Growatt export limit - counter TPM-CT-G/Eastron, CT mounting and percentage settings

Export limitation is a function that installers ask about more often than power today - because more and more new connections are now being provided with conditions with a hard limit on energy output, and overloaded networks turn off inverters during peak hours. Growatt export limit works in MIN, MOD and MID under one hard condition: an external smart meter from the recommended list, correctly connected and with communication enabled. This article goes through the selection of the meter (TPM-CT-G, Eastron, CHINT), installation of CT transformers with the correct direction, three configuration paths, conversion of connection conditions to percentage settings and diagnostics - including Error 311, meter communication warning and commercial variant on the master controller for multi-inverter farms.

How Growatt export limit and when is it required?

The principle on which it stands Growatt The export limit is simple: a meter at the connection point measures the flow to the grid, and the inverter throttles the power so that export doesn't exceed the set point. The limit is set as a percentage of the rated power—an example from the manual: a 10 kW inverter with a 30% limit will feed a maximum of 10 kW × 30% = 3 kW into the grid. The function also has a second, lesser-known side: a negative value limits DRAW from the grid—with a setting of −30% on a 10 kW unit, the grid will supply a maximum of 3 kW, with the remaining needs covered by the inverter from PV and batteries.

Without a counter, there is no function - and in the warehouse system, a counter is required at all, because without it some functions remain unavailable. Growatt export limit is therefore needed in three situations: when the DSO has included an export limit in the connection conditions, when high grid voltage forces the suppression of export (we expand on this topic in the article about Error 300) and whenever the inverter is to control self-consumption and operating modes in a system with a battery.

Element	Value
Operating condition	external smart meter from the recommended list + communication enabled
Positive setting	percentage of rated power allowed for export (10 kW × 30% = 3 kW)
Negative setting	percentage of power allowed to be drawn from the grid
Phase mode	"Phase levels" - limit enforced per phase
Configuration locations	OLED / ShinePhone / Server webpage
Safeguard	Error 311 - export limitation fail-safe

Which counter should you choose? Recommended model matrix

The manual provides a closed list of recommended meters and warns explicitly: any model not listed risks protocol incompatibility. The choice depends on the system architecture—specifically, the number of units and the measurement method:

The third line is often overlooked with costly consequences: in parallel systems, a series MID allows up to 9 units in a networked system - the table indicates the Eastron SDM630MCT for this role. The "single" counter in a farm of several units is a configuration outside the manufacturer's list.

Meter and CT Installation - Three Wiring Pitfalls

First trap: transformer direction. On the meter CT Growatt the K→L designation is printed, where K looks towards the grid and L towards the inverter - an inverted transformer gives a measurement with the opposite sign and the inverter regulates exactly backwards. Second trap: phase sequence. The manual warns that the inverter phase sequence must match the meter's, otherwise neither export limitation nor the operating modes will work - L1 of the meter must be L1 of the inverter, not "any".

Pitfall three: communication. After physically connecting the RS485, the meter must be turned ON in the inverter settings. Skipping this step results in the classic "everything connected, nothing working" error. Growatt communicates via Modbus-RTU with communication address 1 at a distance of up to 200 m; single-phase communication interrupted MIN they report directly with a 401 warning - the first steps are to check whether the meter is powered and connected correctly.

A separate paragraph should be devoted to the meter's power supply: transformer-based models have their own power supply and their own protection in the switchboard—a circuit that someone will eventually turn off "because they don't know what it is." Permanently mark it with the description "PV meter—do not turn off," because a power outage to the meter is the shortest route to fail-safe and a call from the customer. Growatt export limit inherits the reliability of the weakest element of the measurement chain, and this element is almost never the inverter.

Configuration: OLED, App and Server - Three Paths, One Password

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Growatt The export limit is set in three places. On the OLED panel, the setting is located in Settings → Advanced Settings → ExportLimit, next to the country and sensor type selection. ShinePhone and on the Server webpage the path leads through the inverter settings - on the Server directly: Setting → Export limit setting → Enable → Set the Phase level.

There is one "but" that stops most of the independent attempts: changing these parameters in the application and on the Server requires a password, and access to the password is provided by service personnel GrowattThis is a deliberate barrier—the export limit is a requirement for connection, so the manufacturer doesn't leave it to each app user. For the installer, this means: plan the configuration in advance, with service access arranged before the visit, not discovered on a ladder.

How to translate connection conditions into percentages?

The setting is a percentage of the inverter's rated power, and connection conditions typically specify kilowatts—the conversion is a single division, but with two rules. First rule: the basis is the unit's rated power, not the PV installation's power—for a 10 kW inverter with a 3 kW output limit, the setting is 30%, regardless of how many panels are on the roof (editorial conversion based on a numerical example from the manual). Second rule: rounding—if the division is not even, round the setting DOWN; the limit from the conditions is the ceiling, not the target.

