re: “solar powered sleep machine,” there’s an app called “Relax Melodies” (developer is Ipnos Soft) we use on our phones/iPad. There are a myriad of noise options, including a white noise similar to a sleep machine. Might not exactly be a solar powered sleep machine, but if you could use one of the phones/iPads as a sleep machine. We use the app at home most night and also for Fin when we’re on the road and the battery usage is pretty minimal.