SolarKobo Score: 4/5
Introducing Energy Storage Systems (ESS)
Batteries have been in use for a rather long time both in standalone off-grid setups and in backup power systems. In recent years, however, there has been a significant surge in the popularity of domestic energy storage systems. One of the main drivers behind this trend is the desire for energy security.
Lithium-ion batteries, now recently being offered as 'energy storage systems' or ESS, that is, with advanced features and supporting components that may or may not include a hybrid inverter, MPPT capabilities and a battery management unit, and in 'modular' designs that make them easy to install and used as plug-and-play devices, have grown in popularity over the years. One of the many reasons for this includes the increase in research efforts. For instance, the 2019 Nobel Prize in Physics was awarded for research in Lithium-ion battery technology. Also, the success of the Powerwall and the electric vehicle industry has had a profound effect on the ESS market especially. While lithium-based battery cell technologies are still the costliest of the existing battery technologies, production costs are being driven down by optimal manufacturing processes to meet the boom in demand and more competition that has driven major players in the solar industry into the energy storage segment of the market.
Known for its inverters, the makers of Growatt batteries, Growatt New Energy Technology Co. Ltd, is a Chinese solar inverter manufacturing company established in 2010. Growatt has its production plants in China, with offices in Europe, US and Australia. Growatt's products are built to comply with international standards and are ISO and OHSAS-compliant.
At the 2021 edition of the TÜV Rheinland’s solar congress, Growatt won an ‘All Quality Matters’ award for the outstanding performance of its ARK battery. During the test program, the ARK battery achieved first-rate performance in numerous safety and reliability tests, including charge/discharge cycling performance, initial charge/discharge energy measurement, battery high rated charge/discharge and high/low temperature charge/discharge performance.
Growatt offers its lithium-ion batteries in the ARK LV Battery range with power rating for a single battery at 2.5kW at 48V and with a cycle of over 6,000. They can be stacked up to 10 to give an output rating of 25.6kW.
General Features of Growatt's Ark Batteries
Their cells are made with cobalt-free Lithium iron phosphate, LiFePO4 or LFP for short. LFP is one of the most reliable, safe and long-lasting lithium battery technologies. The batteries are free of cobalt and this contributes significantly to the reduction of the market price of the batteries.
They come in a modular design that allows them to be stacked together and to be easily scaled up to 25.6kW just by stacking. Thus, they are easy to install and can be installed by one person.
Like Growatt's inverters, they come in white colours and in a slimline compact design that gives them a very small footprint allowing them to save wall space and giving them an appealing aesthetic that can integrate well with home interiors. They can be installed on the floor or mounted on a wall.
94.5% Depth of Discharge
A battery's Depth of Discharge (DoD) is the proportion of the battery's capacity that can be used. A higher DoD indicates that a larger portion of the stored energy can be utilized. Growatt's ARK LV batteries have DoDs of up to 94.5% indicating a significant usable capacity. This puts them ahead of some of their competition, Sonnen (90%) and Alpha ESS (90%).
Growatt's ARK batteries incorporate Battery Management System (BMS) that provides multi-level protection for the inverters that use them whilst also allowing users to monitor the batteries and manage their energy use.
Growatt's batteries are built to withstand a temperature range of between -10°C and 60°C. This is important for the battery to maintain it’s efficiency, as a stable temperature control ensures that the battery cells are protected during a charging and discharging cycle.
They have an Ingress Protection rating of IP65. This means that the batteries are protected against dust and water and can thus be installed indoors or outdoors. However, Growatt advises that there must be some shade to cover the batteries and there cannot be direct sunshine or rainfall on the battery.
Growatt covers its ARK batteries under a 5-year product warranty with an option for an additional 5 years if the capacity drops below 60% of its nameplate value within the 10 year period.
Growatt's ARK batteries are at the lower end of ESS systems in the market. Their prices compares very favourably with other brands like Huawei, Pylontech and BYD.
The AXE LV Battery
In January 2022, Growatt released the AXE LV battery. According to Growatt, the AXE was designed to meet differentiated needs from daily households to large business and industrial scenarios. Like the ARK, it can also be scaled up to 400kWh and can allow up to 5,000 cycles. Each module is rated 5kW measuring 650 mm x 350 mm x 165 mm and weighing 40 kg. The nominal voltage is 51.2V and the operating voltage range is between 48V and 57.6V. The battery also features IP20-rated protection and internal plus connection.
It has a lifespan of 10 years and is covered by a 5-year warranty.
Growatt first issued lithium-ion energy storage systems (ESS) in 2019. While this does not make them a first mover, it means that they caught on the trend very fast. Regardless, their decade plus experience making inverters means disposes them to expert knowledge about home energy solutions.
Like all lithium batteries known to offer several advantages over traditional lead acid batteries for solar; Growatt ARK batteries are lighter and weigh just 30kg. They are also more efficient and long lasting than their non-lithium ion counterparts.
Learn how Lithium batteries compare with other battery technologies here.
To be sure, Growatt build their batteries for use with a Growatt inverter. Solarkobo has had a lot of experience with the Growatt brand of inverters and will not hesitate to recommend their ARK LV battery to our clients.