I'll add my 22 cents (I'm long winded)... note DW has a cpap and we have been successfully camping offgrid for over a decade.
The very first thing you need to do before you spend money on batteries or solar is to GO CAMPING and pay attention to what you use!!! If you want really good data, invest in a trimetric, TM-2030 battery monitor.
You will quickly waste $$ if you just start guessing how much you need of what. Find out how you like to camp and what you want to use while camping without hookups. For example, if you can live without TV while off grid, that is less power you need.
The ZAMP solar systems, as they are out of the box, are useless for all but trickle charging. It is simple physics, and when you use tiny wire causing a high voltage drop combined with placing your charge controller tens of feet away from the batteries you will never charge anything decently. You can modify them to work better but then why pay the premium for their 'plug-n-play system' that you can't plug-n-play??
Here are Dragon-roo's guidlines... YMMV!
- The first change to make if you want to camp off grid is to conserve.
- The second thing to change if you want to camp off grid is to conserve more!
- When DW doesn't want to conserve it can only be offset by investment $$
- When adding batteries it is 'usually' just as important to upgrade the wiring on most RVs.
- Solar is for charging batteries, NOT for powering your devices (unless you have a solar surplus) and thus offsets the need to plug in or run the generator
- More batteries are dead weight if you don't need them
- not all batteries are created equal
- OEM installed 'converters' are junk if you want to take care of your batteries and/or charge them quickly.
- $$ spent does not have much correlation to how well your system works... there are a lot of so called 'professionals' that do NOT know what they are doing
If you are almost always plugged in, then you have no need for solar. If you want to do the occasional 4 day weekend, unplugged, then get a couple of GOOD group 31 batteries. Leave the extra at home when you don't need it. Some would prefer to have a pair of 6v batteries and just always tote both around. Pros and cons to both.
There are so many 'phantom' loads on the new RVs that you can considerably increase your battery run time by pulling a couple of fuses on things you aren't using while off grid!
Before you invest in ANY solar you should read...
Jack and Danielle Mayer
Note that both of these sources are primarily addressing the fulltime crowd so some of their recomendations are a bit more than some of us 'campers' need.