Hi.
I read in a NATURE article about the "heat island" effect of solar arrays, where they run quite a lot hotter than the surrounding land, and I was interested to know if anybody was using these things as a reliable source of lift?
Related to this, they are building a gigantic solar array at the end of the runway at Christchurch Airport, and I wonder if the resulting thermals would result in a bumpy - or even unsafe - take off or landing.

Thanks
Simon.

On 9/14/2022 7:06 AM, Simon Worrall wrote:
> Hi.
> I read in a NATURE article about the "heat island" effect of solar arrays, where they run quite a lot hotter than the surrounding land, and I was interested to know if anybody was using these things as a reliable source of lift?
> Related to this, they are building a gigantic solar array at the end of the runway at Christchurch Airport, and I wonder if the resulting thermals would result in a bumpy - or even unsafe - take off or landing.
>
> Thanks
> Simon.
>
There was discussion here before about this. A solar array would be
hotter than a forest. But there is nothing about solar panels that
makes them heat up in the sun more than other dark dry objects such as
pavement or buildings. If anything, whatever part (15% or so) of the
solar energy that the panels turn into electricity is SUBTRACTED from
their heating up - that energy is sent elsewhere.

There is a large multi-acre solar field a couple of miles west of the Moriarty Airport. I have been cruising over it on informal "tests" to see whether there is any appreciable change in lift (or sink). I haven't noticed anything different from surrounding terrain, but the reflection of the sun can be more than just distracting. "Blinding" is a better description when the sun's angle matches the panel array and I am in the wrong place. One reason I suspect that the dark solar panels don't generate much of a thermal is that they are raised above the ground surface, leaving the soil in shadow and allowing air to freely flow around the panels without heating up very much. And since the panels do not have much mass compared to the unshaded ground, little energy is transferred to the airmass by convection. The sun heats the ground, the ground heats the air and when enough heat is absorbed, the air expands and rises. The solar array does not appear to transfer sufficient heat for thermal generation. More research is needed. I am going to propose that some of our local pilots make a point to cruise over the array and maybe we can make some valid conclusions about lift/sink presence from their flight traces.

I haven't noticed any extra bumps while flying over the solar panels at
very low altitudes in my gyro.
Dan
5J
On 9/14/22 07:22, Mark Mocho wrote:
> There is a large multi-acre solar field a couple of miles west of the Moriarty Airport. I have been cruising over it on informal "tests" to see whether there is any appreciable change in lift (or sink). I haven't noticed anything different from surrounding terrain, but the reflection of the sun can be more than just distracting. "Blinding" is a better description when the sun's angle matches the panel array and I am in the wrong place. One reason I suspect that the dark solar panels don't generate much of a thermal is that they are raised above the ground surface, leaving the soil in shadow and allowing air to freely flow around the panels without heating up very much. And since the panels do not have much mass compared to the unshaded ground, little energy is transferred to the airmass by convection. The sun heats the ground, the ground heats the air and when enough heat is absorbed, the air expands and rises. The solar array does not appear to transfer sufficient heat for thermal generation. More research is needed. I am going to propose that some of our local pilots make a point to cruise over the array and maybe we can make some valid conclusions about lift/sink presence from their flight traces.

On Wed, 14 Sep 2022 09:36:55 -0600, Dan Marotta wrote:

> I haven't noticed any extra bumps while flying over the solar panels at
> very low altitudes in my gyro.
>
> Dan 5J
>
> On 9/14/22 07:22, Mark Mocho wrote:
>> There is a large multi-acre solar field a couple of miles west of the
>> Moriarty Airport. I have been cruising over it on informal "tests" to
>> see whether there is any appreciable change in lift (or sink). I
>> haven't noticed anything different from surrounding terrain, but the
>> reflection of the sun can be more than just distracting. "Blinding" is
>> a better description when the sun's angle matches the panel array and I
>> am in the wrong place. One reason I suspect that the dark solar panels
>> don't generate much of a thermal is that they are raised above the
>> ground surface, leaving the soil in shadow and allowing air to freely
>> flow around the panels without heating up very much. And since the
>> panels do not have much mass compared to the unshaded ground, little
>> energy is transferred to the airmass by convection. The sun heats the
>> ground, the ground heats the air and when enough heat is absorbed, the
>> air expands and rises. The solar array does not appear to transfer
>> sufficient heat for thermal generation. More research is needed. I am
>> going to propose that some of our local pilots make a point to cruise
>> over the array and maybe we can make some valid conclusions about
>> lift/sink presence from their flight traces.

