The Easun Power ISOLAR-SMX-II series are off-grid inverters with charging functionality, designed for operation in island systems and as backup power for homes or small businesses. In practice, this means providing a stable power supply for loads even when the grid is unavailable, and energy can come from PV, batteries, or an AC input (e.g., the grid or a generator). The key advantage is the pure sine wave and finely-tuned operating priority modes, which facilitate adapting the installation to actual consumption habits.
Depending on the variant, models with single or dual MPPT are available - this is important when dealing with different roof orientations or partial shading, as each string can independently optimize energy yield. High European efficiency translates to more energy delivered to the installation under typical operating conditions, not just in an ideal laboratory setting.
WiFi monitoring and service communication (e.g., RS485/RS232) are available, facilitating diagnostics and integration with energy storage systems (including BMS in lithium batteries). This series is primarily targeted at residential, agricultural, and commercial installations, where independence and control are key.
Ranking
Specifications
Pros and cons
The inverter generates a pure sine wave (THD < 3%), which allows for powering sensitive devices (pumps, household appliances, medical equipment). The SBU/SUB/UTI priority modes enable precise management of energy sources based on usage habits and battery status.
The PV input accepts voltages up to 500 V DC, which allows for the construction of longer strings of panels and reduces transmission losses in the system. This is a significant advantage over older off-grid systems, which are limited to 145-200 V DC.
The declared ability to track the maximum power point with 99.9% efficiency (as stated in the manufacturer's documentation and manuals.plus) translates to minimal energy conversion losses from PV systems, which is particularly important in variable solar conditions.
The built-in WiFi module (available in KP-WIFI variants) allows for remote monitoring of operating parameters without the need for additional accessories. The RS485/RS232 port enables integration with external lithium battery BMS (Battery Management System) and building automation systems.
The series holds the certifications required for the European and Australian markets (CE, SAA), which confirms compliance with electrical safety standards and facilitates legal installation by qualified installers.
The ISOLAR-SMX-II series is officially discontinued. This means limited availability of spare parts, no software updates, and a risk of lack of service support after the warranty period (3 years). Buyers of used units are particularly vulnerable to the risk of being unable to repair them.
Users on the DIY Solar Power Forum measured their own consumption at approximately 50 W in SBU mode under low load, resulting in about 1.2 kWh of daily losses. For island installations in winter (short days), this represents a significant energy cost - competitive models like the Deye SUN-5K-SG03LP1 achieve less than 30 W in idle mode.
On the DIY Solar Power Forum, there have been multiple documented cases of complete device failure ("dead after firmware update") following attempts to update the software. Due to the discontinued product line and limited technical support, the risk of permanent damage is significantly higher than with actively supported competing products.
In island mode, without an AC-IN to DC converter connected, the neutral connection to PE (N-PE bonding) is not automatically performed. This requires the use of an external relay, which complicates the installation and can lead to problems with RCD/RCBO in a residential installation if the design does not account for this requirement.
Alternatives
About the ISOLAR-SMX-II series
These answers cover the whole series. Where a figure differs, the specification above is this model's own.