On Wed, 2 Nov 2011 10:25:06 +0000, tony sayer wrote:

Also if my PV packs in, it is not a national disaster as it would
be
if a major primary substation/power station had problems.

Umm .. when did that happen last with serious consequences?..

Sizewell B and Longannet going off line in quick succesion with the
loss of 1,510,000 kW generation gave the grid summat to think about
in May 2008. Load was shed, ie people had power cuts and most of the
country noticed the dip in voltage and then further voltage
reductions.

--
Cheers
Dave.