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Find reviews of the best Solar Products, SMA Sunny Boy, Aurora Power-One, Growatt, SunPower, SolaX, QCells, Trina Solar, Jinko, Selectronic, Tesla Powerwall, ABB, SMA Sunny Island, Hybrid inverters, battery sizing, Lithium-ion, lead-acid batteries, off-grid, on-grid, stand-alone power systems

4. Battery systems - Energy storage

Jason Svarc

solar battery home energy storage reviews

Most modern battery systems used for solar installations use lithium battery modules housed in a enclosure. Previously sealed lead-acid (Gel or AGM) batteries were used however this review will focus on the newer lithium batteries, plus the unique Sodium and Flow batteries now available. Up until very recently all batteries were DC only but in the last year 'AC batteries' have become available which is a little misleading as a AC battery is simply a DC battery with an integrated DC-AC inverter.

Most modern batteries are housed within a battery enclosure containing many sensors and a dedicated battery management system (BMS). The BMS is essential to monitor battery voltage, state of charge and cell temperature (thermal monitoring). Most of these DC battery systems require an additional solar hybrid or Interactive Inverter to complete the energy storage system.

Battery Evolution - A good example of the rapid changes happening in the battery world is highlighted in the evolution of the Tesla Powerwall. The first generation 6.4kWh Powerwall shown below is a high voltage 'DC coupled' battery which is installed together with a compatible solar hybrid inverter to function. However the second generation Powerwall 2 (AC version) which is due to be released in late 2017 will be an AC battery at double the capacity for close to the same price. Another example is the LG chem RESU range of batteries which has gone from a single battery unit to 8 different battery sizes and two voltage options in just over 1 year of development.

See the battery and energy storage summary table here

 

RESU Series By LG Chem

 

LG Chem Ltd often referred to as LG Chemical is headquartered in Seoul, South Korea and was the 13th largest chemical company in the world by sales in 2014. LG Chem completed development and began mass production of Korea’s first lithium-ion batteries back in 1999.  LG Chem is the world’s third-largest maker with an annual production capacity of 1,000 million cells and is also a supplier of automotive battery for electric vehicles such as the Chevrolet Volt and Ford Focus electric.

Is LG Chem the new leader in Battery Storage Systems?

Basic specifications: (New - 5 battery size available)

  • Type: Energy storage - Battery system
  • Use: Self-use, back-up, Off-grid (when used with an appropriate inverter)
  • Power output: 4.0kW (4.2kW peak) for 6.5kWh module
  • Battery System Voltage: 48V (51.8V) and 400V DC
  • Battery type: Lithium NMC (lithium-nickel-manganese-cobalt)
  • Battery size - 48V:  3.3kWh, 6.5kWh, 9.8kWh
  • Battery size - 400V:  7.0kWh, 9.8kWh
  • Usable capacity: 90%

Features:

  • Compact, lightweight battery module with integrated BMS.
  • High surge/peak power output.
  • Low voltage 48V and High Voltage 400V options
  • Expandable with up to 19.6kWh (with LG adapter)
  • Claimed 4000 cycles at 80% DOD (to EOL 60% capacity)

Note:

  • No DC to AC inverter included.
  • Large range of compatible hybrid inverters: Goodwe, Redback, Selectronic, SMA Sunny island, Schneider, Solax X hybrid, Victron Energy
  • Warranty - 10 years

Price – LV 6.5kWh = AU$5000($760 per kWh)

Powerwall 2 By Tesla

 

Tesla is an innovative company based California, USA specialising in electric vehicles such as the model S and advanced lithium battery technology. Headed by the well known entrepreneur Elon Musk, Tesla is now known as a world leader in energy storage tehnology and is constructing the worlds largest battery manufacturing facility known as the Gigafactory which is predicted to reduce the cost of lithium-ion storage batteries by up to 30% once fully operational in 2018.

Basic specifications: (1 battery size available)

  • Type: Energy storage - AC Battery system
  • Use: Self-use, back-up (UPS)
  • Power output: 5kW (7kW peak)
  • Battery System Voltage: 350-450V DC*
  • Battery type & size: Lithium - NMC (nickel-manganese-cobalt) 13.2kWh
  • Usable capacity: 90% - 13.2kWh of total 15kWh capacity (estimated)

Features:

  • Integrated AC-DC converter.
  • Only outdoor weather rated (IP66) battery on the market.
  • Liquid thermal cooling.

Note:

  • DC model no longer available
  • AC model due for release April 2017
  • Up to 9 additional units to be connected in parallel
  • Warranty - 10 years

Price – AU$8000($590 per kWh)

 

Extra 2000 By Pylon Technology Co.

 

Shanghai Pylon Technologies Co., Ltd. is the leading chinese supplier and manufacturer of Lithium LiFePO Cell batteries. Producing a huge range of battery systems including High Energy LiFePO Cells, Telecom Backup Lithium Battery, Lithium UPS Battery, Car Starter Battery and Electric Vehicle Lithium Batteries.

Basic specifications: (1 battery size available)

  • Type: Energy storage - Battery system
  • Use: Self-use, back-up (UPS)
  • Power output: 2kW (2.2kW peak)
  • Battery System Voltage: 48V
  • Battery type & size: Lithium Iron Phosphate (LiFePO4)- 2.4kWh
  • Usable capacity: 80% - 1.92kWh

Features:

  • Compact battery module with integrated charger & BMS.
  • High surge/peak power output.
  • Expandable with up to 4 x 2.4kWh units
  • Claimed 4000 cycles at 60% DOD (to EOL 80% capacity)
  • Compatible with Redback, SolaX and many well known Inverters

Note:

  • No DC to AC inverter included.
  • Low surge/peak power output.
  • Compatible hybrid inverters: Goodwe, Redback, SMA Sunny island, Solax X hybrid
  • Warranty - 5 years

Price – AU$1600 ($660 per kWh)

E-KwBe 5.6 By GCL

 

GCL (Golden Concord Holdings Limited) based in Hong Kong is an huge international company which is recognised as the world’s largest provider of solar cells. The E-KwBe is the first battery released under the subsidiary GCL system integration technology Co.

Basic specifications: (2 battery sizes available)

  • Type: Energy storage - Battery system (2.5kWh & 5.6kWh)
  • Use: Self-use, Off-grid (when used with an appropriate inverter)
  • Power output: 3kW (continuous & peak)
  • Battery System Voltage: 48V
  • Battery type & size: Lithium NMC (nickel-manganese-cobalt) - 7kWh
  • Usable capacity: 80% - 5.6kWh

Features:

  • Attractive battery module with integrated charger.
  • Expandable (TBA)
  • Compatible with Goodwe SE hybrid inverters

Note:

  • No DC to AC inverter included.
  • Relatively low cycle life (2000 cycles)
  • Two sizes available - 2.5kWh & 5.6kWh
  • Warranty - 5 years

*Price –  $3700 ($660 per kWh)

 

B-Box by BYD

BYD Co is a leading Chinease vehicle and lithium battery manufacturer which began operations in 1995. Initially focusing on electric vehicles and mobile phone batteries BYD has recently entered the competitive home energy storage market.

Basic specifications: 

  • Type: Energy storage - Battery system
  • Size - Capacity: 2.5kWh modular (up to 10kWh), 12.8kWh
  • Use: Self-use, Off-grid (when used with an appropriate inverter)
  • Power output: 2.5kW per module (continuous & peak)
  • Battery System Voltage: 48V
  • Battery type: Lithium LFP (Lithium Iron Phosphate)
  • Usable capacity: 95% - 2.4kWh

Features:

  • Modular battery system with 2.5kWh units.
  • Compatible with common hyrbid battery 48V inverters

Note:

  • No DC to AC inverter included.
  • Cycle life and warranty unspecified
  • Must be installed indoors (IP20 rated)

Price bracket – TBA

PHI by Simpliphi

Simpliphi previously known as LibertyPak is US based battery manufacturer which has been a leading developer of Lithium based batteries since 2002. Initially developed for durable remote and mobile power systems the Simpliphi batteries are known for their high cycle life, safety and stability.

Basic specifications: (2 battery sizes available)

  • Type: Energy storage - Battery system
  • Size - Capacity: 2.6, 3.4kWh modular (up to 10kWh), 12.8kWh
  • Use: Self-use, Off-grid (when used with an appropriate inverter)
  • Power output: 2.9kW per module (continuous & peak)
  • Battery System Voltage: 24V, 48V
  • Battery type: Lithium LFP (Lithium Iron Phosphate)
  • Usable capacity: 100%

Features:

  • Modular battery system up to MWh scale
  • Compatible with common hyrbid battery (24V or 48V) inverters
  • Very high cycle life (10,000+ claimed)
  • Safe, stable battery chemistry

Note:

  • No DC to AC inverter included.
  • Must be installed indoors (IP20 rated)
  • Warranty - 10 years

Price bracket – TBA

 

AHI Battery Modules By Aquion Energy

 

Aquion Energy is headquartered in Pittsburgh, with a manufacturing facility in Westmoreland, Pennsylvania. Aquion’s Aqueous Hybrid Ion (AHI™) battery systems are optimized for stationary, long duration daily cycling applications, including off-grid and microgrids, energy management, and grid-scale energy storage applications. The batteries utilize non-corrosive reactions at the anode and cathode to prevent deterioration of the materials. The water-based chemistry results in a nontoxic and non-combustible product that is safe to handle and environmentally friendly.

