How to Extract Solar Export Data from NEM12

Find the solar export register (B1) in a NEM12 CSV file or a converted table

Last Updated: 2026-08-19

Key Takeaways

Solar Export (B1) is the register that records the electricity your site sends to the grid, in kWh. AEMO fixes this code for every NEM12 CSV file for a site with a Solar Power System.
To extract solar export data, first identify the solar export register. The form your data is already in decides where you read it.
In a raw NEM12 CSV file, read the NMIConfiguration field on the 200 record. In an already-converted table, read the Register column.
The value "E1B1" means the file carries an E1 register and a B1 register.
E1 and B1 record import and export on the same General Consumption Circuits — the standard household wiring, as distinct from a Controlled Load circuit.
E1 and B1 totals are never added or subtracted — they are two separate physical flows.

Which Register Is Solar Export in NEM12 CSV?

A NEM12 CSV file carries the interval data for every metered register at your connection point. Each register has its own code, and one of those codes marks solar export.

Register Code	What It Records
B1	Solar Export — the electricity your meter records as export to the grid, in kWh.
E1	A mains-grid import register. Where a meter carries more than one E register, E1 is almost always the Main/General register.
E2 and E3	Further mains-grid import registers. A controlled load or dedicated circuit sits on a secondary import register, typically E2.

B1 is always Solar Export. E1, E2, and E3 are always mains-grid import registers. The AEMO NEM12 specification fixes these codes, and no retailer or portal changes them.

Why E1 and B1 Cover the Same Circuits

Under Australian regulations, solar inverters attach only to the General Consumption Circuits. An inverter never attaches to a Controlled Load or a Dedicated Circuit. The E1 and B1 registers therefore record import and export on the same circuits.

E1 and B1 remain two separate physical flows, and each one has its own total. Never add an import register total to an export register total. Never subtract one from the other.

How to Identify the Solar Export Register in Your File

A NEM12 file stores its readings one register at a time. The NMI plus the register suffix identifies which register each row belongs to. To extract solar export data, read the register in whichever form your data is already in.

A raw NEM12 CSV file: read the NMIConfiguration field on the 200 record. The value "E1B1" means the file carries an E1 register and a B1 register.
An already-converted table: read the Register column, because every row names its own register.
A renamed column: some DNSP portals label the B1 readings as "Generation" or "Export". Check that label against the NMIConfiguration field.
An unexpected Main/General register: treat a file that makes an E register other than E1 the Main/General register as suspect. Verify it before you rely on the register totals.

Convert Your Solar Export Data to a Spreadsheet

The NEM12 CSV Format can be difficult to work with, and our guide on how to open NEM12 data in a spreadsheet covers the conversion. For what each register code means, see our guide on how to interpret your smart meter data. For the spreadsheet steps that total one register, see our guide on how to analyse NEM12 data in a spreadsheet. Once you have your B1 total, our battery sizing tool turns it into a recommended battery capacity.

Try our NEM12 CSV Spreadsheet Converter Tool

Frequently Asked Questions

Which register is solar export in a NEM12 file? B1 is always Solar Export — the electricity your meter records as export to the grid, in kWh.
How do I extract solar export from smart meter data? Identify the B1 register. Read the NMIConfiguration field on the 200 record, or the Register column of a converted table.
What does "E1B1" mean in a NEM12 file? The file carries an E1 register and a B1 register, and no other register.
How do I find the solar export register in a converted table? Read the Register column, because every row names its own register.
What do DNSP portals call the B1 register? Some DNSP portals label the B1 readings as "Generation" or "Export".
What is the E1 register? E1 is a mains-grid import register, and it is almost always the Main/General register on a multi-register meter.
What if my NEM12 file's Main register is not E1? Treat the file as suspect. Verify the NMIConfiguration field before you rely on the register totals.
Do the E1 and B1 registers cover the same circuits? Yes. Australian regulations require solar inverters to attach only to the General Consumption Circuits.
Can a controlled load appear on the B1 register? No. A controlled load or dedicated circuit sits on a secondary import register, typically E2.
Can I subtract my B1 total from my E1 total? No. E1 and B1 are two separate physical flows, and neither total is derivable from the other by subtraction.
My NEM12 file has no B1 register. What does that mean? A NEM12 file carries B1 data only where the meter records export.
Does the B1 total equal my total solar generation? No. The B1 register counts exported electricity only, and total solar yield also includes the solar the property uses on site. For what that difference means, see our guide on interpreting your smart meter data.

