Annual total net purchased energy is not equal to annual total electricity demand minus total energy generated on site through PV
Hi all,
I am simulating a building with PV generators, strangely I found that the annual total net purchased energy (258kWh) is not equal to annual total electricity demand (4717kWh) minus annual total energy generated on site through PV (4504kWh), i.e 213kWh.
Apologies if I am missing something in the documentation but I couldn't find an explanation for this. I would expect the following to hold true
Annual total net purchased energy = Annual total electricity demand - Total energy generated on site through PV
and therefore annual total energy generated on site to be 213 Kwh.
Many thanks
My guess is that at each timestep if demand is larger than PV generation, then that electricity is purchased. At a timestep if demand is below PV generation, it may not credit that against purchased made at other timesteps.
Hi David and Anton, I've found that the difference is caused by the consideration of the inverter efficiency, and the calculation is correct. Please see my reply: link text