Try to swap the red LEDs with blue ones! The sun has many parts of red and yellow light. The blue light has a higher frequency and so it is much better to see (it seems to be much brighter). The blue LEDs cost much more than the normal LEDs (red, yellow, green).
Be careful: The blue LEDs always have a higher flow voltage and current then the other ones but there are some brighter types of blue LEDs which can be used with lower current.

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Greetings from Frankfurt (Germany),
Sheriff ;-)