SolaX X-ESS G4 home battery system: specifications and warranty

The SolaX X-ESS G4 is an all-in-one home battery system that stores solar power and can keep parts of a house running during a power cut. It is AC coupled, which means it connects to the AC side of an existing solar installation rather than replacing the inverter, so it suits homes that already generate their own electricity and want to add storage¹.

The headline numbers are a power range of 3 to 7.5 kW and storage from 3 to 12 kWh, with the system scaling from 3 kWh up to 12 kWh so capacity can be added over time². SolaX quotes 97% efficiency, LiFePO4 battery chemistry, an IP65 protection degree and an operating temperature range of -30°C to 60°C². The system supports real-time monitoring through SolaXCloud, time-of-use energy management and smart loads management for heat pumps and EV chargers².

The X-ESS G4 is not a standalone product so much as a combination. SolaX describes it as the X1-Hybrid G4 inverter combined with the T30 battery and the Matebox, which together form the all-in-one system³. That matters for anyone comparing it with a single-box unit: the specification is the specification of those parts working together.

What the X-ESS G4 is: an all-in-one AC-coupled storage system

The X-ESS G4 is described by SolaX as a versatile residential hybrid storage system with an all-in-one, plug-and-play design². Its defining characteristic is that it is AC coupled, which SolaX says makes it specifically suited to homes that already have solar¹. In an AC-coupled arrangement the battery system sits alongside the existing solar inverter rather than replacing it, which is the practical difference between adding storage to a working installation and rebuilding the whole system.

The system is assembled from three named parts. SolaX states that the X1-Hybrid G4, when combined with the T30 battery and the Matebox, forms the X-ESS G4³. Elsewhere the same combination is described as the X1-Hybrid G4 inverter, a T30 battery and a Matebox⁴. The T-BAT H 3.0 V2 battery is also described as integrating with the X1-Hybrid G4 and Matebox to create the X-ESS G4 all-in-one system⁵.

Physically, SolaX has described the inverter and battery as designed in a stacked installation, with modules connected via plug-in terminals for plug and play⁶. That stacked arrangement is what gives the system its all-in-one character: the parts are separate products, but they are designed to sit together and connect without bespoke wiring between them.

For a household, the significance is straightforward. An AC-coupled system does not require the existing solar inverter to be removed, so a home with a working non-hybrid inverter is not forced into a replacement. The trade-off is that power passes through two conversions rather than one, which is why AC-coupled systems are generally discussed alongside their DC-coupled equivalents. The wider comparison is set out in AC-coupled and DC-coupled home batteries, and the all-in-one format is covered in all-in-one home battery systems.

Power and capacity: 3 to 7.5 kW output and 3 to 12 kWh of storage

The X-ESS G4 is positioned at 3 to 7.5 kW with 3 to 12 kWh of storage⁴. The product page gives the same figures as a power range of 3 to 7.5 kW and a storage range of 3 to 12 kWh². SolaX also states that the system scales from 3 kWh up to 12 kWh, allowing capacity to be added over time¹.

That scalability is the practical point. A household can start with a smaller battery and expand later rather than committing to the full 12 kWh at the outset. The system also supports up to 200% PV oversizing and 110% AC output, which means the inverter can be paired with more panel capacity than its own rating and can deliver slightly more than its rated AC output². SolaX quotes a maximum 16A DC single string input current and a maximum 30A charging and discharging current².

The wider SolaX range offers larger options where 12 kWh is not enough. The X1-IES is described as offering modular expansion up to 40 kWh⁷, and the T-BAT-SYS-S3.6 expands from 7.3 to 47.9 kWh⁴. Those are different products, not X-ESS G4 configurations, and the X-ESS G4 itself is capped at 12 kWh. Households weighing how much storage they actually need will find the sizing question worked through in what size home battery do you need, and the difference between nameplate and usable capacity in battery capacity and usable capacity.

