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Detailed reviews and information of the best solar panels, inverters and batteries. Plus hybrid and off-grid solar system reviews and information articles on how solar and battery systems work.


Reviews and information on the best Solar panels, inverters and batteries from SMA, Fronius, SunPower, SolaX, Q Cells, Trina, Jinko, Selectronic, Tesla Powerwall, ABB. Plus hybrid inverters, battery sizing, Lithium-ion and lead-acid batteries, off-grid and on-grid power systems.

Best off-grid solar system

Jason Svarc

Selectronic SP PRO and Fronius AC coupled Off-grid system.jpg

Choosing the best off-grid solar system is not easy as off-grid systems are many times more complicated than common grid-connected solar systems. In this article, we highlight some of the many considerations which must be taken into account and discuss the various off-grid system types available. We also explain why a good quality inverter-charger is vital to building a reliable off-grid system. Finally, we will dive into the different brands available and determine which systems are best suited to different applications.

Many people believe off-grid solar systems can be easily put together. This may be true in the case of a small caravan or cabin, but in reality, larger off-grid systems used for homes and businesses need to be carefully designed by an experienced solar installer or system designer.

Solar and battery storage systems must be installed by an experienced licensed electrical professional. Modern large scale off-grid solar systems are typically high voltage and can generate and store huge amounts of energy which can result in damage, fire or serious injury if the installation does not meet all relevant regulations, standards and guidelines.

The 5 main parts of an off-grid system

  1. Battery Inverter/charger or Multi-mode hybrid inverter

  2. Solar inverter (AC) or MPPT Solar charge controllers (DC)

  3. Battery bank

  4. Solar panels

  5. Generator (Optional)

Basic layout of a   AC coupled off-grid system   - Well suited for modern off-grid homes and businesses

Basic layout of a AC coupled off-grid system - Well suited for modern off-grid homes and businesses

Off-grid system types - AC or DC coupled

Off-grid systems are built using either AC or DC coupled power sources. AC-coupled generation sources include common solar inverters, wind turbines or backup generators (gen-sets), while DC-coupled sources include MPPT solar charge controllers or micro-hydro systems.

Whether a system is AC or DC coupled is generally based on the size of the system. Most small-scale systems less than 6kW are DC coupled and use efficient MPPT solar charge controllers. Larger off-grid systems can be either AC or DC coupled depending on the type of off-grid inverter-charger used, and compatibility with different solar inverters (AC) or solar charge controllers (DC). Most modern multi-mode inverters can be both AC and DC coupled, which creates a very secure, flexible power system with multiple charging options and can enable black-start operation if the main inverter shuts down, the backup generator fails or the batteries are depleted.

Basic layout of a DC coupled off-grid system - The most versatile and modular off-grid configuration

Small DIY off-grid solar systems

Small-scale off-grid solar systems and DIY systems used on caravans, boats, small homes and cabins use solar charge controllers, also known as solar regulators, which are connected between the solar panel/s and battery. The job of the charge controller is to ensure the battery is charged correctly and more importantly, not overcharged. Most solar charge controllers also have load output terminals which are often used for simple DC lighting circuits. In small DIY systems, simple ‘plug-in’ style battery inverters are used to provide AC power. These are available in many different sizes, from tiny 150W inverters up to 3000W or even higher.

Note: Small-scale, low-voltage systems can still cause damage or serious injury if not installed correctly - we recommend all systems are installed by a trained, licensed solar or electrical professional.

Small scale off-grid system with a single MPPT solar charge controller and small battery inverter.

Small scale off-grid system with a single MPPT solar charge controller and small battery inverter.

DC-coupled solar charge controllers have been around for decades and are available in two main types, PWM and MPPT. Read more about solar charge controllers here, plus how to size small scale off-grid solar systems correctly. More powerful MPPT Solar charge controllers up to 100A are used on larger scale off-grid solar power systems. These are a very efficient and reliable way of charging and managing high capacity lithium or lead-acid battery systems.

Key considerations when sizing off-grid solar systems

  • Daily average energy consumption (kWh) - Summer and winter

  • Peak load (kW) - Maximum power drawn from appliances

  • Average continuous load (kW)

  • Solar exposure - Location, climate, orientation & shading

  • Backup power options - During poor weather or shutdown

With the above considerations in mind the key component of an off-grid power system is the main battery inverter/charger often referred to as a multi-mode inverter as they can usually operate in both off-grid or on-grid modes.

