Your RV was probably designed to use 12 volt DC power for most things in your RV that are lower power uses, the exception most people notice first is the blower on the heater runs down the battery if used over night. The air conditioning and microwave are usually 120 volt AC and can be used only when plugged into shore power or a generator. While plugged in, running a generator via the battery charger/converter or while driving using the vehicles alternator, these things can charge the house battery bank. By adding Solar additional charging can be gained while the sun is out. By enlarging the battery number and capacity more power can be stored. An inverter simply allows you to use that stored power for 120 volt AC. Inverters come in many different sizes and all use some of the supplied power to work, the larger the inverter the larger the losses, so it pays to get an inverter that is barely larger than your needs to conserve battery power. Some people use multiple converters in order to power smaller loads more efficiently. There are pros and cons of using a 12 volt or 24 volt battery banks but with everything already 12 volt it is generally cheaper and easier to just have everything 12 volt in my opinion as nothing has to be converted from or to 24 volts in order to work with what you already have. Inverter power still has to be isolated from shore power and the battery charger/converter needs to be turned off while using the inverter and the inverter needs to be turned off when using shore power. The inverter 120 volt AC power output can be isolated from 120 volt AC shore power/ battery charger/converter with a transfer switch, simply plugging in or unplugging components, or on/off switches. the 12 volt DC supply to the inverter needs to be turned off as well as it wastes power if left on while on generator or shore power. Generally the more 12 volt DC can be used in place of 120 volt AC the better and more efficient the system will be. It takes a lot of battery bank to run larger AC loads. Generally solar power is used mainly when the sun is out so batteries can get you through the night. Hope this helps!
