Time for research.
http://www.youtube.com/watch?v=_fUMC_WxBNI
These guys have a number of videos relating to Boral tiles.
It doesn't look like walking will be a problem.
It can be challenging to properly mount and seal solar panels.
The quality of the underlayment is important. 15 years before it needs replacing in some cases. Other vids show tile resets to replace paper and battens.
The Oct/Nov 2013 issue of SolarPro has an article on mounting to tile roofs.

Here is a link that might be useful: solar panel install

We would like to use Cedarlite on our roof. Did you use it? Do you like it? We are also getting some solar panels, and have some valleys that require us to get on the roof a few times per year to clean up twig and leaf debris. Our current CalShake roof has lasted 40 years, and we're hoping Cedarlite will last as long.

At great expense, we installed a Cedarlite roof in 2008. It is absolutely terrible! It is very fragile and prone to leak. You have to blow all debris off the roof very regularly. Even then, it finds a way to leak. The tiles are fragile and break easily, making maintenance very difficult. We are considering replacing the roof after only 12 years. It's a beautiful roof, but just awful. Also, the tiles fade. Trust me, you WILL be replacing tiles (if you can find a roofer who will do it) and you can see the contrast between old and new tiles.

Because these tiles break easily, tenting the house for termite treatment is a disaster.

"Because these tiles break easily, tenting the house for termite treatment is a disaster."

Why would the tile being brittle make tenting a disaster?