Product Range at a Glance
• Axpert MAX II 8 kW – 230 VAC / 48 VDC, 16 kW surge, 6-unit parallel.
• Axpert MAX II / MAX E TWIN 11 kW – 230 VAC / 48 VDC, 22 kW surge, 6-unit parallel, dual AC outputs.
All models share a common mechanical footprint (≈ 158 × 503 × 531 mm, 18–20 kg), the same 500 VDC solar ceiling and an integrated 150 A MPPT charger, making spare-parts logistics and installer training wonderfully simple.

Core Architecture – Why “Off-Grid” Really Means “Off-Grid”
Unlike hybrid or grid-tie units that still expect a 50 Hz reference, MAX inverters create their own voltage and frequency. An internal 50/60 Hz auto-sensing module lets you choose either standard on site, perfect for export markets or mixed fleets. The transfer switch is there only for optional AC source (generator or shore) assist; if you never connect it, the unit remains a true stand-alone powerhouse. Battery terminals are galvanically isolated from the PV array, so you can earth the DC bus either pole without drama—a feature welcomed on boats and mountain huts where grounding rods are tricky.

MPPT Solar Charger – Harvest Every Ray
Every MAX ships with at least one 150 A MPPT controller whose tracking range spans 90–450 VDC.
• 99 % MPPT efficiency thanks to 18-bit A/D converters that re-scan the I-V curve every few seconds.
• 500 VDC open-circuit ceiling lets you string 10–12 high-voltage panels in series, cutting cable copper by 30 %.
• Dual-MPPT versions (11 kW models) treat two arrays independently—ideal for roofs with mixed orientations or when you want to add an east-facing string for early-morning ramp-up.
A built-in “PV usage timer” in the DSP lets you time-shift surplus electrons. For example, run the pool pump only when solar power > 3 kW, or automatically enable the ice-machine from 10:00–15:00, all without external relays.

Battery Friendly – Lead, Lithium and Tomorrow’s Chemistry
48 VDC architecture is the sweet spot between safe touch-voltage and reasonable cable diameter. The default charge profile is a forgiving three-stage (bulk-absorption-float) algorithm adjustable 0–150 A.
• Lead-acid: 54 V float, 57.6 V equalize, temperature-compensated −3 mV/°C/cell.
• LiFePO4: 56.8 V bulk, 54 V float, with BMS handshake via RS485 or CAN-bus.
• Third-party lithium: the inverter simply acts as a voltage-controlled current source; BMS remains master.
A replaceable-fan cassette mounted on the battery side keeps electrolyte temperatures within 5 °C of ambient, extending cycle life by up to 18 %.

AC Quality That Powers Everything
Pure sine wave (<3 % THD) is table-stakes nowadays, but MAX adds:
• 230 VAC ±5 % regulation from no-load to full-load, so your espresso machine and CNC router share the same bus without voltage sag.
• 2× surge power for 5 seconds—enough to start a 3 hp deep-well submersible or a 9 kVA lift pump.
• 10 ms transfer (PC-type) or 20 ms transfer (home-type) if you do hook up a generator; even sensitive PLCs stay online.
Galvanic isolation on the low-voltage DC side eliminates neutral-ground loops that plague cheaper high-frequency inverters.

Parallel & Three-Phase Ready
Need 66 kW? Slide six MAX E TWIN 11 kW units side-by-side, connect the supplied RJ-45 loop cable and turn the rotary switch to “1-Master, 5-Slaves”. The system automatically shares current within ±2 % and rotates the master role nightly for wear levelling. Phase-docking boards let you wire three units for 380 V three-phase, opening the door to industrial motors up to 15 kW without VFD derate.

Built-In Connectivity – No Dongle Required
• Wi-Fi Access Point out of the box—connect Android/iOS “WatchPower” app, see every watt, volt and event log in real time.
• USB-On-The-Go means firmware updates or parameter cloning with a plain USB stick—no laptop in the mosquito-infested pump house.
• Modbus-RTU on RS485 and dry-contact summary alarm integrate natively with SCADA or home-automation hubs such as Home Assistant, Node-RED or Victron’s Venus GX.

