Wichit Sirichote has built a solar recorder that stores data to a compact flash memory card, there are full details including code and schematics available so that you can make your own. Even if you don’t need a solar recorder you can see how to store data to compact flash from a PIC microcontroller.

"The EMF from pyranometer is 14uV/Wm-2. For 1000W/m-2, the output EMF will be .0014V. The PIC ADC is +5VFS, thus the gain of the DC amplifier is adjusted to 357. The noninverting DC amplifier is built with TI TLV2451. It was used to amplify an EMF signal from pyranometer to approx. +5V for 1000W/m-2. RD5 and RD6 are two bits PORTD. It used for software generated I2C bus. The RTC chip, DS1307 is connected to the I2C bus with SDA and SCLK signals. The coin Lithium battery powers the RTC chip when main power is turned off. Time setting is done by shorting the ADC channel 1 (thermistor) when power up the board."