The rates are not what I'd call straightforward. I believe I've found everything that goes into my basic residential rate bill and put it into a spreadsheet (just because I wanted to know). It's accurate to within what I'd consider a rounding error. The various charges are basic customer charge, distribution (the year is broken into two parts, each of those has a first 800kwh and a >800kwh), generation (the year is broken into two parts, each of those has a first 800kwh and a >800kwh), peak shaving rider, energy efficiency rider, transmission rider, taxes (broken into first 2500kwh and > 2500kwh) and a fuel rider. All of these except the basic charge are per kwh. These charges were NOT listed in a single place. I had to hunt through multiple documents on their website.
One thing that's going to mess up your comparison is the basic customer charge, which is $7 for me no matter how much I use. If I only use 100 kwh, that's effectively another $0.07 per kwh for the basic customer charge. But if I use 700kwh, that drops down to $0.01 per kwh. This can make a pretty big difference in the per kwh rate if you're using small amounts.
My simplified rate (bill total / total kwh) has ranged from $0.093 to $0.116 over the past three years due to rate changes and amount used.
Keith