Off-grid system using Tesla Powerwall 3

Solar Questions and Comments
1

Considering an off-grid system using Tesla Powerwall 3.

What major components are required? Unclear to me if a seperate inverter is required in addition to Powerwall 3 included inverter.

My assumption is the solar array plugs into Powerwall, and Powerwall is connected to main bus.

2

The Powerwall 3 could be used for an off-grid system but Tesla does not support this so you will void the warranty. Considering it can handle up to 20kW of solar and has an 11.5kW continuous power rating, technically it should be able to handle off-grid use. However, it doesn’t have the required generator controls and other functions designed for off-grid systems.

There are many different types of modular off-grid solar systems available. Why do you want a 13.5kWh Powerwall 3 system?

What are your daily load requirements in kWh? Have you done any basic load calculations?

3

Appreciate the response, but should have left out anything beyond the Powerwall question.

4

Done some homework. Based on experience with solar systems in our area, 4kW array will produce about 16kWh/day at winter solstice, and 28kWh/day at summer solstice. Residence uses average of 20kWh/day, evenly split at 10kWh daylight/dark hours so 13kWh Powerwall will be good size. Probably opt for 5kW array which is only about 2 additional panels (12vs10 440W panels).

So, would system work with Powerwall 3 built in inverter only? Would Powerwall Gateway be required? And, as an alternative to off-grid, could system be installed as grid supported with no feed-in power (residence is located in community with embedded electricity network that does not allow feed-in).

5

While a 4kW solar array may produce 16kWh a day in winter, that doesn’t take into account any daytime loads, which could be 5 to 10kWh depending on your heating requirements and other factors. This leaves very little to charge a battery, especially in poor weather when a system might not produce more than 3 or 4 kWh in a day. These days, the most common solar array size is min 6kW without a battery and up to 10kW with a battery installed.

Have you done a load table or tried a load calculator? This is always the first step before sizing an off-grid or battery system. (I design and install off-grid & hybrid systems for a living)

The full details of the Powerwall 3 have not been released, but it should be no problem to set the system to zero export. Where are you located?

7

Sure! With the Tesla Powerwall 3 for off-grid use, you need: the Powerwall itself (with built-in inverter), solar panels, a charge controller, a main disconnect, and optionally, a backup generator. Solar panels connect to the Powerwall, and the Powerwall connects to your home’s electrical system. That’s the gist!

9

hey @anthonydsouza I am familiar with the Powerwall 3 set up. I am curious how the charge control would integrate into the system?

When we install the PW 3 on-grid there is no charge controller and I was under the assumption that the charge controller was a part of the PW3.

10

@Linc_Reinalda Correct, the PW3 already has 6 built-in MPPTs (solar charge controllers). You cannot use an external charger controller with the PW3. The image below show’s the MPPT inputs and other features. See full details in the full Powerwall 3 Review.

Tesla_Powerwall_3_main_features
Tesla_Powerwall_3_main_features711Ă—810 60.7 KB

11

@anthonydsouza, we’re off the grid just installed 35 panels and two Powerwall 3’s, installation guys haven’t been able to fire up the system without power to the control unit, any ideas?

1 Like
12

Very interested in how you resolve your issue. This is the first actual off-grid installation example since this question appeared.
Any chance you can elaborate on installation configuration? What “control unit” requires power? Are you using a Backup Gateway or Backup Switch?
Seems like Tesla does not want to make PW3 installation manual available.

14

@johnanselmo70, have you had any luck with the system? I assume you are referring to the Gateway unit, which requires a grid connection to operate.

Could you post some photo’s of your installation. It would be great to see it. Cheers

15

Sounds like you’re looking to go off-grid with the Tesla Powerwall 3 – nice choice!

For major components, you’ll need the Powerwall 3 itself, a solar array, and possibly a separate inverter. The Powerwall 3 does have an integrated inverter, but depending on your setup, you might need an additional one for your solar array.

Your assumption is mostly spot on: the solar array connects to the Powerwall, and then the Powerwall connects to your main bus. Just double-check your specific requirements and local codes to make sure everything’s set up safely and efficiently.

16

Yes, the system should work with just the Powerwall 3’s built-in inverter

18

Hi - my installer is trained in PW3 installation and he has told me that it cannot be used to go off-grid. Have you managed to get your system working?

19

For an off-grid solar system using the Tesla Powerwall 3, you will need several key components. Here’s a breakdown of each one and whether or not you’ll need a separate inverter:

  1. Tesla Powerwall 3: This is your energy storage unit. The Powerwall 3 is unique in that it includes an integrated inverter, which converts DC (direct current) power from your solar panels to AC (alternating current) power for use in your home. This feature is new in the Powerwall 3 and eliminates the need for a separate battery inverter, simplifying the setup.
  2. Solar Array: Solar panels generate DC electricity, which will feed into the Powerwall 3. The size of your solar array depends on your energy consumption, location, and the amount of sunlight you receive. Since the Powerwall 3 has an integrated inverter, you can connect the DC output from the solar panels directly to it without needing a separate solar inverter.
  3. Power Distribution Panel (or Main Breaker Panel): This is your home’s main electrical panel, where the Powerwall 3 will connect to supply AC power to your household circuits. In an off-grid system, the Powerwall will act as your primary power source and manage the distribution of electricity.
  4. Critical Loads Panel (Optional): In some setups, it can be beneficial to install a separate panel for essential circuits, ensuring that critical appliances have power during low-energy conditions (like cloudy days or winter). This is optional but can improve efficiency by prioritizing essential loads.
  5. Automatic Transfer Switch (ATS) or Manual Transfer Switch (Optional): Although not always necessary, a transfer switch can help manage multiple power sources (like a backup generator or grid connection, if available). However, in a fully off-grid setup, a transfer switch might be less relevant unless you have a secondary power source.
  6. Backup Generator (Optional): Many off-grid systems include a backup generator for extended periods of low sunlight. This generator can be manually or automatically engaged to charge the Powerwall when solar energy is insufficient.