The selection of off grid inverters needs to be combined with load characteristics, system environment and cost budget. The following are key selection points and analysis

1. Load demand analysis

Load type and power

Resistive load: Calculate directly according to the rated power. For example, 10 100W bulbs require a ≥1kW inverter.

Inductive load: The starting current is 3-5 times the rated current, and a margin needs to be reserved. For example, the starting current of a 500W water pump may reach 2500W, and a ≥3kW inverter needs to be selected.

Mixed load: After calculating the total power of all loads, select 1.2-1.5 times the maximum starting power.

Load characteristics

Continuous load: The inverter needs to continuously output power ≥ the total load power.

Intermittent load: For short-term operation of power tools, the rated power can be appropriately reduced, but it is necessary to ensure that the instantaneous power does not exceed the limit.

2. Input power characteristics

DC input voltage

Match the battery pack voltage, which must be consistent with the system voltage. For example, a 48V battery pack needs to select an inverter that supports 48V input.

Battery type and capacity

Lead-acid batteries and lithium batteries need to confirm the inverter compatibility. Battery capacity affects the battery life, and the battery capacity needs to be calculated based on the load power and backup time.

3. Output performance indicators

Output waveform

Pure sine wave: suitable for all equipment, especially precision instruments.

Modified sine wave: low cost, but may affect motor efficiency or damage sensitive equipment.

Voltage and frequency stability

Voltage regulation rate ≤±3%, frequency regulation rate ≤±0.5%, to ensure stable operation of the equipment.

Peak power

It is necessary to meet the instantaneous power demand when the load starts, for example, 3-5 times the rated power is required to start the water pump.

4. Efficiency and energy consumption

Conversion efficiency

High-efficiency inverters can reduce energy loss. For example, under a load of 1kW, a 90% efficiency inverter loses 100W, while an 80% efficiency inverter loses 200W.

No-load loss

Low no-load loss can extend the backup power life.

5. Protection and safety functions

Basic protection

Overload, short circuit, overvoltage, undervoltage, and overtemperature protection to ensure system safety.

Isolation and grounding

The high-frequency isolated inverter provides electrical isolation and is suitable for scenarios with high safety requirements.

6. Environmental adaptability

Temperature range

A wide temperature type should be selected for extreme environments to avoid high temperature derating or low temperature startup failure.

Protection level

IP65 and above are required for outdoor use, dustproof and waterproof.

Altitude and humidity

Derating is required for high altitude areas, and moisture-proof design is required for high humidity environments.

7. Scalability and compatibility

Parallel expansion

Supports parallel connection of multiple inverters to meet future expansion needs.

Communication interface

RS485, CAN, Wi-Fi and other interfaces are convenient for remote monitoring and system integration.

Energy storage compatibility

Supports lithium battery BMS communication to achieve intelligent charging and discharging management.

Qingdao UNC Technology Co., Ltd wide range of products covers in many fields, including household hybrid inverters, PV inverters, and energy storage PCS. For more information about off grid inverter, please contact us.

Address：No. 115, Jifu Road, Chengyang District, Qingdao City, Shandong Province

Email：unc-service@unc-energy.com

Website：www.uniconvtor.com