Generation is not Enough

As illustrated in Figure 3, the reference project where the daily demand peaks at about 4.5 MW during weekdays. The project incorporates a 2MWp rooftop PV array that offsets daytime project energy use and offers roughly a net 24% reduction in energy.

Figure 3:

Using the grid intensity profiles from Figure 1, this level of generation translates to just about 12% reduction in project GHGI in 2020 and drops by another half to just about 6% in 2030. To reiterate, a 24% renewable energy offset will only avoid 6% of annual GHG emissions as the grid gets cleaner. To ensure that energy offsets coincide with the hours of maximum GHG intensity, there is a need for a dispatch algorithm that can simultaneously look ahead at the building demand and marginal grid emissions factors, and enables a battery bank to charge and discharge optimally to minimize or eliminate drawing from the grid during high emissions

intensity hours.

Electricity demand profile for the reference project during a typical summer week showing onsite PV generation that offsets 24% of the energy use [Top] but avoids only12% of GHG Emissions in 2020 [Middle] and only 6% in 2030 [Bottom].