Basic specifications: (Modular battery system)

  • Type: Energy storage - Battery system
  • Use: Self-use (UPS when used with an appropriate inverter)
  • Power output: 8.1kW (9.7kW peak) - M100 series module
  • Battery System Voltage: 48V
  • Battery type & size: Each Individual S20 stack is 2.4kWh (The M100 module is made up of 12 x S20 stacks for total 25kWh)
  • Usable capacity: 100% - 2.4kWh (only over low 24hr discharge rate)

Features:

  • Battery module with integrated protection
  • 100% Depth of Discharge available
  • Stackable up to MWh storage capacities
  • Non-toxic materials

Note:

  • No DC to AC inverter included.
  • High energy to weight ratio - 113kg per stack
  • Requires inverters with programmable charge voltage parameters which can operate in wide voltage window (40-60V)
  • May require additional battery management system to operate.

Price bracket – TBA

Zcell (ZBM2) By Redflow

 

Redflow, now an International company started in Australia with a manufacturing facility in the US produces one of the worlds first domestic flow battery systems called the Zcell (based on the previous version Redflow ZBM2 battery). The unique zinc bromide flow battery technology was developed by the University of Queensland and is capable of 100% discharge and can withstand partial or no charge for prolonged periods of time without degradation.

Basic specifications: (Modular battery system)

  • Type: Energy storage - Battery system
  • Use: Self-use, Off-grid when used with an appropriate inverter
  • Power output: 3.0kW (5.0kW peak)
  • Battery System Voltage: 48V
  • Battery type & size: Zinc Bromide flow battery - 10kWh
  • Usable capacity: 100% - 10kWh

Features:

  • Unique flow battery system with integrated protection
  • 100% Depth of Discharge available
  • Stackable up to MWh storage capacities
  • Safe, fire retartant system
  • High temperature tolerance

Note:

  • No DC to AC inverter included.
  • High energy to weight ratio - 240kg per unit
  • DC-DC conversion efficiency of 80%
  • Requires inverter with programmable charge voltage parameters which can operate in wide voltage window (40-60V)
  • Warranty - 10 years

Price bracket – $12500 = $1,250 per kWh

 

Enphase AC Battery By Enphase Energy

 

Enphase Energy is a Californian company founded in 2008. Enphase is considered the world's leading manufacturer of solar micro-inverters and is well established in the US market. The recent release of the compact AC battery in mid 2016 is one of the first modular AC battery systems available.

Basic specifications: (Modular AC battery system)

  • Type: Energy storage - AC Battery system
  • Use: Solar self-use and off-peak charging only
  • Power output: 0.26kW per module
  • Battery System Voltage: N/A (AC battery)
  • Battery type & size: Lithium (LiFePO4) - 1.2kWh
  • Usable capacity: 95% - 1.14kWh

Features:

  • Attractive, compact, modular AC-battery
  • Integrated AC inverter
  • Can operate as a stand-alone unit (not back-up)
  • Stackable up to 13 units (15.6kWh)
  • Sophiticated monitoring system (with additional Envoy)
  • Very high cycle life (claimed 7,300 at 80% DOD)

Note:

  • No back-up power capability
  • Additional Enphase Envoy S unit required for setup and monitoring
  • Low power output per module - 260W
  • Low weather rating (IP20) must be installed indoors
  • Warranty - 10 years

Price bracket – $1850 = $1540 per kWh

 

Sonnenbatterie ECO By Sonnen

 

Sonnen is successful German company founded in 2010. Previously known as Sonnenbatterie, Sonnon has become a leader in developing high quality, modular energy storage systems for residential and commercial applications.

Basic specifications: (Modular AC battery system)

  • Type: Energy storage - AC Battery system
  • Use: Solar self-use and emergency back-up power
  • Power output: 3.0kW (8.0kW peak)
  • Battery System Voltage: N/A (AC battery)
  • Battery type & size: Lithium (LiFePO4) - 4kWh to 16kWh (2kWh modules)
  • Usable capacity: 100% (assumed capacity is 2.2kWh)

Features:

  • Attractive, modular system
  • Can operate as a stand-alone unit with some back-up support
  • Stackable up to 16kWh
  • Sophiticated monitoring system
  • Very high cycle life (claimed 10,000 cycles)

Note:

  • Relatively low inverter power output 3.0kW
  • Low weather rating (IP20) must be installed indoors
  • Back-up functionality limited
  • Warranty - 10 years

Price bracket – Approx AU$1250 per kWh