>>818408I made my own solar collector for about 3$ from parts on ebay. The battery container was $1.50 and I have salvaged laptop batteries in it.
I used a multimeter to test how fast it charges, it does about 5% an hour which is about 10% an hour for a standard phone battery.
I only have 2 panels but you could easily add more to get the phone to charge quicker. I wouldn't go above 50% charge per hour.
