So City Hall would actually save less money (12k vs 13k/14k) than the two regular homes I tried in San Francisco. If the numbers are correct, we're looking at $650-700 a year in savings. Not bad, but not that great either, especially considering heating alone in both buildings I looked at ran $150-300 / month (including summer which is hardly warmer at night in SF). Can solar panels be installed at such a price on a regular home? I doubt there's any incentive for City Hall here.
EDIT: I also doubt the calculations are correct considering that city hall's roof is many times larger than the two homes I looked at, yet saves less money.
One of the tunable parameters is the "size of your electric bill", which defaults to $150/month and maxes at $500/month -- far too low for a city hall, I should think. This is the limiting factor here, not the size of the roof. At $500/month, the recommended installation size is 765 square feet, but the total roof size is 50,171 sq feet. Only a small fraction of the roof area is being used.
This has clearly been designed for residences and not larger buildings.
I'm guessing you left the average monthly electric bill slider at the $125/month position. You'd have to adjust the to what it actually is for City Hall, which I'd think is a lot more than $125/month.
It looks like it's only tuned for residences (and maybe small apartment buildings) as you can only set the max electricity bill at $500 per month. I'm sure the city hall's bill is much higher.
EDIT: I also doubt the calculations are correct considering that city hall's roof is many times larger than the two homes I looked at, yet saves less money.