Welcome to RVing, Ted!
Lots of good stuff out there, as I know you know. There's a good RV forum (owned by Good Sam or Camping World now) for reference, I used to use rv.net but now have switched portals to trailerlife.com, as it has ended up being the most reliable portal for me.
I'll try to include links but google may be faster for below:
After reading a bunch of the latest posts, trying to shotgun some responses:
- summary of 12V systems, support, basic info, etc at "The 12V side of life"
http://www.marxrv.com/12volt/12volt.htm
- google "rv electrical system explained" for links that detail the house and coach sides of the systems and how they integrate, as well as the 12VDC and 110VAC parts of the system.
- "12V voltage regulator sort of thing" mentioned above - look at Electrical Management System (EMS) - Progressive Industries seem to be the industry leader
- Black tanks - google "geo method" for keeping them clean and compatible with septic tanks
- batteries ... used to be 12V Deep Cycle lead acids were the standard, then 6V Golf Cart lead acids, AGMs of different brands, styles, sizes and voltages, now the front running experimenters are using lithium Ion, LifePO, etc ... pros and cons to all, including initial cost, Cost of Ownership lifetime, charging systems, environmental issues (temperature for storage, use, charging, etc).
- In my 5th wheel, last year I replaced 4 (10 year old - yeah, got my $$s worth out of those) 12V 85 AH deep cycle marine lead acid batteries with 2 6V 120 AH Golf Cart deep cycle lead acid from Costco (under $100 each) and installed 200 W solar panels and charger. I generally don't use or need an invertor for anything, as my most critical need is my CPAP, which runs off 12vdc (actually needs 24VDC but has a 12v - 24v converter and cord). I also have a Honda 2000 portable generator for my wife's essential 110vac needs - hair dryer and curling iron - but not simultaneously. Most of our RVing spots have electrical, and my fall hunting trips are boondocking but the solar keeps my batteries up to provide power to everything I need, and I can augment with the generator as needed. I have an RV fridge, not residential, so much less 110VAC needed for me.
- my in-laws have upgraded the battery and solar on their class A coach with enough 12VDC and Inverter to be fully off the grid, including running A/C as needed. Not sure of all the specs on what he's done, but he didn't do it all at once in the solar panels - added on as needs dictated. The problem with that is upgrades to solar panel efficiency and output causes a "add on or replace" decision, and battery banks are best built with same age batteries. The forum experts I read recommend an energy audit on the coach, your needs and wants, and build the solar panels, chargers, battery banks and inverter to meet the needs as you define.
-- this guy
www.loveyourrv.com has a pretty decent blog on upgrades, but again, it's fifth-wheel specific - enough similarities to coaches but not everything is exactly the same. His battery upgrade write up is here
https://www.loveyourrv.com/upgrading-my-rv-battery-bank-and-12-volt-system/