Should I tin PV wire ends with solder?

bratan

I normally always tin exposed wire ends for small electronics project. Is it a good idea to do this to 10 AWG wire that's going into Charge Controller terminals (both cables from Solar panel and cable to battery)? This will prevent strands from splitting and should protect bare copper from corrosion...

solarix

Re: Should I tin PV wire ends with solder?

Unless you are actually going to solder them into the terminals (not recommended), no. You can use a wire device called a ferrule or wire sleeve to contain the strands. This is standard practice in the EU and on German made stuff like SMA inverters, you'll see this done. On US designed equipment, it is not commonly done and they intend you to just insert the stripped wire into the terminal and torque it down properly. The goal is to produce what is referred to as a "gas-tight" contact where the contacting surfaces are deformed during the tightening event to cause molecular contact that is not subject to oxidation.

BB.

Re: Should I tin PV wire ends with solder?

It also depends on the type of wire/cable you will be using.

House hold AC cable is either solid or a few, fairly thick, strands of wire. The connection points are designed for these type of cabling (make sure you come back a day or so later and re-torque all the screws).

And then there is very fine stranded cabling (welding cable, lamp cord, high-flex applications). In general, this type of cabling is not supported with standard screw type connections in typical UL/NRTL approved hardware. These wires can/tend to come loose and overheat over time.

Some folks will tin the end of these cables--But it is not a good idea. The solder has a higher resistance and lower melting point than copper--And high current (short circuit/lightning, etc.) can melt the copper and cause the cable to fall from the connector and start a fire.

Also with solder, it wicks up the wire a bit and "stops"--This creates a point of flexure which can cause the copper wire to work harden and fail if subjected to bending. Soldered wiring must be well supported and ensure that there is no flexing at the soldered joint.

As Solarx says--Crimping a ferrule onto the cable end is the "correct" way to make fine wire connections on US equipment--But this is not commonly done and may be difficult to find the parts/tools to do this. In older NEC (national electric codes--don't know about the present code), they did not allow these types of "specialized" fittings (only common tools allowed). That may be why it is still rare in the US.

-Bill

bratan

Re: Should I tin PV wire ends with solder?

Ferrule is great idea! I see if I can find it my local hardware store and some way to crimp it. Otherwise I'll just leave it bare.
BTW cable that I'm using is 10 AWG MC4 cable. It's has some indestructible coating that can be exposed to elements and is real pain in the butt to work with (very inflexible). My fingers still sore from stripping it..

vtmaps

Re: Should I tin PV wire ends with solder?

bratan wrote: »

Ferrule is great idea! I see if I can find it my local hardware store and some way to crimp it. Otherwise I'll just leave it bare.

You need a crimping tool designed to crimp the ferrule. Check out ferrulesdirect.com to browse through a large selection of ferrules and crimpers.

--vtMaps

inetdog

Re: Should I tin PV wire ends with solder?

bratan wrote: »

Ferrule is great idea! I see if I can find it my local hardware store and some way to crimp it. Otherwise I'll just leave it bare.
BTW cable that I'm using is 10 AWG MC4 cable. It's has some indestructible coating that can be exposed to elements and is real pain in the butt to work with (very inflexible). My fingers still sore from stripping it..

Most likely PV wire. Normally you would expect the wire type to be printed on the jacket at intervals, but for UL listed assemblies that may not be required. PV wire can most easily, IMO, be recognized by the extra thickness of the insulation relative to the wire size.

Mustang65

Re: Should I tin PV wire ends with solder?

Interestingly enough, HomePower magazine just had an article in the November 2014 issue.
Here is the link... worth the read!
Don
http://www.homepower.com/articles/solar-electricity/design-installation/inverter-battery-cables