Wi-Fi
Wi-Fi modules, LAN adapters and 4G dongles are the communication accessories that link a solar inverter to the manufacturer's cloud server, so the system can be commissioned from the app, updated over the air and read afterwards in monitoring. Choose by interface (2.4 GHz Wi-Fi, wired Ethernet or 4G with a SIM), by the communication port on the inverter, and above all by brand, because a stick only works with the inverter family it was built for. Modules from Fronius, GoodWe, Huawei, Solis, Solplanet and Victron Energy. Guide
LAN modules are usually more stable in connection as they are less affected by signal interference and offer a higher data transfer rate.
Wi-Fi modules provide a wireless alternative to LAN modules. They allow PV systems to communicate with the grid without the need for physical cables. They are ideal in situations where a wired connection is not practical. However, Wi-Fi modules can be more susceptible to signal interference and may have lower transmission speeds compared to LAN.
Choose the right one and be in control of your PV system.
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Wi-Fi, LAN and 4G: how an inverter gets online
Every modern inverter has a communication port, usually a proprietary connector on the underside of the unit, into which a communication stick is plugged. That stick provides the physical link to the internet and nothing else: it reads the inverter over its internal bus and forwards the data to the manufacturer's portal. Three variants exist. A Wi-Fi module joins the site's wireless network, which is the quickest option and needs no cabling. A LAN module takes an Ethernet cable to the router and is the most stable choice, unaffected by interference and unaffected by a changed Wi-Fi password. A 4G module carries its own SIM and is used where there is no fixed line at all, typically ground mounts, agricultural buildings and remote commercial sites.
These sticks are inverter-brand specific and are not interchangeable. The connector pinout, the internal protocol and the cloud endpoint all belong to one manufacturer, so a Fronius card will not work in a Solis inverter and a GoodWe dongle will not register a Huawei unit even though both plug in physically. Order the module against the inverter's exact model line and generation, and check the manual, because several brands changed their stick between hardware generations. The same accessory also carries firmware updates in the other direction and, on hybrid systems, keeps the smart meter readings and battery state visible in the portal.
FROM THE FIELD
"Half the connection callouts we get are a router problem, not a dongle problem. The installer commissioned it standing next to the inverter with a phone in hand, signal was fine, and nobody checked what the router does at the far end of the house. If the app shows a signal below roughly minus 70 dBm at the inverter, do not argue with it: pull a LAN cable, add a mesh node or fit an external antenna. Retrying the pairing ten times will not create signal that is not there."
Ladislav Proc · Photovoltaics specialist, ONSA Plus
How to choose a communication module for an inverter
There is very little to compare on a datasheet here, because the choice is made for you by two facts: which inverter you have, and what the signal is like where that inverter hangs. Everything else follows.
Work through it in this order: inverter brand and generation first, then the connection medium that the site can actually support, then the signal path from the inverter to the router, and finally the commissioning details, the app account, the logging interval and who owns the data.
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Why the stick is brand specific
A communication module is not a generic network adapter. It sits on the inverter's internal bus, speaks that manufacturer's protocol, and uploads to that manufacturer's cloud with credentials baked into the firmware. Three things therefore have to match.
- The connector: each brand uses its own port and pinout. Some sticks share an outline and still carry different signals on the same pins.
- The protocol: the register map inside the inverter differs by brand and often by product line, so a foreign stick either sees nothing or reports nonsense.
- The portal: the module is pre-configured for one cloud. It has no way to log into a competitor's platform, and the serial number is what registers the plant.
- The generation: within a single brand, an older inverter series and the current one may use different modules. Match the module to the model in the inverter manual, not to the brand alone.
Wi-Fi, LAN or 4G
Pick the medium from the building, not from convenience. Wired is always the safer answer where a cable can be pulled.
- Wi-Fi: no cabling, fastest to install, but subject to interference, wall attenuation and any change of router or password. Best where the inverter is within reasonable range of the access point.
- LAN: an Ethernet cable to the router or a switch. Stable, higher throughput, unaffected by radio conditions, and it survives router replacement as long as DHCP stays on. The default choice for commercial installations and for anything with several inverters.
