[Quoth]

Small is very long recharging times in our climate.
I have a folding panel for 12V that is 30cm x 18 cm open excluding handles, 1.5cm thick open, 3cm closed. It trickle charges a radio using 2700mAH AA cells in a couple of days.

I have 4 off power banks (maybe 10,000 mAH) with integral (built in) solar panels I leave on the windowsill. They have maybe 1/8th of solar panel surface. For long term power cuts or camping for one phone and one ereader.

Unless you are outdoors and in a sunnier climate you can't have small, light, portable and charging in a reasonable amount of time.

My son has Solar panels on the house and on average they give about 15% of rated power. Decent power is April to September, and rated power June & July on a sunny day between about 10 am to about 4.30 pm GMT+1 (approx 11° W, 52° N).

Cheaper gadget panels may have a 1/3rd or less of power for same area as quality PV panels the same area.

Best strategy for power cuts or camping is multiple rechargeable power banks (minimum 2), maybe with a separate larger quality panel about 12" x 8" (30cm x 20cm) as the built in solar panels on power banks don't seem much good. The larger panels are 12V, 24V or 48V (actually less than 45V to allow boot inverter for 48V nominal battery system), so a 12V to 5V Switch mode adaptor like a cigar lighter socket adaptor to 5V might be needed. Some of those are linear regulators so waste power on a panel.

A car dashboard or such may get too hot.