When I checked my brick bases yesterday morning, they were had indeed set firm and were still horizontal and vertical in the correct places. This was pleasing, if not very surprising. At this stage, I was able to make the final measurement of how steep the bank is, or more precisely, the slope between the two bases. Getting a panel set up at the desired angle to the sun isn't straightforward when you're standing it on such an irregular surface. However, having given it much thought, I had a plan, and measuring the slope was the first step.
As previously mentioned, the compass proved less useful than anticipated (and wasn't needed for this stage of the job, in any case), and it turns out that a paperclip makes a poor plumb bob, but the spirit level and protractor, held against a floorboard resting across the brick bases, were quite effective. Once I'd measured the angle of the bank, and I knew (from calculations) the desired angle towards the sky, I could prop up the solar panel box indoors at the right attitude.
It's not the most stable of arrangements, perhaps, but it did the job. With this in position, I took the spirit level and drew horizontal lines around all the legs. This part was more difficult than I expected, but I ended up with this:
Do you see where I'm going with this yet? If I cut the legs to horizontal, and have brick bases that are also horizontal, the two should fit together to give me the right angle of the panel. Added to this, I need a
vertical hole in each leg for the peg. That is, it will be vertical when it's all in position, but at time of drilling, it has to be perpendicular to the cut surface of the leg. These holes also need to be exactly the right distance apart, so I measured the pegs again, for the umpteenth time. I used a gimlet to make pilot holes as it's much easier with a hand tool to give it half a turn or two then check again with a set square to make sure it's still going in the right direction.
Having drilled the holes, I couldn't resist taking the box up to the bank to see whether it fitted. Halfway up the steps I thought,
I'm not going to want to do this again. Luckily, it fitted!
Not only did it fit perfectly, but it stood up on its own, too. That was better than I expected but I thought I'd better stick to the plan and add the back legs. After all, it will be carrying a lot more weight when it's finished. Having got the box in position, the next step was to find the positions for the back legs, which I did with a plumb line made by tying a brass nut to a piece of string and hanging it under the legs. I then mortared bricks and pegs into position, again aiming for horizontal bricks and vertical pegs, though it was slightly less critical this time.
Once the mortar had set (I left it over night, with the panel propped up for extra support, though it didn't really need it), it was time to fill in the gaps. There were some bits of wood up there that I'd taken up some time ago when first thinking about how to support solar panels. I think they were from the leylandii hedge. In any case, they looked quite suitable for making back legs from. I measured these against the gaps between panel feet and brick bases, cut them to length, drilled holes, somehow eased them into the gap, and finally added brackets to connect them up at the top.
After that, I applied copious quantities of creosote then brought the glass cover out to go on top, which I finished just as the first few drops of rain fell. Now I can turn my attention to the second panel.