There is a federal tax credit in effect that reduces the total net cost of a solar system by 30 percent! (earth911.com)
Here, you'll state the cost of your solar energy system and calculate the value of the credit, along with the amount of the credit that you will be able to claim. (joinmosaic.com)
The main study you refer to is very interesting, especially when they talk about how embodied energy of solar panels is calculated. (lowtechmagazine.com)