The new solar panels measure 40" by 66". We have 4 panels giving a total of 73 square feet of surface area. A 100 MPH wind exerts 25 pounds per square foot so a 100 MPH wind load would be 1,825 pounds of force. The wind at ground level is generally lower than at a moderate height so hopefully the panels will not see that much force but we still need good anchoring. The ground where the panels will be mounted is very rocky making digging very difficult. We have dug two rows of holes with 5 holes in one row and 6 in the other. This placement is due to limitations of digging in the rocky ground.
The ground slopes to the west with the west most hole about 30 inches below the level of the east most hole. So a frame mounted one foot above the ground at the east most hole would be 3 1/2 feet above the west most hole. The plan for mounting the frame was to run two parallel rails the length of the holes and then place triangular frames on these rails which will hold the panels at the desired angle. We may wish to break this up into two sets of parallel rails one lower than the other in order to keep the panels lower to the ground. Due the very rocky round it is not possible to dig deep holes. The intent is to drive some 1/2 rebar at an angle in the sides of the holes to help anchor concrete. One inch steel tubing will be set in the holes and anchored with concrete.
A diagram of the hole placement and depth may be found here.Images of the site and road to the site follow.