EG4 Inverters

An EG4 inverter is an all-in-one unit that combines a solar charge controller, a battery inverter, and, on hybrid models, a grid-tie connection in a single box. A1 SolarStore carries two EG4 product lines built for different setups: hybrid solar inverters and off-grid inverters.

Hybrid models stay connected to the utility grid and switch to battery power during an outage. Off-grid models run independently, with no utility connection at all. This article covers what separates the two lines, how to match a model to your situation, which specs affect real-world performance, and what to check before buying.

Hybrid and Off-Grid: The Two EG4 Inverter Lines Explained

The EG4 hybrid inverter line includes the 12kPV, 18kPV, FlexBOSS18, and FlexBOSS21. All four connect to the grid, to solar panels, and to a battery bank at the same time. They can export surplus power to the grid, draw from it when needed, and island the home on stored solar power during a blackout.

EG4's off-grid line covers the 3000EHV-48, 6000XP, and 12000XP. None of them connect to the utility grid. Each all-in-one inverter runs entirely on solar and battery power, so the battery bank has to be sized to cover nighttime and low-sun loads without grid backup. Off-grid systems often add a generator for extended cloudy stretches.

Every model in both lines is also an EG4 inverter charger: it inverts stored battery power to usable AC and recharges the battery bank from the same unit, whether the input is solar, grid, or generator power.

Both lines output split-phase 120/240V power, the standard for US homes, so neither requires a separate transformer to run typical household circuits. The FlexBOSS18 also carries EMP hardening, a feature aimed at installations that want protection beyond normal surge suppression.

Enclosure rating is another practical difference to check, and it runs the opposite way many people assume. The 18kPV, FlexBOSS18, and FlexBOSS21 hybrid units carry a NEMA 4X rating, which allows outdoor mounting. The 12000XP off-grid unit is rated IP20, indoor use only, so it needs a garage, shed, or equipment room.

Which EG4 Line Fits Your System

The right EG4 line depends on one question: does the home have a utility grid connection worth keeping? From there, sizing depends on daily and peak power draw, since an undersized inverter will trip under load even if the battery bank is large enough to cover it.

• Grid-tied home that wants backup during outages: a hybrid inverter, the 12kPV or 18kPV, because it keeps grid export and import while adding battery backup for blackouts.
• No utility connection nearby, cabin or remote property: an off-grid inverter, the 3000EHV-48 or 6000XP, sized to the property's expected daily load.
• Large off-grid home or workshop with heavy loads, such as a well pump or welder: the 12000XP, or a paralleled set of 6000XP units, where continuous output and stacking headroom matter more than grid access.
• Whole-home backup with high loads on a grid-tied property: the FlexBOSS18 or eg4 FlexBOSS21, which carry the largest AC output in EG4's hybrid line.

Specs Worth Comparing Before You Buy

Once the line is decided, model-to-model differences come down to six factors: continuous AC output, PV input capacity, MPPT count, battery voltage, parallel capacity, and warranty length.

Each of these plays out differently once a system is running:

• Continuous AC output determines what can run at once (a well pump and an air conditioner together, for example) and matters more than PV input for most buyers.
• PV input and MPPT count set how many solar strings the inverter can accept without an external combiner.
• Parallel capacity varies by model, not by line: the 12kPV and 18kPV scale to 10 units, while the FlexBOSS18, FlexBOSS21, 6000XP, and 12000XP all scale to 16 units. The table above lists each model's combined output.
• Battery voltage governs compatibility. Current EG4 inverters run on a 48V bus, which works with EG4's own LiFePower batteries and most third-party 48V systems.
• Warranty length affects total cost of ownership if a unit ever needs replacement: five years on the off-grid XP-series, 10 years on the FlexBOSS hybrid units.

Monitoring is a smaller factor but worth confirming before purchase. EG4 inverters report battery state, PV production, and load through a Wi-Fi companion app, rather than a front-panel display alone.

Choosing Between EG4 Hybrid and Off-Grid Inverters

The hybrid-versus-off-grid decision is really a decision about grid access, not price or brand. A home with a utility connection gains little from an off-grid inverter and loses the ability to sell back excess power. A remote property gains nothing from grid-tie hardware it can never use.

Once that's settled, size for the load, not the label. A 6000XP running at its 6kW continuous limit will trip on a startup surge from a well pump and an air conditioner at once; the 12000XP, or a paralleled pair of smaller units, solves that without changing the underlying inverter type.

Frequently Asked Questions