In multi-unit systems, the calculation is made on the sum of the rated powers, and the implementation depends on the architecture: a common counter and configuration in accordance with the table of recommended models for parallel systems, and on a commercial scale - a master controller from the section o ShineMasterEnter the conversion result into the protocol next to the source value from the conditions: "3 kW → 30% on a 10 kW unit" - this one line ends any future discussion about where the setpoint came from.

Phase Limit - Why "Phase levels" changes the score

W Growatt The export limit phase mode determines how the setpoint is distributed across L1/L2/L3. The manual provides a calculated example: a 10 kW unit with a 30% limit and a 1 kW load only on phase L1 will produce L1: 2 kW and L2 and L3: 1 kW each — so that the export on EACH phase is exactly 1 kW. Without phase mode, the limit monitors the total; with phase mode — each phase separately.

The connection conditions dictate which option to choose: if the operator bills a per-phase limit (typical for unbalanced installations), phase mode is mandatory, as a total of 3 kW could mean 3 kW on a single phase and violate the conditions. Negative values ​​also apply per-phase, making this function also a tool for monitoring contractual power consumption in systems with storage.

Export limit and connection conditions - formal order

Increasingly, the limit is not a choice, but a condition: operators are including delivery restrictions in the connection conditions for new installations and expansions, especially in circuits with exhausted capacity. In such a situation Growatt The export limit is the technical implementation of a contractual obligation, and this changes the importance of the configuration: the setting must precisely match the value from the connection documents, and proof of this (protocol, screenshot, meter model) must be able to be shown. Conditional provisions vary between operators and cases. Always read the values ​​and the method of their settlement (total or per phase) from your own documents, not from other people's examples.

On the hardware side, the same function handles both commitment directions: a positive setting monitors export, a negative setting monitors consumption, which can be useful for monitoring contracted power in facilities with storage. In practice, when the conditions call for a per-phase limit, enable "Phase Levels" mode without question – summary billing with an asymmetric load can appear correct in the application while simultaneously violating the conditions for one phase.

What can be seen in the monitoring when the limit is in effect?

Working properly Growatt The export limit leaves a characteristic image in the application: the production curve rises in the morning as usual, then flattens out during the surplus hours, precisely at the setpoint level—not a binary one like with Error 300, but an even plateau. Underneath, the inverter constantly keeps up with changes in the house load: turning on the kettle increases production, turning it off returns to the plateau. This "breathing" on the graph is the simplest proof that the meter reading is working and the control is alive. Take a snapshot of such a day for documentation—this same plateau, shown to the customer in advance, builds trust instead of suspicions of faulty equipment.

It's also worth showing the client the other side of the coin: the area between the potential production curve and the plateau represents uncreated energy. At low limits, this area grows rapidly—and this is the real argument for storage, which turns the truncated peak into evening self-consumption. Growatt export limit and battery do not compete with each other: the limit monitors obligations to the grid, the storage saves the economy - in battery-ready systems, both things are configured on the same meter.

Commercial Systems - ShineMaster-X as limit supervisor

Above several units, the regulation is taken over by a dedicated controller. ShineMaster-X manages up to 124 inverters and has a system export restriction function built directly into the datasheet. It is ready for communication with C&I objects: four RS485 buses with a range of up to 500 m, LAN, CAN, and a 2G/3G/4G modem, with Modbus-RTU, Modbus-TCP, and IEC 60870-5-104 protocols—the latter being the language spoken by operator dispatch systems.

For control and measurement, the controller provides inputs and outputs (DI ×5, DO ×2, AI ×4), and commissioning is carried out via the built-in web and application via Bluetooth/WiFi. Growatt The farm-scale export limit is therefore in a different league of implementation than a home-based percentage setting—but the logic remains the same: measurement at the connection, power regulation, proof of compliance with the conditions. Projects of this scale should be conducted in conjunction with the technical department; the controller card is a starting point, not complete implementation documentation.

What NOT to do when configuring an export limit

• Do not use a counter that is not listed as recommended - the manual warns about communication protocol incompatibility.
• Do not install CTs "as is" - the direction K→L is defined: K from the grid, L from the inverter.
• Do not mix up the phase sequence between the inverter and the meter - without a matching sequence, the limits and operating modes do not work.
• Do not forget to enable the meter communication programmatically after installation.
• Do not use a meter for a single unit in a parallel system - for multiple inverters the table indicates SDM630MCT.
• Don't promise the customer "I'll set the limit from the app in 5 minutes" - changes in the APP/Server require a service password.

