Tesla’s long-awaited DC expansion packs have now arrived, and at Spirit Energy we’re proud to offer them as an affordable way to boost your Powerwall 3 system. Priced at around £5200 per unit, these DC expansion packs provide additional battery storage without the need to install another full Powerwall 3. In this blog, we’ll explain what these expansion packs are, their key features, installation options, and how they can benefit your home energy storage setup.
What Are Tesla Expansion Packs?
The expansion pack is essentially a dedicated DC battery storage unit designed exclusively for Powerwall 3 customers. Unlike installing an extra Powerwall 3, the expansion packs do not include integrated electrical components such as inverters, solar MPPT trackers, or computing power. Instead, they rely on the main Powerwall 3, the ‘brain’ of your system, to manage the entire storage solution. Each expansion pack offers:
- 13.5 kWh of storage capacity
- 100% depth of discharge for full utilisation of stored energy
These packs provide a cost-effective method to expand your energy storage capacity, especially if you require more than the base unit can offer.
System Configuration and Compatibility
How Many Expansion Packs Can You Install?
For a single Powerwall 3 unit, you can add up to three expansion packs. Additionally, you can connect up to four Powerwall 3 units on one supply, which, in theory, allows for up to 216 kWh of storage. However, please note that at present, expansion packs can only be added to one Powerwall 3. Tesla’s software update, expected in four to five months, will eventually enable each unit in a multi-battery setup to support its own expansion packs.
Compatibility Considerations
It’s important to note that these expansion packs are only compatible with Tesla Powerwall 3 systems. If you currently have a Powerwall 2 installation, the expansion packs will not be an option. Tesla’s focus is on providing larger storage capacity rather than releasing smaller units, reflecting the market’s demand for more extensive energy storage solutions.
Performance and Charging Details
A key technical aspect to consider is the system’s charge rate. The main Powerwall 3 unit charges at a rate of 5 kW. When you add an expansion pack, the overall system’s charging capacity increases to 8 kW. However, this rate remains constant regardless of whether you add one, two, or three expansion packs. For instance:
- Single Powerwall 3 + 1x Expansion Pack: Charges at 8 kW
- Multiple Expansion Packs: Even with 3x expansions (totalling 54 kWh of storage), the maximum charge rate remains 8 kW
This means that in the largest configurations, a full charge from 0% to 100% would take approximately 6¾ hours. Fortunately, in practical terms, you’re unlikely to be charging from a complete depletion as most systems will be managed with a minimum reserve level for backup power.
Installation Options
There are two primary ways to install the expansion packs alongside your Powerwall 3:
1. Stacking Behind the Main Unit
- Pros: A neat, compact design if floor support is available.
- Considerations: The entire system must be floor-supported; you cannot mount the main unit above ground and then stack an expansion pack behind it due to bracket strength limitations. Additionally, the main Powerwall 3 must always be at the front of the stack.
2. Mounting Adjacent on the Wall
- Pros: This option often comes at a slightly lower installation cost, as the expansion pack is mounted next to the main unit and fitted with its own frosted glass panel to match the finish.
- Considerations: Installing adjacent may require minor adjustments, such as extending cabling and ensuring that the main unit has the required 30 cm of free space at the front.
Both installation methods utilise Tesla’s dedicated DC connection cables, available in half-metre, 2-metre, and 4-metre lengths. However, these cables cannot be linked together, so the maximum distance between batteries is around 3.5 metres.
Additional Features and Warranty
Tesla’s expansion packs come equipped with active thermal management—a feature that preconditions the battery to operate at an optimal temperature in colder weather, using technology similar to that found in Tesla’s Model 3 and Model Y vehicles. The expansion packs are also slimmer than a full Powerwall 3 (168 mm deep compared to 193 mm) and carry the same warranty terms:
- Unlimited cycles
- 80% capacity retention after 10 years
Pricing and What It Means for You
At Spirit Energy, we’re offering these expansion packs from around £5200 per unit. The final cost may vary depending on the complexity of the installation:
- New Installations: A straightforward installation alongside a new Powerwall 3 could keep costs below £5200 per unit.
- Retrofits or Complex Setups: More challenging installations might incur a slightly higher price.
Importantly, the cost remains largely consistent whether the expansion pack is stacked behind or mounted adjacent to the main unit.
Final Thoughts
Tesla’s Powerwall 3 expansion packs represent a significant step forward in customisable home battery storage. They provide an effective, cost-efficient way to expand your energy storage capacity, ensuring that your home can better harness solar energy and improve grid independence. With Spirit Energy’s extensive experience—we installed over 250 Powerwall units last year and proudly won the Tesla Installation Excellence Award in 2024, you can be confident in a seamless, expertly managed installation.
If you’re considering upgrading your home’s battery storage system or simply want to learn more about how Tesla’s expansion packs can work for you, please get in touch. Whether you’re in the early stages of planning or ready for a bespoke technical quotation, our team at Spirit Energy is here to help.
