Using the Sun to Light a Salt Water Reef Tank

Question
QUESTION: Can I use directed sunlight to light up a tank? I bought a house that has a 300 gallon salt water reef tank in it.  Unfortunately, the current metal halide system sucks a whopping 1600 watts per hour (4 bulbs at 400w each).  Also, we live in Las Vegas, the bulbs simply heat up the tank too much.  Here is my question:  Could I install a heliostat (solar tracking system with a mirror) to direct sunlight through the glass window into the tank?  More specifically, does the spectrum of real sunlight meet the requirements for corals to live?  To add another complexity, the windows are Low-E coated, which to my understanding, removes the infrared light from the spectrum but leaves all the visible light.  If I could put this system in place, it would save 516 dollars a year and a lot of carbon dioxide from going into the air.  Your response is HIGHLY appreciated.  I realize this is not an easy question.

ANSWER: Brian,          I really don't know that much about reef tanks, but I can tell you that this type of lighting creates alot of heat....I think you should stick to what it came with. Sometimes if its not broke don't fix it. I understand that it may be abit costly..., but it is a living peice of art. You get what you pay for. Good Luck, Tina

---------- FOLLOW-UP ----------

QUESTION: Using sunlight creates considerably less heat (almost none at all with the Low-E window coating) then using the metal halide system raises the tank temperature past 82 degrees in less than an hour, its literally unusable here in Las Vegas.  Seems I have two choices, use sunlight or use and LED system, which is quite costly.  If you don't feel like researching this, which I understand, would it be okay to ask the question to someone else?

Answer
Brian,          Actually as soon as I saw you had a follow up question , I thought I needed to research this more.Knowledge gained is never wasted. Give me a day or two and I will get back to you..........Tina