As grids in the CIS, Middle East and Southeast Asia absorb more solar and BESS capacity, interconnection studies are increasingly asking a question that barely existed five years ago: can your inverter form the grid, or only follow it? Getting the answer wrong at the design stage can mean a failed grid code study and a re-engineered plant months before commissioning.
What Makes an Inverter "Grid-Forming"?
A grid-forming (GFM) inverter regulates its output as a voltage source with a fixed internal phase angle and magnitude, the same role a spinning synchronous generator has always played. It can set voltage and frequency independently, ride through disturbances by injecting fast fault current, and — in the right configuration — energize a de-energized bus without any external reference. A conventional grid-following (GFL) inverter, by contrast, is a current source: it measures the grid's existing voltage and frequency via a phase-locked loop and injects current in sync with it. Take the grid reference away and a pure GFL inverter has nothing to follow.
Grid-Following Inverters: The Incumbent Standard
Grid-following control has been the default for utility-scale solar inverters for two decades because it is simple, cheap, and works well on grids with abundant synchronous generation to set the voltage and frequency reference. The vast majority of installed string and central inverter capacity worldwide is grid-following, and for a strongly interconnected grid with low renewable penetration, that remains the right economic choice. The limitation shows up as renewable penetration rises: a grid with too few spinning machines and too many GFL inverters can lose frequency stability during a fault, because nothing is actively holding the reference the GFL fleet depends on.
Why Grid-Forming Matters on Weak Grids and High-BESS Sites
This is precisely the scenario many Econo Solar clients are designing into: remote grid segments in Central Asia, island and mining microgrids in Southeast Asia, and Middle Eastern transmission networks adding gigawatts of solar and storage faster than new transmission and synchronous capacity can be built. On these systems, grid operators are starting to write GFM requirements directly into interconnection codes, particularly for battery energy storage assets that can supply the short-circuit current and inertia response a weak grid needs. A GFM-capable ST255CS-2H PCS, for example, can stabilize local voltage and frequency during a fault on a section of grid that would otherwise trip a purely GFL solar plant offline.
Sungrow's Grid-Forming Capable Platforms
Sungrow has rolled grid-forming control out as a firmware-selectable mode across several utility and storage platforms rather than a separate product line. On the storage side, PCS units in the MGL060 and ST255CS-2H families support GFM operation for microgrid and weak-grid applications, including black start sequencing when paired with the appropriate plant controller. On the solar side, Sungrow's central inverter platforms used in large utility-scale utility inverter deployments are being certified against GFM-inclusive grid codes in select markets as those codes are finalized. Because GFM is a firmware and control-loop capability rather than a hardware SKU, the exact availability depends on model, firmware revision, and the target grid code — always confirm current certification status with your Econo Solar sales engineer before finalizing equipment on a single-line diagram.
| Characteristic | Grid-Following | Grid-Forming |
|---|---|---|
| Control reference | Follows measured grid voltage/frequency (current source) | Sets its own voltage/frequency (voltage source) |
| Blackout / islanded start | Cannot start without an external reference | Can black-start an islanded section |
| Fault ride-through | Limited fast fault current contribution | Higher, controllable fault current injection |
| Best fit | Strong grids, low renewable penetration | Weak grids, microgrids, high BESS/solar penetration |
| Typical cost premium | Baseline | Low single-digit % on PCS/inverter cost |
Specifying Grid-Forming Inverters: A Procurement Checklist
When an interconnection study or grid code flags a GFM requirement, procurement teams should confirm five things before issuing a purchase order:
- Which specific firmware version and control mode delivers certified GFM behavior on the proposed model
- Whether black start capability is included or requires a separate license and plant controller
- The short-circuit current multiple the unit can sustain during a fault (commonly 1.1–1.5x rated current for several cycles)
- Type-test or grid code compliance reports from an accredited lab for the target country's code
- Whether GFM mode is compatible with the plant's chosen hybrid inverter or PCS topology and existing SCADA/plant controller
Grid Codes and Compliance Across CIS, Middle East and SE Asia
Grid code requirements around grid-forming behavior are moving fast and vary significantly by country — some transmission operators in the Gulf and Central Asia are now referencing IEEE 2800 or similar inverter-based-resource standards directly in interconnection agreements, while others still operate under legacy codes with no GFM language at all. Because these requirements can change between the feasibility study and commissioning of a multi-year project, EPCs should build in contractual flexibility to update inverter firmware or, in rare cases, swap PCS models without a full re-engineering cycle. Econo Solar tracks grid code updates across our active markets and flags GFM requirements during the initial equipment quotation stage precisely to avoid this kind of late-stage rework.
For EPCs bidding on tenders in these regions, the practical takeaway is to treat grid-forming capability as a line item in the technical specification, not an assumed default. Ask the grid operator's interconnection team directly whether GFM behavior is required, request the relevant IEEE 2800 or local grid code clause in writing, and get equipment compliance confirmed by the manufacturer before pricing is locked. That single step avoids the most common source of late-stage cost overruns on weak-grid solar and storage projects today.