SolaX X1-VAST inverter: models and specifications

The SolaX X1-VAST is a single-phase hybrid inverter, meaning it manages solar generation and battery storage in one unit. It comes in four power ratings: 5kW, 6kW, 8kW and 10kW¹. Every version shares the same MPPT voltage range of 40 to 560 V and the same 20 A DC input per MPPT, so the differences between the models are about output, not about how the array connects¹.

The headline capability is backup. SolaX states the X1-VAST provides up to 200% EPS output for 10 seconds with under 10 ms switchover, which the maker describes as UPS-level². It also carries dual battery ports, microgrid and generator compatibility, and V2G and V2H readiness¹.

The warranty position is more conditional than the headline suggests. The standard term is 5 years, and it is freely upgraded to 10 years when the inverter is connected to SolaX Cloud with generation data uploaded³. That upgrade is the difference between a five-year and a ten-year product, and it depends on a cloud connection rather than on anything physical in the box.

What the X1-VAST is, and the four power ratings

The X1-VAST is a hybrid inverter, so it takes DC from the array, converts it for household use, and manages a battery on the same unit rather than through a separate charger¹. SolaX sells it in 5 kW, 6 kW, 8 kW and 10 kW versions². The 5K model accepts a maximum recommended PV array power of 10 kWp, which is a useful indication of how much array the smallest unit is designed to sit behind¹.

Choosing between the four is a matter of peak household demand and array size rather than of house size. A 5 kW inverter will carry a typical home's base load and most of its daytime demand; a 10 kW unit suits a larger array, higher simultaneous demand, or a household planning to charge a car and run a heat pump from the same system. The X1-VAST sits in a crowded part of SolaX's own catalogue: the X1-Smart G2 is offered in 5kW, 6kW, 7kW, 8kW, 9kW and 10kW ratings, and the X1-SPT comes in 10 kW and 12 kW versions⁴. The X1-VAST's distinguishing features are the four-MPPT input, the dual battery ports and the backup specification rather than the power range itself.

For a household, the practical point is that the inverter rating sets the ceiling on how much power can flow at once, not how much energy the system generates over a day. A 5 kW inverter on a 10 kWp array will clip at peak output on the brightest days, which is the trade-off that 200% oversizing is designed to make acceptable. More on how hybrid units compare with plain string inverters is at hybrid solar inverters.

Specifications at a glance: 5 to 10 kW, four MPPTs, 200% PV oversizing

The X1-VAST supports 200% PV oversizing and 20 A DC input per MPPT². Oversizing means the array's rated output can be up to twice the inverter's rated AC output. The reason to do it is that panels rarely produce their rated output in real conditions, so a larger array spends more of the year working the inverter near its capacity rather than below it. The 20 A per MPPT input matters because it allows higher-current panels to be connected without exceeding the tracker's limit.

The MPPT voltage range is 40 to 560 V, identical across the 5K, 6K, 8K and 10K models¹. The low PV start-up voltage of 50 V means the inverter can begin working at low array voltage, which extends generation into the early morning, late afternoon and overcast conditions¹. For comparison, the X1-Hybrid G4 has a 70 to 550 V MPPT range, and the X1-SPT models run 35 to 490 V⁶.

The Type II surge protection device on both AC and DC sides is built in rather than optional, which is worth noting because SPD specification varies across the range: the X1-FIT G4 lists SPD integrated, and the X1-Hybrid G4 datasheet gives DC Type II and AC Type II¹. AFCI, which detects arc faults in DC wiring, is listed as optional on the X1-VAST, as it is on the X1-Lite LV and the X1-Hybrid LV series¹. Where arc fault detection is wanted, it has to be specified rather than assumed. Background on what these protections do is at solar PV safety.

Backup power: 200% EPS output for 10 seconds, under 10 ms changeover

The backup specification is the X1-VAST's strongest claim. SolaX states the unit provides up to 200% EPS output for 10 seconds with under 10 ms switchover, and separately describes the changeover as UPS-level². In plain terms, the inverter can deliver twice its rated output for ten seconds to absorb the starting surge of a motor, a pump or a compressor, and it changes over from grid supply to battery supply so quickly that most equipment will keep running.

