Saturday 12 September 2015

PV Base.

One of the guiding principles when I designed the house was that although it is on the side of a rocky outcrop and earth sheltered, and as such, the concrete of the earth retaining wings and facade would be easily visible until the concrete weathered, everything should be done to make the minimum impact on the landscape. This is totally contrary to local practice where it seems a certain kudos is attached to building on top of a hill and making the house as visible as possible!

When presented with the problem of where to sight the PV and solar water heater panels not only was the position to maximise solar power imperative but this needed to be balanced against the visual impact of 10 large solar panels and 3 solar water heating panels.

During the build a number of options options for the PV panels were considered including arranging them in clusters on the hillside open to the sun but hidden by the mature trees on site.

A factor that has to be fully considered on this particular site are the very strong winds that blow down the mountain at all times of the year.

Looking around at all the local solar farms it was apparent that the usual approach was to place the long side of the panels in the vertical plane. This concerned me given the power of the wind and was indeed borne out at one of the solar farms where panels were lost last winter.

Given the long low horizontal nature of the house design it seemed out of keeping to have a significant vertical structure on the roof. My thought was to place the PV panels with their long side horizontal so as to keep a low visual profile whilst allowing the wind to pass freely below and above them.

I proposed this to Euripidis, the engineer, who became increasingly enamoured with the idea. The plan was to spread the PV panels in banks of five at each end of the earth sheltered roof and to have the solar water heating panels, similarly with their long sides horizontal, located in the middle between them. All this would be possible within the roof span of the house. Unfortunately it emerged that the solar water heating panels that had been purchased could not be used in this way. It is possible to have panels this way but is to special order only as it entails shutting down the normal production line, re arranging the tools to make the panels required and then shutting down the line again to return to normal production. I could not justify the prohibitive cost of doing this so the solar water heater panels will have their long sides vertical.

However, since the house is only overlooked by the local birds of prey circling overhead, by moving the line of the PV installation some metres back from the front of the house the installation will not be visible from down the valley such is the steepness of the slope.

In order to anchor the panels sufficiently it was important to have a very solid concrete base the whole length of the installation.

This was duly marked up, a suitable trench in the earth sheltered roof dug, materials and equipment moved to the roof and the reinforced slab laid.

Marking up the PV panel base slab.

Soaking the dried out earth before digging out a deeper trench.

Moving the materials onto the roof.

The conrete mixer ready for its transportation onto the roof.

The move begins.

Sheer brute force and energy shift the mixer ever upwards.

All ready for casting the slab.

Reinforcing in place concrete laying progressing.