Ruggedisation – Born for Harsh Corners
Operating envelope −10 °C to +50 °C full power, 95 % RH non-condensing, altitude >2000 m with linear derating. Conformal-coated PCBs and an IP54 dust kit keep out red Sahara sand or Amazonian condensation. Fans are hot-swappable without tools; a magnetic dust filter pops off for a quick rinse, cutting MTTR to under five minutes.

Typical Bill of Materials – 10 kWh / Day Cabin Example
• 12 × 550 W bifacial panels (6.6 kW STC)
• 1 × Axpert MAX II 8 kW inverter
• 4 × 100 Ah 48 V LiFePO4 batteries (≈ 20 kWh)
• 1 × 6 kW auto-start diesel genset (optional)
• Mounts, breakers, surge kits ≈ USD 7,200 (ex-VAT)
Simulation in PVSyst for Madrid gives 98 % solar fraction; only 42 h of generator runtime expected per year.

Installation Tips Straight From the Field
a) String sizing: even in −20 °C alpine sites, 12 × 450 W panels (Voc 49 V) stay below 500 V.
b) Battery cables: keep 70 mm² and ≤1 m one-way to avoid voltage ripple that can fool the BMS.
c) Grounding: create a single earth bar, bond AC neutral and DC negative once, then run separate PE to array frames—this passes IEC 60364-4-41 and keeps leakage currents off the CAT5 cables.
d) Firmware: update to 18.10 or later to unlock the “silent fan” mode for night-time lake-side operation.

Economics & ROI – Off-Grid Does Not Mean Off-Wallet
Assume 15 kWh daily load, 0.15 €/kWh diesel, 1.5 €/l fuel. A MAX-based 9 kW array + 30 kWh lithium system pays for itself in 3.8 years versus a 24/7 genset, or 6.2 years versus a grid extension (over 700 m). After year seven the inverter is still at 80 % capacity, but the fuel saver kitty has already bought you a new battery pack.

Environmental Footprint
By shipping a single 20 kg box that replaces a 120 kg copper-wound transformer + separate MPPT + separate ATS, MAX saves 58 kg of steel, 11 kg of copper and 0.9 t of CO₂ before the first kWh is produced. Over a 20-year life the avoided diesel translates to −148 t CO₂ for a 15 kWh/day site.

Certifications & Bankability
CE compliant to EN 62109-1/-2 (safety), EN 61000-6-1/-3 (EMC), IEC 61727 (PV), marked for LVD & RoHS. Optional UL 1741 SA is in draft, opening future North-American markets. Several African micro-finance institutions already list MAX as “Tier-1 inverter” for PAYGo solar kits, simplifying loan approval.

Real-World User Stories
• Maasai Mara Research Camp, Kenya – Two 11 kW TWIN units in parallel feed a 380 V three-phase freezer and 30 guest tents; generator use dropped from 10 h to 1 h per day, saving 3 600 l of fuel annually.
• Alpine Refuge “Refuge du Sénépy”, France – 8 kW MAX II with 5.2 kW PV and 23 kWh LiFePO4; operates at 2 160 m elevation, −18 °C in winter, no fan failures after three seasons.
• Catamaran “Zingaro” – A single 8 kW unit replaces a 6 kW noisy diesel genset; sailors enjoy silent 230 V at anchor, and the 12 VDC output keeps navigation lights on even if the main pack BMS trips.

Future-Proofing – Firmware Road-Map
Voltronic Power has committed to a six-year feature release cycle. Coming firmware (V20.xx) will add:
• VPP (virtual power plant) mode – aggregate fleet control via JSON-MQTT.
• Peak-shaving for grid-tie retrofits – useful when utilities finally reach your valley.
• LiFeMnPO4 & Sodium-ion chemistry tables – drop-in ready for the post-Li era.