PV buttress at Locust Hill
A general prefatory note is needed. It is important to know that the tall towers with their requisite large buttressed bases are not intrinsically necessary in most photovoltaic installations. Their use at Raven Rocks is a specific consequence of their location within a project that is deeply committed to the restoration and long-term protection of native forest. With tracking that uses state-of-the-art technology that can add 40% to a PV cell's production, we felt our demonstration should include it. At the same time we felt that we would not compromise another message that we feel is at least equal to the issue of energy supply and a benign source for that energy. That issue is, of course, the protection and enlargement of forersted areas. These, after all, are the lungs of this Earth. Seen in this light -- which is most certainly a factual light -- we have no sense whatsoever that we are undertaking an expense that is unwarranted. With the sun having reached a significant energy output at 15 degrees altitude, it is easy to see that without some significant elevation above the ground, trees of any significant height would have to be kept clear for hundreds of feet on all but the north sides. Moreover, as is true throughout the Locust Hill project, further significant amelioration of the cost is won with care about the engineering design, and with proper placement and curing of the concrete for these towers. They should have a remarkably long and hence a very economical life.
Following are photographs of the construction of our first (the western) of four towers. Again, because of the shading issues that tracking introduces, this particular tower, located downhill from the others, required a taller and hence a heftier base.
In most circumstances, neither the array elevations nor the extra construction of this west tower would be required. Recommended elevation on any particular site would vary according to such considerations as shading from any source, snowfall, pedestrian or other traffic under the array or aesthetics.
|1. South aerial view||2. Big and bigger tracker||3. PV with Pavel Stary of the Czech Republic||4. Steelbending|
Chris ties steel
||7. Don on wall||8. Don tying steel|
|9. Ringwall complete||10. Sandblasting||11. Applying Hey'di||12. Forming of buttress begins|
Warren at controls
Ted wheeeling up ramp
||16. Herb waiting|
Herb and John, dump and scrape
||18. Wheelbarrow action||19.Don on the vibrator||20. Evening work|
Working through the night
||22. Expert welds||23. Tower galvanized||
Welds, bolts grout
Tower from north
||27. Tada, a tower!|