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Yes, the rates I'm pulling through SAM include the DWR charge, and match what is shown as the total rate in the Schedule DR effective 8/1/14. There are two entries listed for each of the climate zones to choose from though, but only the first one is correct.
Days per billing period variation definitely sets a ceiling to SAM's ultimate accuracy, and so I've typically been just averaging the days per generation season and using that to set the level of tiers for summer and winter. Not perfect, but it has agreed reasonably well with some of the other numbers you've shared. It supports 12 rate periods, so for a motivated user, each month could be tweaked to have an appropriate number of billing days. It doesn't solve the problem of the number of days changing from one year to the next, but would probably be more accurate than just the seasonal averages.
Also, the 0.17 / day min charge needs to be manually set as a $5.17 minimum monthly charge. Again, an approximation, but close enough for what I've been doing with it. Mostly, I've been relying on SAM for hardware specific energy production estimates that should be slightly improved over PVWatts, and doing the cost estimation work in a spreadsheet. Testing assumption sensitivity in SAM is kind of a pain with either re-simulating or running "parametrics", which itself has some UI quirks, while a spreadsheet can handle it more cleanly, once validated.
Days per billing period variation definitely sets a ceiling to SAM's ultimate accuracy, and so I've typically been just averaging the days per generation season and using that to set the level of tiers for summer and winter. Not perfect, but it has agreed reasonably well with some of the other numbers you've shared. It supports 12 rate periods, so for a motivated user, each month could be tweaked to have an appropriate number of billing days. It doesn't solve the problem of the number of days changing from one year to the next, but would probably be more accurate than just the seasonal averages.
Also, the 0.17 / day min charge needs to be manually set as a $5.17 minimum monthly charge. Again, an approximation, but close enough for what I've been doing with it. Mostly, I've been relying on SAM for hardware specific energy production estimates that should be slightly improved over PVWatts, and doing the cost estimation work in a spreadsheet. Testing assumption sensitivity in SAM is kind of a pain with either re-simulating or running "parametrics", which itself has some UI quirks, while a spreadsheet can handle it more cleanly, once validated.
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