Building the shed
Your first quandry with any solar system is where the heck to put it.
You have to hang panels that are 3 feet by 5 feet in my case and weight 50 lbs each. You have to store batteries: 720 lbs of lead for me. And you need a safe dry spot for your charge controller, your inverter, your combiner boxes. And, if you’re like me, cheap, you have to do it on a limited budget.
What do you do? Here’s my solution:
Keeping it real
See, first I thought I’d build a 2 axis tracker and run the wiring to the house which would hold the batteries. When I realized that the house, budget wize, was years in the future: and when I got the panels and had a better idea as to size and weight … then I looked at the time I had to get the install moving … well … I realized I was in trouble.
Then, luckily, I saw a neat video where a “solar shed” floats down out of the sky, the panels unfold, the system is done. A light went on in my head, hey, I can build that.
Sure. Maybe it won’t float down from the sky, but … doable.
There were issues beyond the usual:
- One: my soil is very soft and in the spring, moist is an understatement.
- Two: at zone 5b, we get cold winters. As I would discover, cold batteries are weak batteries. How to keep the batteries warm?
- Three: if I couldn’t do two axis tracking, could I still adjust the
panels to allow for seasonal adjustment. This is said to gain 15% more power. And after 4 years in service, being able to change the axis of panels seems to gain more like 20% peak efficiency.
Some highly technical drawings later: a solution is realized.
Now it’s time to swing hammers.
For the base I went with 2x8s pressure treated hung on Simpson joist hangers. This makes for a water resistant strong base.
Some mistakes only appear in retrospect
I would now make a mistake. Didn’t seem like a mistake at the time. But it illustrates two things:
- One: you will make mistakes. I try to tell myself that “the perfect is the enemy of the good.”
- Two: modern building technology is moving quickly right now. See BuildingScience.com for better techniques.
My mistake was I insulated the underfloor with a layer of foil covered polystyrene insulation between the joists. I foamed the gaps. This creates a waterproof barrier. I then insulated the open underfloor with Roxul insulation between the joists. Finally, I covered the entire bottom of the base with chicken wire to avoid nesting critters. A great idea.
And, after four years, I can say the base is holding together well and no critters are nesting in the insulation. Though, the moles love the underside of the shed. I suspect it attracts earthworms.
However, the insulation creates a vapour barrier. Not a bad thing. As the elevated base lets air in to aid in keeping the Roxul dry.
But, what I now know, is the freeze/thaw cycle that we experience in my climate means that the frame is being subjected to wet/dry and freeze/thaw cycles. This will hurry the day the frame needs repair.
Not a big mistake … but one you can avoid. My frame is fine, but I now would recommend you put your insulation inside the building on top of the floor. This way the entire frame freezes and thaws as one unit. Not one part is warm and further down it freezes.
Now onto the build: Solar Shed: Part Two