Solar panels - a box

This has taken me longer than it might have done because I keep getting distracted by things like gardening and visiting relatives. Also, I had a nagging feeling that my design, such as it is, probably isn't very good. A friend recommended someone who could make a nice aluminium case, If you want to spend a bit of money. Well, yes, I'm sure an aluminium case would be good, but I don't want to spend money. Maybe I could treat mine as temporary, and upgrade sometime when we do have money to spend. At that point I started feeling better; it doesn't matter if my design's not very good, it doesn't have to be the last word on the subject.

Here we go, then. Not wanting to spend money on materials if I can help it, my box is made principally from old floorboards. I used lengths of 2x2 for the corners - I can't remember what we bought that for, but we evidently didn't use it. I kept the old radiator brackets when we took the radiators off the wall, so I can re-use those, too. Here's the frame, with brackets in place:

Framework of case for the first solar panel

The gap in one side is not for want of a long enough floorboard, it is part of the design. If water gets into the panel we'll get condensation all over the glass, which won't help efficiency, so I'd like to be able to let water vapour out, hence the vent. I don't want it open all the time, because air flow across the radiator isn't good for efficiency either, so I'll fit a sliding piece over the gap. That means ventilation will have to be manual, but it's better than permanently open.

At this point I would very much like to have put the radiator and glass in place to make sure they fitted. However, both these items were in service as a very basic solar panel which I didn't want to take apart. To move the radiator, particularly, would involve draining the system. Both items are heavy and unwieldy, and at that time, an awkward flight of steps away from the frame.

Ho hum, I'd just have to trust my measurements. This was unfortunate, as it was very difficult to measure things up there on the steep, slippery bank, especially the back of a radiator that was lying on the ground under a sheet of glass.

The next step was to insulate. I taped sheets of radiator backing between the brackets. This is the stuff that you can put behind radiators to reduce the heat lost to the wall, so ideal for this purpose. My friend Ellie gave me one sheet and the other I acquired from goodness knows where. I then turned the box over and added a layer of sheep's wool insulation, left over from insulating under the floors.

I retrieved a sheet of plywood that used to be the back of a fitted wardrobe. It was damp from standing against the workshop wall, so I left it in the sun to dry out for a bit. Once it was dry I cut it to size - most pleasingly, it was just long enough for the box. That's funny, I thought that last time I measured it, it was just too short. Well, it was hard to get at in amongst all the clutter in the workshop - I must have made a mistake. Here's the underside of box, with plywood in place:

Box from beneath

Before dinner yesterday, I applied creosote to protect the woodwork, particularly the legs. I put a coat over the plywood as well, even though it's been varnished before so it wasn't absorbed in most places. I'm sure it'll dry out eventually.

By this morning, there was really nothing left to do before assembling the pieces, which had to be done on the bank because the assembled panel would be too heavy to move. I woke up early, which was nice as I could make a start before the sun got high. I had to drain the system first, which is a pain because it needs the valve to be open but the pump off, which means disconnecting the wires to the pump. I remembered this detail just as I was applying flux to a solder joint, but I'm getting ahead of myself. Here's the insulated box in the early morning sunlight, with the glass ready to be fitted.

Hmm, that doesn't look quite right...

Pebble confirmed the matter: The glass doesn't fit. Oh, &*%#!

I went indoors and had breakfast. And tea. Tea makes things better. I realised that it doesn't actually matter very much if the glass sticks out a bit. I cut a couple of notches in the frame to accommodate the window frame, and left it at that. I'm sure I can stuff something into the small gap between the wood and the glass, so I don't have excessive ventilation.

Next, I checked that the radiator fitted onto the brackets. At first I thought they didn't line up, but it was just the angle of the bank, and my anxiety primed by the window measurement error. The radiator does fit, but getting it into position was one hell of a job. It's big and heavy. The bank is steep and slippery. It's not possible to see either of the two parts I'm trying to fit together at the time I'm manoeuvring them. This would have been easier with two people, but Ian was out driving a bus, and I wanted to get the job done so I could catch some of the sun's rays today.

Once I'd managed to get the radiator onto its brackets, and determined that it does fit quite nicely, actually, I marked positions of holes for the pipes. Radiator was removed and holes were drilled, then the box needed moving into position. This wasn't too difficult without the weight of the radiator, but I did need to fetch some bricks to go under one of the legs.

Before putting the radiator back in the box, I stuffed bits of wool into each end of the tubes on the back. This way, the fins will provide additional insulation instead of conducting heat away from the radiator, as they were designed to. I then fitted the radiator onto its brackets (which was a lot easier second time around), threaded the pipes through the holes I'd drilled and screwed up the fittings (thanks for the foresight to use compression fittings there, Dad), and reconnected my temporary plumbing. After mopping off and leaving it to dry a little (radiator not entirely empty) I put the glass back on.

While I had the system drained, there was one more job to do. At the end of the plumbing job, I was left with one tiny leak. It really was tiny and we were OK living with it for a while, but it should be fixed. I thought I'd have to take it apart and start from scratch, which proved almost impossible, but on the advice of blokes in the pub I learnt that it's possible to redo solder joints without taking them apart, so that's what I tried today. I'm not 100% sure, but I think I've fixed it. If it is still dripping, it's doing so far more slowly than it was before.

Plumbing concluded, I refilled the system. My temporary connections out on the bank are rather more leaky than they were before I took them apart and put them back together again. I can cope with a few drips, but I'll have to do those properly before too long. Nonetheless, I once again have a working solar panel, hopefully considerably more effective than it was before. Here it is, the nearly-finished solar panel:

Solar panel, functional again after only 8 hours disconnected, and, as far as we can tell from the temperature of the pipes, as much more effective as hoped.

I say nearly finished because there are a few bits and pieces still to do. It could do with a bit more creosote on the woodwork that's immediately under the glass and I haven't finished the sliding cover yet. It's also not in its final position, because positioning is a job in itself. Not the next job, though. The next job is the fun bit: The automatic pump controller.