New House Thermal

Per, your pompous post implies that no heat will be exerted from the 800 acres of black panels. I guess my 40 years of soaring and a two plus thousand hours of hp glass time have proven me wrong before, but I would bet on a good thermal from that huge array of panels. Bob

These started appearing in the uk big time last year. My experience so far
is
that like wind farms they are good thermal generators.
Not sure it has anything to do with the solar bit per se as that would
imply
inefficiency but i would think may have the same effect as a busy asphalt
car
park in that it allows the hot air to cling to the ground a bit longer due
to the
panels being on a 30-45 deg slant.

At 18:29 29 June 2017, wrote:
Per, your pompous post implies that no heat will be exerted from the 800
ac=
res of black panels. I guess my 40 years of soaring and a two plus
thousand=
hours of hp glass time have proven me wrong before, but I would bet on a
g=
ood thermal from that huge array of panels. Bob

Why does stating something scientifically make a person "pompous"?

On 6/29/2017 12:29 PM, wrote:
Per, your pompous post implies that no heat will be exerted from the 800 acres of black panels. I guess my 40 years of soaring and a two plus thousand hours of hp glass time have proven me wrong before, but I would bet on a good thermal from that huge array of panels. Bob

--
Dan, 5J

Just got off the roof, where I measured my installation with an IR thermometer. Believe that's what Bob meant by heat gun.

Exposed roof: 135 to 140F, 57 to 60C
Shaded roof: 100F, 38C.
PV panels: 120F, 49C

Jim


On Wednesday, June 28, 2017 at 8:56:15 AM UTC-7, Dan Marotta wrote:
How did the temperature of the roof surrounding the PV panels compare?
Dan, 5J

On Thu, 29 Jun 2017 17:02:56 -0700, JS wrote:

Just got off the roof, where I measured my installation with an IR
thermometer. Believe that's what Bob meant by heat gun.

Exposed roof: 135 to 140F, 57 to 60C Shaded roof: 100F, 38C.
PV panels: 120F, 49C

Do you know what the electrical output from your panels was at that time?
Watts/m^2 would be v.interesting.

Just curious. I thought about fitting solar electric and/or water heating
panels to my roof a while back, but its a non-starter because the town
council owns a row of very large oaks just over my southern fence (10m
from the house), and I haven't a cats chance in hell of getting them
trimmed.



--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Friday, June 30, 2017 at 4:16:52 AM UTC-7, Martin Gregorie wrote:
On Thu, 29 Jun 2017 17:02:56 -0700, JS wrote:

Just got off the roof, where I measured my installation with an IR
thermometer. Believe that's what Bob meant by heat gun.

Exposed roof: 135 to 140F, 57 to 60C Shaded roof: 100F, 38C.
PV panels: 120F, 49C

Do you know what the electrical output from your panels was at that time?
Watts/m^2 would be v.interesting.

Just curious. I thought about fitting solar electric and/or water heating
panels to my roof a while back, but its a non-starter because the town
council owns a row of very large oaks just over my southern fence (10m
from the house), and I haven't a cats chance in hell of getting them
trimmed.



--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Didn't look, Martin.
The system has been in so long that as a rule I don't think about it any more. This was a test for the temperatures, for anyone who'd like to calculate if thermals would be better or worse.
Jim

On Fri, 30 Jun 2017 08:07:42 -0700, JS wrote:

On Friday, June 30, 2017 at 4:16:52 AM UTC-7, Martin Gregorie wrote:
On Thu, 29 Jun 2017 17:02:56 -0700, JS wrote:

Just got off the roof, where I measured my installation with an IR
thermometer. Believe that's what Bob meant by heat gun.

Exposed roof: 135 to 140F, 57 to 60C Shaded roof: 100F, 38C.
PV panels: 120F, 49C

Do you know what the electrical output from your panels was at that
time?
Watts/m^2 would be v.interesting.

Just curious. I thought about fitting solar electric and/or water
heating panels to my roof a while back, but its a non-starter because
the town council owns a row of very large oaks just over my southern
fence (10m from the house), and I haven't a cats chance in hell of
getting them trimmed.



--
martin@ | Martin Gregorie gregorie. | Essex, UK org |

Didn't look, Martin.
The system has been in so long that as a rule I don't think about it any
more. This was a test for the temperatures, for anyone who'd like to
calculate if thermals would be better or worse.

Yes, understood, Jim. I was just curious to see if it was possible to see
how much of the roofanel temp difference was due to generated power
and how much was down to albedo difference.

Just wish I was in a better position both w.r.t latitude (51.779N) and
oak trees to consider adding some solar stuff to my roof.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

The panels presumably are isolated from the roof with an air gap, thus their lower temperature. They passed some of the heat on to the air. The thermal-generating effect would depend on the flow of heat to the air, not the temperature of the sun-illuminated object. In a steady state equilibrium, that flow equals the solar input, minus the reflected light, and minus any power siphoned off in other forms (whether electricity from the PV panels, or evaporation of water from green plants).

Per Carlin wrote on 6/29/2017 12:17 AM:
I see that some of you are physics and some know economics but no one understand thermodynamics.
.....
The only way a solar plant could be useful for us is if the albedo of the panels are so small so it compensates for the power drain it is designed to do.

Solar panels are a deep black and do a superb job of absorbing the radiation from
the sun. The ones on my house and my motorhome feel significantly hotter than the
roof area without a solar panel on it.

What might keep them from getting hotter than the ground near a solar farm is the
wind cools BOTH sides of the panel - air circulation across the bottom of the
panel is an important design consideration, as a cooler panel is more efficient.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf

wrote on 6/27/2017 7:29 AM:
Question: How much energy does it take to produce a solar array (Aluminum mining, refining, manufacture, Silicon panel manufacture, etc.)? How does it compare to the energy output of the array over its life?

It varies with the location (the amount of sun, basically) where the panels are
used, the kind of panel, etc, but the current range is 1 to 4 years. That's a big
improvement compared to 20 or 30 years ago, due to using much thinner silicon
wafers, fabricating higher efficiency solar cells, and other manufacturing
improvements.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf