Best Off-Grid Inverters

Modern off-grid solar systems utilize advanced inverters to manage batteries, solar power, and backup AC sources like generators. The off-grid inverters, often referred to as an inverter-charger, serves as the heart and brain of an off-grid system. Its main function is to provide pure sine wave AC power and it must be capable of meeting the power demands of all appliances under various conditions.

In off-grid systems, multi-mode inverters manage all the energy. They can be connected to solar inverters either AC- or DC-wise, and they can work with MPPT solar charge controls.

Choosing a Reliable Off-grid Inverter

When designing an off-grid power system, it’s crucial to choose an inverter that is adequately sized and selected based on the appliances it will be powering. Certain types of equipment, like air conditioners, water pumps, and fridge motors, need a lot of surge (peak) power when they first turn on. A lot of less expensive inverters may not be able to handle these big surges well.

Key considerations when choosing a reliable off-grid inverter:

Surge Power Capability

Ensure the inverter can handle the high surge power demands of appliances like water pumps and air-conditioners during startup. Look for inverters with a high surge rating to accommodate these loads without tripping.

Continuous Power Capacity

The inverter should be able to supply continuous power under all conditions, including simultaneous operation of multiple appliances. Calculate the total power requirement of all appliances running at the same time to determine the minimum continuous power capacity needed.

Temperature and Load Conditions

Inverters should be sized correctly to account for temperature de-rating, especially in high-temperature conditions. Cheaper, transformerless inverters can often trip during hot summer temperatures when operating at high loads.

Reliability and Quality

Choose inverters from reputable manufacturers known for their quality and reliability. Read reviews and seek recommendations from professionals who have experience with off-grid systems.

Efficiency

Look for inverters with high efficiency ratings to maximize the energy harvested from your solar panels and battery storage system.

Support and Warranty

Ensure the inverter comes with a good warranty and has local support available. Off-grid systems can be complex, and having reliable support can be crucial in resolving any issues that may arise.

By carefully considering these factors, you can choose a reliable off-grid inverter that meets the specific needs of your off-grid power system and provides stable, uninterrupted power to your appliances.

Best off-grid inverters for home use

Inverter Cost and Power Ratings

There are many different sizes of off-grid inverters, ranging from 2.4kW to 20kW. They can be linked in parallel or three-phase to meet larger power needs. It makes sense that these powerful inverters cost more than normal grid-connected solar inverters or small all-in-one hybrid inverters. Depending on how much power it has, prices can range from $1400 for a small 2.4kW unit to $9,000 for a big 15kW one.

Rating for Surge Power – Transformers

Top-notch off-grid inverters utilize robust transformers to effectively manage heavy surge loads, preventing overheating and shutdowns. The top off-grid inverters often feature large toroidal core transformers, which provide high surge power ratings. These transformers are designed with exceptional precision, ensuring minimal magnetic flux leakage and maximizing inductance. As a result, they offer superior operating efficiency and an extended lifespan. Inverters from Selectronic, SMA, Schneider Electric, and Victron are examples of brands that use large, powerful toroidal core transformers.

Off-Grid Inverter Power Comparison Chart – Continuous and Peak Surge Power Ratings

A lot of off-grid inverters can give twice as much power for a short time to deal with power spikes from motors, fans, pumps, and other devices. The surge grade is very important for off-grid systems to be able to work with different loads without tripping out or shutting down without warning. Keep in mind that the output power is limited when there are high temperatures and constant high loads.

Control Software & Monitoring

Most of the time, the off-grid inverter is the brains and heart of an off-grid power device. Regardless of the hardware and build quality, if the control software is problematic and unreliable, it can impact the performance and reliability of the off-grid system.

The best off-grid inverters can be set up to handle a number of different energy sources, such as backup engines, AC and DC-coupled solar panels, and other AC sources. Features like tracking and remote control for the backup generator are must-haves. To charge the battery and power AC loads at the same time, the inverter needs to be able to start and sync with a backup generator from a distance.

System monitoring and remote control are crucial as they allow off-grid professionals to troubleshoot any issues remotely and view the operating history to diagnose problems effectively.

Grid-Interactive Off-Grid Inverters

Most modern off-grid inverters can work with or without the power grid, and they can be used to build either AC or DC-coupled solar systems. Because these inverters are used for different things and are made in different ways, different words are often used to describe them.

This includes the term multi-mode inverter and, more recently, grid-interactive inverter due to their ability to synchronize with the grid and either export or import energy. The word “inverter-charger” is also often used, since many modern off-grid inverters have chargers built in.

• Standard Terms Used to Describe Modern Multi-Mode / Off-Grid Inverters:
• Multi-mode inverter – Capable of both on-grid and off-grid operation modes.
• Grid-interactive inverter – Similar to a common hybrid inverter.
• Inverter-charger – An inverter that also functions as a charger for batteries.

There is a transfer switch inside grid-interactive transformers that lets the system disconnect from the grid during a blackout. This is called “islanding.” Standard (all-in-one) hybrid inverters can also be used as islands and in off-grid mode, but they don’t usually have backup generator control and aren’t made to be used off-grid all the time.

However, there are exceptions, such as the Deye Hybrid inverter, which is one of the few hybrid inverters that can operate continuously in off-grid mode.

These modern inverters are versatile and can accommodate various grid-connected and off-grid applications, making them suitable for a wide range of solar power systems.

Multi-mode inverters function similarly to basic battery inverters, but they possess the capability to connect to the grid and can be programmed to initiate and operate a backup generator automatically.  They work like simple battery inverters. These inverters are made to handle very high surge loads, and if the batteries are low or the load is very high, they can pass through extra power straight from the grid.

The pass-through power capability provides numerous benefits, such as the convenience of powering an entire home without the hassle of distinguishing between essential and non-essential loads or circuits. This makes multi-mode inverters highly versatile and suitable for managing both on-grid and off-grid power systems efficiently.

Off-grid AC-Coupled Solar

In off-grid installations, it’s crucial that the solar inverter is compatible with the inverter-charger to optimize battery charging. For instance, when the loads are low and the battery is full, the master inverter-charger needs to control or lower the solar output to keep the battery system from overcharging and getting damaged. SMA, Victron, and Outback Power use a technique known as ‘frequency ramping’ to achieve this, which is effective but not always ideal.

This coordination between the solar inverter and inverter-charger ensures efficient operation and longevity of the battery storage system in off-grid scenarios.