Our first tracker job was for Y2K here in central Va. --a lot of red clay soils, especially down 3'+. The client had been in the 8' Satellite dish business. He suggested using his backhoe to dig a ' chicken foot' foundation--3 horizontal footings, as deep and as long as you want. This leaves a central space ,where the footings merge, for the 8-10 " , schedule 40 or 80 pipe. We typically make the feet 4' -5'deep--especially at the bottom of the pole-- and 6' long and 12 " wide, with plenty of rebar circling the pipe and extending into the feet, at 1' increments of depth. Rebar is cheap so use plenty of it, and use a 3-4000 psi concrete , as dry as possible. The windiest location has probably taken 70-100 mph gusts--enough to take the roof off the nearby farm building, and necesitate the elevation actuator to need upgrading-- but the foundation is unmoved.
One little trick is to get your own 6" box beam --less expensive than shipped from Wattsun-- and make it a little longer than typical in order to allow a 2" space between modules to relieve the air pressure. We also like to have the manual control so the array can be set flat, although that was not activated by the owner during the last several wind events. Hence the need to upgrade the elevation actuator--------- Never had it engineered tho, so use your own judgement. Ken CommonWealth Solar Ashland , Va ----- Original Message ----- From: Solarguy To: 'RE-wrenches' Sent: Saturday, October 27, 2012 10:19 AM Subject: Re: [RE-wrenches] Wattsun Tracker Foundations We've installed a number of AZ225s and big Zomeworks trackers to date. There are a number of companies that do foundation pier drilling but only a handful that have the capacity for a 36" pier. Even fewer will drill thru rock if it's down there. Water must be pumped out when it starts to collect and dealing with that pita is something to take up in advance with the cement contractor. Jim Duncan North Texas Renewable Energy Inc www.ntrei.com NABCEP PV 031310-57 TECL-27398 [email protected] 817.917.0527 From: [email protected] [mailto:[email protected]] On Behalf Of Ryan Harkins Sent: Friday, October 26, 2012 2:36 PM To: RE-wrenches Subject: [RE-wrenches] Wattsun Tracker Foundations Hey Wrenches, I planning some AZ-225 tracker installs, and I would like to avoid full excavation for slab/pier type and opt for the drilled pier option. The pier is supposed to be 30-36" diameter and 9.5' deep. This would require a terex reedrill or similar rig. If you know of a firm with that equipment in Wisconsin please contact me off list. Also, one site has a high water table, so any tips on pouring in that environment would be welcomed. Thanks Ryan Harkins NABCEP Certified Solar PV Installer / Project Manager ------------------------------------------------------------------------------ _______________________________________________ List sponsored by Home Power magazine List Address: [email protected] Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
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