New House Thermal

On Wednesday, June 28, 2017 at 11:56:15 AM UTC-4, Dan Marotta wrote:
How did the temperature of the roof surrounding the PV panels compare?

On 6/26/2017 6:43 PM, wrote:
On Monday, June 26, 2017 at 4:23:32 AM UTC-4, wrote:
The Treasure Coast Soaring Club will soon have a new house thermal. Florida Power And Light is in the process of building a 400 acre solar power plant within 3/4 mile from our airport. Heat from this type of farm should make for a great house thermal. Anyone out there with experience flying over solar farms? Thanks, Bob
lets make this somewhat simple, the temp of the solar panes on top of the hangar today was in excess of 115 degrees F. I measured the temp reading with a heat gun. The panels number about 16, and the output is a max 8kw. I don't have the output capacity of this project, but I would guess that 100 acres of solar farm could produce 20 MW therefore 400 acres would be 80MW.. I would think that if those panels produced the same amount of heat as the ones on the hangar roof and heat travels up, I would assume that we would get some thermal activity from the project.

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Dan, 5J

Good question Dan. The roof is white and was about 12-15 degrees cooler than the solar panels. Also just west of the 400 acre solar project FPL is building another solar plant exactly the same size. That would be 800 total acres of panels within 2 miles of our strip. will be interesting to see what difference it makes. These farms are to be finished by September, unless a hurricane strows them all the way to Nebraska.

If you want a house thermal, you want a refinery. Chicago glider club has two of them within 5 miles, and there are a lot of days in fall when cross country soaring involves a "refinery tour." Also some 7 knot thermals when nothing else is going up more than 3. Of course, if you arrive low and counting on it, you will meet the bubble theory of thermal formation first hand. It was interesting when it was shut down for a few months. You'd think sun hitting the concrete was most of it, and there was a thermal there, but the operation of the refinery made a big difference. Point your wing at the flame in the smokestack...

John Cochrane.

Adding on to Bob's thoughts, at the New Hibiscus Airpark in Vero Beach, FL, we already have three consistent thermal generators right next to the airport: a CVS distribution center just northwest, an outlet mall just east, and the Quad Lakes development just to the southwest. All are within a half mile of the pattern. Add that to the rotation of plowed fields to the west and we have a pretty nice setup here.

Adding these solar farms could significantly increase our house thermals and provide some nice, close to home, final glide thermals for those coming back from XCs. Time will tell...

Paul A.

I see that some of you are physics and some know economics but no one understand thermodynamics.

All that we have is sun-radiation. A typical good day where I fly is the radiation about 500W/m^2. Some of this radiation will be reflected back to the atmosphere. This is called Albedo and is depending on the ground, in average is the albedo about 33%. The remaining energy (500 x 0,67 = 335W) will be heat into the ground and eventually thermals for us to use.

If you now put a solar panel (electrical or water) into the system with and efficiency of 20%, will the ground and the air be wormer or colder?

The purpose of a solar panel is to convert solar radiation to energy (electrical or heat) and transport it to another place for usage. Therefor will it be less energy left to heat up the ground/air and therefore no thermals for us to use.
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.

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

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Dan, 5J

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

On Wednesday, June 28, 2017 at 11:56:15 AM UTC-4, Dan Marotta wrote:
How did the temperature of the roof surrounding the PV panels compare?


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Dan, 5J
On 6/28/2017 11:36 AM, wrote:

The roof is white and was about 12-15 degrees cooler than the solar panels.
During my formative years in soaring, I learned (rightly or wrongly)
that temperature differentials across a surface, e.g., the boundaries
between forests and open spaces, dirt and rocks, etc., are good areas to
look for thermals. That idea has worked for me for a long time. Maybe
you'll find something there after all. Please keep us informed.
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Dan, 5J