IIRC solar panel output is reduced as the panel temperature rises, so its
in the solar farm owner's interest to design the panel's mountings to keep
them as cool as possible. That seems to be one reason why there's interest
in using floats to support solar panels on water storage ponds/lakes. Its
seen as a win/win situation: the solar panels are kept cool and water loss
by evaporation from the pond is reduced.

--

Martin | martin at
Gregorie | gregorie dot org

The relative albedo between the surrounding vegetation and the panels can make a big difference. I've found the solar farm south of New Hibiscus to be a reliable source for a moderate thermal, though bubbly at times. It's surrounded by green vegetation, so it has a significant difference in albedo.

In the other thread, there was discussion about the lack of any sigificant difference in Uvalde over a solar farm and someone pointed out this albedo concept. It's worth looking it up for your edification.

PA

On Wednesday, September 14, 2022 at 7:06:50 AM UTC-4, cindyh...@gmail.com wrote:
> Hi.
> I read in a NATURE article about the "heat island" effect of solar arrays, where they run quite a lot hotter than the surrounding land, and I was interested to know if anybody was using these things as a reliable source of lift?
> Related to this, they are building a gigantic solar array at the end of the runway at Christchurch Airport, and I wonder if the resulting thermals would result in a bumpy - or even unsafe - take off or landing.
>
> Thanks
> Simon.
Simon, great topic! I fly in an area that is projected to be the largest solar array in the USA within a short period of time. As I flew today I noticed a couple thousand more acres being prepared for solar panels. At this time we are within a very short distance of possibly one thousand acres of solar fields. On any day I work thermals over those panels and at times it can become very good. There is a good bit of information written about this and you may want to read, Heat Transfer In Photovoltic Panels", written by Gomez at Lund University in Sweden. He specifically writes about wind generated heat from conductive panels and radioactive heat produced from the panels. Old Bob, The Purist

On Wednesday, September 14, 2022 at 6:06:50 AM UTC-5, cindyh...@gmail.com wrote:
> Hi.
> I read in a NATURE article about the "heat island" effect of solar arrays, where they run quite a lot hotter than the surrounding land, and I was interested to know if anybody was using these things as a reliable source of lift?
> Related to this, they are building a gigantic solar array at the end of the runway at Christchurch Airport, and I wonder if the resulting thermals would result in a bumpy - or even unsafe - take off or landing.
>
> Thanks
> Simon.

My home field, Butler, Georgia, USA, is adjacent to several large photovoltaic farms. A couple of these are over 4000' per side. We haven't seen any correlation between the solar panels and locations of thermals.

On Wed, 14 Sep 2022 15:56:20 -0700 (PDT), youngbl...@gmail.com wrote:

> radioactive heat produced from the panels. Old Bob, The Purist
>
Really? Are these solar panels mounted on a nuclear power plant or a spent
uranium waste dump?

--

Martin | martin at
Gregorie | gregorie dot org

On 9/15/2022 5:48 AM, Martin Gregorie wrote:
> On Wed, 14 Sep 2022 15:56:20 -0700 (PDT), youngbl...@gmail.com wrote:
>
>> radioactive heat produced from the panels. Old Bob, The Purist
>>
> Really? Are these solar panels mounted on a nuclear power plant or a spent
> uranium waste dump?

I think Towed Bob was a victim of auto-correct (radiation changed to radioactive) and
insufficient review of his writing; regardless, the paper gave no hint of solar panel heat
on thermal production that I could find.

