What the product is and who it suits

SolaX Triple Power 5.8kWh TP58 Slave Battery V2 is the expansion battery for the T-BAT-SYS-HV-5.8 range. It is not a standalone starter battery and it is not a replacement for the master. Instead, it is the correct add-on module for customers who already have, or are buying, the TP58 master unit and want to increase the total energy stored in the system.

This makes it ideal for homeowners and light-commercial users whose first-stage battery system is no longer large enough. In real use, that often happens after the owner sees how the battery performs over a few months, adds new electrical loads or wants more overnight support from solar generation stored during the day.

The real value of the TP58 slave is that it lets capacity grow in consistent 5.8kWh increments inside the same system family. That is more attractive than replacing an entire battery setup just because the original size is no longer the best match.

Key features and practical benefits

SolaX documents the HV11550 V2 slave battery with 115.2V nominal voltage, 100-131V operating voltage, 50Ah nominal capacity, 35A maximum charge and discharge current, 25A recommended charge and discharge current, 2.8kW standard power and 4.0kW maximum power. In simple terms, that means every added slave pack is a meaningful storage increase, not just a cosmetic expansion.

The battery uses LiFePO4 chemistry and the official TP58 documentation states 90% depth of discharge, 99% faradic charge efficiency, 95% battery roundtrip efficiency and 6000 cycles. These are strong practical figures because extension batteries are usually added for more frequent daily use, not only rare backup events. If an owner is expanding a system, it is because the battery is already working hard enough to justify more capacity.

SolaX also makes clear in the user manual that one T-BAT system may include one T-BAT H 5.8 V2 master with up to three HV11550 V2 battery packs at most. That creates a very clear planning path for installers and buyers alike.

• 5.8kWh total capacity added per slave unit
• LiFePO4 chemistry for stable high-voltage storage
• 35A maximum charge and discharge current
• 90% depth of discharge and 95% battery roundtrip efficiency
• Designed for expansion up to T-BAT H 23.0 V2 system size
• Direct fit for the TP58 V2 master-led platform

Expansion logic and system growth

The biggest advantage of this slave module is the simplicity of the published SolaX expansion path. The TP58 V2 user manual shows the following system configurations: one master only for T-BAT H 5.8 V2, one master plus one slave for T-BAT H 11.5 V2, one master plus two slaves for T-BAT H 17.3 V2 and one master plus three slaves for T-BAT H 23.0 V2.

That matters because it gives customers a clear, staged upgrade route. A site can start smaller and grow as load demand changes. If a household adds an EV, moves to electric heating, shifts more consumption to stored power or simply wants more protection against evening imports, the slave battery gives a direct and consistent way to expand capacity.

Compatibility also sits within a wider SolaX ecosystem rather than a single narrow pairing. SolaX knowledge-base guidance lists T-BAT-SYS-HV-5.8 as compatible across supported versions of X1-Hybrid/Fit G4, X1-IES, X3-IES, X1-Vast, X3-HYB-G4 Pro, X3-Ultra and X1-SPT systems. That makes the slave battery useful across a wide range of SolaX hybrid projects as long as the underlying TP58 platform is already in place.

Installation and physical detail

The HV11550 V2 slave battery is listed with dimensions of 474 × 193 × 647mm and weight of 68.5kg. That is slightly shorter than the master because the control side is handled by the master unit, but it remains a serious high-voltage battery pack that should be treated as such in system planning and installation.

SolaX lists IP65 protection for the platform and the user manual states that the Triple Power battery can be installed outdoors as well as indoors, while advising installers to avoid direct exposure to the sun and humid air. In the UK market, that is a useful practical message because it gives flexibility while still reflecting the need for sensible site selection.

The same manual also documents V2 operating temperatures of 0 to 55°C for charging and -10 to 55°C for discharge. That matters because additional battery capacity is often installed precisely to make the system work harder and more often. Getting location and installation conditions right helps preserve performance over the long term.

Why this variant may be the right choice

This slave module is the right choice when the project already includes a TP58 master battery and the owner wants more capacity without changing architecture. It is not the correct first purchase for a TP58 storage system, because the master must come first, but it is the correct next purchase for expansion.

It is particularly attractive for customers who started conservatively and now want more overnight or shoulder-season energy coverage. Rather than replacing a working system, the TP58 slave simply builds on it in a documented and supported way.

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