Friday, June 10, 2016

Solar Washington, Part Trois.

Part Trois?

Well, more of a patois really, because this array is completely nonstandard and much less conventional than the first two!  Via Craigslist, I happened upon a remarkable creation on the back lot of a local farmer.  His son built a large solar concentrator quite a few years ago by laboriously glueing hundreds of hand-cut mirrors to a ten-foot diameter C-band satellite dish (state flower of West Virginia, common 1980's yard art).  This aluminum mesh dish took the liquid nails perfectly, and very few little mirrors had been knocked off during its years of neglect.  The dish mounting pole was welded to a very beefy base of heavy steel tube and channel, which was mounted on casters (which could even still roll after being encased in a turkey manure slurry for the past decade!  The young man's creation can still set fire to green wood in seconds and melt aluminum.  Though it has a focal length of about five feet (meaning that at ten feet away the un-focused sunlight is no stronger than what's already pouring down from heaven), the local high school's science fair administrators refused to allow the device on campus, fearing it would burn the place down.  Such small-mindedness is no doubt a contributing factor to that lad now being a grown engineer working far from home...

Anyway, good neighbor Tom loaned a wide-decked trailer and good buddy Tim helped me haul the device home, which we did under cover of darkness to avoid undue attention to our oversize load, but it sure got the attention of stopped motorists at the crossroads, when their headlights were reflected back at them by the passing monstrosity.  To stimulate discussion with the neighbors, I left it parked out front for a few days, declaring that we'd all have free TV very soon.....
After arousing sufficient curiosity, I managed to unload it without flipping the dish, thanks in no small part to its sturdy foundation.  
The dish was dubbed "Archimedes' Death Ray", and served to entertain and roast food during Jason's 8th birthday party on a partly cloudy Saturday in March.  Word to the wise- sunshine doesn't really roast marshmallows, it just turns them into an iris-searing white blob of incandescence before they melt and slide down the skewer...  Hot dogs, on the other hand, blister in seconds.  Patience was required to warm the core without burning the skin!  
After our fun with the sun it was time to get serious about making greater use of said solar energy, so removed the dish (again, without flipping it even though the thing weighed a ton!).  It awaits reincarnation as a padoga roof over our hot tub, complete with a disco ball hanging from the center!

The antenna base was refitted with a uni-strut frame and grid of aluminum solar rail leftover from my salvaged Kaneka array, and topped with the 18 BP modules that were originally mounted on the WattSun dual-axis tracker (sidelined in favor of more productive and powerful made-in Washington Itek Energy PV panels).  The original 36" linear actuator is plenty powerful to move this new array, even after hibernating in a barn for a decade after being removed from the salvaged satellite dish during it's first afterlife. My current plan is to just manually adjust the elevation on a seasonal basis with the original elevation screw, and  use the actuator for daily east-west action, which does the most to maximize production.  I'm using the Axe-Tracka controller from Australia again on this array after a good experience with this hand-built unit on my first array and excellent customer service from the actual man who designs and builds 'em at home, rather than some nameless corporation or Ali-Baban. You'll also notice that I added wheels and a removeable tongue (which also serves a the removeable hitch for the Karmann Eclectric!).  That allows repositioning of the array and trailer loading with minimal effort.  The frame was cleverly welded so as to allow pass-through outriggers for stabilization.  I haven't found the ultimate solution yet, but will start with some timbers inserted through the steel for safety and added stability.  The tip-tilt motion of a satellite dish is not as refined as the WattSun tracker, which keeps modules parallel to the ground as the array is rotated about the pole, but the mechanisms are much simpler and robust this way.  

After this assembly and testing, the frame was painted (green, of course) and the new-old-stock Outback Power PS-1 installed on the base.  Next comes 48 Volts of EV-salvaged batteries, which will ballast the array against wind loading while also providing backup power for critical circuits in the home.  It doesn't get much better than this!!

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