What firmware actually is on a solar inverter
Firmware is the low-level software written directly to the processor chips inside your inverter and battery. Unlike an app on your phone that runs in memory, firmware controls the hardware itself — the switching transistors, MPPT algorithm, battery charge controller, grid protection logic, and communications stack. Updating it replaces the instructions the hardware runs on, not just the interface you see.
Each firmware release typically contains a mix of: bug fixes (correcting fault code false positives, fixing charging errors), algorithm improvements (better MPPT tracking, smarter battery discharge curves), new feature support (new tariff integrations, new battery model compatibility), grid standard compliance updates (new G98/G99 requirements, voltage tolerance adjustments), and communications improvements (portal connectivity, app protocol updates).
Most updates improve the system. The problems arise because firmware writes are not like saving a document — they replace the executable instructions on the chip, and any interruption or incompatibility can leave the chip in a broken state. The settings side-effects are a separate issue: many firmware updates reset configuration parameters to factory defaults as part of the write process.
Modern hybrid systems typically have three separate firmware components, each on its own processor: the inverter main board (controls power conversion, grid interface, MPPT), the battery BMS firmware (controls charge/discharge curves, cell balancing, fault protection), and the communications dongle firmware (handles WiFi, portal connectivity, app protocol). Updates may target one, two, or all three simultaneously.
Most modern inverters update over the air (OTA) through the monitoring portal or app — you trigger the update from a dashboard, the server pushes the firmware file to the dongle, and the dongle writes it to the inverter over its internal communication bus. Some older models require manual update via a USB drive or direct laptop connection. OTA updates are convenient but depend on a stable internet connection throughout — any drop mid-write is the leading cause of corrupted firmware.
The five realistic risks of a firmware update
These are not theoretical edge cases — they are the failure modes we diagnose regularly. Knowing them in advance means you can check the right things immediately after any update, rather than discovering problems days later when you receive an unexpected electricity bill.
The most common post-update problem. Many firmware updates wipe or reset the configuration partition as part of the write process. The settings most frequently affected are: charge/discharge schedules, export limit value, CT clamp direction, EPS mode, battery reserve (minimum SoC), and peak-rate avoidance windows. The inverter continues to run after the update — it just runs on defaults, which may mean it is charging your battery at the wrong time, exporting more than your DNO limit allows, or providing no backup reserve.
If the internet connection drops, the inverter loses power, or the portal server times out during the firmware write, the update can stall mid-process. The result ranges from a recoverable frozen progress screen (the write actually completed but the portal did not receive confirmation) to a genuinely partially written firmware partition that leaves the inverter unable to boot. A genuinely bricked inverter shows no display, no output, and does not respond to normal startup procedures.
Manufacturers develop and validate inverter and battery firmware together. When a new inverter firmware introduces a change to the BMS communication protocol — which happens in major version updates — battery firmware from two or more versions behind may not understand the new commands. The result is typically the battery appearing offline, the inverter reporting BMS communication errors, or the battery being stuck at a fixed charge level because the inverter cannot query its actual SoC.
This is why update sequences matter: update inverter and battery in the correct order the manufacturer specifies, and do not leave the job half-done if you have a multi-battery stack.
Firmware updates that include a dongle component can affect WiFi connectivity between the dongle and your router, or the protocol between the dongle and the portal. After some updates, the dongle needs to re-authenticate with the server. Monitoring data may appear to stall or show the system offline for hours. In some cases, a full dongle re-registration is required — a process that is not always straightforward and can temporarily break access to historical data.
If monitoring goes offline after a firmware update, wait 30 minutes for the dongle to re-establish connection before investigating. Power-cycling the dongle (not the inverter) is usually the correct first step.
Firmware updates occasionally introduce new bugs — fault codes that were never present before the update, charging behaviour that has changed subtly, or export limiting that is less precise than it was. This is more common in major version updates and in updates released close to a new product launch (when engineering resources are stretched). It is why reading release notes matters — the solar community on forums like GivEnergy Community and Sunsynk users groups often reports new issues within days of a release, before the manufacturer has acknowledged them.
If you can, wait two to three weeks after a major firmware release before applying it to your system. Let other users identify any regressions first. Minor releases (patch versions) are generally safer to apply promptly.
What to do before triggering a firmware update
Five minutes of preparation before an update saves hours of diagnostic work afterwards. Record your current settings so that if a reset occurs, you can restore them from notes rather than having to rediscover them.