Efficiency, charging speed and battery chemistry

SolaX states that the X-ESS G4 delivers 97% efficiency². The same figure appears across the company's hybrid inverter range: the X1-Hybrid G4 is quoted at up to 97% battery charge and discharge efficiency⁸, and the X3-Hybrid G4 at up to 97.5% charging and discharging efficiency⁹. The X1-FIT G4 is quoted at up to 97.0%¹⁰. These are manufacturer figures for the conversion stages, not a measured whole-system result in a particular house.

The battery chemistry is LiFePO4, which SolaX describes as ultra-safe². That is the lithium iron phosphate family, the chemistry most commonly sold for stationary home storage. The general comparison between chemistries is covered in home battery chemistries, and the efficiency question in more depth in round-trip efficiency and standby losses.

On charging speed, SolaX states one-hour fast charging for the X-ESS G4². That figure needs reading carefully. A one-hour charge time is a statement about the system's capability under favourable conditions, not a promise that any installation will fill a 12 kWh battery in an hour. The maximum charging and discharging current is 30A², and the actual rate depends on the inverter, the battery modules fitted and whether the input is solar or grid. A 3 kWh system and a 12 kWh system on the same input will not charge in the same time.

The system also supports two charging periods on the X1-FIT G4 platform¹⁰, which is the mechanism behind charging at cheap-rate times. How that interacts with tariffs is covered in stacking a home battery with smart and time-of-use tariffs.

Backup power and off-grid operation

The X-ESS G4 supports on-grid and off-grid operation, and SolaX describes smart energy management across grid and off-grid modes². The backup capability comes from the inverter at the centre of the system. The X1-Hybrid G4 is described as offering EPS output support with fast switchover¹¹, and the datasheet gives a switchover time of under 10ms for EPS off-grid output with a battery, at a rated EPS output voltage and frequency of 230V, 50Hz/60Hz¹².

EPS stands for emergency power supply. It is the output that keeps selected circuits live when the grid goes down. SolaX quotes up to 150% EPS output for 10 seconds on the X1-Hybrid G4⁴, and the X3-Hybrid G4 is quoted at up to 200% EPS overload output for 10 seconds on supported models¹¹. Those overload figures matter because motors in fridges and pumps draw a surge at start-up that is well above their running current.

The X-ESS G4 is not an off-grid system in the sense of a standalone power supply for a property with no grid connection. It is a grid-connected system with off-grid capability for outages. Households considering genuine off-grid use are looking at a different design, covered in off-grid battery systems.

Smart management: SolaXCloud, ToU optimisation and EV charger and heat pump integration

The X-ESS G4 supports real-time monitoring via SolaXCloud². SolaX describes advanced smart management through SolaXCloud allowing real-time monitoring, time-of-use optimisation and integration with EV chargers and heat pumps¹³. The product page lists intelligent ToU-driven energy management and smart loads management for devices such as heat pumps and smart EV chargers².

Time-of-use optimisation is the function that charges the battery when electricity is cheap and discharges it when it is expensive. SolaX describes the X-ESS G4 as an all-in-one residential ESS with SolaXCloud monitoring, intelligent TOU-driven energy management and compatibility with EV chargers and heat pumps¹⁴. The company's own smart EV charger is described as designed to integrate with the X-ESS G4 solar and storage system¹⁵.

The integration is not limited to SolaX's own hardware. SolaX describes integration between the hybrid inverter, battery, battery management system, EV chargers, heat pumps and SolaXCloud for real-time monitoring, dynamic load management and time-of-use optimisation¹⁶. The X1-Hybrid G4 at the centre of the system is described as integrating with heat pumps³, and the X1-FIT G4 as integrating seamlessly with smart EV chargers¹⁰.

This is where the system's dependence becomes visible. Local control at the inverter continues without an internet connection, but remote monitoring, ToU scheduling and smart load coordination depend on a home broadband connection, SolaX's cloud service and the manufacturer's app. A household that wants the tariff optimisation to keep working needs that chain intact. The monitoring question is covered in monitoring a home battery, and the wider picture in can a home battery run a heat pump or charge an EV.

