Help for newbe?

I don't know what the exact watt-hrs will be as that is hard to predict.  If I lose power in the summer, I just need to run some lights and misc small items.  If winter, perhaps some more.  It also depends how long power is out and time of day.  When I use the inverter in the RV with existing batteries, I can get 4 or more hrs of running TV, lights, water pump and even the heater blower thru the night.  Something similar for the home would be fine.  I have a generator and can use that to charge the batteries if/when needed.  I lost power for 7 days last winter and really didn't like filling the fuel every 2 hrs or so, especially during the night and at $4 a gallon.  Not to mention that when I finally got to shut the gen off after running 7 days, it seized up, prob from being overworked.

The inverter is a TRACE 2000w, I'm not sure what the batteries are, they are deep cycles I got at Sears.  I run them and inverter at 12v in the motorhome.  The motorhome is parked about 20' from the house, I am going to run conduit underground from house to RV.  If power is out in summer, we'll just live in RV till power comes back on and only run a small circulation water pump (28w) on our aquarium in the house.  So, not much load with that and a few lights.

I have a south facing roof and should get sun from approx 10:30 am to 3mp or later.  I'm having 3 trees cut down in the spring and that should give them more exposure in the AM.

Greg at altE has helped with planning and I've got 4 Evergreen 205w panels coming, a 80W MTTP controller, and varius other things to get me started.  In the future I'll be adding 2 more 205w panels and at that time a separate battery bank and invertor for the home.

Thanks,Bob

I would tell you to forget about the RV.
Are you planning to turn your existing on grid home to off grid? If so, I say more power to you!. I think its a great idea. Its not going to be easy and its not going to be cheap. Look at your light bill. The national average for grid electricity is about $0.12 per kWh or kilowatthour so if your electric bill is $60.00 a month then your using about 500 kWh's per month or 16.6 kWh's per 24 hours. That 800 watt PV array you want might offset about 3.2 kWh's of that 16.6 it all depends on a lot factors. Namely, the number of hours of equivalent full rated charge you can expect from a PV module. Go here http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/ and enter; Average, Annual, Flat Plate Tilted South at Latitude then find your place on the map. If where you are shows a number 4 then that 800 watt PV array you want, might make 3.2 kWh's.
If you are converting your on grid home to off grid, the smart money is on reducing your dependence on electricity first. To give you an idea, I've lived of grid for about 30 years now. Only within the past 15 have I had the luxury of PV. We use about 72 kWh's per month which if I had to pay $0.12 for it would be about 8 dollars and some change. But I do have an LP bill that averages out to about $25 a month. There is four of us in the household. Sometimes five.

Is it your plan to turn your existing on grid home to off grid? Are you willing to give up air conditioning and outdoor lights that burn all night long? How will you refrigerate and pump water? These are all concerns when making a move to off grid living. Just how much electricity can you live without? Think about it. Oh! Get yourself a subscription to home power magazine. Learn about electricity in particular Ohm's Law and the National Electrical Code. Most importantly, scower the web looking for the best prices. Just when you think you have found a good price, lok again.

Not to add carbon emitting greenhouse gas producing gas onto the fire, but I have to agree with Mr. Ken on this one. He may have come across as cross (not to me mind you) but his words ring true.
Having an idea of what you want to power during a power out, and for how long is important. Not essential but important. I did it the other way and its working out just fine. However, i do not intend on releying on it for power outages. Mine is just experimentation, learning, and lots of fun (if not slightly dangerous!).
For you, it sounds like powering the beer fridge and the TV (the essentials)is key. Having an idea of the above will really help. First and foremost for me would be those batteries. Auto batteries (yes, even the deep cycle marine ones) are designed for cold cranking amps, with a dept of discharge in the neighborhood of 3-5%. Solar batteries are the ones that will work better. They are designed to be discharged to, say, 60 or as low as 50%. So when Ken says you may end up smoking them, he's probably right. Car Barteries will still work, but you may want to really oversize things on the batt side.
Either way, like ken said, good luck! -m

Oh! I think I get it now. The mention of an "off grid system" threw me. So, the immediate plan is; the 800 watt PV array will be on the roof of the garage. The 200 amp hour? batteries will be on-board the RV with the 2000 watt inverter and during times of black out, a "drop cord?" will supply 120 vac power to a load in the home from the 2000 watt inverter on board the RV and you want to know where the best place for the charge controller and combiner box would be. 
Then eventually you will add more batteries (to the RV?) and more PV modules to the array on the garage.

(A battery monitor such as the Bogart 2020 is still a good idea to give you an interface with the system.)
Personally, I don't like the idea of having all those cords going to and from the RV and house. Its do-able but what you describe is really mis-matched taboot. Movable and non movable power sources and loads, inside and outside, 200 amp hour battery, 2000 watt inverter, 800 watt PV array, anyway.
If I had to do this, there was no other choice, I would set the combiner box and charge controller and monitor on the outside garage wall as near the to PV array as possible making sure its all Nema 4X and I would use GFP. I'd hard wire in conduit under ground from there to a box above ground near the RV, close to where the batteries are inside, and put a recessed male plug on both the RV and the box, both with in use covers and all of ample amperage ratings. I would make a cord with females on both ends to fit. This is because the batteries are "on" all the time and the PV array should be considered as "on" all the time. I would also want to be able to lock in and lock out everything so curious fingers can't find their way to live terminals. Essentially the same power transfer set up with the vac power minus the controller and all of course.  Whats going to happen with the PV power when the RV is logging milage? What would an electrical inspector have to say about it all? I guess there is no place to mount the PV array on the roof of the RV? Whats going to happen if the vdc cord is not removed and the RV drives off?