Battery Inverter-chargers

In most off-grid systems, the battery inverter-charger is the heart and brains of the system. Its primary job is to supply ‘pure sine wave’ AC power, and it must be able to meet the power requirements of the appliances under all conditions. In addition, the inverter-charger regulates the battery charging and monitors energy flow from all other sources such as solar, wind, hydro or backup generators. Below is more detail about selecting the best inverter chargers.

AC coupled off-grid system using SP PRO inverter/charger and a Fronius solar inverter. 26kWh LiFe lithium battery system from PowerPlus Energy - Installed by Transfer Solar and Harpoon Electrics.

The battery inverter-charger should be adequately sized and designed to power appliances such as water pumps, fridge compressors and air-conditioning units which require very high surge (peak) power during startup. This is where many cheaper inverters can fail. If multiple appliances are running at the same time then the inverter must also be able to supply continuous power under all conditions including higher temperatures, so must be sized correctly to account for temperature de-rating. Again this is where cheaper (transformerless) inverters can often trip, especially during high summer temperatures.

Technical Guide

Recommended for solar Professionals - See our Technical guide to selecting and sizing off-grid and energy storage systems.

A solar professional should be able to put together what is known as a load table to help determine which type and size inverter is best suited to your individual needs. A detailed load table is also used to size the solar array, battery and backup generator.

Detailed Off-grid inverter-charger comparison table listing power/surge ratings and transfer ratings.

Detailed Off-grid inverter-charger comparison table listing power/surge ratings and transfer ratings.

Off-grid Battery Options


Until recently, traditional lead-acid deep cycle battery systems were the most common and reliable option for off-grid systems. Lead-acid batteries are a proven technology and can last up to 15 or more years if they are not held at elevated temperatures (above 40 degC), and are not regularly discharged too low. Lead-acid batteries require precise battery charging following a specific charge cycle plus temperature sensors to adjust voltage settings. Most well known off-grid inverter/chargers offer programmable charge voltage settings along with sensors to precisely charge under all conditions. Lead-acid deep cycle batteries are still widely used and offer several advantages over lithium.

Lead-acid deep cycle battery options - 2V, 6V or 12V options and various types - Gel, AGM, Flooded

Lead-acid deep cycle battery options - 2V, 6V or 12V options and various types - Gel, AGM, Flooded

One of the most significant benefits of lead-acid batteries is unlike modern lithium batteries; the battery will not shut-down at a low voltage or low state of charge (SOC). This is important, especially in emergencies or when a backup generator fails. Lead-acid batteries can be discharged down to 0% state of charge if needed for backup, but it is not recommended as it can severely reduce the life of the battery.


  • Compatibility with most inverters.

  • Proven and trusted technology.

  • Safe, very low risk (sealed Gel/AGM).

  • Battery will not cutout at low SOC or low voltage**

  • Long life (if not over discharged)

  • Easily recycled.


  • Lower efficiency - around 80%

  • Low energy density - Very heavy

  • Usable capacity limited - Max 40% DoD on regular basis

  • Not modular - Fixed size once installed

  • Cannot sustain partial state of charge for long periods

  • High temperatures can drastically reduce battery life

** Cutout voltage & SOC based on inverter settings and rate of discharge.


More recently lithium-ion battery systems have become extremely popular due to the high efficiency (92% to 98%), compact size, lightweight and scalability. In contrast, lead-acid battery banks have a fixed size or capacity whereas lithium systems do not suffer this limitation. This flexible sizing allows for additional capacity to be added at a later stage, which is a real bonus for both installers and customers alike.

Lithium batteries have a much higher energy density compared to lead-acid and are therefore lighter and more compact. A huge advantage of lithium is the ability to sustain a low state of charge (partial state of charge) for a prolonged amount of time without any negative effects such as sulfation which is a common problem with lead-acid batteries. Also, extremely high charge rates can be achieved using lithium with charging times up to 70% faster than lead-acid.

