it'll take 60 hours to charge. If any of
>>> these conditions are not optimal it'll take longer. They really ought
>>> to do the science before the marketing.
>>
>> basic arithmetic more like
>
>IIRC, solar panels were integrated into more or less the entire outer
>surfaces of the car, and its light weight and aero-dynamic styling means
>that it can go a long way on not much electricity.
>
>Perhaps you ought to watch the programme before claiming to have done
>the science?

I don't need to watch any programmes to be able to divide 60kWh by
1kW. There isn't much science in that.

What percentage of the surface area of a typical car is likely to be
facing towards the Sun at any time? I doubt if it amounts to much more
than one square metre, or not enough to make a serious difference.

Rod.

On 12/12/2022 14:53, Max Demian wrote:
> On 12/12/2022 13:12, Bob Latham wrote:
>> https://youtu.be/vyS9uqRLbB8
>>
>> I'd not seen this until today, I think it was a while back but...
>>
>> Heaven help us all. :-(
>
> He's Australian. When it's night there it's day here. All they need in a
> cable through the centre of the Earth.
>
> (Hardly much less absurd than the idea we could get our electricity from
> solar panels and wind turbines in Morocco:
> https://www.itv.com/news/2021-11-03/how-cables-2500-miles-long-could-bring-solar-power-from-morocco-to-uk-homes
> )
>

Silly idea. Much better to charge a load of batteries in Morocco and
transport them to the UK. Electric ships could use the same batteries to
power the engines.

Bill

On 12/12/2022 20:00, Java Jive wrote:
> I had the same anxiety with a petrol car in Scotland in the 80s when
> doing the North Coast Route on a Sunday.

Very specific set of circumstances there! And you could have put a jerry
can full in the boot.

Bill

On 13/12/2022 17:32, William Wright wrote:
>
> On 12/12/2022 20:00, Java Jive wrote:
>>
>> I had the same anxiety with a petrol car in Scotland in the 80s when
>> doing the North Coast Route on a Sunday.
>
> Very specific set of circumstances there!

It's analogous to running out of electric charge.

> And you could have put a jerry
> can full in the boot.

That's like saying that I could also have been clairvoyant and known
that all the filling stations would have been closed on Sunday, and
bought a jerry can before setting out, when a single gallon probably
wouldn't have been enough anyway.

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

Roderick Stewart wrote:

> NY wrote:
>
>> Giving him the benefit of the doubt, maybe he's means solar panels that have
>> a storage battery, so the daytime sun charges the storage battery that then
>> charges the car overnight. That allows the car to be charged at a time when
>> there is no sun.
>
> For that you'd need another battery with at least the same capacity as
> the battery in your car.

Can't see it'd need to be that big, why have a house battery bigger than the kWh
your panels can generate on their best day, if you're just dumping it into the
car after sundown?

On 13/12/2022 16:48, Brian Gaff wrote:
> I know hat we need a clockwork car.
> Brian

I saw something yesterday that seemed to be as small as C5, don't think
it was but wondered what it might be?

On 13/12/2022 18:09, Java Jive wrote:

> That's like saying that I could also have been clairvoyant and known
> that all the filling stations would have been closed on Sunday, and
> bought a jerry can before setting out, when a single gallon probably
> wouldn't have been enough anyway.
>

Some places still have Wednesday early closing for shops as well as
having no Sunday trading for small shops.

Many years ago when most pubs in the UK closed at 10:30pm the town in
which I was living first had 11pm closing in the Summer and a year later
11pm all year. A pub crawl out of the area was arranged where one coach
would drop us off at the last pub at 10pm and another would pick us up
at 11pm (erroneously assuming 11pm closing plus a leeway for drinking up
time). Unfortunately last orders was called at 10:15pm and kick-out was
dead on 10:30pm :( The weather was not that good.

--
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In article <jvs0nuFivgfU1@mid.individual.net>,
Andy Burns <usenet@andyburns.uk> wrote:
> Roderick Stewart wrote:

> > For that you'd need another battery with at least the same
> > capacity as the battery in your car.

> Can't see it'd need to be that big, why have a house battery bigger
> than the kWh your panels can generate on their best day, if you're
> just dumping it into the car after sundown?

