NASA on Wrenches? [RE-wrenches]

[Jeff Clearwater, Village Power Design]

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Hi Folks,

Well I think we should invite Scott Parazynski - 
the astronaut who repaired the P6 Solar Array 
today on the International Space Station (ISS) - 
to the Wrenches list.   I mean -  after all - 
consider his job and what he works on.

Customer:  Taxpayers
System Type:  Off-Grid

Sound familiar?

Some More Specs:

FOR THE P6 ARRAY:

Array Wattage:  32.8 KW
# of Cells:  33,000 with 4100 diodes (Does not come with Evergreen Diode Kits)
Array Vmp:  124 VDC (must not have consulted 
SMA's sizer for optimizing high voltage)
Array Imp: 264 Amps !
Array Dimension:  107' x 38'
Array Area:  4066 ft2
Array Design Life: 15 yrs (Customer plans to replace arrays on his own!)
Racking: Accordion Blankets (engineering calcs 
not available from UniRac & no permit required - 
snow load not a factor)
Tracking:  360º Single Axis (with 2nd axis pitch 
control of 4-5º) (sensor unit said to be better 
than even Wattsun's)
Charge Control:  BCDU Battery Charge/Discharge Unit (not from Outback)
Batteries:  Not L16s - They are Nickel-Hydrogen 
at 8 KW Charge Rate. 6 KW Discharge Rate.
38,000 rated C/D cycles at 35% DOD.  Actual Ahrs 
or KWhrs not clearly stated (that I could find). 
Design life:  6.5 Yrs.
Dump Load:  14 KW per array. (Not yet available from AEE)

TOTAL INTERNATIONAL SPACE STATION PV: (8 Arrays)

Wattage:  262 KW
Array Vmp:  124 VDC
Array Imp: 2116 Amps!
Array Area: 32,528 ft2

Contractor: Lockheed Martin Space Systems, 
Sunnyvale, CA (Doesn't even have a C-46 License!)
Total Contract Cost for 8 Arrays:  US $450 
Million (2000 dollars) (payment required upfront)

Price/Watt:  $1715/Watt (it's a lot more if you 
want a ground mount - but UniRac will take a 
while to get back with you)

Well much of this is just like our work - well 
except maybe the price - and the view.  But the 
part about him hanging out on the end of a 110' 
arm.  That feels just like some of our work!

I really think he's a candidate.

What do others think?

Jeff Clearwater
Village Power Design

PS A complete description of the power 
electronics/storage on the ISS PV system (on the 
P3-P4 truss array)  can be had from:

http://www.boeing.com/defense-space/space/spacestation/components/docs/P3-P4.pdf

and a good paper on space PV trends can be had at:

http://www.aec-able.com/corpinfo/Resources/PAJ-IEEE-98.pdf












The Space Systems ISS solar arrays are the 
largest deployable space structure ever built and 
will be by far, the most powerful 
electricity-producing arrays ever put into orbit. 
When the Station is completed a total of eight 
flexible, deployable solar array wings will 
generate the reliable, continuous power for the 
on-orbit operation of the ISS systems. The eight 
array wings were designed and built under a $450 
million contract from the Boeing-Rocketdyne 
Division in Canoga Park, Calif., for delivery to 
the Boeing Company and NASA.
Each of the eight wings consists of a mast 
assembly and two solar array blankets. Each 
blanket has 84 panels, of which 82 are populated 
with solar cells. Each panel contains 200 solar 
cells. The eight photovoltaic arrays thus 
accommodate a total of 262,400 solar cells. When 
fully deployed in space, the active area of the 
eight wings, each 107 by 38-feet, will encompass 
an area of 32,528-sq. ft., and will provide power 
to the ISS for 15 years.
--
~~~~~~~~~~~~~
Jeff Clearwater
Village Power Design
Sustainable Energy & Water Solutions for Home & Village
http://www.villagepower.com
gosolar at villagepower.com
NABCEP (tm) Certified Solar PV Installer

877-765-2784
FAX: 530-466-3663
425 Nimrod St,
Nevada City, CA 95959
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