On Sun, 26 Feb 2012 23:40:56 -0800 (PST), harry wrote:

I think on a day when the sun is so strong, you won't need your
storage heaters anyway.

Certainly in the summer. If I'd installed PV I'd arange any surplus
to be dumped into the thermal store rather than storeage heaters. I'd
only actually export in extremis, like thermal store completely
heated to 90C+.

--
Cheers
Dave.