Brett BeesonBrisbane, Australia

ARTICLE / 2020.12.08

Solar PV, Batteries and ... Maths

See updated version at https://brettbeeson.com.au/energy-monitoring-circuit-positives-and-negatives/ Some, it all seems pretty simple, right? It's just import, export, consumption. This post clarifies the sign (+ or -) conventions I use which seem to make thi…

Energy MonitoringSustainable Buildings
net

See updated version at https://brettbeeson.com.au/energy-monitoring-circuit-positives-and-negatives/

Some, it all seems pretty simple, right? It's just import, export, consumption. This post clarifies the sign (+ or -) conventions I use which seem to make things easiest.

[table id=11 /]

  • net
    CV1
  • ControlVoolume1
    CV2
  • cv2
    C3

Each of the three images has a 'control volume' where we measure power flow across.

CV1 is the meter: the 'Net' reading is positive (import) or negative (export) at any time.

CV2 simply breaks Net into positive (importing) and negative (exporting). 

Import - Export = Net

C3 shows production and consumption. Note production is of any kind (e.g. solar, battery, whatever). Battery storage within the building is consider production, it's just shifted in time.

Production - Consumption = Net

So putting this together:

Production - Export + Import - Consumption = 0