Open your monitoring app or portal and take a screenshot of your charge/discharge schedule settings. Include the start and end times of each window, the target SoC, and whether AC or DC charging is selected. This takes 30 seconds and means a reset schedule can be restored in under two minutes.
Record the current export limit — the maximum power the system is permitted to export to the grid. This is set per your DNO agreement and typically does not change, but knowing the value means you can restore it immediately if it resets.
If your inverter has a software CT clamp direction setting (common on GivEnergy, Sunsynk, and Fox ESS systems), note which way it is set. A reversed CT clamp direction causes immediate, obvious problems — the inverter reads grid power backwards — but it is easily corrected if you know what the correct setting was.
Search for the specific firmware version number before applying it. Manufacturer community forums (GivEnergy Community, Sunsynk Users, Solis forum etc.) often have user reports within days of a release. If the version has a known regression — battery going offline, monitoring breaking, specific fault codes appearing — you will find it there. If it is a very new release with no user reports, waiting a week is prudent.
Trigger updates during daytime hours when the system is generating but not during your overnight cheap-rate charging window. If the update resets your schedule and you do not notice until morning, you will have missed an entire overnight charge cycle at peak rate. Midday on a weekday is ideal — you are likely to be around to check the settings immediately after the update completes.
Confirm the system is showing as online with a stable connection in the portal before initiating the update. A marginal WiFi signal that sometimes drops is the most common cause of a stalled or corrupted firmware write. If your dongle has intermittent connectivity, improve the WiFi signal or use a wired connection before attempting any firmware update.
A remote diagnostic can review your current configuration against your tariff and DNO agreement before you update — so you have a verified baseline to restore from if anything resets.
The six things to check after every firmware update
Check these immediately after the update completes — not the next day. Most settings resets are trivially easy to fix if caught within an hour. Caught after 24 hours, they may have already caused an avoidable expensive import cycle.
Open the schedule settings in the portal or app. Verify that your timed charge windows are still set to the correct hours with the correct target SoC. If you are on Octopus Go, Flux, or Economy 7, the charge window must align with your cheap-rate hours exactly. A reset schedule typically shows as disabled or set to a generic 00:00–06:00 window that does not match your tariff.
Check the export limit setting and confirm it matches your DNO agreement. A reset to zero blocks all grid export (you lose SEG payments). A reset to maximum may exceed your G99 agreement. Both need correcting before nightfall.
If your inverter has a software CT direction setting, check it has not been reset. Signs of a reversed CT clamp include the portal showing grid export when you are importing, the battery charging at unexpected times, or generation figures appearing negative. See our guide on CT clamps explained for more detail.
If you have EPS (Emergency Power Supply) or backup power configured, verify EPS mode is still enabled and the backup SoC reserve is still set to your desired minimum level. A reset here means the battery can fully discharge during normal operation, leaving nothing in reserve for a power cut.
Confirm the system is reporting live data to the portal. If it shows offline, power-cycle the WiFi dongle (not the inverter) and wait 10 minutes. Most post-update monitoring outages resolve within 30 minutes without intervention as the dongle re-authenticates with the server.
During daylight hours, confirm the system is actively generating. Zero or significantly reduced output on a clear day after a firmware update should be investigated immediately — it may indicate a configuration change that is preventing normal operation, or in rare cases a firmware regression that has introduced a grid connection fault.
Brand-specific firmware notes
Firmware behaviour varies significantly between manufacturers. These are the patterns we see most often in practice.
Updates are triggered via the givenergy.cloud portal under My Inverter → Software. The portal updates inverter and battery firmware sequentially — do not interrupt between the two. After any update, the four most commonly reset settings are charge schedule, export limit, CT clamp direction, and EPS mode. The dongle firmware is updated separately and occasionally requires a re-pair to the portal.
GivEnergy firmware update guide →Huawei firmware is typically pushed automatically via the FusionSolar platform, but manual updates are possible via the FusionSolar installer app. LUNA2000 battery firmware is often updated separately from the inverter. Version mismatches between the SUN2000 inverter and LUNA2000 battery can cause the battery to appear offline or report inaccurate SoC. After any update, check battery status in the FusionSolar app and verify that the energy storage system shows as connected and active.
SolarEdge firmware is typically pushed automatically by the MySolarEdge platform. Because the update is often automatic and silent, homeowners frequently discover post-update issues without knowing an update occurred. If your SolarEdge system behaviour changes unexpectedly, check the system event log in the monitoring portal for a firmware update event in the preceding 48 hours before investigating hardware faults.
