Very impressive, I like it!
Love the idea of being able to put calculators on the wiki, there are several "we" could do. I had a peek at the code and it looks to be way beyond me, so the onus may be on you to put them together though!
To make it more useful, how about adding cost to the calculator? Wouldn't it just be a multiplying kWhs from another input of unit cost?
So, you're good with sums then? 'Cos I'm struggling with the Methanol purity page. Can I send you a spread sheet I've been playing with?