If you’ve been researching battery storage, particularly the Tesla Powerwall 3, you may have come across terms like DNO approval, inverter limits and export restrictions.
For many homeowners, this is where things start to feel complicated.
In reality, the principles are quite straightforward once they’re explained clearly. This guide breaks it down in simple terms, so you understand what to expect and how it may affect your system.
First things first: what is the DNO?
The Distribution Network Operator (DNO) is the organisation responsible for managing the local electricity network in your area.
Any solar or battery system above a certain size must be approved by the DNO before it can be installed. This ensures the local grid can safely handle the energy being generated and exported.
This is a standard part of the process, and it’s completely outside of the installer’s control.
Why are there limits at all?
The DNO’s job is to protect the stability of the electricity network.
Depending on where your property sits on that network, for example, rural locations, end-of-line properties, or areas where lots of solar has already been installed, there may be limits on what can be connected.
These limits are not about your system specifically, but about the wider network capacity in your area.
The two types of limits you might see
When applying for a system like the Tesla Powerwall 3, the DNO may apply one or both of the following:
1. Inverter (power) limit
This controls how much power your system can deliver at any one time.
The Powerwall 3 has a built-in inverter capable of delivering up to around 11 kW. However, the DNO may require this to be reduced, for example, to 5 kW.
Think of it like this:
- The battery capacity (13.5 kWh) is how much energy you can store
- The inverter size (kW) is how quickly you can use it
A useful analogy:
- The battery is like a fuel tank
- The inverter is like the engine size
So even if you have a full “tank”, the “engine” may be limited in how much power it can deliver at once.
2. Export limit
This controls how much electricity you can send back to the grid.
For example, your system might be allowed to export 5 kW, even if it is generating more than that.
Any extra energy must either:
- Be used in the home
- Be stored in the battery
- Or be reduced (this is called clipping)
How this affects a Tesla Powerwall 3
The key thing to understand is this:
DNO limits affect how fast energy can flow, NOT how much you can store.
Even with restrictions:
- You still get the full 13.5 kWh battery capacity
- You can still store and use your own energy
- The system still works exactly as intended
However:
- The maximum discharge power may be reduced (e.g. from 11 kW to 5 kW)
- High-demand appliances may still draw some power from the grid
- EV charging speeds may be limited by the inverter cap
A simple example
Let’s say your inverter is limited to 5 kW:
- Your home is using 5 kW → battery can cover it fully
- Your home is using 7 kW → battery provides 5 kW, grid supplies the extra 2 kW
The battery is still doing its job, it’s just capped on how much it can deliver at once.
What about solar generation and ‘clipping’?
If your system generates more power than your home is using, your battery can store, or your export limit allows, the system will reduce output.
This is known as clipping.
While this might sound negative, in reality:
- It usually only happens on the brightest days (spring/summer)
- The overall impact on annual performance is often small
- Systems are designed so the benefits outweigh these occasional limits
Adding a Powerwall 3 to an existing solar system
If you already have solar and are looking to add a Tesla Powerwall 3, a DNO application will be required.
- This typically costs around £279
- Sunlit Solar charges a £90 admin fee, which is deducted from your final bill
This process ensures your upgraded system complies with current grid requirements.
Important: the DNO may restrict output more than expected
One of the biggest surprises for customers is this:
The DNO can set limits significantly lower than the battery’s full capability.
For example:
- A Powerwall 3 capable of 11 kW output
- The DNO may limited to 5 kW, or even 3.68 kW in some cases
This doesn’t mean the system isn’t worthwhile, but it’s important to understand this upfront.
Why transparency matters
At Sunlit Solar, we always share DNO conditions clearly and early in the process.
Even when the impact is small, it’s important that you understand:
- How your system interacts with the grid
- What limitations may apply
- What that means for your usage and expectations
Because while we design and install the system, we don’t control the DNO’s decisions.
The bottom line
Despite the technical detail, the key takeaway is simple:
- You will still benefit from solar and battery storage
- You will still reduce your reliance on the grid
- You will still make meaningful savings
The limits simply shape how the system operates, not whether it works.
Thinking about adding battery storage?
If you’re considering a Tesla Powerwall 3, whether as part of a new system or added to existing solar, we’ll guide you through the DNO process and explain everything clearly along the way.
Get in touch with our Somerset-based team to talk through your options:
Phone: 01458 834 936
Email: info@sunlit-solar.co.uk
Website: www.sunlit-solar.co.uk