- 4G: a mobile module with a SIM, for sites with no fixed connection. It needs mobile coverage at the inverter and an active data plan, and monthly data use is small because only measured values are sent.
2.4 GHz and 5 GHz
Almost every inverter Wi-Fi stick is 2.4 GHz only, on 802.11 b/g/n. That is a deliberate design decision, not a shortcoming: the 2.4 GHz band travels much further through brick, concrete and metal enclosures than 5 GHz, the radio is cheaper and draws less power, and the data volume involved is a few kilobytes per interval, so bandwidth is irrelevant. A monitoring stick needs range and penetration, not speed.
The practical consequence appears on modern routers, which broadcast 2.4 GHz and 5 GHz under one name with band steering. The stick cannot see the 5 GHz radio at all, and during pairing the phone is frequently attached to 5 GHz while it tries to hand credentials to a device on 2.4 GHz. If commissioning stalls, split the bands temporarily or create a separate 2.4 GHz guest network for the inverter. Watch the channel width as well: 40 MHz channels on 2.4 GHz cause problems for simple clients, so 20 MHz is the reliable setting.
Tip from practice
Before mounting the inverter, stand at the chosen spot with a phone and check the signal on 2.4 GHz specifically. Anything weaker than about minus 70 dBm will connect on a good day and drop on a bad one. Reserve a fixed IP or a DHCP lease for the module on the router, keep the WPA2 passphrase free of exotic characters, and give the inverter its own SSID if the household network is rebuilt often. A missing connection costs you data in monitoring, never production.
When the inverter sits in a cellar or a garage
Inverters end up in exactly the places radio does not reach: basements, plant rooms, metal-clad garages and outbuildings. Reinforced concrete and metal enclosures attenuate 2.4 GHz heavily, so treat poor signal as a design problem to be solved before handover rather than a fault to be discovered later.
- LAN cable: the definitive fix. A run of Cat 5e or Cat 6 to the router removes the radio question entirely and costs less than a service visit.
- Powerline adapters: the data travels over the existing mains wiring. Effective when both ends sit on the same phase and the same consumer unit, weaker across phases or through an isolating transformer.
- Mesh or a second access point: a mesh node in the hallway above the cellar, or an access point in the garage, usually restores a usable link. Make sure the node broadcasts 2.4 GHz.
- External antenna: several sticks have a detachable antenna with an SMA connector, which can be extended on a short low-loss cable and moved outside the enclosure or into the doorway.
- Metal doors and cabinets: a closed steel door can cost more than a floor of concrete. Where the inverter lives in a metal cabinet, plan for wired connection from the outset.
Commissioning, firmware and logging interval
Commissioning happens through the manufacturer's app, and the sequence is broadly the same for every brand: install the app, create an installer or owner account, connect the phone to the module's own temporary hotspot or scan the QR code on the stick, then pass the home network name and password to the module. The plant is registered under the stick's serial number, and the end customer gets access to that plant afterwards.
- Firmware over the air: once online, the manufacturer can push updates to the module and to the inverter itself. Updates fix grid-code behaviour, battery compatibility and portal bugs, so an inverter that is never connected is also never updated.
- Logging interval: typically 5 minutes for cloud upload, with some brands sending every minute and averaging to 15 minute or hourly values for long-term storage. Live screens refresh faster because the app polls the inverter directly.
- What the portal shows: instantaneous and daily production, monthly and annual totals, per-string DC values on inverters that measure them, self-consumption and import or export when a smart meter is fitted, battery charge state on hybrids, plus event and fault codes.
- Accounts: keep the installer account separate from the customer account. Handing over your own login is what makes later service work awkward.
What happens when the connection drops
Nothing happens to production. The communication module is a monitoring accessory and has no part in the power path: the inverter keeps converting DC to AC, keeps feeding the house and the grid, keeps charging and discharging the battery and keeps its export limit, because that control loop runs between the inverter and the meter, not through the cloud. A lost connection means lost visibility, not lost yield.
What you do lose is the record. Most sticks and inverters buffer recent data internally and upload it once the link returns, so a short outage backfills, but a long one leaves a gap in the portal that cannot be reconstructed. Remote firmware updates and remote diagnostics stop as well, and any alert rule that watches the plant will report the site as offline instead of reporting the real fault. That is why an inverter that carries a service or performance guarantee should be wired rather than left on marginal Wi-Fi.
