Two things matter in developing PV--the system design, and the cap stack. 

Luigi Sciabarrasi reminded me again of this fact the other day when he pointed out that most public companies are judged by their book earnings, and if the after tax value of their pv power system has a greater net present value than the book value, the system has an effect beyond merely saving the planet.

Now, I am not a tax accountant, but I needed to understand if this book vs tax thing was a headwind or a tailwind in adopting this new technology.  Turns out it is a nice little tailwind--but you get your tax advice from your accountant, not your pv power developer.

The difference is basically the early year benefits of the 5 year MACRS versus the 25 year straight line w/ $0 salvage value.  I didn't include a residual system value in this analysis, but it would be the same for either option.

I am the first to counsel that you don't do PV for the tax benefits.  We have larger problems to fix.  But it is comforting to know that these systems are CFO-friendly.

Grazie mille, Luigi!