Kostal PLENTICORE plus 4.2
A three-phase 4.2kW residential hybrid inverter with 3 MPPTs and smart battery management: the German pick for a well-equipped home.
Characteristics
- Power: 4200W, three-phase, 3 MPPTs
- Solar input: 6300W max
- Battery compatibility: BYD (headline) and 9 other HV brands
- Warranty: 5 years, free extension to 10
- 3 MPPTs, three-phase and broad battery compatibility
Detailed overview: Kostal 4.2kW three-phase hybrid inverter
The Kostal PLENTICORE plus 4.2 is a hybrid inverter for a fixed, grid-tied solar installation on a house roof, not a balcony plug and play micro-inverter or a portable power station. It converts DC power from panels into three-phase AC power, while optionally managing a high-voltage home battery.
It carries three independent MPPT trackers, accepting up to 6300W of panels in total, spread across three separate inputs to handle multiple roof orientations or partial shading. Conversion tops out at 4200W, three-phase, sized for a family home with sustained power demands rather than a small flat. Peak efficiency is rated above 97%.
On the storage side, the PLENTICORE plus 4.2 pairs with a wide range of high-voltage batteries over its RS485 interface: BYD (Battery-Box HV, Battery-Box Premium HVS/HVM, HVM+, HVS+, HVB), the most heavily marketed option, but also Kostal's own HELIVOR HV range, LG Energy Solution RESU FLEX, Pylontech Force H1/H2/H3, VARTA wall.BM1/BM2, Dyness Tower/Tower Pro/Stack100/Stack100 Pro, BMZ HYPERION, AXITEC AXIstorage Li (SH/SV1/SV2) and ZYC SIMPO HV. Its built-in intelligence continuously determines the cheapest power source between solar, battery and grid, and regulates battery charging to preserve its lifespan. The zero-export function keeps grid feed-in within a contractual limit without wasting the excess. If the home is unoccupied for a stretch, the unit detects and automatically recharges the battery.
Control runs over Ethernet and Wi-Fi via the KOSTAL Solar App, with real-time monitoring. The unit measures 563 x 405 x 233mm and weighs 19.6kg. The base manufacturer warranty is 5 years, extendable free of charge to 10 years through the Smart Warranty plus activation on Kostal's online portal, within 6 months of commissioning, a step worth not forgetting. Built in Europe, it's an inverter designed to last in a demanding residential setup.
Availability note for UK buyers: at the time of writing, no confirmed UK retailer stocks this exact model with a direct online checkout, so this listing links to Kostal's own product page for reference. The price shown is converted from the real price observed on the French market at today's exchange rate, not a price directly quoted in pounds.
Full specifications
Detailed characteristics
Power and protection
| Output power?Maximum power delivered (for storages with a 230 V output). | 4200 W |
|---|
Solar section
| MPPT controllers?Number of built-in MPPT solar controllers (lets you connect panels facing different directions). | 3 |
|---|---|
| Max solar input?Maximum connectable PV power. | 6300 W |
| Micro-inverter?Power of the inverter that feeds energy back into the home grid. | 4200 W |
Connectivity
| Wi-Fi?Remote control and updates over Wi-Fi. | Yes |
|---|
Durability and format
| Ingress protection?Water and dust resistance (IP rating). | IP65 |
|---|---|
| Weight?Weight of the battery. | 19.6 kg |
| Dimensions (L × W × H)?Length × width × height, in millimetres. | 563 × 405 × 233 mm |
Availability and warranty
| Warranty?Length of the manufacturer's warranty. | 5 years |
|---|
Comparison
How does the Kostal PLENTICORE plus 4.2 compare with other residential hybrid inverters in its class?
| Criterion | Kostal PLENTICORE plus 4.2 | Huawei SUN2000-3K-LB0 | SMA Sunny Boy Smart Energy 4.0 |
|---|---|---|---|
| AC power | 4200W, three-phase | 3000W, single-phase | 4000W, single-phase |
| MPPTs | 3 | 2 | 3 |
| Battery | BYD HVS/HVM (external) | LUNA2000 (external, plug and play) | SMA Home Storage (external) |
| Warranty | 5 years (10 free) | 10 years | 10 years |
The Kostal is the only three-phase unit of the three, a genuine plus for a home with a three-phase supply and sustained loads such as a heat pump or EV charger. Against the Huawei, cheaper but single-phase and less powerful, and the SMA, comparable in power but also single-phase, the Kostal stands out for its especially thorough zero-export management. Its shorter base warranty is easily fixed with the free activation to 10 years.
Related video
Video: So gut ist der Kostal Plenticore Plus Hybrid Wechselrichter | Produktvorstellung
Our tester's review: Julien De Jurquet
The PLENTICORE plus 4.2 has a reputation to live up to: the G2 generation has repeatedly done well in independent storage efficiency tests, and in use it's easy to see why. Our tester's three-phase install went smoothly, with a clear KOSTAL Solar App for tracking production, consumption and battery charge. The real standout is zero-export management: the unit adjusts output to respect a contractual grid limit without wasting energy unnecessarily, a feature few rivals implement as neatly. Two honest caveats: the base warranty is only 5 years (you need to remember to activate the free extension to 10 within 6 months, an easy step to forget), and battery compatibility is narrower than some competitors, centred on the BYD high-voltage range. For a three-phase home with heavy loads, a heat pump or an EV charger, it's a solid, built-to-last unit, provided you don't skip the warranty activation step.
In-depth review Kostal PLENTICORE plus 4.2: our review of the three-phase hybrid inverter 4.2/5 Read our full review → Efficiency 4.3 Portability and size not measured Weather resistance not measured Output ports not measured Capacity and expansion not measured Solar input and MPPT not measured Control and smart features not measured Installation and compliance not measured Build and endurance 4.2 Battery compatibility not measured Safety and protections not measured Storage battery compatibility 4.6 Control and smart features 3.7 Compliance and grid connection 3.9Frequently asked questions: Kostal 4.2kW three-phase hybrid inverter
No, it only works with high-voltage batteries connected over RS485, but the choice is wide: BYD (the most heavily marketed option), Kostal's own HELIVOR HV range, LG Energy Solution RESU FLEX, Pylontech Force, VARTA wall.BM, Dyness Tower/Stack100, BMZ HYPERION, AXITEC AXIstorage Li and ZYC SIMPO HV. Check exact compatibility with your battery model beforehand if you already own one from a different brand.
The base warranty is 5 years. Kostal offers a free extension to 10 years through its Smart Warranty plus programme, activated on its online portal within 6 months of commissioning, a simple step but easy to forget.
No, the PLENTICORE plus 4.2 is a three-phase model. For a single-phase installation, look at a different inverter or check whether Kostal offers a single-phase variant.
It automatically limits the power fed into the grid to a contractual value (sometimes zero), redirecting the surplus to the battery instead of wasting it, useful if your grid connection agreement requires it.
Yes, like any three-phase residential inverter wired into the consumer unit, installation must be carried out by a qualified electrician and registered with the grid operator before commissioning.
Need help choosing?
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Published on 04/09/2026