I just bought a lightweight 60 watt solar panel that folds up to 18"x18" $99 on amazon. It will recharge a portable power supply also purchased off amazon in about 6 hours. My friend is testing it with his cpap machine this week. 3 nights on a/c power before needing a recharge. There are hundreds of power supplies to choose from. I settled on this inexpensive($189) one:Amazon.com : PAXCESS Portable Power Station 200W, 230Wh/62400mAh Emergency Backup Lithium Battery, 110V Pure Sine Wave AC Outlet, QC 3.0, USB-C PD Input/Output, Solar Generator for Home/Outdoor Camping Adventure : Electronics

and this solar panel:Amazon.com: 60W Portable Solar Panel Charger Kit, Foldable Solar Charger for Outdoor Camping RV, Suitable for Portable Power Station(2 USB, 1 Type C, 1DC Port): Electronics