How Inverted Energy Designed High Voltage Energy Storage System

Lithium-based Energy Storage System is the need of the hour. Day by day the energy demand is increasing. No doubt, India has the capability of generating power via various sources including solar energy, wind energy, hydro, and many more. But when it comes to power storage, India lacks the technology. The present energy storage solutions which India has been creating more problems than becoming the solution.

We at Inverted Energy took the challenge of designing a high voltage energy storage solution to help India to become Energy Independent.

What is an Energy Storage System?

Well, we already have published content related to Energy Storage Systems describing what are they and why they are important. 

You can check the article here.

Applications of the Energy Storage System

  1. Peak Shaving
  2. Load Shifting
  3. Emergency Backup
  4. Microgrids
  5. Grid level storage

Why present ESS are bad for the environment?

If we look at the market, we can observe that where there are a lot of power outages, diesel generators or lead-acid-based batteries are employed.

The issue with diesel generator sets is that they are extremely noisy, resulting in noise pollution. Then they emit carbon, which pollutes the air.

Regular maintenance and a lot of space are required for diesel generators or lead-acid batteries.

The life cycle of lead-acid batteries is not very long; in fact, it is quite brief. Not to mention that the diesel generators have a few moving mechanical parts which require additional maintenance for their efficient performance

The Power Ministry of India said in 2021 that the government of India intends to delicense stand-alone energy storage, meaning that anyone can now build up their own energy storage system.

With all of this in mind, it seemed clear that Inverted Energy would try its hand at designing an Energy Storage System, and thus we began.

Energy storage solutions are big because they have a lot of power storage capacity. As a result, the first stage in creating a high-voltage energy storage system was to design tiny solutions, which began with selecting the appropriate lithium cell for the energy storage solution.

Which type of cell is required for the Energy Storage System?

LFP is commonly utilized in energy storage systems because it offers benefits such as safety, long lifecycle, and low cost. The energy density is less relevant in the energy storage business.

Working with LFP was not new to us because we are already manufacturing the lithium batteries for the 2W and 3W EVs using NMC. Lithium batteries are something with which we have a lot of experience.

We began development on a system with a 240V 200Ah configuration. But first and foremost, a compact solution with the same voltage setup has to be designed.

As a result, our initial challenge was to build a 48V 200Ah energy storage system.

Steps we followed in developing this high voltage LFP

Cell Grading and Grouping were the first steps in the design of any lithium battery. It’s the same for every battery, whether it’s a high-voltage energy storage system or an NMC-based Lithium Battery for EVs.

Why and how cell grading and grouping is done?

Because the voltages and capacities of each cell can be different, cell grading and grouping are done, and it’s very important. If these discrepancies aren’t handled and cells are chosen at random, the battery’s overall efficiency will suffer.

Cell Grading: All the cells are grouped based on their capacity. 

Cell Grouping: After sorting cells based on the capacity, they are further sorted based on the voltage and after that, they are again sorted based on the Internal Resistance.

Cells after being sorted based on the IR are used to design the battery. These cells will have the same capacity, voltage, and IR which will lead to a battery with good performance.

Battery Assembly:

Once the cells are sorted, we assembled them in parallel and series based on the required capacity.

Battery Testing:

After the assembly, we did battery performance testing. We did 3 different tests including two charge and discharge tests and one capacity test to check the performance of the battery.

  1. Charge and discharge test based on the International Standards
  2. Charge and Discharge test on Maximum Power Rating
  3. Other tests certified by International Standards

After the battery testing, the structure test was the last thing we did. It’s the most crucial test of all because even the tiniest flaw in the construction can cause a calamity.

Now let’s understand what challenges we faced in this journey.

making of high voltage energy storage system

Challenges We Faced

We faced 5 types of challenges in the process of designing a high voltage energy storage system

  1. Design Challenge
  2. BMS Selection Challenge
  3. Structure Challange 
  4. Thermal Management Challenge
  5. Cable Sizing Challenge

Design Challenge:

240V 200Ah is a huge battery. Its weight is around 450 kg. To achieve the desired result, 5 units of 48V 200Ah were connected in series.

A Modular Design was used. That resulted in a system with distributed cell structure. 

BMS Selection Challenge:

Because of the distributed cell structure, we also had to deal with the issue of selecting the appropriate BMS. The BMS is a critical component of the energy storage system.

The Multistage BMS with a daisy chain connection was required for the full energy storage. The BMS (A) passes its data to the next BMS(B) in a daisy chain link. BMS (B) compares its data with the data provided by BMS (A), then sends the whole set of data to the further BMS in the chain.

Structure Challenge:

The structure of the overall energy storage system was the next hurdle after the smaller units of 48V 200Ah were designed.

The server rack design was chosen since it is well acknowledged in the market. This server rack can easily be installed on any site, whether it’s a distant island in Andaman & Nicobar, the Himalayan region, or tribal communities, where the energy solution is needed. Furthermore, designing a container-based energy storage solution employing server racks is relatively simple.

Thermal Management Challenge:

Thermal management is one of the very important parts of energy storage. If we have to explain the very simple terms, then we can say that heat is the enemy of battery. Heat decreases the lifecycle of the battery. It is very important for the battery to get rid of the heat being generated while charging and discharging the battery.

For a 240V 200Ah battery, the standard rate of charge and discharge is 24 kW while it can go up to 48 kW. That means 48 kW of energy is being transferred per hour which will generate a lot of heat, enough to damage the system if not managed properly.

We needed a heat exchange or cooling management system for the stable functioning of the battery at 48 kW charge and discharge.

Cable Sizing Challenge:

At last, we encountered the cable sizing challenge. For a 240V 200 Ah energy storage system, we needed cables that can perform efficiently for 10 years at a rate of 48 kW.

Finally, the system was designed. 

With this energy system designed and developed, we joined the exclusive league of a handful of Indian startups who have the capability of in-house designing the high voltage energy storage system.

Where currently our Energy Storage Systems are Deployed

  1. Many Gram Panchayat of Maharashtra
  2. Many Gram Panchayat of Chhattisgarh
  3. Residential Societies and Farmhouses

Click Here to know more about the High Voltage Energy Storage System

  1. What is High Voltage Energy Storage System
  2. Types of Energy Storage Systems and why it’s important for India
  3. Business Opportunities with Energy Storage Systems