Also see our complete solar battery review - Detailed comparison of the leading lithium and lead-acid batteries from the leading manufacturers


  • Very high efficiency - Approx 97%

  • Very high energy density - Compact and Lightweight

  • High charge and discharge rates allowed

  • No degradation issues with partial state of charge

  • Modular and scalable systems (upgradable)

  • Safe and low risk (if charged correctly)

  • Most lithium batteries come with a 10 year warranty


  • Can shutdown at high temperatures (45+ degC)

  • Can shutdown at low temperatures (below 5 degC)

  • Can ‘trip off’ under continuous high surge loads.

  • More difficult to recycle at end of life.

  • May not function without a compatible inverter.

Lithium Battery options for off-grid

  • Managed lithium

    Many lithium battery systems contain a BMS which requires a dedicated communication link to the inverter in order to operate. If the inverter isn’t compatible with the battery then they cannot function together and will not work. One of the biggest issues with this type of system is that if communication is lost or suffers interference then often the inverter or battery will shutdown to ensure the battery is not over charged or discharged.

The BYD B-Box Pro battery is a popular managed lithium battery used for grid-connected systems as they are compatible with a large range of hybrid and off-grid inverters including SMA and Selectronic, and Victron. However, some performance and operational issues have been noted with the BYD batteries, especially in low temperature locations. LG chem RESU 48V batteries are popular, but only for ‘smaller’ off-grid systems due to the limited continuous discharge rate of 5kW. For larger off-grid systems the LG chem rack mount battery system is a more suitable, larger capacity option.

Modular self-managed lithium LFP battery system from  PowerPlus Energy .

Modular self-managed lithium LFP battery system from PowerPlus Energy.

  • Self-managed lithium

There are several self-managed lithium battery options available which contain a BMS but do not require a fixed communication in order to operate. Most self-managed batteries are very modular and are able to be scaled to create very large capacity battery banks (up to 500kWh). Popular brands include include Simpliphi, GenZ, Discover AES and Powerplus Energy. Much like managed batteries, the internal BMS is still used to manage charging, monitor the state of charge, temperature and cell voltages. Another advantage with this type of battery is they can be easily retrofitted and used to replace existing lead-acid battery banks, since they do not require any special communications or connections.

best batteries for off-grid solar

In my direct experience and based on feedback from many professional off-grid installers, self-managed lithium batteries are the best and most reliable choice for off-grid systems. Managed lithium batteries can be problematic as they rely on communications which can trip off or become unstable, especially at low state of charge and low temperatures. Most self-managed lithium battery systems are generally high quality and do not suffer from communication issues. They are also modular, flexible and can be expanded to create larger capacity energy storage systems which are better suited to off-grid systems. Additional capacity can also be added at a later stage if required. Self-managed lithium batteries can also be used as a ‘drop-in’ replacement for older lead-acid batteries and are compatible with most off-grid inverter/chargers and MPPT solar charge controllers.

Best lithium off-grid battery options self-managed.jpg

The recommended self-managed lithium (Lithium Ferro Phosphate) batteries from the leading battery manufacturers include Simpliphi, GenZ, Discover AES and PowerPlus Energy.

Lead-acid Batteries

In certain applications high performance lead-acid batteries are still an excellent choice for off-grid systems. Lead-acid is a well proven and reliable technology which is compatible with virtually all off-grid inverters and solar charge controllers. Lead-acid battery banks can also be more reliable in some situations as the battery will not automatically shutdown in extreme temperatures or when low state of charge is reached. In addition, they can be easily recycled using existing infrastructure.

The heart of an off-grid system - The battery Inverter/charger

Modern off-grid solar systems use multi-mode inverters/chargers to manage batteries, solar, and back-up power sources such as a generator. The inverter/charger is the central energy management unit and can be either AC coupled with solar inverter/s, or DC coupled with solar charge controller/s, or both. Read more about AC and DC coupled systems here.

Early off-grid systems used basic battery inverters and were very simple in comparison as the battery charger was a separate unit. These simple inverters generally had low power rating below 2kW and thus were only capable of powering low energy appliances like lights, fans and small pumps.

