Besides backpacking, another reason to have one of the backpackable solar panels is for emergency power following a natural disaster — hurricane, earthquake, et al. The primary threat here is the recent earthquake swarm just east of LA near Fontana, CA.

After the testing I did on small (21W and less) panels, I bought a 100 watt panel and a 10 Amp 12V/24V Solar Charge Controller. The system would primarily be used to keep a Goal Zero Yeti 400 charged, keeping it available to recharge batteries, lights, radios, cell phones...

A lot of homes in my neighborhood have solar panels on their roofs connected to the electric grid. In the event of a wide spread power outage where the grid is down, all those solar panels are essentially useless. Mine is off-grid and independent of other system failures.

FWIW, $.02 and all the other disclaimers.