Electric Shock Therapy

You may remember back when I posted about our solar panels I said something along the lines of  “How hard can it be?”, well it turns out it's a little more complicated than I had first presumed. Because I had wired all eight panels in series it resulted in the voltage being pushed above the maximum voltage that the charge controller can handle. This means that the controller doesn't pass on all those lovely solar-generated electrons into our batteries which means that our batteries haven't been charging which is not ideal given we need the power in the batteries for propulsion, any power tools we use for the refit, and (more importantly) I can't listen to the radio.

Isolator switch mounted into ply (rear view).

Additionally, we have no way of isolating the panels which means I risk an electric shock any time I do maintenance work on the electronics, now and in the future. So far I haven't had a shock but it seems silly to tempt fate. Therefore it seemed prudent to re-wire the panels, and whilst doing so, add in some isolator switches. This should allow us to charge the batteries properly, and do maintenance work safely in the future.

Front view of switch.

Having purchased some isolator switches, crimp ring connectors, cable, and a crimping tool I set off for the boat. My first task was to make some wooden mounts for the switches to screw into. I used a ply off cut and cut it into 2 strips to fit to the underside of the panels, then, after marking up where the switches would be mounted, I drilled a hole using a spade bit and then used the jigsaw to cut out a a hole big enough to slot the switches into. Once that was completed it was just a simple task of bolting the switches to the ply, and mounting them under the solar panels.

Getting wired.

With the switches ready to go, I set about tackling the wiring. As the sun was sinking in the sky and we were shaded by trees I rather foolishly assumed it'd be ok to just go poking around with a screwdriver. I quickly realised my mistake when the current decided to pass through my arm, into the steel roof, and to earth via the hull which (being a boat) is sitting in more than a little water. Remember what I said about tempting fate? I think I just proved my point.

More wiring. Negative block on the right, awaiting the final connection.

I haven't had an electric shock before, and I don't intend to have another one. It's not exactly a pleasant experience, especially when you're on the roof of a boat with no one else around. Fortunately it was only a small shock and I survived to tell the tale. With my lesson learned I covered as many of the panels as I could and very cautiously, keeping myself out of direct contact with the boat, took apart the wiring. The ring connectors I had weren't large enough to fit over the poles on the isolator switches, so I chopped them in half to create some fork connectors (ish) that would allow me to connect the cables to the switch.

One switch, ready to go.

Reconfiguring the panels was pretty straightforward. I added a bolt to one of the pieces of ply to act as a negative block and countersunk it far enough into the wood so that you can't touch it accidentally and shock yourself. Each set of 4 panels is now wired in series, with the wires re-joining before they re-enter the boat so I only have to deal with two wires on the inside which makes life much s

impler.

Totally switched on.

All in all it was a pretty successful evening. Only one shock, and hopefully the changes I've made will mean there will be no more! Plus when the sun comes up tomorrow we should start to get some juice into the batteries so I can listen to the radio! Oh, and use power tools and actually move the boat.

New configuration of solar panels with isolator on each set of four.