That 200% figure is at the top of what SolaX claims across its range. The X1-Hybrid G4 is listed at up to 150% EPS output for 10 seconds, and the X3-FIT G4 datasheet gives 150% EPS output for 10 seconds¹⁰. The X1-IES-A, X3-IES-A and X3-NEO-LV are all listed at up to 200% for 10 seconds, so the X1-VAST sits with the higher-output end of the catalogue rather than above it¹¹.

Two conditions matter. First, backup requires a battery: the inverter cannot supply the house from an array alone when the grid is down. Second, the 200% figure is a short-duration peak, not a continuous rating, so it covers motor starts rather than sustained heavy loads. SolaX's own guidance on backup planning notes that microgrid and generator modes exist for broader resilience planning, and that single-unit UPS-level switchover is a feature of specific models¹⁴. The X1-Lite LV is listed with a single-unit UPS-level switchover time under 6 ms, which is faster than the X1-VAST's stated figure¹⁴. What a household should take from this is that the X1-VAST will ride through a grid interruption without most appliances noticing, provided the battery is charged and the backup circuits are wired to the EPS output. What it will not do is run the whole house indefinitely: the duration is set by the battery, not the inverter. More on the general principle is at solar panels in a power cut.

Battery, generator and microgrid compatibility

The X1-VAST has dual battery ports, which SolaX describes as supporting expansion, alongside a 2-in-1 function¹. Two ports mean a second battery can be added later without swapping the inverter, which is the practical difference between a system that can grow and one that has to be replaced. The maker groups the dual ports with microgrid and generator compatibility and V2G and V2H readiness as the unit's headline features².

Generator and microgrid support is what allows the system to keep running when the grid is not available at all, rather than only during a short interruption. SolaX describes the X1-VAST as built for seamless integration into microgrids and generators for reliable off-grid use¹. The same capability appears across the range: the X1-Hybrid LV series lists easy generator and microgrid integration, the X1-Lite LV lists a microgrid and generator function, and the X3-NEO-LV lists micro-grid, generator, AC coupling, wind turbine and EVC solutions, with the EVC solution currently applicable only in on-grid scenarios⁹.

For a household, the generator input is the difference between a battery that covers an evening and a system that can be recharged when the sun is not doing it. It is also the point at which the installation stops being a straightforward grid-tied solar system and becomes something closer to an off-grid setup, with the additional cost and complexity that implies. The X1-VAST is a grid-tied hybrid inverter with off-grid capability, not an off-grid inverter. More on the distinction is at off-grid solar.

V2G, V2H and VPP readiness

SolaX lists V2G and V2H applications as supported on the X1-VAST, and describes it as VPP ready with compatibility across OpenADR, IEEE2030.5, FCAS and API¹. V2H means the home can draw power from an electric vehicle's battery; V2G means the vehicle can export to the grid. VPP readiness means the system can be enrolled in a virtual power plant, where a network of home batteries is aggregated and paid for providing services.

The VPP claim is consistent across SolaX's range. The X1-Hybrid G4 is listed as VPP-ready, the X1-FIT G4 as VPP ready, the X3-IES-A as VPP ready, and the X1-IES datasheet gives VPP ready with OpenADR, IEEE2030.5, FCAS and API compatibility⁷. SolaX has also partnered with Axle Energy so that battery owners can connect SolaXCloud to Axle's VPP, and the company presented an AC-side V2H system at Intersolar Europe 2026¹⁷.

What this means in practice is worth stating carefully. V2H and V2G are capabilities of the inverter, but delivering them also requires a vehicle and charger that support bidirectional flow, and a network connection that permits it. The inverter being ready is a necessary condition, not a sufficient one. VPP participation similarly depends on a scheme being available and on the household opting in, and it turns the battery into something a third party can dispatch. That is a genuine trade: revenue in exchange for giving up some control over when the battery charges and discharges. The independence question is real here, because a VPP connection is a dependence on an aggregator, a network and a platform, in the same way that the cloud warranty upgrade is a dependence on SolaX's servers.

