Adding Solar to Bigfoot Roof

[ZachO]

Thanks.

Francois yours is definitely more secure since you don't have an air gap. I've got over 2" of space under my panels to catch air. But yeah, I'll probably add some eternabond or something for another layer of protection.

I've got the charge controller all hooked up. Just waiting till I don't need to mess with the panel wires at all (another entry hatch is on the way...) before I connect the panels to the controller.

I bought an inline fuse holder with a rubber cover, for a blade fuse. That's what my portable panel came with and the connection has been attached to my battery for 3 years on the trailer tongue and worked fine.

While I was at it, I replaced my main camper fuse. Now I'm curious, though. Why, in 1991, would they build a trailer with all blade fuses except one? The main camper fuse is a glass fuse. I got sick of tracking down a 30amp glass fuse while on the road, so I replaced it with a blade fuse. Is there any reason that's a bad idea?

The Renogy instructions say to always connect the charge controller to the battery before connecting the panels to the controller. Why? What happens if I need to disconnect the battery? Do I have to disconnect the panels first?

View of the cable routing.

[Jon Vermilye]

Originally Posted by ZachO

Thanks.

Francois yours is definitely more secure since you don't have an air gap. I've got over 2" of space under my panels to catch air. But yeah, I'll probably add some eternabond or something for another layer of protection.

I've got the charge controller all hooked up. Just waiting till I don't need to mess with the panel wires at all (another entry hatch is on the way...) before I connect the panels to the controller.

I bought an inline fuse holder with a rubber cover, for a blade fuse, that's what my portable panel came with and the connection has been attached to my battery for 3 years on the trailer tongue and worked fine.

While I was at it, I replaced my main camper fuse. Now I'm curious, though. Why, in 1991, would they build a trailer with all blade fuses except one? The main camper fuse is a glass fuse. I got sick of tracking down a 30amp glass fuse while on the road, so I replaced it with a blade fuse. Is there any reason that's a bad idea?

The Renogy instructions say to always connect the charge controller to the battery before connecting the panels to the controller. Why? What happens if I need to disconnect the battery? Do I have to disconnect the panels first?

View of the cable routing.

Attachment 130497

It depends on the controller. In some cases, connecting the solar panels without a battery will "let the blue smoke out". Others don's seem to care. Obviously, portable systems with the controller mounted on the panel will almost always have the panel connected without the battery, at least until you hook it up, but they are usually small systems.

I called Renogy about the situation when I replaced a failed controller on a 160 watt portable panel with one of their controllers, and the said it wouldn't be a problem.

It would probably be good practice to install a switch or switchable breaker between the panels & the controller in a permanent installation, or, if you rarely disconnect the battery, cover the panels or do the work at night.

[ZachO]

Originally Posted by Jon Vermilye

It depends on the controller. In some cases, connecting the solar panels without a battery will "let the blue smoke out".

I had to google that phrase. Learned something new

A switch between the panels and controller is probably a good idea. Probably doesn't matter whether + or -?

[Jon Vermilye]

Originally Posted by ZachO

I had to google that phrase. Learned something new

A switch between the panels and controller is probably a good idea. Probably doesn't matter whether + or -?

Nope.

[Alex Adams]

Originally Posted by ZachO

The Renogy instructions say to always connect the charge controller to the battery before connecting the panels to the controller. Why? What happens if I need to disconnect the battery? Do I have to disconnect the panels first?
Attachment 130497

If you disconnect the batteries before the panels, the charge controller can fry. It is not designed to have power input with no output which is what happens when the battery is disconnected. Disconnect the panels first. Some people use a cutoff switch mounted in an easy to reach location so they don't have to remove a fuse or disconnect wires.

[ZachO]

Great, thanks. Well, another quick project before these will be functional. An easy one, though.

[ZachO]

In anticipation of either someday adding more solar to the roof, or tying in a small portable panel, what can I do now to ensure less frustration when/if that happens? Aside from leaving some extra length in the wires from the panels to charge controller so I can more easily splice some connections, is there anything else I should do before everything is hooked up and wires are trimmed?

[Alex Adams]

If you are going to join the roof panels and/or the portable inside the trailer then I would run the wires to a terminal block and then connect that to the charge controller. That would give you the most flexibility as far as hooking up more panels. If you add another roof panel, you can run the wire to the terminal block or if you get a portable, you can put an outlet connected to the terminal block for the panel to plug into on the outside. Of course I am assuming you will use your panels in parallel.