Solis updates via the SolisCloud portal and require the installer code (typically 2014 or a dealer-specific password) to access advanced settings. After a firmware update, Solis systems commonly reset the meter/CT direction and the self-use mode priority order. If the battery starts importing from grid during peak hours after an update, check both the operating mode and the meter direction setting.
Growatt firmware can be updated via the ShinePhone app or ShineServer portal. The update process for Growatt systems is generally reliable, but the SPH (hybrid) range is known to reset the charge window settings after major updates. The Growatt MIN series (string-only inverters) update less frequently and have fewer post-update settings issues due to simpler configuration.
Sunsynk firmware updates have historically introduced more regression issues than most brands — particularly affecting CT clamp direction handling and charge/discharge priority logic. Community forums report each release closely. Sunsynk and Deye share the same core firmware but may receive releases at different times. Wait for community confirmation before applying major Sunsynk/Deye firmware releases to a running system.
Fox ESS firmware is updated via the FoxCloud portal. The H3 and T-series ranges have separate inverter and battery firmware packages. After major updates, the Fox Manager app settings (particularly charge/discharge time periods and work mode) should be verified. Fox ESS systems have an additional on-board data logger that occasionally needs a restart after a firmware update to re-establish cloud connectivity.
Enphase microinverter firmware is pushed automatically by Enphase and cannot be manually triggered or delayed by the homeowner. The Enphase IQ Battery (IQ8 series) has its own firmware stack separate from the microinverters. Post-update issues on Enphase are less common than on hybrid string systems due to the simpler per-panel architecture, but IQ Battery systems can exhibit profile reset issues after major updates affecting the export limit and backup reserve.
What to do if your firmware update goes wrong
The correct response depends on what has failed. Most post-update problems are settings issues, not hardware failures — they look alarming but are straightforward to resolve.
Wait 30 minutes first — most OTA updates cause a brief offline period as the dongle restarts and reconnects to the portal server. If still offline after 30 minutes, power-cycle the WiFi dongle (not the inverter) by unplugging and re-plugging its power supply. Wait a further 10 minutes. If still offline, check whether the inverter display itself is showing data — if the display is active and showing generation, the inverter is working and only the cloud connectivity is affected, not the system operation.
Check the inverter display for fault codes. If codes are present, look them up in the relevant brand fault code guide — a post-update fault code is often a settings issue rather than a hardware failure. If no fault codes are shown and the inverter is in standby during daylight hours, check whether the grid voltage reading is within normal range (the update may have changed a voltage tolerance setting). A remote diagnostic reviewing the inverter event log is the fastest way to diagnose this without a site visit.
Restore the charge schedule from your pre-update screenshot first. If the schedule was intact but behaviour is still wrong, check CT clamp direction and operating mode. If the battery is reporting as offline or showing BMS communication errors, the battery firmware may need to be updated to match the new inverter firmware version — check the manufacturer's update sequence documentation and apply the battery firmware update if a mismatch is confirmed.
A genuinely bricked inverter — no display, no relay click at startup, no response to normal startup — requires the manufacturer's factory reset procedure. Most manufacturers have a USB or serial recovery process that reinstalls the base firmware without erasing the hardware. Contact the manufacturer's technical support line immediately and provide the firmware version you were updating to and from. Do not attempt any further power cycles or resets until you have spoken to technical support.
Check the manufacturer's community forum and release notes for the firmware version you installed. If the fault code is a known regression, the manufacturer may have already issued a patch update or a rollback procedure. If the fault is not in the release notes and not reported by other users, treat it as a genuine fault and investigate with the inverter event log. New fault codes after a firmware update are not always caused by the update — some pre-existing hardware faults only become visible after a firmware change improves the fault detection logic.
Related guides and pages
Step-by-step portal update process, the one-hour stall rule, and settings to check after every GivEnergy update.
Understanding the inverter hardware that firmware controls — MPPT, grid sync, anti-islanding, and operating modes.
Why CT clamp direction is the first setting to check after a firmware update — and what happens when it resets.
BMS firmware, SoC management, and why inverter-battery firmware compatibility matters.
Full diagnosis for inverters that won't start — including post-firmware-update no-boot scenarios.
For systems that won't recover from a failed firmware update — remote and on-site options available.