Many modern multi-mode inverter/chargers are very powerful (up to 20kW) and are designed to run high consumption appliances like air-conditioners, large pumps, electric ovens and hot water systems, which require high continuous power or high startup ‘surge’ current. Naturally these powerful inverter/chargers are much more expensive than common grid-connected solar inverters or small capacity hybrid (battery ready) inverters and can cost anywhere from $1500 to $6000* depending on the rated power output. (* 48V inverters up to 8kW)

Best off-grid inverters - Multi-mode Inverters

Here is our list of the leading off-grid inverters on the market based on reliability, service, continuous and peak (surge) power rating, energy management software, AC source control, flexibility and monitoring.

Best off-grid inverters - Selectronic SP PRO, Victron Multiplus and Quattro, SMA Sunny Island, Schneider Electric XW+ and Outback Radian series from the US.

Best off-grid inverters - Selectronic SP PRO, Victron Multiplus and Quattro, SMA Sunny Island, Schneider Electric XW+ and Outback Radian series from the US.

  1. Selectronic - SP PRO series (Australia)

  2. Victron Energy - Multiplus or Quattro (Netherlands)

  3. SMA - Sunny Island series (Germany)

  4. Outback Power - Radian or FXR series (USA)

  5. Schneider Electric - Conext SW or XW+ (Italy)

These inverters are all available in a range of different power output ratings (kW) to suit different applications depending on the continuous and peak power requirements. In addition these top 5 inverter/chargers can be both AC or DC coupled using compatible solar inverters or solar charge controllers.

See futher details in the off-grid/hybrid multi-mode inverter review

Off-grid Inverter power comparison

There are many inverters available with different output ratings from as low as 2.4kW up to very large 20kW continuous output. Most of these inverters can supply double or more of the continuous rating for a short amount of time to handle surge power spikes from motors, compressors, pumps etc. This surge rating is critical for off-grid systems to operate under all the various load conditions expected without tripping out or shutting down unexpectedly. This output power rating can also be reduced under higher ambient temperatures.

Off-grid inverter power comparison chart - Continuous and peak surge power ratings shown

For more detailed information about selecting off-grid and hybrid inverters see our ‘Technical guide to sizing a hybrid inverters and off-grid power systems’.

  1. Selectronic SP PRO

Best off-grid inverter - 5kW+ power ratings

Selectronic SP PRO Multi-mode Inverter.jpg

When comparing the leading multi-mode inverters specifications and power ratings under all conditions, the SP PRO inverters from Selectronic outperform all others with both the highest 30 minute rating and highest peak/surge rating. However, it is the advanced energy management software, 63A (15kW) pass through power capability and high charge ratings that put the SP PRO into a league of its own. Premium quality comes at a premium price and the SP PRO inverters are one of the most expensive options available, however, considering the high cost of off-grid systems, paying a little more a is well worth it for the power and features needed for a reliable off-grid system. The impressive features and high performance, together with a leading 10 year warranty place the SP PRO at the top of our list.

See the full Selectronic SP PRO review here

SP PRO basic specifications

  • Type: Multi-mode Inverter/charger (AC or DC coupled)

  • Use: Solar storage, back-up (UPS), off-grid

  • Sizes available (power output): 3.0kW, 4.5kW, 5.0kW, 7.5kW, 20kW

  • Pass through power: 15kW built-in (28kW external contactor)

  • Compatible Battery types: Lead-acid, lithium-ion, flow, sodium-ion

  • Battery System Voltages: 24V, 48V, 120V


  • 63A pass-through power rating (15kW AC)

  • Very high surge power output (2.5 x rated cont power)

  • Battery temperature monitoring for longer battery life (lead-acid)

  • Battery sense monitoring and mid string sensor for precise battery charging (lead-acid Gel and AGM)

  • Managed AC coupling with ABB or Fronius Primo solar inverters

  • Very powerful software package with remote access and monitoring.

  • Unique pre-charge feature for safer startup

  • Compatible with many popular lithium battery systems

  • Generator auto start, control and monitoring

  • AC / DC coupling capability

  • Parallel and 3-phase capability


  • Separate solar inverter or solar DC regulator required

  • Full off-grid capability when used with Selectronic certified (Scert) Fronius or ABB solar inverters

  • Additional generator contactor required if used with dual AC sources.

  • Additional unit required for remote monitoring and setup.