[John in Santa Cruz]

vehicles always fuse the + side, since the - side is the chassis. a negative wire 'shorting' to the chassis will do nothing, no current as there's no potential. a positive wire shorting to the chassis will definitely let the 'magic smoke' escape...

[Franswa]

yeah Zacho, my panels are just a half inch off the roof....probably not best for ventilation/cooling....but where I live I should be so lucky to generate too much heat
my "redundancy" was/is a couple of wire "safety straps" hooked to the air covers.....yeah, that was all "temporary" when I first put them up there...and four years later it's still all the same....funny how that happens....


I used a 12 fuse holder on an 8 wire close to the battery....(shortened the 12 leads to almost nothing)...as mentioned before the short length makes it ok



a switch between the panels and the controller is easy to do and a good idea really...it sure makes it quick to check the performance (VOC=voltage open circuit)...also if you're ever doing some work on your electrical system you don't have to scratch your head and wonder if EVERYTHING is off


I did same as you and got rid of the barrel fuse....all blades now
there's no problem adding fuses if you get worried...as I was building mine I added a couple behind my wooden "dashboard" ....just in case (vibration or something coming loose)....nobody wants blue smoke

[ZachO]

Thanks.

I feel like this should be easier...but I guess I still know less than I think.

I want to wire this switch. I would have just spliced it into the + wire. But this diagram is throwing me off...This is for the solar panel cutoff.

[John in Santa Cruz]

Originally Posted by ZachO

Thanks.

I feel like this should be easier...but I guess I still know less than I think.

I want to wire this switch. I would have just spliced it into the + wire. But this diagram is throwing me off...This is for the solar panel cutoff.

Attachment 130541

Attachment 130542

the diagram is the way it is, as its for using the switch to control an accessory load like a light, and that accessory is usually wired to ground, and you switch the power (+) side.

just wire the switch in series with the + output of the solar panel, you're good.

[Franswa]

the load is the appliance/light/motor... whatever....
there's a pos. and neg. wire going to the "load"
you install the switch anywhere on the positive wire.

[Jon Vermilye]

The diagram just switches the position of the switch & load. Switches are in series with the load, so either position will work, as will placement in either the + or - leg.

[redbarron55]

If we were talking 120 AC wiring switching in the return lean is not allowed.
It is a good idea to follow the same convention in DC circuits as well.
Since now a days the negative is usually grounded (at least in the US) the switch should go in the positive lead.
If you placed a switch in the negative lead then the power supply is still hot and accidentally touching the wires or chassis could result in problems and loss of high pressure magic smoke from wires and parts.

[John in Santa Cruz]

otoh, on a lot of electronic circuits, the control signal causes the ground to be closed, via a bipolar transistor in an 'open collector' configuration.

so really, it all depends on the application.

[redbarron55]

Originally Posted by John in Santa Cruz

otoh, on a lot of electronic circuits, the control signal causes the ground to be closed, via a bipolar transistor in an 'open collector' configuration.

so really, it all depends on the application.

Within a circuit, but rarely as a standalone box.
In most cases the switch should not be installed in the return circuit.
In an AC circuit it is a violation of the NEC without a doubt.
Probably in a DC circuit as well

But, the NEC devotes an entire article (404) to switches. Article 100 provides six separate definitions for "switch," covering bypass isolation, general-use, general-use snap, isolating, motor-circuit, and transfer. Article 404 requirements apply to all switches, switching devices, and circuit breakers used as switches.

You wire a switch to make or break the supply conductor-also called the hot lead. The NEC specifically bars switching the grounded (neutral) conductor or the grounding conductor [404.2(] (Figure 404-2).

[WizWid]

Originally Posted by ZachO

Thanks.

I feel like this should be easier...but I guess I still know less than I think.

I want to wire this switch. I would have just spliced it into the + wire. But this diagram is throwing me off...This is for the solar panel cutoff.

Attachment 130541

Attachment 130542

That switch is on the positive lead.
What is the confusion?

Get 'er done.

[ZachO]

Thanks everyone.

The confusion is that the diagram shows a positive and negative attached to the switch, with the appliance spliced in to the negative wire.

For my solar wires I don't even understand how this would work. I don't get how a switch works with positive in one end of the switch and negative at the other.

But this is getting into the weeds...it's stuff I should learn but maybe not the best for this particular thread.

[gordon2]

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