Small, starter PV setup

[jackluminous]

This is a continuation from  my first post in the Newbies section. The basics of this my first PV system are there.

Some answers and tips from my PV supplier:

1. I need a 20amp fuse, not a 30amp fuse, between the PV setup and the charge controller. With just the one panel I would only need a 5amp fuse. Since I eventually want 4 of the 54-watt panels in an array, connected in parallel for 208 watts, a 20amp fuse makes sense. This fuse should be in a liquid-tight 6"x6"x4" box as close to the panel as possible. I'm using an automotive-type "maxi fuse" that comes with 5" lengths of #6 wire out either end; I'll have to connect this to the #10 wires to the panel and charge controller using big blue wire nuts.
   
2. I need the same fuse setup between the charge controller and the battery, only it will be secured on the control board inside the cottage (so no liquid-tight stuff needed). The fuse should be as close to the charge controller as possible.
   
3. For some reason I had it in my head that putting a fuse block inside the battery box is a bad idea. It's not. The 110amp fuse block for the inverter is going inside the battery box.
   
4. It will work to use a temporary connection for the battery charger, with automotive clamps. Just buy a set of heavy-duty jumper cables (#4 or larger) and cut the clips off one end.
   
   

Still gotta figure out whether and how to ground this.

[valterra]

Don't make the mistake of fusing for what your system WILL be.  Fuses should be as small as possible.

Fusees should be small enough to insure that they WILL burn out easily if something isn't right.

Besides, replacing 5 or 10 amp fuses for 20 or 30 amp ones at a later date is as easy as changing a light bulb.

[electronbaby]

Im not sure where your located, but if your in the US, check out the NEC (National Electric Code) Article 690. It will point you in the right direction.

[jackluminous]

Good reminder, thanks! I knew that, really I did. :-)

The PV supplier suggested I didn't need a fuse at all on the line from the panel to the charge controller. The amount of electricity in the line would be really small with a single 54-watt panel. The PV guy said if I really wanted a fuse that 5 amps would be all I needed.

Only I'm not sure why it matters if the fuse is a 20-amp fuse, since it's actually protecting the 20-amp charge controller, right? Or is it protecting the solar panel also?