As this has popped up again, I'll just add into the general mix, that we have had no problems with our solar thermal panels, now 10 years old. I wonder how old Oldnproud's son's panels are.
As muse will find, it isn't easy with a new build, to work out what you would have saved, as you have no base. Leaving aside photo-voltaic panels (as they are very expensive and have the feed-in tariff attached, it complicated calculations) I would say from my PoV:
Top energy saving is insulate, insulate, insulate
Next, I can't decide between the solar thermal panels - which produce hot water as long as the sun is shining, even on very cold days; or the Mechanical Heat Recovery Pump which I mentioned above.
I would also say that the underfloor heating (from the solar thermal panels, topped up with gas) makes a huge difference.
But again, it is most efficient if fitted at the time of building.