I built a custom integration for the Span MAIN 40 (Gen3) smart electrical panel and wanted to share it with the community.
Why?
I got a Span MAIN 40 installed and immediately wanted it in Home Assistant. The problem: the Gen3 hardware completely replaced the REST API with a new gRPC-based protocol. The existing SpanPanel/span integration (which is great for the older MAIN 32) doesn’t work — the REST endpoints return 502 on Gen3 panels.
So I reverse-engineered the gRPC protocol and built a new integration from scratch.
What it does
Real-time circuit monitoring — power (W), voltage (V), current (A) for every circuit
Main feed sensors — total household power, voltage, current, line frequency
Breaker state detection — binary sensors that show ON/OFF for each breaker
Dual-phase support — correctly handles both 120V single-phase and 240V dual-phase (dryer, range, etc.)
Config flow — set up through the UI, just enter the panel’s IP address
100% local — direct gRPC to the panel on port 50065, no cloud, no API keys
On my 25-circuit panel, it creates 104 entities (4 main feed + 75 circuit sensors + 25 breaker binary sensors).
How it works
The Gen3 panel uses a gRPC trait system:
Trait 26 (power metrics) — discovered via GetInstances, streamed via Subscribe
Trait 16 (circuit names) — fetched via GetRevision
Trait 17 (circuit config) — used to detect single vs dual phase
The integration subscribes to the gRPC stream for continuous real-time updates — no polling.
Installation
Available as a HACS custom repository (HACS default submission pending):
HACS → Custom Repositories → add https://github.com/Griswoldlabs/span-panel-ha as Integration
Install “Span MAIN 40”
Restart HA
Settings → Integrations → Add → “Span MAIN 40” → enter panel IP
If you have a Span MAIN 40 Gen3 panel, I’d really appreciate you trying this out and reporting any issues. And if anyone has an MLO 48, I’m curious whether it uses the same gRPC protocol.
OMG… I wanted this sooo bad… you can’t imagine how many calls I had with SPAN and long waiting for their release of an API… I just came across this by pure chance as I was trying to collect more information to start doing something… I didn’t read anything you posted yet…but this is me after reading that you reverse engineered it.
I’ve the Span40, I want to help I’ve some experince with programming. My SPAN40 is connected wirelessly but I don’t have the port 50065 open or responding. the ping is working normally and I’ve the panel set to fixed IP on my pfSense. any help?
Update — Span disabled gRPC access in firmware 7.2.0
Hey everyone, unfortunate update here.
About 4 days after I posted this integration, Span pushed firmware 7.2.0 to Gen3 panels which intentionally disabled gRPC access. The
port changed from 50065 to 50058, and all gRPC methods now return UNIMPLEMENTED. REST still returns 502. So as of 7.2.0, there is no
local API access at all on Gen3 panels.
Span’s official statement was that the “gRPC service was unintentionally accessible” and they “deployed a release to remove access to
this gRPC service from any external network” — with “external” meaning your own home LAN.
So to be clear: if your panel has updated to 7.2.0, this integration no longer works. If you’re still on an older firmware and it’s
working — I’d strongly recommend blocking OTA updates if you can.
Where things stand now:
Span has announced an official local API (SPAN API + SPAN Home On-premise) but it’s only available on MAIN 32 right now. Gen3 support
(MAIN 40, MLO 48) is slated for H2 2026 — so months away at best.
All undocumented local access methods are being deprecated December 31, 2026.
There’s active work on PR #169 in the SpanPanel/span repo to upstream Gen3 gRPC support, but that’s obviously blocked by the same
firmware lockdown.
It’s frustrating. We had full local monitoring working — real-time, no cloud, no polling — and it lasted 4 days. I understand Span wants
to control their API rollout, but locking out local access on hardware people own and installed in their homes is a tough look.
I’ll keep the repo up and update it if/when local access becomes viable again — whether through Span’s official API or community efforts.
SPAN Management and Legal Team,
I am writing to formally document a consumer complaint regarding my SPAN smart electrical panel.
The device was installed in 2025 at my residence in Texas through an authorized installer (------------). I did not sign any direct contract with SPAN.IO.
Product Information
SPAN Panel Main 40 + MID
Serial Number: --------------
Software Version: 7.2.0
The panel performs energy monitoring and circuit control through the SPAN mobile application. However, several critical capabilities that would reasonably be expected from a smart electrical panel appear to be restricted.
Primary Concerns
Local Control Restriction
The panel cannot be accessed or controlled locally without internet connectivity. All monitoring and control functions depend entirely on SPAN’s cloud platform.
Data Access Limitations
The application displays circuit-level energy consumption. However, the only available export is a low-resolution CSV file that must be manually requested through multiple steps within the mobile application and is delivered by email.
High-resolution telemetry required for meaningful automation, diagnostics, and analysis is not accessible to the homeowner and cannot be retrieved locally without internet connectivity.
The device clearly measures detailed circuit telemetry because that information is displayed within the SPAN application, yet homeowners are prevented from accessing that data directly.
Smart-Home Integration Blocked
My home uses Google Home and Home Assistant automation platforms. These systems cannot integrate with the panel because SPAN does not provide a local API or supported integration interface for this model.
Community developers previously demonstrated local monitoring using the panel’s gRPC interface. According to the Home Assistant developer discussion, firmware version 7.2.0 disabled that local access capability.
Reference:
https://community.home-assistant.io/t/span-main-40-gen3-integration-grpc-based-local-only-first-gen3-support/987697/8
Automation and Safety Limitations
Because the panel cannot receive commands from local automation systems, several safety and energy management automations cannot be implemented. Examples include:
• water-leak sensors automatically disabling affected circuits
• gas-leak sensors triggering electrical isolation
• smart-home systems controlling specific devices based on circuit consumption data
These are common use cases within modern smart-home environments.
Installer-Only Configuration
Certain configuration tasks require a SPAN authorized installer and proprietary installer tools.
I recently paid for a service visit solely to configure communication between the SPAN panel and my Tesla Powerwall despite already completing the physical wiring.
During installation I also had to correct several wiring and termination issues left by the installer.
Evidence
I have retained screenshots from SPAN marketing pages describing the product as a smart electrical panel capable of circuit-level control and energy monitoring. I also have email correspondence with SPAN support confirming that local API access is not supported for this model.
**Consumer Rights Concern**
The limitations described above raise concerns regarding whether the operational restrictions, data access limitations, and cloud dependency were clearly disclosed prior to purchase. Because this device is marketed as a smart electrical panel with circuit-level monitoring and control capabilities, the inability for the homeowner to access telemetry data locally or integrate the panel with standard smart-home automation systems may materially affect how the product can be used within a residential energy management environment.
Requested Resolution
I respectfully request the following:
1. Access to circuit-level telemetry at a usable resolution
2. Adocumented local interface or API for monitoring and automation
3. Clarification regarding homeowner access to device-generated energy data
4. The ability for the device owner to manage firmware updates and software control features
This complaint has also been copied to the Texas Attorney General Consumer Protection Division, the Texas State Board of Professional Engineers, and the Federal Trade Commission for documentation purposes.
I would appreciate a written response within ten (10) business days describing whether these capabilities can be made available to the homeowner.
Regards,