Quick question, what is the best type of wire to use to connect panels to the charge controller?
Solid wire or multi-strand?
Multi-strand. However, I must caution you that the answers to these questions are not a simple as you may think. If you just want to hook up a few panels to charge a battery as mentioned in your previous posts then we can help, but it you want to take it further then you should consult an electrician.
The insulation on any common wire that you purchase will deteriorate in the sunlight so it should be run in a conduit from the panels to the controller. You can purchase wire that can be exposed to the sunlight, but that is much more expensive. An example of that would be the MC connector cables that come attached to the PV panels.
Once you have decided on the guage (size) wire that you will be using (more on this below) then you will have to consult the NEC code manual to see how many wires you can put in a conduit. Once you know how many wires you have, then you can determine what size conduit you will need.
Also is there any effect if there is a long run of wire between the panel and controller
Yes. There will be a voltage drop on the conductor. ie the wire. The larger (and more expensive) the wire, the smaller the voltage drop. Again the NEC code tables will give you ampacity for the wires so you can calculate the voltage drop that you can live with as well as the ampacity that you must have.
Ampacity refers the amount of current that the wire can safely carry. Once you know how much current your panels will be generating then you match that with the correct wire size.
As an interesting aside, I find it best to wire panels for the highest possible voltage thus giving the lowest possible current since your power losses are due to current flow. Also, a lower current means you can get by with smaller, and cheaper, wire.
If the distance between the controller and panels is quite long, then you may want to consider putting a combiner box near the panels and then use just two large wires to carry the aggregate current from the combiner box to the controller.
The combiner box would have the individual fuses or breakers for each PV, as you need those to protect both the panels and the controller or whatever equipment you have them attached to.
If you are just doing some tinkering then we can help you, but if you want to do more then you need to seek help from a professional. Give us the details on everything that you have, including specs on the panels and controller, and we can probably figure out wire and conduit sizes for you, but I repeat, if you want more then seek professional help or do a lot more reading.
John