Price bracket – From AUD$4500 (4.5kW)

See detailed specification datasheet - Selectronic SP PRO series

Off-grid solar power system using a SP PRO inverter/charger coupled with a Fronius Primo solar inverter and BYD B-box Pro lithium battery - System designed and installed by Off-grid Energy Australia.

2. Victron MultiPlus

Best off-grid Inverter - 2kW to 5kW power rating


Victron Energy based in the Netherlands is a well known, international, high quality manufacture with a wide product range including battery chargers, sinewave inverters, inverters-chargers, DC/DC converters, transfer switches, battery monitors, charge controllers and more. Victron offer the most cost effective range of multi-mode inverters with a huge range of sizes including the new MultiPlus II inverters/chargers. For many applications the Victron is a great quality, lower cost option, especially for DC coupled systems. The Victron remote system options are extremely advanced and offer full remote access and control, as well as some powerful monitoring features. Victron products are also simple to setup and offer a huge range of different add-ons and configuration options.

See the full Victron Energy Review here

For smaller off-grid systems the most cost effective combination is Victron inverter/charger and DC coupled solar charge controllers with the BYD B-Box Pro lithium LFP battery system.

Basic specifications:  (5 sizes available) plus other variations

  • Type: Inverter/charger (DC or AC coupled)

  • Use: Solar storage, back-up (UPS), off-grid

  • Solar Array Size (Solar input): N/A

  • Sizes available (power output): 0.7kW, 1.3kW, 1.6kW, 2.4kW, 4.0kW,

    (Larger sizes up to 15kVA available in the Victron Quattro range).

  • Pass through power: 3.6kW - 11.5kW

  • Compatible Battery types: Lead-acid or lithium-ion

  • Battery System Voltage: 12V, 24V, 48V


  • Economical Inverter/charger option

  • Med-High surge power output

  • Pass through power capability

  • Battery temperature monitoring for longer battery life

  • Generator auto start and monitoring available

  • AC coupling with ABB or Fronius Primo solar inverters

  • Dual AC outputs for non-essential loads (high-power units only)

  • Programmable software with remote access and Wifi App

  • 3-phase capability + parallel for higher power output


  • Separate solar inverter or solar DC regulator required

  • Victron size the inverters in kVA not kW (ref data sheet)

  • Full capability only when used with Victron regulators and color control panel (CCGX) and Venus GX

  • Larger capacity Quattro inverters also available (up to 15kVA)

Price bracket – from AUD$1600 (2.4kW)

See detailed specification datasheet - Victron Multiplus inverter specs

DC coupled off-grid solar system with 2 x Victron smartsolar MPPT charge controllers, 3.2kW solar array and Multiplus inverter/charger.

24V DC coupled off-grid solar system with 2 x Victron Bluesolar charge controllers, 2.4kW solar array and Victron Phoenix 2.4kW battery inverter.

3. SMA Sunny Island

Best off-grid inverter for extreme environments


SMA Solar Technology is a leading German solar energy equipment supplier founded in 1981 and is one of the world's largest manufacturer of solar inverters. The well regarded Suny island inverters are a proven performer in harsh outdoor environments in particular sub zero temperatures.

See the full SMA inverter Review.

Basic specifications:  (3 sizes available)

  • Type: Inverter/charger (AC coupled)

  • Use: Solar storage, back-up (UPS), off-grid

  • Solar Array Size (Solar input): n/a

  • Sizes available (power output): 3.3kW, 4.6kW, 6.0kW

  • Pass through power: 11.5kW

  • Compatible Battery types: Lead-acid, lithium-ion (refer to manufacturer)

  • Battery System Voltage: 48V


  • High pass through power capability

  • High surge power output

  • Battery temperature monitoring for longer battery life

  • Powerful software package with remote monitoring

  • Generator auto start and monitoring (optional)

  • Dual AC inputs (grid and generator)

  • Very good IP54 weather rating

  • AC / DC coupling capability

  • 3-phase capability + parallel for higher output


  • Separate solar inverter or solar DC regulator required

  • Full capability when used with SMA or compatible solar inverters

  • External automatic transfer switch required to enable battery backup

  • When configured as a hybrid inverter, grid isolation (backup mode) is not instantaneous - 2-3 sec delay.

