I'm looking at solar powered pir outdoor leds. Does the solar panel have to face the sun or is sky view sufficient. ( Id need to make up a bracket to allow the panel face south)

fred wrote:
I'm looking at solar powered pir outdoor leds. Does the solar panel have to face the sun or is sky view sufficient. ( Id need to make up a bracket to allow the panel face south)

South facing would be highly desirable, 30-40 degrees up from horizontal
ideally too.
Don't expect much charge from now-ish until March.

On 23/10/2018 12:46, fred wrote:
I'm looking at solar powered pir outdoor leds. Does the solar panel
have to face the sun or is sky view sufficient. ( Id need to make up
a bracket to allow the panel face south)

Apart from in midwinter when even professional grade solar powered
devices die a horrible death wrecking the batteries - it doesn't matter
too much whether you point a solar panel E,S or W. It must get direct
sunlight to have a sensible efficiency but it isn't all that critical
which way it points - a 30 degree pointing error loses about 15%.

--
Regards,
Martin Brown

They work better facing the sun, but in this country, you are not going to
get much out of those i fancy.
Brian

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"fred" wrote in message
...
I'm looking at solar powered pir outdoor leds. Does the solar panel have
to face the sun or is sky view sufficient. ( Id need to make up a bracket
to allow the panel face south)

Stick em under a streetlight? :-)
Brian

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The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Chris Hogg" wrote in message
...
On Tue, 23 Oct 2018 04:46:58 -0700 (PDT), fred
wrote:

I'm looking at solar powered pir outdoor leds. Does the solar panel have
to face the sun or is sky view sufficient. ( Id need to make up a bracket
to allow the panel face south)

Be aware that they're pretty useless in the winter months. Not enough
sun to charge them up, and too much night-time darkness during which
they run down.

--

Chris

What about some kind of lens or something. I guess the moving and focussing
electronics would use up any extra you gained.
Brian

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The Sofa of Brian Gaff...

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Note this Signature is meaningless.!
"Martin Brown" wrote in message
news
On 23/10/2018 12:46, fred wrote:
I'm looking at solar powered pir outdoor leds. Does the solar panel
have to face the sun or is sky view sufficient. ( Id need to make up
a bracket to allow the panel face south)

Apart from in midwinter when even professional grade solar powered devices
die a horrible death wrecking the batteries - it doesn't matter too much
whether you point a solar panel E,S or W. It must get direct sunlight to
have a sensible efficiency but it isn't all that critical which way it
points - a 30 degree pointing error loses about 15%.

--
Regards,
Martin Brown

On Tuesday, 23 October 2018 12:47:00 UTC+1, fred wrote:
I'm looking at solar powered pir outdoor leds. Does the solar panel have to face the sun or is sky view sufficient. ( Id need to make up a bracket to allow the panel face south)

You can get them with separate panels on a short wire so the panel can face South if necessary.
You need to avoid shading too.

Some have a small night light + brighter PIR.
In Winter packs in after a few hours due to lack of charging and this small night light..
But lasts longer the nearer to South pointing & least shading the panel has.

I have several. Only last about 5hrs in Winter and dull days.
You only find out after you've bought them.

PIR alone might be better (ie without night light)

On 23/10/2018 12:46, fred wrote:

I'm looking at solar powered pir outdoor leds.

Let me guess, they are off! ;-)

Does the solar panel
have to face the sun or is sky view sufficient. ( Id need to make up
a bracket to allow the panel face south)

Just position them near a bright halogen, and they will be fine.

Yup, pointing toward the sun will help a bit, but they are generally
unsuited to UK winter operation IME.


--
Cheers,

John.

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

On 23/10/2018 14:50, Brian Gaff wrote:
What about some kind of lens or something. I guess the moving and focussing
electronics would use up any extra you gained.
Brian


A lens doesn't work, but a trick that can be used at the risk of cooking
the solar panel is to put the panel at the base of half a hexagonal
prism with two mirrors either side reflecting light onto it. It roughly
doubles the output for minimal extra weight. Sort of trick that some
portable charging devices sometimes use - it can fold flat to carry.

ASCI Art sketch (sorry Brian - no help to you)

\_/

Solar panel at the base. Mirror either side. Doesn't work well for
larger panels because of wind loading but OK on a small scale.