--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications

On Thursday, September 15, 2022 at 9:38:01 AM UTC-4, Eric Greenwell wrote:
> On 9/15/2022 5:48 AM, Martin Gregorie wrote:
> > On Wed, 14 Sep 2022 15:56:20 -0700 (PDT), youngbl...@gmail.com wrote:
> >
> >> radioactive heat produced from the panels. Old Bob, The Purist
> >>
> > Really? Are these solar panels mounted on a nuclear power plant or a spent
> > uranium waste dump?
> I think Towed Bob was a victim of auto-correct (radiation changed to radioactive) and
> insufficient review of his writing; regardless, the paper gave no hint of solar panel heat
> on thermal production that I could find.
>
>
> --
> Eric Greenwell - USA
> - "A Guide to Self-launching Sailplane Operation"
> https://sites.google.com/site/motorgliders/publications
Thanks for the correction Eric, I should have stated hear radiation created by the panels. Old Bob, The Purist

On Thursday, September 15, 2022 at 11:17:45 AM UTC-4, youngbl...@gmail.com wrote:
> On Thursday, September 15, 2022 at 9:38:01 AM UTC-4, Eric Greenwell wrote:
> > On 9/15/2022 5:48 AM, Martin Gregorie wrote:
> > > On Wed, 14 Sep 2022 15:56:20 -0700 (PDT), youngbl...@gmail.com wrote:
> > >
> > >> radioactive heat produced from the panels. Old Bob, The Purist
> > >>
> > > Really? Are these solar panels mounted on a nuclear power plant or a spent
> > > uranium waste dump?
> > I think Towed Bob was a victim of auto-correct (radiation changed to radioactive) and
> > insufficient review of his writing; regardless, the paper gave no hint of solar panel heat
> > on thermal production that I could find.
> >
> >
> > --
> > Eric Greenwell - USA
> > - "A Guide to Self-launching Sailplane Operation"
> > https://sites.google.com/site/motorgliders/publications
> Thanks for the correction Eric, I should have stated hear radiation created by the panels. Old Bob, The Purist
Heat radiation, only the second mistake that I have ever made, better record than the late Rush Limbaugh. OBTP

On Thursday, September 15, 2022 at 11:07:35 AM UTC-7, youngbl...@gmail.com wrote:
> On Thursday, September 15, 2022 at 11:17:45 AM UTC-4, youngbl...@gmail.com wrote:
> > On Thursday, September 15, 2022 at 9:38:01 AM UTC-4, Eric Greenwell wrote:
> > > On 9/15/2022 5:48 AM, Martin Gregorie wrote:
> > > > On Wed, 14 Sep 2022 15:56:20 -0700 (PDT), youngbl...@gmail.com wrote:
> > > >
> > > >> radioactive heat produced from the panels. Old Bob, The Purist
> > > >>
> > > > Really? Are these solar panels mounted on a nuclear power plant or a spent
> > > > uranium waste dump?
> > > I think Towed Bob was a victim of auto-correct (radiation changed to radioactive) and
> > > insufficient review of his writing; regardless, the paper gave no hint of solar panel heat
> > > on thermal production that I could find.
> > >
> > >
> > > --
> > > Eric Greenwell - USA
> > > - "A Guide to Self-launching Sailplane Operation"
> > > https://sites.google.com/site/motorgliders/publications
> > Thanks for the correction Eric, I should have stated hear radiation created by the panels. Old Bob, The Purist
> Heat radiation, only the second mistake that I have ever made, better record than the late Rush Limbaugh. OBTP
Switching from hip waders to chest waders!! :-)

Funny coincidence about this string. Last week I was flying near Palo Verde AZ and observed a very large dust devil form right in the middle of a solar array. It looked like the solar panels were on fire and smoking. I agree with most of Mark M's comments - but would add that sometimes the panels act to suppress the buoyancy of the warmer air below them - much like the large leaves on cornstalks can do. So - you can get pretty strong thermals over them when they pop -even if they are not too frequent.
Roy

On Thursday, September 15, 2022 at 11:07:35 AM UTC-7, youngbl...@gmail.com wrote:
> On Thursday, September 15, 2022 at 11:17:45 AM UTC-4, youngbl...@gmail.com wrote:
> > On Thursday, September 15, 2022 at 9:38:01 AM UTC-4, Eric Greenwell wrote:
> > > On 9/15/2022 5:48 AM, Martin Gregorie wrote:
> > > > On Wed, 14 Sep 2022 15:56:20 -0700 (PDT), youngbl...@gmail.com wrote:
> > > >
> > > >> radioactive heat produced from the panels. Old Bob, The Purist
> > > >>
> > > > Really? Are these solar panels mounted on a nuclear power plant or a spent
> > > > uranium waste dump?
> > > I think Towed Bob was a victim of auto-correct (radiation changed to radioactive) and
> > > insufficient review of his writing; regardless, the paper gave no hint of solar panel heat
> > > on thermal production that I could find.
> > >
> > >
> > > --
> > > Eric Greenwell - USA
> > > - "A Guide to Self-launching Sailplane Operation"
> > > https://sites.google.com/site/motorgliders/publications
> > Thanks for the correction Eric, I should have stated hear radiation created by the panels. Old Bob, The Purist
> Heat radiation, only the second mistake that I have ever made, better record than the late Rush Limbaugh. OBTP