Diagnostics: Error 311 and Warning 401

The system has a built-in logical fuse: Error 311, or export limitation fail-safe. The inverter reports this when limit monitoring loses reliable data, and the instructions instruct the user to check the CT and meter connection after shutdown. This protection is based on connection conditions: since the inverter cannot see the measurement, it cannot guarantee the limit, so it responds. The second signal is warning 401 about incorrect communication with the meter. This is the first signal when the limit "stops working" after months of correct operation, as the most common cause is a disconnected meter power supply or a broken RS485 connection.

Diagnostics sequence from practice: meter power supply → RS485 continuity and polarity → communication enabled in settings → CT direction → phase sequence. Growatt export limit after correct installation is maintenance-free - if it returns in reports, it is almost always due to interference in the switchboard between visits.

Finally, some context that ties this article together with the rest of the knowledge base: Growatt The export limit is one of three tools for dealing with an overloaded connection – alongside the energy storage (described in the battery family guide) and voltage diagnostics from the Error 300 article. A well-executed project uses them together: a two-point measurement tells you whether the problem is yours or the grid's, the limit closes formal obligations, and the battery saves the economy of what the limit would have cut. Growatt An export limit configured without this comprehensive diagnosis can be a symptom treatment – ​​effective, but more expensive than necessary.

From the installer's practice

Four observations from limit implementations – practical tips, not manufacturer requirements.

• From practice: document the phasing with a photo of the marked wires at the meter and at the inverter - disputes about "who swapped the phases" return every time the switchboard is modernized.
• In practice: after configuration, perform a throttling test: turn on the large receiver, then turn it off, and watch in the app as the export stalls at the set point. One test upon receipt replaces three future complaints.
• From practice: enter the limit setting and the meter number in the acceptance protocol together with a photo of the confirmation screen - when checking the connection conditions, this is your proof of proper configuration.
• From practice: when handing over the installation, explain the plateau on the graph to the client before asking - "why is it cutting off?" is the most common call during the first sunny week after implementing the limit.
• From practice: in switchboards with a reserve of space, install the meter immediately after the first battery-ready installation, even if the limit is not yet necessary - adding a CT in a tight, live switchboard after two years costs more than the meter module today.

FAQ - Frequently asked questions about Growatt export limit

What does "Power Limit Active" mean in the app?

The inverter is currently throttling power to the set limit—meaning the function is doing exactly as configured. This is an operating condition, not a fault—and this is precisely how it should be described to the customer upon delivery, before the first sunny day turns into a service call. Something else should be a cause for concern: Error 311, which indicates that the limit monitoring device has lost measurement.

Can I set export to zero?

The percentage mechanism allows for settings as low as zero, while the phase mode monitors them per phase. Remember the energy consequences: unexported and unconsumed energy will not be generated – at limits close to zero, storage ceases to be an additional benefit and becomes a requirement for the installation's viability.

Czy Growatt export limit works without batteries?

Yes, this feature requires a meter, not a battery. The battery only changes the cost-effectiveness calculation: with it, any excess over the limit is charged to the bank instead of being lost.

What happens when the meter stops responding?

Fail-safe mode is activated: Error 311 signals the loss of reliable measurement and the inverter stops guaranteeing the limit instead of guessing. Diagnostics begins with the meter power supply and RS485, and on single-phase MIN in parallel, watch out for warning 401. This is design behavior - a system with a limit in connection conditions cannot "fly blindly".

Where can I find the password for the settings in the app?

The manual refers you to service personnel for this. Growatt — In distribution practice, you agree on access through the channel where you purchased the device. We do not publish service passwords and advise against using those circulating on forums — configuring the limit is your responsibility to comply with the connection conditions.

Export Limit Implementation Checklist

1. Counter from the recommended list, selected for the number of units (parallel → SDM630MCT).
2. CTs mounted with direction K to the grid, L to the inverter.
3. Phase sequence consistent between meter and inverter.
4. RS485 connected; meter communication enabled in settings.
5. Service access to APP/Server agreed before the visit.
6. Limit setting (and phase mode if required by conditions) set and throttle tested.
7. Protocol entry: meter model, setting, confirmation dump.
8. Customer informed that "Power Limit Active" is working as configured.
9. Communication loss test discussed in handover documentation: who responds to Error 311 and what the service contact looks like.
10. For parallel systems: measurement architecture (one SDM630MCT meter) confirmed before ordering, not on site.

If the export limit is due to an overloaded grid, consider storing energy instead of giving it away for free - you can calculate the selection for your inverter in configurator Growatt, and the starting point for battery-ready is set APX 5 kWh for MIN-XH and other configurations from the category Energy storageInstructions with full procedures are published download center Growatt.