NEM12 Solar-Export Battery-Sizer Tool
Last Updated: 2026-09-18
NEM12 Solar-Export Battery-Sizer takes a Smart Meter Data File in NEM12 CSV Format, containing Solar Export Data (on Meter Register B1) ...
... and produces a Simple Report summarizing: the Solar-Export currently available to Charge a Battery; Indicative Annual Savings; and the Battery Capacity required.
See the Example Report immediately below ...
See Example Charts comparing Solar Export, Mains Import and Battery Sized for that Export ...
Or read How To get Smart Meter Data in NEM12 CSV Format ...
EXAMPLE REPORT:
Solar-Export available to Charge a Battery
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Import (E1) | 1.9 | 2.5 | 2.1 | 2.2 | 2.8 | 2.8 | 3.1 | 3.5 | 3.0 | 3.0 | 2.6 | 2.4 |
| Export (B1) | 4.7 | 4.5 | 3.1 | 1.8 | 1.4 | 1.0 | 1.2 | 2.0 | 3.5 | 3.5 | 4.4 | 3.8 |
| Battery (BATT) | 1.9 | 2.5 | 2.1 | 1.8 | 1.4 | 1.0 | 1.2 | 2.0 | 3.0 | 3.0 | 2.6 | 2.4 |
| Data Series | Description |
|---|---|
| Import (E1) | Demand for Electricity currently met by Import from the Mains Grid ... and thus could be met by capturing Solar Export in a Battery. |
| Export (B1) | Excess Solar Generation currently Exported back to the Mains Grid ... and thus Available to Charge a New Battery (or Additional Battery Capacity) |
| Battery (BATT) | The Mains Import that could actually be reduced using a Battery (because Excess Solar Generation is actually available on the Date that it is required) |
Solar-Export available to Charge a Battery
FINDINGS:
Approx 760 kWh of Solar Energy available to charge a Battery each year
Approx $ 228 of Savings each year (when avoiding a Peak Import Rate of $ 0.30 per kWh)
Approx 4 kWh of (Useable) Battery Capacity would need to be added
DISCLAIMER: This analysis is GUIDE ONLY because: it considers Current Solar Export based on Existing Solar Panel Capacity and does not consider Adding Any More Solar Panels; it considers Daily Averages for Each Month and does not consider the Import Export and Battery State of Charge down to a 30 Minute Interval; it considers a Flat Rate to import a kWh at All Times and does not consider Varying Import Tariffs at Different Times of Day or Days of Week; it considers Current Electricity Demand and does not consider Changes to Electricity Demand (due to Getting Off Gas, Buying an Electric Vehicle, ...); it considers a Battery Size intended to capture All Available Solar Export and does not consider whether that is a Cost-Effective Strategy. And note that: the USEABLE Capacity of a Battery is typically less than the Total Capacity - for Lithium 80% to 90% is Useable and for Lead-Acid 30% to 50% is Useable before excessive discharge causes damage. So if 10 kWh of Useable Capacity is desirable, and a Battery Product had 50% Useable Capacity, then the Total Battery Capacity must be 20 kWh.
For detailed, accurate, and definitive recommendations, consider a full Energy Assessment ...
Launch NEM12 Solar-Export Battery-Sizer
Examples: Solar Export, Mains Import & Battery Sizing
Mains Import exceeds Solar Export All Year
- A Battery sized to use All Solar Export available in Summer, would be greater than required in Winter.
- A Larger Battery might offer good economic returns.
- Adding More Solar Panels would be required to Charge a Larger Battery
Solar Export exceeds Mains Import in Summer; close to Import in Winter
- A Battery sized to use All Solar Export available in Winter, would be greater than required in Summer.
- A Battery sized to Mains Import in Winter would be greater than required in Summer.
- A Battery sized to Mains Import in Winter would be not get Fully Charge without some Additional Solar Panels.
- Adding More Solar Panels to meet some a small amount of additional demand might not offer good economic returns in 2026 (Detailed Analysis and Costing advised ...)
- Adding More Solar Panels could make sense at the right price at the right time in future ...
Solar Export exceeds Mains Import in Summer; below Import in Winter
- A Battery sized to use All Solar Export available in Summer, would be approximately meet that required in Winter.
- But More Solar Panels would be required to Charge that Battery
Features
- Load Interval Data from your Smart Meter in NEM12 CSV Format (How to get the Data ...)
- Summary Chart: Solar Export, Mains Import, Battery Usage
- Summary Table: Solar Export, Mains Import, Battery Usage
- Key Findings:
- Total Annual Solar Export [kwh] that can be cycled through a Battery
- Dollar Savings provide by a Battery
- Battery Capacity [kwh] required
- Print Report (to PDF) ...
- Displays on Desktops, Laptops, Tablets & Smart Phones
- Browser-Based (No Installation)
- Free for Personal and Commercial Use
- No Payment & No Signup
Use Cases
Get Answers to Questions like:
- Is it worth adding a battery to existing solar panels ?
- Are my current solar panels enough to charge a battery ?
- Is my current solar system big enough to charge a battery ?
- Is my current solar system big enough to charge a battery in Winter ?
- Is current solar export enough to charge a battery ?
- How do I calculate the benefits of adding a battery to my solar panels ?
- What Battery Size could be changed by my existing solar panels ?
- How big does a battery need to be to use all of my current solar export ?
- What battery capacity do i need to use all of my current solar export ?
- How many batteries do i need to use all of my current solar export ?
- Should I get a solar battery to use my current solar export ?
Size a Battery to Solar Export
- When you do not have the Budget to add more Solar Panels but are considering Adding a Battery.
- When you do not have Roof Space to add more Solar Panels but are considering Adding a Battery.
- When your Electricity Demand is Unlikely to Increase (and you want to find out if Current Solar Export will hopefully be sufficient to meet that Electricity Demand)
- When your Electricity Demand is Likely to Increase (and you want to find out if Current Solar Export will or will not be sufficient to meet that Increased Electricity Demand)
Place a Value on Solar Export
- When your Solar Feed-in Tariff is Low to Negligible and you want to find out what Solar Export could be worth.
- When you are Selling your Home and want to present the Potential Value of Solar Export to Buyers.
- When you are Renting a House and want to present the Potential Value of Solar Export to a Landlord when negotiating the Installation of a Battery.
- When you are considering Adding a Battery and want consider the Annual Opportunity Cost of NOT doing so.
Free for Personal or Commercial Use.
Energy Assessors & Solar Sales Consultants
Please feel free to:
- Save Reports to accompany your own Quotations & Proposals
- Print Reports (to PDF) to email to your Customers
Easy and Secure
- Browser-Based (No Installation)
- No Payment & No Signup
- Private - Your Data is not shared with 3rd Parties
Getting 30 Minute Interval Data in CSV Format
This NEM12 CSV Series of Free Online Microtools currently supports 30 Minute Interval Data in AEMO NEM12 CSV Format.
The NEM12 Format can be obtained from Australian Electricity Distributors (or Electricity Retailers)
Getting NEM12 Data from Australian Electricity Distributors
Your Electricity Distributor (not your Electricity Retailer, but the company behind them who actually own the Poles & Wires ... often called a DNSP), typically have a Web Portal where you can access 30 Minute Interval Data from your Smart Meter in AEMO NEM12 Format (or similar) without a time-consuming email request to your Electricity Retailer.
Read a Guide about How to Download / Access Your Smart Meter Data ...
Each Data Series shows the Average Daily Amount in Each Month.