[RE-wrenches] Off-grid ground mount: Can it be done cheaper

[William Miller]

Daryl:

Thanks for the photos and description of the mounts you are installing.  We 
have installed many of the DPW ground mount systems in similar 
configurations. 
http://millersolar.com/MillerSolar/Portfolio/ground-mount/engineered_ground_mount.jpg

We are realizing two things:

1. Concrete footings of any type are expensive.  The cost of excavation, 
forming and concrete really adds up.

2. For off-grid, when the module tilt angle increases to 45 degrees, the 
foundations need to be substantial.  During one install we had our heavy PV 
trailer blow over due to high winds.  We decided to have the foundations 
reviewed by an engineer and when we received the results, we had to go back 
and double our piers and strut.  We had bid the job so the updates came out 
of our 
pocket.  See: 
http://millersolar.com/MillerSolar/Portfolio/ground-mount/full_size_photos/engineered_ground_mount.JPG

We are now required by the AHJ to provide a wet stamp from a structural 
engineer for every PV structure over 6 feet in height.  This means every 
off-grid.  We know the engineers will require massive foundations which 
will cost a lot.  I am looking for a cheaper way to install these racks.  I 
have not found it yet.

Thanks for your input.

William Miller


At 04:37 AM 3/24/2012, you wrote:
>William,
>    I'm attaching a picture of a system we just completed in Eleuthera
>using DPW racks on concrete pilings. We tied the pilings and rebar
>reinforcement into the limestone bedrock with rebar down 16 inches and
>used 12 inch sono tubes as forms.
>    We do a lot of ground mounting since our summer work is mostly in New
>England and snow removal is always a factor. I have two pole mounted
>arrays at my home, but it is the most expensive option, and therefore
>do a lot of this type of ground mounting. We also have an economical
>"cribworks" type structure made from solid railroad ties and weighing
>in at about 2800 lbs each that we will sometimes offer to customers in
>off grid situations.
>
>Daryl