wire size needed between battery and to scc

i ordered 10 ga wire. it is only going to run less than 6 ft into a waterproof box were scc and fuse are. going to put 6am inline fuse. not going to be an inverter. at present time only have one battery. 100ah agm. will be adding another within next 2 months. not going to ground.
also, have 2 100 watt renology solar panels. i have them on ground in brackets in a shady area, in middle of woods. is better to run in series or parallel to scc?
thank you in advance. hopefully this will be my last question. going to put everything together this week.

I suspect you will need to find a better location for your solar panels. To really get any production you need unimpeded sunlight to reach them between 10am and 4pm. Mounting them at an angle will increase production over being mounted flat.

Wire size for SCC to batteries of 10 ga. will allow up to 30amps. 30a X 12v =360w

honestly figuring same thing. may clear out more trees to get southern exposure.

Ten awg will work, but I use 4 awg wire between the charge controller and batteries. I also have about a 6-foot run. I like to minimize voltage drop as much as possible.

What kind of wire are you using? If it's aluminum or copper-clad aluminum (CCA) I'd definitely use bigger wire. Otherwise your charge controller could be sending 14.4v but the battery is receiving around14.2v, which is below the recommended charging voltage for a 12v AGM battery. I'm assuming you have a 12v system. Many would tell you to just use pure copper, but it's expensive stuff these days and many won't opt for that.

But if your charge controller allows customization, instead of changing the wire you could program it to send a little more voltage. You'd need to calculate the voltage drop for your system and increase the charge controller's voltage output enough to compensate for that.

Voltage Drop Calculator

10g is fine for 200w of panels. Series will work better for an mppt SCC.