There is no point in having a house battery that has a storage
capacity greater than what can be charged from the panels in 24 hours
if that is the fixed pattern of usage. However, it may be that using
the weekend (or similar) to give a once a week extra charge might
help if the battery was large enough.

Then how do you transfer the energy from one battery to another?
I presume the house battery would need to be a higher voltage than
the car battery. then some sort of regulator.

The cost of this though would be very high. Second hand electric cars
are a dodgy buy due to the battery replacement cost which many think
are unviable.

Imagine being in a electric car stuck on a motorway in snow and ice.
How are people going to keep warm? If they use an electric heater
from the battery how are you going to get a large number of cars off
the motorway later? You can't just poor a gallon of fluid in the tank
and it's gone.

Imagine the irony of freezing to death stuck in an electric car.

We don't yet know how many people will die due to the cost of heating
their homes this year. We may never know, it will be hidden by
the 700+ excess none covid deaths we have every month now which the
media ignore. It doesn't match a narrative.

Bob.

On 14/12/2022 08:58, Bob Latham wrote:
> There is no point in having a house battery that has a storage
> capacity greater than what can be charged from the panels in 24 hours
> if that is the fixed pattern of usage. However, it may be that using
> the weekend (or similar) to give a once a week extra charge might
> help if the battery was large enough.

I suppose you need to calculate whether the cost of the extra storage
would be less than just taking peak demand from the grid.

It could be said that with the lack of resilience of the grid because of
its dependence on wind, it would be useful to have some independence but
it is likely to be needed at times when you might not be getting much
from solar.

On 14/12/2022 08:58, Bob Latham wrote:
> Then how do you transfer the energy from one battery to another?
> I presume the house battery would need to be a higher voltage than
> the car battery. then some sort of regulator.

The voltages can go either way, and that is also what you will get in a
mobile phone power bank. In the latter, typically a nominal 3.6V
battery will be boost regulated up to 5V (or even more), in the power
bank, then buck regulated down to the current charging battery voltage
(which can vary from the low 3s, to about 4.2V during the course of the
charge.

The second regulation step is necessary for efficiency, as just dumping
the excess as heat would be wasteful.

A purpose designed system would work with varying voltages on both sides
and no fixed intermediate with a buck-boost regulator.

Solar systems need regulators anyway, as the optimum voltage to take
from a solar cell is variable (look up maximum power point tracking).

On 14/12/2022 08:58, Bob Latham wrote:
> The cost of this though would be very high. Second hand electric cars
> are a dodgy buy due to the battery replacement cost which many think
> are unviable.

Home solar systems often do have batteries anyway, as energy usage
doesn't peak with solar input.

I believe people have used second hand car batteries for this, as,
whilst not meeting the standards required for cars they are still quite
good enough for other purposes.

On 14/12/2022 08:58, Bob Latham wrote:
>
> Imagine being in a electric car stuck on a motorway in snow and ice.
> How are people going to keep warm?

In the immediate future, most people will be using electric cars for
short commuting travel, so by definition they shouldn't be getting stuck
in the snow miles from anywhere.

> We don't yet know how many people will die due to the cost of heating
> their homes this year. We may never know, it will be hidden by
> the 700+ excess none covid deaths we have every month now which the
> media ignore. It doesn't match a narrative.

ITYM 600 deaths per *week*:

https://coronavirus.data.gov.uk/details/deaths

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Fake news kills!

I may be contacted via the contact address given on my website:
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MB <MB@nospam.net> wrote:
> On 14/12/2022 08:58, Bob Latham wrote:
>> There is no point in having a house battery that has a storage
>> capacity greater than what can be charged from the panels in 24 hours
>> if that is the fixed pattern of usage. However, it may be that using
>> the weekend (or similar) to give a once a week extra charge might
>> help if the battery was large enough.
>
>
>
> I suppose you need to calculate whether the cost of the extra storage
> would be less than just taking peak demand from the grid.
>
> It could be said that with the lack of resilience of the grid because of
> its dependence on wind, it would be useful to have some independence but
> it is likely to be needed at times when you might not be getting much
> from solar.
>
>
>

I have a solar and battery system. In winter any solar generation is a
bonus. I fill my battery up over night on Economy 7 and then use it during
the day. This removes my house from any of the peak demand periods that the
grid appears to worry about satisfying. It also effectively gives me half
price day time electricity. There’s some sun out right now, first time for
days, so my battery is being topped up at the moment. If it becomes full
I’ll start to export to the grid. Happily my export rate just about matches
my E7 import rate, so it all sorts itself out to give me the minimum cost
without much thought or intervention.

