Solar Trackers
Solar Trackers
(OP)
I've been doing some rough studies concerning the economic feasibility of using solar panels mounted either in a fixed tilt position on close-to-ground supports, or mounted on 1 or 2 axis elevated solar tracking structures. The extra costs of the tracking structures and mechanisms supposedly can be balanced by higher daily energy production and the resulting income from grid power sales, but so far I have not been able to prove there is a positive return on the required incremental investment for the trackers. I think this is curious, since many projects appear to be using trackers. I am wondering if there is something missing in my analysis. I have included some cost reduction for smaller plot plan footprint of the trackers, but even that doesn't seem to be sufficient to justify their use. Is there an increase in generated power due to the elevation of the trackers and their being more exposed to cooling effects and a consequential reduction in operating temperature that I need to consider? Or ...is the use of trackers just a sales gimick of some kind? Has anybody been able to economically justify the use of solar trackers for a ground based pv installation?






RE: Solar Trackers
The extra power collected by tracking with a flat panel would only be a benefit in early morning and late afternoon. The total available power at those times is not high to begin with so the benefit is low.
RE: Solar Trackers
http://virtualpipeline.spaces.msn.com
RE: Solar Trackers
http://virtualpipeline.spaces.msn.com
RE: Solar Trackers
I don't remember the exact book that I read it in, or if it is even true.
RE: Solar Trackers
You could contact the editor and see if he has some comments or further information. It's Richard Perez.
RE: Solar Trackers
http://virtualpipeline.spaces.msn.com
RE: Solar Trackers
World is upside down from where I am....
RE: Solar Trackers
http://virtualpipeline.spaces.msn.com
"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein
RE: Solar Trackers
Trackers will also be much more vulnerable to high winds and storm damage than rigidly mounted flat panels.
RE: Solar Trackers
RE: Solar Trackers
"if all Walmart stores were covered with PV panels, they could supply a couple % of the US generation demand"
(Does 1 sq ft of solar panels use 1 sq ft of roof space? If not, ? ?)
For Walmart roof area, I found these facts on Walmart's web site,
http://www.walmartfacts.com/articles/2502.aspx
1,000 discount stores in the United States.
Discount stores average 107,000 square feet.
107,000 * 1,000 = 107,000,000 sq ft of roof top (on average)
Supercenters today number more than 2,300 nationwide.
Supercenters average 187,000 square feet.
2,300 * 187,000 = 430,100,000 sq ft.(on average)
430,100,000 sq ft + 107,000,000 sq ft = Walmart's potential roof area = 537,100,000 sq ft of roof space.
Dan
RE: Solar Trackers
Average insolation values for north American cities:
http://www.porta-energy.com/Insolation_USA.htm
Assuming average photovoltaic panels are 10% to 15% efficient.
A wild guess 5KwH per day x 12% = 600 watt hours per sqM
RE: Solar Trackers
Maintenance is a real cost for anything that moves. A big, new installation should need very little... at first, which can be a problem, because you'll need to create/expand the maintenance crew when things start failing, at which time you may have lost much of the needed documentation/ skills.
If you've got a 'farm' of articulated panel assemblies, you only need one that actually tracks the sun; the rest could be slaved to that.
Actually, in theory, you don't need a sun tracker at all; a modest computer with a real time clock should be able to point the array to where the sun _should_be_ at any given time.
Mike Halloran
Pembroke Pines, FL, USA
RE: Solar Trackers
1 square foot = 0.093 square meter
537,100,000sqft x 0.093 = 49,950,300m2
"600 watt hours per sqM/day"
49,950,300m2 x 600Whr/m2/day = 29,970,180,000Whrs/day => 30GWhrs/day
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Solar Trackers
The equatorial mount itself could also be driven to vary it's tilt throughout the seasons. As the earths tilt is 23.5 degrees, this could be adjusted with a crank and connecting rod coupled to a one year per revolution gearbox.
The whole mess could just grind away slowly, day and night, slewing back and forth to where the sun should be. No need for anything fancy, just some dumb gears, cranks, and connecting rods, and a bit of imagination.
Bravo Itsmoked, I was trying to work it out on my fingers, but quickly ran out of fingers.
RE: Solar Trackers
One tricky part is getting the synchronous motor to 'catch up' after an outage.
I guess if you used slip rings, the continuous rotation in azimuth wouldn't be a problem.
Mike Halloran
Pembroke Pines, FL, USA
RE: Solar Trackers
At very high latitudes, where the sun never sets in the summer months, continuous rotation would be preferable.
As the effective gearbox torque multiplication would be fairly enormous, the motor drive power should be minimal. A crystal oscillator backup, and battery power could keep the gears grinding away during short power outages. The power grid as a frequency source has the very great advantage of constant frequency correction.
The whole thing could be made less crude with stepper motors and an off air broadcast time/frequency standard. But the idea of constant angular rotation, without having to play hide and seek with the sun in cloudy conditions appeals to me.
RE: Solar Trackers
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Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Solar Trackers
http:/
30 GWh/day = 0.29%
RE: Solar Trackers
30GWhrs/day / 10,500GWhr/day => 3/10ths of 1%.
Answer: Factoid is bogus.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Solar Trackers
RE: Solar Trackers
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Solar Trackers
RE: Solar Trackers
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com