Now I don't want to criticize to harshly, but I think he could have done been much more green for less money. Now the obvious thing he could do would be to downsize his house once his kids are a ways. How big of a house do two people need.
Apart from that there are several other cheaper things you can do. I have tried to "Green" up my house a lot too, however I live in Minnesota so solar panels are even a worst investment. But here goes.. list of cheaper green things that I do.
1. When a bulb goes out I replace it with a CFL. hen can be expensive so when I see them on sale for a $1 each I grab a few. I do not recommend replacing all you light bulbs at once because that gets expensive, but when one goes out, go for it.
2. New windows - this was my most expensive energy improvement. $9,000, but it did make my house quieter and drop my heating bill by 45%... My old windows will really bad.
3. My furnace and A/C.... probably don't need that efficient of a furnace where he lives, but in Minnesota, I am rocking the 95% efficient furnace. The furnace and new windows dropped my worst heating bill (January) from $240 to $105. I save between 500 and 600 a year in heating. (Again my windows were REALLY bad)
4. Whole House Fan.. I got one from http://www.airscapefans.com/
You turn off your A/C at night, and pull in fresh air. It uses much less power than you A/C, on low the smallest model only uses 38 watts. And for a cost between $500 - $1300, they do not hurt the wallet too much.