Getting Off-Grid System Sizing Right
The DPA Off-Grid Load Calculator is designed to simplify system sizing for your next project.
Where possible, complete the calculator with the homeowner or site manager to ensure all energy requirements are captured accurately.
Once finished, you can export or print the results and include them as part of your system design approval.
Use the Off-Grid Load Calculator
Why Load Calculation Matters
In off-grid systems, everything flows from the load.
If it’s underestimated:
- Systems get overloaded
- Performance becomes inconsistent
- Backup generators run more than expected
If it’s overestimated:
- Systems become unnecessarily expensive
- Components are oversized
- Projects become harder to justify commercially
Getting this right upfront saves time, cost, and problems later on.
How the Calculator Works
The calculator is split into three simple sections:
- Appliances – what’s being used
- Consumption – how much energy is required
- Contact – optional, if you want support
We’ve pre-loaded common household and site appliances to make it faster to work through.
How to Use It
- Select the appliances used on site
- Adjust the quantity using the plus/minus controls
- Enter the wattage (check the appliance nameplate if needed)
- Input daily usage hours
- Add additional appliances if required
The goal isn’t perfection – it’s getting a reliable working estimate.
A Practical Approach
A few things to keep in mind:
- Always account for peak load, not just daily consumption
- Be realistic with usage hours — especially for intermittent loads
- Confirm assumptions with the client where possible
- Leave some headroom for future expansion
This is where most system design issues start or get avoided.
Important Note
This calculator assumes the system includes an auto-start generator.
Refer to AS4509 for full system design considerations.
Need a Hand?
If you’re working through a system and want a second set of eyes:
Email sales@dpa.energy or get in touch — we’re happy to help you size it correctly upfront.