the cell 60 output is insufficient to power the main circuitry then the batteries 34 provide the necessary power when the output of the cell is at a low level e g at dusk or dawn and the batteries are utilized the microcontroller performs fewer mpp cycles to conserve battery power if the sunlight level drops to near zero e g at night and the photo sensor output is below the minimum level the device 10 is put into sleep low power mode the real time clock 48 maintains the current date and time even when the device 10 is shutdown or in sleep mode the usb connector 58 provides a usb interface for transferring data to and from a personal computer pc of a user or with a usb flash drive the collected sun radiance data and other run time data is retrieved control parameters such as the location 39 s date and time are updated though the usb interface the housing 12 is detachably secured to a platform 80 illustrated in fig6 the platform 80 has an upper surface and lower surface with a pair of rods 82 of the base affixed to the lower surface the platform 80 has a guide 84 and a clamp 86 affixed at opposed ends of the upper surface as means to secure the base 20 the front and rear extension mounting guides 24 of the base 20 are secured to the guide 84 and the clamp 86 respectively the rods 82 slide under roof asphalt shingles to mount the device 10 on an angled roof adhesive may be applied to the lower surface of the platform 80 to assist with securing.