Tech Ingredients on YouTube reciently did some videos about increasing small scale solar efficiency by adding DIY reflector panels.
Overview: https://www.youtube.com/watch?v=FKhszB4E1_M
Build instructions: https://www.youtube.com/watch?v=knlQFlxCwrs
Overview: https://www.youtube.com/watch?v=FKhszB4E1_M
Build instructions: https://www.youtube.com/watch?v=knlQFlxCwrs