Smart energy functions and monitoring

The X1-VAST carries Smart Schedule, Smart Scene and 7×24h TOU functions¹. Time-of-use scheduling lets the battery charge when electricity is cheap and discharge when it is expensive, which is the main way a battery earns its keep on a tariff with peak and off-peak rates. Smart Schedule and Smart Scene are the controls that set those patterns.

Monitoring runs through SolaX Cloud, which SolaX describes as providing real-time monitoring, load management and time-of-use optimisation¹⁸. The X1-Micro 2 in 1 lists smart monitoring via the SolaX Cloud App, and the Smart EV Charger G2 offers scheduling and real-time monitoring¹⁹. The X1-VAST also lists wireless meter compatibility, which matters for accurate measurement of import and export without additional cabling¹.

The dependence here is worth naming plainly. Local operation of the inverter continues without an internet connection, but scheduling from away, energy monitoring, remote diagnostics and the free warranty upgrade all run through SolaX Cloud. A household that wants the ten-year term has to keep the inverter connected and uploading generation data. That is a manufacturer's platform in the loop, and it is the clearest ongoing dependence the X1-VAST creates beyond the grid itself. More on what monitoring covers is at monitoring a solar PV system.

Dimensions, weight and installation considerations

The X1-VAST measures 590 × 400 × 180 mm². That is a mid-sized wall-mounted unit: for comparison, the X1-Hybrid G4 is 482 × 417 × 181 mm, the X1-IES is 717 × 350 × 210 mm, and the X1-Mini G4 is 290 × 206 × 120 mm⁶. The X1-VAST is wider than the X1-Hybrid G4 and shorter than the X1-IES, so it sits between them in wall space.

Weight is reported inconsistently. One SolaX product page gives about 28 kg, and another gives 28 ± 2 kg². The two figures are close and the difference is within a stated tolerance, but no single number is given, so a wall-fixing assessment should allow for the upper end.

Installation considerations follow from the specification rather than the dimensions. The 40 to 560 V MPPT range and 50 V start-up voltage give the designer latitude in string length, and the 20 A per MPPT input allows higher-current panels¹. The dual battery ports mean battery cabling has to be planned for expansion rather than for a single unit. The Type II SPD on both sides is built in, but AFCI is optional and has to be specified¹. SolaX publishes a step-by-step installation guide covering the general process²³. Mounting, clearances and the electrical work are matters for a qualified installer, and the connection itself is subject to the usual grid notification requirements, covered at G98 and G99.

Warranty and where the X1-VAST sits in SolaX's range

The X1-VAST carries a 5 year standard warranty, starting from the earlier of the installation date or six months after the date of production³. That term is freely upgraded to 10 years when the inverter is connected to SolaX Cloud and generation data has been successfully uploaded to SolaX's server³. The upgrade is not a paid extension and not an installer condition: it is a connectivity condition.

The same 5 year standard term applies across the X1/X3-Hybrid-G4, X1/X3-Fit-G4, X1/X3-IES, X3-ultra and X3-HYB-G4 PRO families, with the same 10 year cloud upgrade³. Other parts of the range differ: the X1 Smart and X1-AC carry a 5 year standard warranty that upgrades to 5 years plus a 5 year parts warranty when connected to SolaX Cloud with data uploaded, the X1-Boost G4 is listed at 5 years, and the X1-Micro series carries a 12 year standard warranty with options to upgrade to extended coverage²⁴. SolaX's UK warranty page carries the same terms¹⁷.

Where the X1-VAST sits in the range is best understood by what it adds rather than by its power ratings. Against the X1-Hybrid G4 it offers a wider MPPT window, 200% rather than 150% EPS output, and dual battery ports⁶. Against the X1-SPT it gives up the 10 kW and 12 kW continuous ratings and the split-phase EPS output, but keeps the dual battery ports⁵. Against the X1-Lite LV it is slower to switch over, since the Lite LV is listed under 6 ms, but it carries the higher EPS peak⁸. The X1-VAST is the unit for a household that wants the strongest backup specification in the single-phase range and is prepared to keep it connected to the maker's cloud to get the full warranty. A wider view of the family is at SolaX X1 inverters, and the comparison against another budget brand is at SolaX vs Growatt.