My builder and I were wondering if a solar slab like the one in Kachadorian's book is worth it. We are building a passive solar house in Lake Tahoe. We are building in the Angora Burn area, so we have a pure south aspect and almost no trees left. We are putting in a 6 inch insulated slab in the living room for mass. No hydronics in the slab, just windows and concrete. It is almost always sunny here, like 300+ days. Would a solar slab add anything?

SierraSkier
A concrete floor such as you descibe will absorb heat & release it slowly to moderate the temperature swings, so it should be helpful. Make sure it is isolated from the exterior concrete foundation wall as well as insulated underneath.

In 2009 we had a passive solor slab home built near Divide Colorado, the solor slab was a waste of money.
Inovative Structures, Matt Freidell built the home and fan he put in is noisy and annoying.

We built in a high radon area and he did not advise us of this. The slab is poured on concrete blocks, which were poorly sealed from radon.
The space below the slab acts as negitive air space and sucks the radon to levels of more than 40.

I had to seal all ventilation from the slab, and draw the air from the slab to the outside to get the radon levels under 4.

For us it was a waste of money, this is possibly due to an incompetant contractor, Inovative Structures.