[RobbyG]

Really nice looking board, I am not sure but you seem to be using Altium designer like me. While I like your idea, I think your going to find that this is not as easy as you may have thought. your going to have a lot of problems working with op amps in the uV range and accuracy is going to be really hard to achieve. Good luck, I made a complete meter for my older apogee unit, that multiplied the voltage by 5 then I used a regular Chinese LCD voltmeter display that reads up to 2V max. When pointed at direct sunlight at noon I get about 1.980V or 1980 PAR which is close to the 2000 they suggest. My fluke 87V shows that the circuit works well, but it did require a bit of work even in the mV range to get it to have an even slope across the input range and I had to fiddle with the resistor values to get the gain exactly right and the offset. I suspect yours will be a lot harder to get just right. Good luck, it's nice to see some other EE's on the forum.

Rob