Hi Adam, Might you be able to bring in a contractor that has the ability to drill out, or pre-punch holes? We use the Sunmodo Sunturf ground mount racking. A 3" hole has been working well in rock for those ground screws. On the large scale community solar farms around here, they pre-punch all the holes. For doing residential scale systems, I got my hands on a 3" rock bit, and then had a 5' steel rod fabricated that the bit could screw into, and then had an adapter for an auger attachment on the other end. This was a bit slow in solid rock but worked well until we used it continuously for a few hours and it heated up to the point of melting the bit and threads. But I am pretty sure that there are other rock drilling setups out there that would work better for a larger scale.
Cheers, Dave On Wed, Aug 19, 2026 at 5:32 PM AE Solar <[email protected]> wrote: > Wrenches, > We have a 400 kW ground mount on an east/west slope with shale bedrock at > about 4'. A driven pile system won't work, so we are looking at ground > screws with TerraSmart, but it's a significant price increase. Seems like > the combo of slope (it's upward of 25% and a lot of racking solutions don't > support that) and system size (quite a few racking options aren't available > until you start getting into the .5MW or 1MW range). I don't know if this > is the right place to ask for suggestions, but seemed like a good start! > Thanks for any thoughts > Adam > > Adam Katzman (he/him) > Autonomous Energies | Owner/Operator > www.AutonomousEnergies.com <http://www.autonomousenergies.com> > (518) 567-1468 > > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/[email protected]/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org >
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