> but the fundamentals pass a reality check vs amount of energy delivered by the sun (lots).

  Solar panels produce about 150 watts of energy per square meter since most solar panels operate at 15% efficiency this translates to 15 watts per square foot.

Which is 100 Watts solar energy per square foot, so 35 Watts certainly has the right order. (LEDs are not 100% efficient, sunlight is not 100% efficient with chlorophyll, some edible plants grow in shade).