I used to run a Wyze cam offline that would record to the SD card and use my phone as a hot spot to connect when back in range, This worked quite well for me previously. To make it solar you would need to have the solar charge some battery and then the Wyze connected to the battery - maybe one of those Solar batteries like this? https://www.amazon.com/VITCOCO-Charger-Portable-Foldable-Waterproof/dp/B088CW79YF/ref=sr_1_4?dchild=1&keywords=solar+panel+usb&qid=1610805718&sr=8-4.