Welcome to IRV2:
There are many oxygen concentrators available. Portable units work well but with 24/7 use- those that provide only "pulse" operation may not be suitable. Most with COPD require steady flow when sleeping as their breathing may not trigger the pulse system.
DW uses a Sequal Eclipse portable, operates on 115 volts, 12 volt DC or internal batteries. (Her Sequal is 10+ years old and I'm sure technology has come a long way in that time.)
A consideration if using a inverter to supply 115 volt power, some devices do not work on a modified sine wave, and require a true sine wave inverter.
Some of the medical device companies have info online showing most of the various concentrators and specifications. We have purchased equipment from "Oximedical" and they are very knowledgeable. Here's a link to them but also look around at the various equipment available. Size, power requirements and long term maintenance are important.
SeQual Eclipse 5 Portable Oxygen Concentrator | OxiMedical.net
Hope this helps..