I am modeling a building with rooftop solar in OpenStudio, and am calculating the annual utility bill using the 'Tariff Selection Time and Date Dependent with Maximum Demand Charge' measure.
This building has a large rooftop area, and a low electricity use intensity (kWh/sqft), and as a result, produces more electricity from the PV array than the building uses annually. Compared to the same building without rooftop solar, I notice that the electricity utility for this building decreases by ~50% with the addition of solar, and the demand charge only decreases by 12%.
I assume that the utility bill is calculated for the net difference between building demand and PV production for each time interval, and that no power is assumed to be sold back to the grid. Can someone confirm or debunk this assumption? I'm having a hard time finding proof in the documentation.