Price bracket – From $3800

See detailed specification datasheet - SMA Sunny Island specs

Off-grid solar power system using a SMA sunny Island inverter/charger coupled with a Sunny boy solar inverter - System designed and installed by Off-grid Energy Australia.

4. Outback Power FXR & VFXR

Best small capacity off-grid inverter - Split phase, North America

Founded back in 2001 by three power systems design engineers, Outback Power has grown to become one of the leading manufacturers of off-grid power systems in North America. The company produces an advanced range of inverter/chargers designed for off-grid residential and commercial installations, along with the highly regarded Flexmax range of MPPT solar charge controllers. In addition to the popular FXR & vented VFXR series designed for off-grid use, the Radian series of bi-directional inverter/chargers were developed for advanced hybrid (grid-connected) energy storage systems.

Basic specifications:  (5 sizes available) plus other variations

  • Type: Inverter/charger (DC coupled)

  • Use: Solar storage, back-up (UPS), off-grid

  • Solar Array Size (Solar input): N/A

  • FXR sizes available (power output): 2.0kVA, 2.5kVA, 3.0kVA

  • VFXR sizes available (power output): 2.8kVA, 3.5kVA, 3.6kVA

    (Modular configuration - parallel for greater power requirements).

  • Compatible Battery types: Lead-acid or lithium-ion

  • Battery System Voltage: 12V, 24V, 48V


  • Available in six models for 120VAC or 230VAC

  • Med-High surge power output

  • Pass through power capability

  • Battery temperature monitoring for longer battery life

  • Generator auto start and monitoring available

  • Programmable software with remote access.

  • 3-phase capability + parallel for higher power output


  • Separate solar DC regulator required

  • Inverters sized in kVA not kW (ref data sheet)

  • Full capability only when used with Mate3 control

  • Larger capacity available with parallel configuration up to 10 inverters.

  • AC coupling only available with Radian series inverters.

Price bracket – from US$1800 (2.0kW)

See detailed specification datasheet - Outback FXR & VFXR inverter specs

Outback Power  FLEXpower One FXR system  - Fully Pre-Wired solar Inverter Systems

Outback Power FLEXpower One FXR system - Fully Pre-Wired solar Inverter Systems

5. Sol-Ark 12K

Best All-in-one Off-grid Inverter - Split phase, North America

Sol-Ark 12K hybrid inverter.jpg

Sol-Ark is a relatively new US-based company that distributes a popular all-in-one hybrid/off-grid inverter made by Deye inverter Technology Co. The powerful 12K inverter has been customised to suit the US market with an impressive range of features including dual MPPT’s, ground-fault, arc-fault and lightning protection built-in, integrated load centre with DC and AC isolators, and remote access including monitoring and control.

Basic specifications: 

  • Type: Hybrid Inverter/charger - All-in-one unit

  • Use: Solar storage, back-up (UPS), Off-grid

  • Max Solar Array Size (Solar input): 13kW

  • Power rating (continuous output): 9.0kW (16kW peak)

    (Modular configuration - parallel for greater power requirements).

  • Compatible Battery types: Lead-acid or lithium-ion

  • Battery System Voltage: 48V


  • Split phase - 120VAC or 240VAC

  • High surge power output rating - 16kW (10 sec)

  • 63A pass-through power rating (15kW AC)

  • Inbuilt Ground-fault and Arc fault detection (GFD)

  • Inbuilt lightning protection (PV)

  • Integrated battery DC isolator and AC source/load isolator

  • Generator auto-start and monitoring built-in

  • Programmable software with remote access.

  • Parallel capability for higher power requirements.

  • Colour touch-screen display


  • Transformerless Inverter

  • Higher power output available with parallel configuration

  • 12K model not currently available outside North America

Price bracket – from US$6800

See detailed specification datasheet - Sol-Ark 12K inverter specs

About the Author - Jason Svarc is an accredited off-grid / stand-alone power system specialist who has been designing and building off-grid solar power systems for 10 years. During this time he also taught the CEC accredited off-grid design and installation course at Swinburne University (Tafe). Having designed, installed, commissioned and monitored hundreds of off-grid systems for households and business’s over the years, he has gained vast experience and knowledge of what is required to build a quality, reliable, high performing off-grid solar power system.

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