What Is A "Walking Pad"
and
Why Do I Need Them?
Our roof is not homogeneous. We are blessed with a small deck, a cluteratti of 21 PV solar panels and "zero to a few" feet of snow every winter.
The logic of walking pads works this way.
- In order to maximize your PV solar generation (= MicroFIT revenue$) you need to keep the solar panels clear of all impediments like leaves, pollen and snow / ice.
- To keep the panels clean, you need good safe access so your can sweep the snow away, or pollen as the season dictates..
How often? It varies with snow fall. Last winter (2014-2015) was 16 sweeping events. The prior winter it was swept 14 times. It is my experience that the sun will melt about 2 mm (1/8 inch) of snow fairly easily and quickly, but if you have more than that depth and you need to sweep, or you'll miss out on a days solar production. I don't sweep frosts, but will sweep pretty much any and all snow falls. [ I don't worry about clear ice, especially if it's thin. Does not seem to inhibit PV production. I daresay, its all about direct sunlight.]
- You can't walk on sedums, and certainly not repetitiously. This is a big concern for the living roof.
Even if there is a thick mantle of snow insulating the sedums.
Therefore, I have created a demon called a "walking panel' to provide me with a safe, sturdy place upon which I can walk, and sweep snow, while not damaging our precious sedums.
Therefore, I have created a demon called a "walking panel' to provide me with a safe, sturdy place upon which I can walk, and sweep snow, while not damaging our precious sedums.
A walking panel is basically a box 12" (0.3m) wide by 3-4 feet (0.8 - 1.2m) long, about 7" high (17.5cm) (edge railing height, by definition), with a durable top - concrete wall cladding in our case.
My initial thought was to make plywood boxes. But, at $70 per sheet for good, water protected Crezon wood, the cost would have been prohibitive. Especially as I have a building site next door with a small forest of scrap timber that is also PT (pressure treated) and where "the price was right". I also wanted a more durable topping surface than plywood would provide.
In the end, my walking pads were framed with (mostly) scrap PT wood, capped with crezon panels that were left over from another project (the "Shrubs In Tubs" blog entry) and topped with offcuts of the same concrete panels that were used for the rain shield for the house.
As the winter progressed I refined this pathway to its minimum, while still providing sufficient coverage for a clean sweep.
That drawing provided the locations for the walking pads.
My initial thought was to make plywood boxes. But, at $70 per sheet for good, water protected Crezon wood, the cost would have been prohibitive. Especially as I have a building site next door with a small forest of scrap timber that is also PT (pressure treated) and where "the price was right". I also wanted a more durable topping surface than plywood would provide.
In the end, my walking pads were framed with (mostly) scrap PT wood, capped with crezon panels that were left over from another project (the "Shrubs In Tubs" blog entry) and topped with offcuts of the same concrete panels that were used for the rain shield for the house.
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Last winter I kept track (poor pun) of where I walked every time I swept the solar panels. |
As the winter progressed I refined this pathway to its minimum, while still providing sufficient coverage for a clean sweep.
That drawing provided the locations for the walking pads.
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