Solar garden lamp mk I

I created my own solar lamp. My plan is to build a solar lamp which can be switched on and off via wifi. To start a project like this you need a solid project platform to build everything up. I created a housing, which can be used for. This lamp is the first step and can be used already for a working simple lamp.
For my first version, I used the following set from ebay. I’m sure there will be other equal kits available in your country.
http://www.ebay.de/itm/352063089252

Unfortunately, the solar cell doesn’t deliver enough Volt to power up 2 AA batteries or more.
It delivers 2 V, perfect would be 5 - 6 Volt to power up a LiPo with 3,7V. This is needed for a esp8266 to use the Wifi functionality.

The battery holder is the following part which I found here on thingiverse https://www.thingiverse.com/thing:456900