Solar posts

With the roofing membranes and flashing installed, we were finally able to get to the first component of our solar PV array: The solar posts.

PV modules are installed in rows, and mounted on rails, which are in turn attached to the solar posts. A shorter solar post is used along the south side of the row and a longer post on the north side, to give the module a tilt towards the sun.

The solar post assembly consisted of four components:

  1. A base
  2. The post
  3. A curb
  4. Sealant

The base was seated in a layer of sealant and anchored into the solar blocking, which we had previously installed. The post was subsequently screwed tight into the base. The curb was also seated in a layer of sealant over the base and post, and then filled with a sealant composite. This way the roof penetration for the base anchor should be completely waterproof.

I had taken scrupulous measurements for the location of the solar blocking, which was concealed since the installation of the roofing membranes. The big question was, would we be able to accurately trace the location of the blocking with the measurements?

It turned out that we did not need the measurements at all. The morning dew pattern that collected on the roof showed us exactly where the solar blocking was, due to the thermal difference between the lumber used in the blocking and the roof insulation on either side. If you look carefully at the time lapse, you may be able to spot that pattern.

Sometimes a little luck goes a long way.

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About Marcus de la fleur

Marcus is a Registered Landscape Architect with a horticultural degree from the School of Horticulture at the Royal Botanic Gardens, Kew, and a Masters in Landscape Architecture from the University of Sheffield, UK. He developed a landscape based sustainable pilot project at 168 Elm Ave. in 2002, and has expanded his skill set to building science. Starting in 2009, Marcus applied the newly acquired expertise to the deep energy retrofit of his 100+ year old home in Chicago.

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