Catalog shopping is your best bet. Try American Scientific & Surplus, or perhaps Harbor Freight Tools, (at least that’s what I use, this is not an endorsement). You will need a power inverter of the appropriate wattage to handle whatever it is you want to power. A deep cycle battery or two will also help. As for the downside, cloudy days don’t help much, solar panels are kinda fragile, they don’t charge at night (obviously), and so far they aren’t quite cost effective. That said, this is how I power my travel trailer. You get used to it.