You also misspelled "voltaic":
Heat Transfer In Photovoltic Panels", written by Gomez
https://www.lth.se/fileadmin/ht/Kurser/MVK160/2009_reports/Gonzalo_calero.pdf.pdf

Tom

On Sunday, September 18, 2022 at 9:42:40 AM UTC-7, 2G wrote:
> On Thursday, September 15, 2022 at 11:07:35 AM UTC-7, youngbl...@gmail.com wrote:
> > On Thursday, September 15, 2022 at 11:17:45 AM UTC-4, youngbl...@gmail.com wrote:
> > > On Thursday, September 15, 2022 at 9:38:01 AM UTC-4, Eric Greenwell wrote:
> > > > On 9/15/2022 5:48 AM, Martin Gregorie wrote:
> > > > > On Wed, 14 Sep 2022 15:56:20 -0700 (PDT), youngbl...@gmail.com wrote:
> > > > >
> > > > >> radioactive heat produced from the panels. Old Bob, The Purist
> > > > >>
> > > > > Really? Are these solar panels mounted on a nuclear power plant or a spent
> > > > > uranium waste dump?
> > > > I think Towed Bob was a victim of auto-correct (radiation changed to radioactive) and
> > > > insufficient review of his writing; regardless, the paper gave no hint of solar panel heat
> > > > on thermal production that I could find.
> > > >
> > > >
> > > > --
> > > > Eric Greenwell - USA
> > > > - "A Guide to Self-launching Sailplane Operation"
> > > > https://sites.google.com/site/motorgliders/publications
> > > Thanks for the correction Eric, I should have stated hear radiation created by the panels. Old Bob, The Purist
> > Heat radiation, only the second mistake that I have ever made, better record than the late Rush Limbaugh. OBTP
> You also misspelled "voltaic":
> Heat Transfer In Photovoltic Panels", written by Gomez
> https://www.lth.se/fileadmin/ht/Kurser/MVK160/2009_reports/Gonzalo_calero.pdf.pdf
>
> Tom

Unfortunately that article is purely theoretical and gives no guidance whatsoever to what the real-world coefficients are (PottyMouth Bobbie probably doesn't care). Here is an article that is far more practical (and the equations are readable!):
"Roof-mounted photovoltaic generator temperature modeling based on common brazil materials"
https://www.researchgate.net/publication/357627841_Roof-mounted_photovoltaic_generator_temperatue_modeling_based_on_common_brazil_roofing_materials/link/631211865eed5e4bd13e28b0/download

