Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
If you have, for instance, excess PV generation (with or without storage), this would show up in the eplustbl.htm file under "Electric Loads Satisfied", as illustrated here. Compare "Electricity Coming From Utility" vs "Surplus Electricity Going To Utility". The latter seems to be what you're after (based on the title of your question).
If the "Electricity Coming From Utility" is 0 (or nearly), then the PV kit (array/inverter/distribution/storage) is sufficient to render the building model "off-grid". If the PV kit is instead insufficient, EnergyPlus will draw from the utility to meet demands, as explained here and here (search for "All demand not met by available generator capacity (or storage) will be met by purchased electrical").
| | 2 | No.2 Revision |
If you have, for instance, excess PV generation (with or without storage), this would show up in the eplustbl.htm file under "Electric Loads Satisfied", as illustrated here. Compare "Electricity Coming From Utility" vs "Surplus Electricity Going To Utility". The latter seems to be what you're after (based on the title of your question).
If the "Electricity Coming From Utility" is 0 (or nearly), then the PV kit (array/inverter/distribution/storage) is sufficient to render the building model "off-grid". If the PV kit is instead insufficient, EnergyPlus will draw from the utility to meet demands, as explained here and here (search for "All demand not met by available generator capacity (or storage) will be met by purchased electrical").
You may find this paper of some interest.
| | 3 | No.3 Revision |
If you have, for instance, excess PV generation (with or without storage), this would show up in the eplustbl.htm file under "Electric Loads Satisfied", as illustrated here. Compare "Electricity Coming From Utility" vs "Surplus Electricity Going To Utility". The latter seems to be what you're after (based on the title of your question).
If the "Electricity Coming From Utility" is 0 (or nearly), then the PV kit (array/inverter/distribution/storage) is sufficient to render the building model "off-grid". If the PV kit is instead insufficient, EnergyPlus will draw from the utility to meet demands, as explained here and here (search for "All demand not met by available generator capacity (or storage) will be met by purchased electrical").
You may find this paper of some interest.
EDIT: Add the following to an .idf file to get monthly tallies of "Electricity Coming From Utility" vs "Surplus Electricity Going To Utility"
Output:Variable,
*, !- Key Value
Facility Total Purchased Electricity Energy, !- Variable Name
Monthly; !- Reporting Frequency
Output:Variable,
*, !- Key Value
Facility Total Surplus Electricity Energy, !- Variable Name
Monthly; !- Reporting Frequency
Look up the last 12 occurrences of each output variable in the generated .eso file.