Try our NEM12 Solar-Export Battery-Sizer Tool

Glossary

200 Record: In the NEM12 Format, a Metadata row that declares the NMI, NMI Suffix, Meter Number, Unit of Measure, and interval length for the data rows beneath it.
AEMO: Australian Energy Market Operator — the body that administers the National Electricity Market and defines and maintains the NEM12 specification.
B1: In the NEM12 Format, the Meter Register code for Solar Export — electricity generated on site and fed back to the grid, typically measured in kWh.
Controlled Load: A separately metered circuit controlled by a signal from the DNSP. These circuits typically contain a single specific appliance or type of appliance - eg. an Electric Hot Water Service (and historically Air-Conditioners or Electric Slab Heating). They are typically billed at a discounted rate and often run only during off-peak hours. They appear on a separate Meter Register on an Electricity Bill. See also: Dedicated Circuit.
CSV: Comma-Separated Values — a plain text file in which each row is a record and fields are separated by commas.
Dedicated Circuit: The physical wiring and breaker serving a Controlled Load device, isolated so the DNSP can independently control supply. See also: Controlled Load.
DNSP: Distribution Network Service Provider - the company that owns and operates the physical poles and wires of the local electricity network, and usually provides the smart meter data portal. Not the same as your Electricity Retailer. See also: Electricity Retailer.
E1: In the NEM12 Format, the Meter Register code (or NMI Suffix) for the sole/main/primary mains grid import channel — electricity drawn from the network. Where there is No (Solar) Generation on site, this is the Total Consumption. Typically measured in kWh.
E2: In the NEM12 Format, the Meter Register code (or NMI Suffix) for a secondary mains grid import channel — typically controlled-load or off-peak consumption such as dedicated hot water. Present only where that tariff exists.
E3: In the NEM12 Format, the Meter Register code (or NMI Suffix) for a third mains grid import channel — a further separately measured import circuit. Present on a small number of connections only.
Interval Data: Energy readings recorded at fixed time steps — typically every 30 minutes (but sometimes 5 or 15 minutes on newer meters) rather than as a single billing total. This allows charging different Tariffs at different times of day or days of the week. See also: Time-of-Use (TOU) Tariff.
kWh: KiloWatt-Hour — the standard unit of (Electrical) Energy: 1,000 Watts of Power used continuously for one hour is equivalent to 1000 Watt-Hours or 1 KiloWatt-Hour. NEM12 CSV records Electricity Use in kWh. See also: kW.
NEM12: The AEMO file format (version 12) for exchanging Interval Data from Smart Meters across the Australian National Electricity Market (NEM). NEM12 Format records the Amount of Energy per Time Interval in kWh. And also other types of data, using specific types of labelled rows or records (100, 200, 300, 400, 900) to record different types of data. This makes it a 'Semi-Structured' 'Non-Tabular' Format. See also: AEMO, NEM, kWh, Semi-Structured, Non-Tabular.
NEM12 CSV: A NEM12 File stored as comma-separated values — the form most DNSP and retailer portals distribute. See also: NEM12, CSV.
NMI: National Metering Identifier — the unique 10-digit identifier for an electricity connection point (11 with the Check Digit), permanent to the property. Note that the electricity connection point identified by the NMI, typically has multiple NMI Suffixes, and can have multiple Physical Meters. See also: Check Digit, NMI Suffix.
NMI Suffix: In the NEM12 Format, the short two-character code (E1, E2, E3, B1, B2, Q1, K1) identifying a specific Meter Register for recording electricity flows on the mains electricity connection identified by that NMI — also called the Meter Register or Register Code. See also: NMI, NEM12.
NMIConfiguration: The field on a NEM12 200 record listing every NMI Suffix present for the meter (e.g. "E1B1") — the quickest way to see which channels a file carries. See also: NMI, NMI Suffix.
Smart Meter Data: Electricity import and export readings recorded by a digital interval meter at regular intervals. In Australia, typically supplied in NEM12 CSV Format with 30 Minute Intervals. See also: NEM12 CSV.

Try our NEM12 Solar-Export Battery-Sizer Tool