Durability and safety: IP65, -30°C to 60°C and fire testing

The X-ESS G4 carries an IP65 protection degree and SolaX states it operates in temperatures from -30°C to 60°C². The same temperature range is repeated in SolaX guidance describing reliable operation in extreme temperatures¹³. IP65 is a weather-resistant rating, which supports siting in a garage, outbuilding or sheltered external position rather than requiring an indoor airing cupboard.

The battery is described as ultra-safe LiFePO4 with IP65 and fireproof testing². SolaX has also published material on validating system-level safety through extreme testing, and separately recorded a large-scale fire test on its ORI energy storage system under extreme conditions¹⁷. Those are company announcements about its own testing programme, not independent certification of the X-ESS G4 specifically.

For colder parts of the UK, SolaX guidance for Scotland and northern England discusses hybrid inverters and LFP batteries in colder climates¹⁸. The X3-Hybrid G4 is quoted with an operating temperature range of -35°C to 60°C¹⁸, and the X1-Hybrid G4 datasheet gives -35 to 60°C with derating at higher temperatures¹². Derating means the system reduces its output as temperatures climb, which is normal for power electronics.

Fire safety for home storage is a subject in its own right, covered in home battery fire safety and how safe are home battery storage systems.

Installation: a single-technician, under-an-hour job in many cases

SolaX states that in many cases installation can be completed by a single technician in under an hour, helping control overall project cost¹. That claim sits alongside the plug-and-play design and the stacked arrangement with modules connected via plug-in terminals². The X-ESS G4 is also described as having plug-and-play installation¹⁴.

The claim needs reading in context. An under-an-hour installation refers to the physical fitting of the storage system in favourable circumstances, not to the whole project. A retrofit involving a new circuit, a backup circuit, a changeover arrangement or a change of position takes longer. Independent guidance on retrofit work describes heating controls and smart systems as usually installed in a few hours¹⁹, and official guidance on ECO4 and GBIS work states that where health or safety risks are identified, installers are required to make them safe within 24 hours²⁰. Those are different kinds of work, but they show that the headline fitting time is rarely the whole story.

For a household, the practical expectation is a survey first, then a fitting visit, then handover and registration. The process is described in home battery installation, and the notification requirement in telling the network operator about a home battery. Siting options are covered in where a home battery can be installed.

Warranty, company and what the system depends on

SolaX issued new warranty terms and conditions, version 1.7, effective for products sold or installed on or after 10 September 2026²¹. That is the document that governs a system bought now, and the terms should be read as they apply to the specific product rather than assumed from older material.

The company's position in the UK market is established. SolaX Power recorded its fifth consecutive year of EUPD Top Brand PV recognition in the UK on 30 April 2026¹⁷. It has also partnered with Axle Energy so that battery owners can connect SolaXCloud to Axle's virtual power plant¹⁷, and it extended its Borussia Dortmund partnership through 2028¹⁷. Those are company announcements about its own activities.

On availability, distributor listings show a mixed picture. The SolaX Triple Power HV 5.8kWh LFP Main Battery MASTER V2 was listed as discontinued on 1 September 2026, with the reason given as phased out²². Several other SolaX products were listed as awaiting stock arrival in September 2026, including the X1-VAST-8K, the 7.5kW G4 X1-Hybrid Inverter and the X1-IES 6.0K²². Stock status changes, but it is worth checking availability at the point of order rather than assuming a catalogue item is on the shelf.

For a household weighing independence, the position is this. The X-ESS G4 reduces dependence on grid electricity for the hours it can cover, and it can keep selected circuits running during an outage. It does not remove dependence on the grid, because it is a grid-connected system that charges from solar or from cheap-rate electricity. It adds a dependence on a home broadband connection and on SolaX's cloud service for the monitoring and tariff optimisation features. And it keeps the household tied to a manufacturer for warranty, parts and support. The wider question of what a battery can and cannot do for independence is covered in home batteries and household energy independence, and the SolaX range as a whole in SolaX home batteries and Triple Power storage.