If you want to be fancy then a parabolic mirror curve on either side
with its focus at the base of the opposite side will ensure any light
ray that enters the front aperture will eventually hit the PV cell.

There are whole families of cunning non-focussing flux intensifiers
mainly intended for high energy physics photomultipliers.

MOst of it is behind a paywall but this review article isn't. YOu want
chapter 4 Compound Parabolic Concentrators.

http://inpressco.com/wp-content/uplo...r27168-182.pdf

--
Regards,
Martin Brown

On 23/10/2018 16:49, John Rumm wrote:
On 23/10/2018 12:46, fred wrote:

I'm looking at solar powered pir outdoor leds.

Let me guess, they are off! ;-)

Does the solar panel
have to face the sun or is sky view sufficient. ( Id need to make up
a bracket to allow the panel face south)

Just position them near a bright halogen, and they will be fine.

Yup, pointing toward the sun will help a bit, but they are generally
unsuited to UK winter operation IME.

I have one of the PIR devices powered by 3x C cells over my front door.
Been going nearly two years now on the same batteries. I fitted one
outside the VH. I bring the solar PV garden lamps in for the winter.

The dank foggy weather and winter frosts destroys their batteries. We
have plenty of solar powered "Please go round the (dangerous) bend"
signs round here. They are great fun in mid-summer flashing away and for
an hour after sunset in winter but completely dead in the water on a
cold frosty winters morning when they might actually do some good.

--
Regards,
Martin Brown

fred wrote

I'm looking at solar powered pir outdoor leds.
Does the solar panel have to face the sun or is
sky view sufficient. ( Id need to make up a
bracket to allow the panel face south)

Not possible to give an absolute answer, it depends
on the design, the area of the panel and the power
consumption of the system, and how often it is triggered.

Plenty of the commercial ones dont work right thru
the night so it works first thing in the morning when
its still dark, even with the panel facing south etc.

On Wed, 24 Oct 2018 04:34:46 +1100, cantankerous trolling senile geezer Rot
Speed blabbered, again:


I'm looking at solar powered pir outdoor leds.
Does the solar panel have to face the sun or is
sky view sufficient. ( Id need to make up a
bracket to allow the panel face south)

Not possible to give an absolute answer,

Putting down THAT sentence must have really hurt you, Mr Know-it-all! LOL

--
pamela about Rot Speed:
"His off the cuff expertise demonstrates how little he knows..."
MID:

On Tue, 23 Oct 2018 13:00:08 +0100, Martin Brown
wrote:

On 23/10/2018 12:46, fred wrote:
I'm looking at solar powered pir outdoor leds. Does the solar panel
have to face the sun or is sky view sufficient. ( Id need to make up
a bracket to allow the panel face south)

Apart from in midwinter when even professional grade solar powered
devices die a horrible death wrecking the batteries - it doesn't matter
too much whether you point a solar panel E,S or W. It must get direct
sunlight to have a sensible efficiency but it isn't all that critical
which way it points - a 30 degree pointing error loses about 15%.

As insolation for a region is reasonably predictable on an annual basis, as is
the 5:1 maximum summer to minimum winter seasonality for much of the UK, then
some would conclude these 'professional grade' solar devices are anything but.

You can, space and windload permitting, over provide to meet winter demand
requirements at the expense of more panel area and a means to dump excess in the
summer. Any battery charge management is relatively easy too if you have a grip
on the load profile and the predicted pv output and in my experience actual PV
output really doesn't vary much from the predicted.

https://pvwatts.nrel.gov/pvwatts.php

http://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#PVP

--

On Tuesday, 23 October 2018 21:48:31 UTC+1, The Other Mike wrote:
On Tue, 23 Oct 2018 13:00:08 +0100, Martin Brown
wrote:

On 23/10/2018 12:46, fred wrote:
I'm looking at solar powered pir outdoor leds. Does the solar panel
have to face the sun or is sky view sufficient. ( Id need to make up
a bracket to allow the panel face south)

Apart from in midwinter when even professional grade solar powered
devices die a horrible death wrecking the batteries - it doesn't matter
too much whether you point a solar panel E,S or W. It must get direct
sunlight to have a sensible efficiency but it isn't all that critical
which way it points - a 30 degree pointing error loses about 15%.

