What a pleasant day for once!

Temps in the high eighties, mild breeze, and sun! Sun (apparently) all day! I can barely remember such a phenomenon.

Got a late start outside because I wanted to roast one of those frozen lumps of pork I have in Ian’s fridge before it got hot. Went over to Landlady’s to tend the chicks and see how S is coming along – I’ll be going back there presently and I’ll bring back a picture of her new layout, which is shaping up to be very professional-looking compared to…well…

Anyway. I had some hauling of things around to do, then home to take advantage of the sun and get the laundry caught up…

Then some lunch and an old-man nap while I pondered how to build this rack.

The actual construction is nothing. It’s a few poles on a few piers. Big deal. But do I need four supports or six? What’s the overall size? How do I get the right panel angle? How do I make sure the piers are in the right places? How do I get a level emplacement on a slope? Or aim the whole thing in the right damned direction? I don’t even remember the declination for this area.

It’s when I get intimidated by all the things I don’t know that I can go into a pretty-much-permanent state of procrastination. Good news is that I can’t afford to put this off, and an imperfect installation is better than none. So let’s pick the very first thing: The location of a single corner. Dig that hole.

From there I found a straight 2X6 and my compass. Looked up the declination on-line, turned out I already had it dialed into the compass. Set the compass cross-ways on the board and move the board until it’s true east/west. That’s my baseline.

It’s just poles on piers, it’s not the Parthenon. When I built the cabin I didn’t think about declination at all, just oriented magnetic north/south, so my panels have always been several degrees off true south. Matters, but not very much: As long as you’ve got enough sun and enough panels, Solar is very forgiving that way. Level doesn’t really matter at all; I’m only worried about getting it level so it won’t look funny.

I’m also interested to know at what point the evening shadow from my little mouseproof shed hits my chosen location. I’m as far from it as I can get without doing something completely different. If it doesn’t beat the shadow of the ridge by much, I won’t worry about it.

Anyway, once I get it all figured out it’ll go fast. Poles on piers. But it’s times like this I wish I’d picked a father who actually enjoyed his career in the building trades.

About Joel

You shouldn't ask these questions of a paranoid recluse, you know.
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6 Responses to What a pleasant day for once!

  1. Ben says:

    You are definitely on the right track. Every project is just a series of little tasks. Attack them one at a time, repeat!

  2. Chuck says:

    Is there any advantage in – perhaps, best expressed as “is it worth the effort” – designing the panel mount system as adjustable to accommodate the different solstice sun angles ?

  3. coloradohermit says:

    Our panels were installed with a tiltable rack. It wouldn’t be particularly cheap if Joel had to buy/cut/weld the necessary iron parts. I think that since Joel isn’t an energy hog(no refrig/freezer or washer/dryer etc), mounting the panels without tilt capacity shouldn’t cost him much in input loss.

  4. Joel says:

    Chuck, ten years ago adjustable racks made more financial sense than they do now. When people were paying $8 per watt for solar panels, panel arrays tended to be small and needed all the help they could get. There are racks that are not only tiltable for the season, but that also track the sun morning to evening.

    Adjustable racks have the disadvantages of being expensive (tracking racks are *very* expensive, plus they don’t work well) a pain in the ass to adjust because solar panels are not light, and most don’t stand up to wind well. I don’t know anyone with a tilting rack that actually tilted their rack after the first year.

    Solid racks are sturdier and less expensive, and with solar panels wholesaling at 80 cents/watt it makes more sense to just throw more panels at whatever problem you’re having.

  5. Chuck says:

    I suspected as much, since adjustable racks seem to not be discussed much anywhere. So, what’s the optimum fixed adjustment? A rack can be angled halfway between solstices, which is either the best or the worst of both extremes, or since winter days are shorter, biased toward the winter solstice and sacrifice some efficiency at the summer solstice, compensated for by longer summer days. I’m guessing the latter. Is there some formula one can use to find the optimum angle, or is it trial and error?

  6. Joel says:

    No, there’s quite a science to it. And it’s all explained here.

    😀 I don’t say this often, but buy my book! 😀

    But to give you the short answer: For year-round efficiency most people set the angle at their location’s latitude. So if you’re in Phoenix, the average angle would be 33o. Winter you add 15o from that, summer you add 15o. In my case I plan to end up with just what you said; I’m starting with my location’s latitude and then tilting a little more toward winter. Summer pretty much takes care of itself. We’ve usually got lots of sun in summer.

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