New user in need of help from wiz kid

[littleted1516]

Hi I am new to electronics and maybe a bit old in the tooth but ah ho.
I need some help from a wiz kid. I am building a solar cooker (more my bag so to speek)to take to Uganda in July on a charity trip. And I need a devise to tell the local cook when he needs to redirect the reflector to get the best from the sun. A powered tracker would be great but once I leave there will be no one to fix it so manual is best. So I want an audible warning device that has to be powered by solar, I have purchased a simple solar panel from Maplin that tops up 12v batteries (17.5v 1.5w). I envisage a tube pointing at the sun with a Photo Light Sensitive Resistor at the bottom, when the tube is not pointing at the sun I want an noise to alert the cook to do his bit and turn the cooker at the sun, all powered by the Maplin solar panel. I can follow a simple wiring diagram make the box to hold it all in, know what I want but cant work it out myself. Who can help me please.

Littleted1516 Aka Alan