Originally Posted by senormechanico
MC4 is a standard connector for solar panels
Ten gauge wire is also standard.
The 140 watt panels
I bought from DM Solar
came with 12g wire leads that ended in MC4 connectors. It isn't easy to find prefabbed cables
with anything other than 12g MC4 connectors. If you have MC4 connectors already on the panels, you can buy a long length of cable with connectors on either end then cut it in the middle. The cut ends will fit in the charge controller connections.
Additionally I recall
that my inexpensive charge controller would only take 12g wire at the terminal connections.
MC4 connectors are designed for your stated purpose. You can easily find a company that will make up custom cables
for you, but if your panels don't have the connectors already you will have to buy a tool to attach them yourself. The connectors are really tough, but I suppose it is possible for them to fail so you should have a backup plan to repair them.
It might be easier just to get heat shrink crimp sleeves that will accept both 10g and 12g wire which are ubiquitous and easy to apply, and cut them when you need to stow the panels, which won't be often.
There are charts
available to determine how much voltage drop you will suffer based on the two way length of the run and wire diameter. 12g worked fine for me.