The solar panel is small and very good for mobile application and Adruino as well as other MCU and wifi boards like Nodemcu, Wemos, and similler boards,it has an output voltage up to between 5V with current of 80mA  If you want your battery to charge faster, you can use several solar panels in parallel.

Note: To wire solar panels in parallel solder the (+) terminal of one solar panel to the (+) terminal of the other solar panel. Do the same for the (-) terminals. 

Note: you can use the TP4056 lithium battery charger module to connect a lithium battery to power up your projct, this circuit comes with circuit protection and prevents battery over-voltage and reverse polarity connection.

Specifications:

• Size: 60*60mm
• Voltage: 5.0V
• Current: 80mA
• Main material: Epoxy AB glue, PCB or fiberglass substrate.