As insolation for a region is reasonably predictable on an annual basis, as is
the 5:1 maximum summer to minimum winter seasonality for much of the UK, then
some would conclude these 'professional grade' solar devices are anything but.

You can, space and windload permitting, over provide to meet winter demand
requirements at the expense of more panel area and a means to dump excess in the
summer. Any battery charge management is relatively easy too if you have a grip
on the load profile and the predicted pv output and in my experience actual PV
output really doesn't vary much from the predicted.

https://pvwatts.nrel.gov/pvwatts.php

http://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#PVP

professional means someone's making money out of it, hence the mickey mouse panels.


NT

On 23/10/2018 21:48, The Other Mike wrote:
On Tue, 23 Oct 2018 13:00:08 +0100, Martin Brown
wrote:

On 23/10/2018 12:46, fred wrote:
I'm looking at solar powered pir outdoor leds. Does the solar panel
have to face the sun or is sky view sufficient. ( Id need to make up
a bracket to allow the panel face south)

Apart from in midwinter when even professional grade solar powered
devices die a horrible death wrecking the batteries - it doesn't matter
too much whether you point a solar panel E,S or W. It must get direct
sunlight to have a sensible efficiency but it isn't all that critical
which way it points - a 30 degree pointing error loses about 15%.

As insolation for a region is reasonably predictable on an annual basis, as is
the 5:1 maximum summer to minimum winter seasonality for much of the UK, then
some would conclude these 'professional grade' solar devices are anything but.

They are widely deployed by highways on remote rural roads to try and
stop muppets speeding into tight corners when it is frosty. They work
brilliantly in mid summer but last at most a couple of hours after dark
on a typical dull mid winters day. Even less if it has been dull and
foggy for a few days in a row.

You can, space and windload permitting, over provide to meet winter demand
requirements at the expense of more panel area and a means to dump excess in the
summer. Any battery charge management is relatively easy too if you have a grip
on the load profile and the predicted pv output and in my experience actual PV
output really doesn't vary much from the predicted.

https://pvwatts.nrel.gov/pvwatts.php

http://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#PVP

It doesn't vary that much, but you have to be very very remote before it
can compete with physically swapping a rechargeable battery. The big
problem is that bad weather comes in periods of weeks in winter and at
our high latitude the signs never get properly recharged again.

--
Regards,
Martin Brown

In article , Martin Brown
wrote:
On 23/10/2018 21:48, The Other Mike wrote:
On Tue, 23 Oct 2018 13:00:08 +0100, Martin Brown
wrote:

On 23/10/2018 12:46, fred wrote:
I'm looking at solar powered pir outdoor leds. Does the solar panel
have to face the sun or is sky view sufficient. ( Id need to make up
a bracket to allow the panel face south)

Apart from in midwinter when even professional grade solar powered
devices die a horrible death wrecking the batteries - it doesn't
matter too much whether you point a solar panel E,S or W. It must get
direct sunlight to have a sensible efficiency but it isn't all that
critical which way it points - a 30 degree pointing error loses about
15%.

As insolation for a region is reasonably predictable on an annual
basis, as is the 5:1 maximum summer to minimum winter seasonality for
much of the UK, then some would conclude these 'professional grade'
solar devices are anything but.

They are widely deployed by highways on remote rural roads to try and
stop muppets speeding into tight corners when it is frosty. They work
brilliantly in mid summer but last at most a couple of hours after dark
on a typical dull mid winters day. Even less if it has been dull and
foggy for a few days in a row.

You can, space and windload permitting, over provide to meet winter
demand requirements at the expense of more panel area and a means to
dump excess in the summer. Any battery charge management is relatively
easy too if you have a grip on the load profile and the predicted pv
output and in my experience actual PV output really doesn't vary much
from the predicted.

https://pvwatts.nrel.gov/pvwatts.php

http://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#PVP

It doesn't vary that much, but you have to be very very remote before it
can compete with physically swapping a rechargeable battery. The big
problem is that bad weather comes in periods of weeks in winter and at
our high latitude the signs never get properly recharged again.

The BBC built a tv relay in the west of Scotland which was powered by a
combination of solar and wind. worked well. The IBA tried a similar one in
Cornwall. A storm blew the blade off the wind turbine which, on its way
down, smashed the solar panel

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle