Solar adventure 2

Bernie strongly recommended we buy a “regulator” to go with our new batteries. Apparently, it’s really not good to overcharge AGM batteries (which ours now are) – it can seriously damage them – and a regulator is an electrical gadget that stops that happening. So off we go to Google and our old solar system quotes to work out which one to buy.  We decided on a Plasmatronics PL40, which we bought online for $399 including postage.

How not to connect a regulator

Felice had to go away for a few days, which left me some peace and quiet (!) to do the connecting up. So I claim full responsibility for Embarrassing Mistake Number 3: in the absence of any understanding at all of how the house was wired, I mixed up the solar panels cables with one set of house lights cables. I did test which was which, but didn’t understand that our house lights can turn on even when they aren’t connected to the battery, as long as there’s sun on the panels. So when I connected up the solar panels to the battery, and disconnected the house lights, then tried turning on the lights, lo and behold, they turned on! So I assumed the cable I’d just connected to the batteries was the house lights. And the other one was the panels. Wrong.

Regulator and batteries

I took this proud photo of the batteries hooked up incorrectly to the regulator (on the wall), blissfully unaware that the batteries were being damagingly overcharged.

The result was that the way I connected the batteries and the solar panels to the regulator made everything function as if the regulator wasn’t there. So for 4 days, our nice new batteries were being overcharged, one day even up to 16V, which usually leads to a moment of silence at the other end of any conversation with solar system installers. Oh well.

16V didn’t seem right, so I called Plasmatronics, who were very gentle and informative, after the moment of silence. They recommended I check my wiring, and so I did – each of the many 12V wires that thread through our house now has a little label saying where it goes and where it’s from. It’s like living in a P-touch labeler advertisement.

And after much standing on stools to see where wires went, it became obvious what I’d done, so I connected the real solar panel cables to the solar panels connectors.   Our batteries breathed a sigh of relief.

The mystery of the load cables

But I still had to connect the correct “load” wires (the ones to all the 12V lights in the house) to the load connector of the regulator.  It turned out that only some of the house’s load wires went directly to the battery (easy to hook up) but others went to a little box on the wall of the upstairs living room.  It looked so clean and white and smooth on the outside, but …well… this is a picture of the inside:

White box wiring

The entrails of the white box. The cables to the left lead to a smaller tangle of meters and switches on the inside door.

Having at my disposal a mostly-forgotten mix of high school physics and one term of first-year circuit analysis in 1992, I spent a lo-o-o-ng time figuring this one out.  I even had to start by googling whether black or red cable meant negative (or positive), such was the extent of my ignorance.  (It turns out that black=negative, red=positive).  And there wasn’t much time before Felice’s parents were due to arrive for their first Christmas here (oh the tension! would we make it?).  Felice patiently put up with my little diagrams and scribblings out, and nicely made me cups of tea as I muttered over the electricians’ tape.  The question was, which were the wires that lead to the 12V house lights?

All the wires exiting the box disappeared quickly into the wall behind, so it wasn’t just a simple matter of tracing the cables.  But finally, after a bit of trial and error, it became apparent that the house light wires exited the bottom right hole of the box, along with a couple of other wires.  All we needed to do was to disconnect the house light wires from the box, and extend the cables enough to connect them to the regulator and batteries 5m away downstairs.

Extending the cables

Having never connected any electrical cables before, and not having any fancy schmancy crimp connector things, I resorted to copying what the previous owners had done to extend their wires:  strip the ends of both wires to be connected and tape them together with electrician’s tape.  Looks a bit messy, but it seems to work.

Cable extensions and box

Cable extensions and box. The white tape on the cables at the bottom are where the extra cable lengths are attached.

Luckily we happened to have a single roll of (white) tape in the garage, and a few scraps of electrical cable as well, obviously left over from when the previous owners put the lights in.  If we didn’t, one of us would have had to make the long traipse into town, a fate even worse than having no electricity while the in-laws visited.  Bless our lovely bottomless garage!

To make things as neat as we could (which as you can see, isn’t actually that neat!) we drilled a hole in the wall and pushed the extended cables through, and threaded them down through the outside covered deck to the batteries and regulator below.

The end…

So, just in time for Felice’s family to arrive, we attached the final load wires to the regulator/batteries and patted ourselves on the back.  I’m pretty sure I’ve made some embarrassing mistakes that I don’t know about yet (any sparkies please feel free to let me know).  But at the time of writing, nothing’s exploded yet, and we seem to have more power than we need.   Fingers crossed.

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