Tom

On Sunday, September 18, 2022 at 1:01:31 PM UTC-4, 2G wrote:
> On Sunday, September 18, 2022 at 9:42:40 AM UTC-7, 2G wrote:
> > On Thursday, September 15, 2022 at 11:07:35 AM UTC-7, youngbl...@gmail.com wrote:
> > > On Thursday, September 15, 2022 at 11:17:45 AM UTC-4, youngbl...@gmail.com wrote:
> > > > On Thursday, September 15, 2022 at 9:38:01 AM UTC-4, Eric Greenwell wrote:
> > > > > On 9/15/2022 5:48 AM, Martin Gregorie wrote:
> > > > > > On Wed, 14 Sep 2022 15:56:20 -0700 (PDT), youngbl...@gmail.com wrote:
> > > > > >
> > > > > >> radioactive heat produced from the panels. Old Bob, The Purist
> > > > > >>
> > > > > > Really? Are these solar panels mounted on a nuclear power plant or a spent
> > > > > > uranium waste dump?
> > > > > I think Towed Bob was a victim of auto-correct (radiation changed to radioactive) and
> > > > > insufficient review of his writing; regardless, the paper gave no hint of solar panel heat
> > > > > on thermal production that I could find.
> > > > >
> > > > >
> > > > > --
> > > > > Eric Greenwell - USA
> > > > > - "A Guide to Self-launching Sailplane Operation"
> > > > > https://sites.google.com/site/motorgliders/publications
> > > > Thanks for the correction Eric, I should have stated hear radiation created by the panels. Old Bob, The Purist
> > > Heat radiation, only the second mistake that I have ever made, better record than the late Rush Limbaugh. OBTP
> > You also misspelled "voltaic":
> > Heat Transfer In Photovoltic Panels", written by Gomez
> > https://www.lth.se/fileadmin/ht/Kurser/MVK160/2009_reports/Gonzalo_calero.pdf.pdf
> >
> > Tom
> Unfortunately that article is purely theoretical and gives no guidance whatsoever to what the real-world coefficients are (PottyMouth Bobbie probably doesn't care). Here is an article that is far more practical (and the equations are readable!):
> "Roof-mounted photovoltaic generator temperature modeling based on common brazil materials"
> https://www.researchgate.net/publication/357627841_Roof-mounted_photovoltaic_generator_temperatue_modeling_based_on_common_brazil_roofing_materials/link/631211865eed5e4bd13e28b0/download
>
> Tom
Dickhead, the article and equations seem much more relevant than you, if you could offer any better theory please post it. Old Bob, The Purist

On Sunday, September 18, 2022 at 1:23:49 PM UTC-7, youngbl...@gmail.com wrote:
> On Sunday, September 18, 2022 at 1:01:31 PM UTC-4, 2G wrote:
> > On Sunday, September 18, 2022 at 9:42:40 AM UTC-7, 2G wrote:
> > > On Thursday, September 15, 2022 at 11:07:35 AM UTC-7, youngbl...@gmail.com wrote:
> > > > On Thursday, September 15, 2022 at 11:17:45 AM UTC-4, youngbl...@gmail.com wrote:
> > > > > On Thursday, September 15, 2022 at 9:38:01 AM UTC-4, Eric Greenwell wrote:
> > > > > > On 9/15/2022 5:48 AM, Martin Gregorie wrote:
> > > > > > > On Wed, 14 Sep 2022 15:56:20 -0700 (PDT), youngbl...@gmail.com wrote:
> > > > > > >
> > > > > > >> radioactive heat produced from the panels. Old Bob, The Purist
> > > > > > >>
> > > > > > > Really? Are these solar panels mounted on a nuclear power plant or a spent
> > > > > > > uranium waste dump?
> > > > > > I think Towed Bob was a victim of auto-correct (radiation changed to radioactive) and
> > > > > > insufficient review of his writing; regardless, the paper gave no hint of solar panel heat
> > > > > > on thermal production that I could find.
> > > > > >
> > > > > >
> > > > > > --
> > > > > > Eric Greenwell - USA
> > > > > > - "A Guide to Self-launching Sailplane Operation"
> > > > > > https://sites.google.com/site/motorgliders/publications
> > > > > Thanks for the correction Eric, I should have stated hear radiation created by the panels. Old Bob, The Purist
> > > > Heat radiation, only the second mistake that I have ever made, better record than the late Rush Limbaugh. OBTP
> > > You also misspelled "voltaic":
> > > Heat Transfer In Photovoltic Panels", written by Gomez
> > > https://www.lth.se/fileadmin/ht/Kurser/MVK160/2009_reports/Gonzalo_calero.pdf.pdf
> > >
> > > Tom
> > Unfortunately that article is purely theoretical and gives no guidance whatsoever to what the real-world coefficients are (PottyMouth Bobbie probably doesn't care). Here is an article that is far more practical (and the equations are readable!):
> > "Roof-mounted photovoltaic generator temperature modeling based on common brazil materials"
> > https://www.researchgate.net/publication/357627841_Roof-mounted_photovoltaic_generator_temperatue_modeling_based_on_common_brazil_roofing_materials/link/631211865eed5e4bd13e28b0/download
> >
> > Tom
> Dickhead, the article and equations seem much more relevant than you, if you could offer any better theory please post it. Old Bob, The Purist

MY MY! PottyMouth Bobbie has BLOWN HIS TOP yet again!