Can a smart plug relay a command to an inverter cut off from the internet?

You cut your inverter off from the internet. You never gave it the Wi-Fi password, and the app shows it as offline. In the next room sits an ESP32 smart plug. It has power around the clock and stays online, because it won’t work without the manufacturer’s cloud. Could it pass the inverter, over radio, something the inverter won’t get through the internet?

I don’t know. The factory firmware is closed, and I haven’t seen evidence that such a feature exists. I haven’t seen evidence that it doesn’t, either. I’ll start with what has already happened: a manufacturer shut down inverters in several countries, and it didn’t need radio to do it.

Have inverters been shut down remotely before?

Yes. On 15 November 2024 Deye shut down its inverters in the US, the UK, Pakistan and several other countries. The screens showed “This inverter is not allowed use at: USA”.

The blogger solarboi explained why: in the US, only Sol-Ark sells Deye inverters officially, and the units that got shut down were the ones imported around it. So the motive was money. Still, the manufacturer shut down inverters in several countries with one decision, and the command came from the cloud. An inverter without internet would never have received it.

Is it enough to keep the Wi-Fi password from the inverter?

That closes one channel. In May 2025 Reuters (as summarized by Utility Dive) reported that US experts taking apart Chinese inverters and batteries had found undocumented communication devices, including cellular radios. The sources are anonymous, nobody knows how many such devices there are, and SolarQuotes was skeptical.

The attack vector stays the same either way: a separate modem goes around your firewall. And the modem doesn’t have to sit inside the inverter.

Can a smart plug relay a command to an offline inverter?

Here is the scenario: the plug is the Trojan horse, and the inverter is the target. The plug always has power and internet. The inverter is offline, but it still has a radio chip. The plug has to receive a command from the cloud and transmit it over the air, and the inverter has to listen on that frequency and act on a specific frame with no network at all.

The plug can transmit, and that part is no hypothesis. The Wi-Fi module transmits as designed, and arbitrary signals from a cheap chip were demonstrated on the Raspberry Pi long ago: F5OEO’s rpitx transmits AM, FM, SSB and SSTV from 5 kHz to 1500 MHz on a wire attached to GPIO 4, with no extra hardware.

What nobody knows is whether the plug’s factory firmware does this and whether the inverter’s factory firmware listens. Both are closed, I haven’t seen any public teardowns, and an owner can’t check this from their side.

If it exists, it affects more than one house: identical firmware gets an identical command everywhere. Reuters wrote about other devices, the radios in inverters and batteries. One of the two anonymous sources said about them: “That effectively means there is a built-in way to physically destroy the grid”. The Utility Dive summary says nothing about plugs.

How many of these plugs do I have?

Sixteen. On 25 October 2026 I pulled the connection table from my router. Every Tuya device (the WIFI Smart Meter Pro energy meters and the plugs) holds an encrypted connection to the Tuya cloud on port 8883 around the clock, which is MQTT. The servers are in AWS in Frankfurt.

device                            destination               packets from device
meter on the air conditioner  →  AWS eu-central-1:8883   171 805
plug on the outdoor line      →  AWS eu-central-1:8883   150 394
... 14 more devices, all to the same place

Two of them run off the inverter, and one more meter in Home Assistant is literally named “Invertor”. Four of them also send UDP broadcasts to port 6667, which is how Tuya discovers devices on the local network.

The chip in these meters, by the way, is a Beken BK7231N (Tuya CBU module) rather than an ESP32. That changes nothing for my question: it is also 2.4 GHz Wi-Fi with closed firmware and a permanent channel to the cloud.

What did esp-sdr show about the ESP32 radio?

In October 2026 we learned more about the ESP32 radio. esp-sdr came out (Hackaday covered it on 3 October, CNX on 4 October): firmware that, according to its authors, turns an ESP32 into a 2.4 GHz radio receiver with no extra hardware. The authors found an undocumented path the processor can use to read radio samples, bypassing the Wi-Fi modem. ESPARGOS deliberately didn’t publish the transmitter: they were afraid people would use it for jamming.

The community started adding transmit support by 11 October: esp-sdr-zephyr v0.1.1 shipped with experimental transmit on the ESP32-S3. The authors of lozaning/ESP32SDR write that on the S3 the signal doesn’t make it onto the air this way, so they work with a Wi-Fi tone instead. esp32-C5-sdr-tx draws text on a waterfall. Their descriptions don’t make it clear whether all these forks put a signal on the air.

My scenario doesn’t need esp-sdr itself: the plug already has Wi-Fi. Officially esp-sdr only receives, and you have to flash it onto the chip in place of the factory firmware.

It shows that the ESP32 has a path to the radio that the documentation didn’t mention. What a given plug’s factory firmware does with its radio, I can’t see from the plug.

What should you do about smart plugs and inverters?

My meters are queued for reflashing to OpenBeken (ESPHome doesn’t support the BK7231N). After seeing that connection table, it’s the first item on my list.

You can check where a plug connects in a minute: look at the DNS queries and connections from its IP address on the router. If it still does something after you block it but you can’t see it on the network, open the case and look for a SIM slot or a module that isn’t in the documentation.

The router can’t see radio. So I’d handle the question of what to do if someone shuts down the inverter at the distribution panel, outside the network: you need to be able to switch critical loads by hand to another source, the grid or a generator.

I haven’t run esp-sdr myself yet. When I use it to look at the 2.4 GHz band around my house, I’ll add what I see here.