Yes brilliant, It rates with the Irish suggestion of to stop the traffic
problems associated to road works, they propose to start doing them from
underneath.
The Helicopter ejector seat was down to a similar out of the box thinking
individual.
I guess in the US the Irish are replaced by Poles and although this
suggestion is politically incorrect apparently, why is it that its the Irish
who seem to tell them?

I think we are taking unbridge with just banter these days. There are loads
of jukes about blind people, and apart from having heard most of them far
too many times, they are quite funny.

This blind guy with his dog got off of a bus and attached a rope to his dogs
harness and started whiling him around over his head. a passer by said,
what are you doing? He replied, just having a look around.
Thud.

Brian

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"JNugent" <jenningsandco@mail.com> wrote in message
news:jvp9ouF649kU1@mid.individual.net...
> On 12/12/2022 01:12 pm, Bob Latham wrote:
>
>> https://youtu.be/vyS9uqRLbB8
>>
>> I'd not seen this until today, I think it was a while back but...
>>
>> Heaven help us all. :-(
>
> :-)
>
> "Solar panels, on the roof, charging your vehicle overnight. That's what
> [the future] looks like".
>
> Utterly brilliant. Why didn't anyone else think of it?

On 13/12/2022 23:13, MB wrote:
> On 13/12/2022 16:48, Brian Gaff wrote:

>> I know hat we need a clockwork car.

> I saw something yesterday that seemed to be as small as C5, don't think
> it was but wondered what it might be?

How the fuck would we know?

--
Max Demian

On 14/12/2022 12:38, Brian Gaff wrote:

> Yes brilliant, It rates with the Irish suggestion of to stop the traffic
> problems associated to road works, they propose to start doing them from
> underneath.

Well why not start building houses starting with the roof so as to
protect the builders from the rain? (Actually they do nowadays with
elaborate covers supported by scaffolding. Wimps! And they have to have
Portaloos.)

> The Helicopter ejector seat was down to a similar out of the box thinking
> individual.

> I guess in the US the Irish are replaced by Poles and although this
> suggestion is politically incorrect apparently, why is it that its the Irish
> who seem to tell them?

With the number of Poles in this country I'm surprised that we haven't
adjusted our jokes. Many years ago The Times printed similar stories
about Andorrans on the grounds that there are unlikely that any would be
reading it.

--
Max Demian

In article <tncdes$2pmr5$1@dont-email.me>,
David Woolley <david@ex.djwhome.demon.invalid> wrote:
> On 14/12/2022 08:58, Bob Latham wrote:
> > Then how do you transfer the energy from one battery to another?
> > I presume the house battery would need to be a higher voltage than
> > the car battery. then some sort of regulator.

> The voltages can go either way, and that is also what you will get
> in a mobile phone power bank. In the latter, typically a nominal
> 3.6V battery will be boost regulated up to 5V (or even more), in
> the power bank, then buck regulated down to the current charging
> battery voltage (which can vary from the low 3s, to about 4.2V
> during the course of the charge.

In language I understand, you mean you would use an inverter to get
to a higher voltage as part of a DC to DC converter?

> The second regulation step is necessary for efficiency, as just
> dumping the excess as heat would be wasteful.

I was thinking that analogue control of flow from a higher voltage
would waste heat energy but if the source battery was a higher
voltage than the destination you could use switching regulation
between the two to reduce losses and not require an inverter.

I accept that may well not be the industry way of doing things.

Bob.

On 14/12/2022 16:45, Bob Latham wrote:
> In language I understand, you mean you would use an inverter to get
> to a higher voltage as part of a DC to DC converter?

Boost convertors aren't conventional inverters; they don't generate a
fixed AC signal, rather they generate pulses to top up the output
capacitor. They are similar in topology to the buck convertor
configuration used for downconverting DC to DC regulators. The key
components are an inductor and a MOSFET switch. They use the kick back
from the inductor, when the switch is opened, to produce the output.

<https://en.wikipedia.org/wiki/Boost_converter>

<https://en.wikipedia.org/wiki/Buck_converter>