sensors etc.

[Pommie]

A voltage divider with a smoothing capacitor can be sampled very fast. The acquisition time is the time it takes to charge the internal 10pf capacitor. When it is in parallel with a much bigger (10uf) cap it charges very quickly. An opamp is not needed.

Mike.

 

[flatfootskier]

Just for learning purposes; Please show us how you would get from a resistor to 1V or 5V for the ADC, with out wasting much power.
Remember the Hall has 1.2mOhms of resistance. So the power loss number is small. But the Hall uses 50mW in silicon.

Here's where I make a fool of myself maybe...anyway here goes, in the interest of learning.
Potential divider 100k and 20k
30V worst case input delivers 5v, ignoring input impedance of ADC. consumes 250uA = 7.5mW
Small capacitor across the ADC input, determined by the required response time.

That said, I think this is possibly a moot point for this design - the voltage or current from the panel is predominantly determined by the load connected to it, assuming its being used to harvest energy, rather than just drive an ADC. There's some great heliostat designs using LEDs as photo detectors, which tell the panel which way to drive, assuming that's the application.