My end vents are wide open and always have been.
http://i46.photobucket.com/albums/f1...0slot/peak.jpg
I do have the new ridge vent obstructed about 3 or 4 feet on either side of the air intake in the peak..
Otherwise, I end up pulling cold outdoor air into the basement..
If you cover your roof with PV panels, you won't be getting much direct solar heating.
But the bottom side of PVs get
really hot, so there will be considerable radiant heat to the roofing.
I've studied Radon abatement a bit, and I've come to the conclusion that
positive air pressure to the slab can't work in this house,
without replacing the entire slab with a new one. It's got way too much damage.
Besides, I've discovered that my radon levels can be kept low by
relatively small amount of fresh air ventilation.
Radon abatement has been very successful, so far.