Quick comparison of connection types
| Connection | What it needs | Where it fits |
|---|---|---|
| Wi-Fi 2.4 GHz | 802.11 b/g/n network in range, WPA2 passphrase, 20 MHz channel | Family houses where the inverter is near the access point and no cable can be pulled |
| LAN | Cat 5e or Cat 6 cable to the router or switch, DHCP | Cellars, plant rooms, commercial sites, multi-inverter installations |
| 4G | SIM, data plan, mobile coverage at the inverter | Ground mounts, farm buildings and sites with no fixed line |
| Powerline | Two adapters on the same phase and consumer unit | Retrofits where a cable route is impossible but the mains is shared |
| Wi-Fi plus mesh or antenna | Mesh node with 2.4 GHz, or an SMA external antenna | Garages and outbuildings just outside usable range |
Swipe the table to the left
Frequently asked questions about Wi-Fi and communication modules
Can I use a Wi-Fi stick from another inverter brand?
No. The connector pinout, the internal protocol and the cloud portal are all manufacturer specific, so a module from one brand will not register an inverter from another even if it plugs in. Order the module for your exact inverter model and generation.
Does my inverter stop producing if the Wi-Fi drops?
No. The communication module only reports data. The inverter keeps converting, keeps supplying the house and the grid and keeps its export limit, because that control loop runs between the inverter and the smart meter. You lose visibility, not production.
Why do inverter Wi-Fi modules only support 2.4 GHz?
Because range and wall penetration matter far more than speed. The 2.4 GHz band passes through brick and concrete much better than 5 GHz, and a monitoring stick sends only a few kilobytes per interval, so the extra bandwidth of 5 GHz would be useless.
The app will not finish pairing. What is wrong?
Usually band steering. Your phone is on 5 GHz while the stick can only join 2.4 GHz, so the credentials never take. Split the two bands temporarily, or set up a separate 2.4 GHz network with a 20 MHz channel and a simple WPA2 passphrase.
My inverter is in the cellar and there is no signal. What are my options?
In order of reliability: run a LAN cable to the router, fit powerline adapters on the same phase, add a mesh node or access point that broadcasts 2.4 GHz, or move the stick's antenna outside the enclosure using an SMA extension. A cable is the permanent fix.
Is LAN better than Wi-Fi for an inverter?
Yes, where a cable can be pulled. A LAN link is unaffected by interference, wall attenuation or a changed Wi-Fi password, offers higher throughput and survives a router swap. It is the standard choice for cellars, plant rooms and multi-inverter commercial sites.
How often does the inverter send data to the portal?
Cloud upload is typically every 5 minutes, with some brands sending every minute and condensing to 15 minute or hourly values for long-term storage. Live screens in the app refresh faster because they poll the inverter directly on the local network.
Does a 4G module need its own SIM and data plan?
Yes. A 4G module needs an active SIM with data, and some are supplied with one preinstalled. Data use is small because only measured values are transmitted, but mobile coverage has to be checked at the inverter position before installation.
Can the inverter firmware be updated over the connection?
Yes. Once the module is online the manufacturer can push firmware to the module and to the inverter itself, covering grid-code behaviour, battery compatibility and portal fixes. An inverter that is never connected also never receives those updates.
Do I lose the data recorded while the connection was down?
Short outages usually backfill, because the module and inverter buffer recent readings and upload them when the link returns. A long outage leaves a permanent gap in the portal. Production during that time is unaffected and is still counted by your smart meter.
Communication modules are inverter specific. Check the module against your exact inverter model and firmware version before ordering.
About ONSA Plus
Why installers across Europe order communication modules from us
ONSA Plus is a European B2B distributor of photovoltaics, battery storage, heat pumps and EV charging stations. In our own EU warehouses we keep over 1,500 products from 25+ brands, including Huawei, Solis, SolaX and Dyness.
We are not just a trading company. We design and service energy systems ourselves, so we answer questions on inverter communication and monitoring setup from engineering practice, not from a catalogue. You handle a warranty claim directly with us and you buy per job.
