Growatt AC Coupled Battery Storage Inverter Faults and Warnings:

Some of the advice we give related to identifying, confirming and or resolving some of the faults detailed below, starts with safely shutting down and restarting the inverter and the solar PV system. This is something that nearly all solar PV systems installed in the UK would have been designed to be carried out safely by the solar PV system owner. However, paperwork, schematics and manuals are not always clear or available, so if you have any concerns about how to do this, Contact us and we will be pleased to talk you through the process over the telephone at no charge.

• No AC connection - The inverter is not measuring a grid (mains) voltage suggesting that mains power to the unit has been disconnected. If this fault persists and mains power is available to other local circuits then check that all isolators, MCBs and RCDs on the AC side of the solar PV system are 'On'. If automatic safety devices such as MCBs or RCDs have switched 'Off' then leave them 'Off' and contact us to arrange for a solar engineer to visit to establish whether the fault lies with the inverter, the supply circuit or with the grid.


• AC V Outrange - The inverter is measuring a grid (mains) voltage or a grid impedence that is either too high or too low in relation to the parameters that the inverter has been set to safely operate within. If this fault persists and mains power is available to other local circuits then check that all isolators, MCBs and RCDs on the AC side of the solar PV system are 'On'. If automatic safety devices such as MCBs or RCDs have switched 'Off' then leave them 'Off' and contact us to arrange for a solar engineer to visit to establish whether the fault lies with the inverter, the supply circuit or with the grid.


• AC F Outrange - The inverter is measuring a grid (mains) frequency that is either too high or too low in relation to the parameters that the inverter has been set to safely operate within. If this fault persists and mains power is available to other local circuits then check that all isolators, MCBs and RCDs on the AC side of the solar PV system are 'On'. If automatic safety devices such as MCBs or RCDs have switched 'Off' then leave them 'Off' and contact us to arrange for a solar engineer to visit to establish whether the fault lies with the inverter, the supply circuit or with the grid.


• Error 408 - The inverter is too hot. This could be due to a number of factors, for example 1) If the inverter is exposed to direct sunlight 2) If the inverter has been installed without adequate ventilation around the chassis which would allow excess heat to dissipate 3) The inverters components are getting too hot due to an internal component fault. If the unit isn't running hot and if after the system has been safely shutdown and restarted this condition persists then contact us.


• Output High DCI - The inverter is measuring too much current (I) from the batteries. Assuming that this is an existing installation that has been specified correctly, hasn't recently been changed or added to and has operated before without problems. This could mean either a problem with the batteries or with the inverter. We would advise that the DC side of the system is disconnected using the DC Isolator installed between the batteries and the inverter (if available) and contact us to test the DC side of the system including and excluding the inverter.


• Error 407 - Auto Test Failed - The inverter has recognised a problem (which may be temporary) upon initialisation at startup. If after the system has been safely shutdown and restarted this condition persists then contact us.


• Error 411 - Internal Communications Failed - This is an internal inverter communications fault between the master and slave processors. If after the system has been safely shutdown and restarted this condition persists then contact us.


• Error 405 - Relay Fault - This is an internal error within the inverter. If after the system has been safely shutdown and restarted this condition persists then contact us.


• Error 417 - Sample Fault - This is an internal error within the inverter. If after the system has been safely shutdown and restarted this condition persists then contact us.


• Error 418 - DSP and COM firmware version mismatched, system fault - Assuming that this is an existing installation that has been specified correctly, hasn't recently been changed or added to and has operated before without problems, this is most likely an internal problem with the inverter. If after the system has been safely shutdown and restarted this condition persists then contact us.


• Error 120 - Model set up does not meet with certification - Assuming that this is an existing installation that has been specified correctly, hasn't recently been changed or added to and has operated before without problems, this is most likely an internal problem with the inverter. If after the system has been safely shutdown and restarted this condition persists then contact us.


• Error 121 - This is an internal inverter communications fault between the master and slave processors. If after the system has been safely shutdown and restarted this condition persists then contact us.


• Error 122 - Bus Voltage Fault - This is an internal error within the inverter. If after the system has been safely shutdown and restarted this condition persists then contact us.

We provide solar power system testing and maintenance services for residential, commercial, industrial and agricultural clients across Southern, South West England and the West Midlands, with specialist experience working with farmers, developers and commercial and industrial buildings owners.

Many modern solar inverters can now use wireless home networks to transmit solar generation data to PCs, tablets and smartphones, so if you would like something like this, let us know and we will be happy to set it up as part of the installation.

Deliveries to anywhere in the UK are quick, tracked and accurate, technical support (by phone and on site if needed) and design/product advice is available before, during and after installation. The recording and collating of serial numbers, factory and other test results, manuals any other information required for equipment warranties, add ons and extensions is included.

Trade, DIY and Retail Clients Welcome.

A whole house surge protector is installed to provide protection from transient overvoltages originating from the mains/grid. A whole house surge protector is installed directly inline and as close as possible to the incoming mains/grid supply meter, this allows for surge protection for all circuits and equipment including solar inverters, routers, stereos and other sensitive electrical equipment within the network. The addition of a 100Amp lockable isolator also allows for safe and convenient isolation of all electrical equipment within the network including consumer units, solar inverters, battery storage units and EV chargers from the mains/grid in one place.

Surge protectors are in compliance with the recently updated 18th edition amendment 2 of BS7671.

Growatt Inverter Faults and Repairs

Established in 2011 in Shenzen, China, Growatt launched it's first products for the UK market in 2013. Growatt is now one of the top 4 solar inverter manufacturers in the world. The MTL-S Series solar inverters were widely installed in the UK from 2013 through to 2019.

BSI - PAS 63100:2024 - Protection Against Fire of Battery Energy Storage Systems for use in Dwellings

This Publically Available Specification (PAS) from the British Standards Institution (BSI) was sponsored by The Department for Energy Security and Net Zero. Although not yet a British Standard, this guidance was developed in response to an urgent demand for clarity as to good practice across the industry including product, service and process standards.

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Ground Faults, Isolation (ISO) Faults, RISO Faults and Insulation Resistance Faults with Solar PV Systems

After a number of years exposed to wind, rain, snow, ice and sometimes animals; solar panel systems can start to develop faults. The most common faults we find related to exposure are ground faults, isolation (ISO) faults, RISO low faults and insulation resistance faults. In this article we take a look at what these faults are, the possible causes and what steps are taken to identify and resolve them.