Electricity generated from any source, whether traditional or renewable, needs to be consumed instantly. This limitation of electricity has led to the development of energy storage technologies.
Energy storage can play a very important role in grid integration and balancing of variable generation sources. By increasing the system’s overall flexibility, it can improve power quality, reduce peak demand, enhance capacity of distribution / transmission grids, avoid/reduce deviation penalties etc.
Applications of Battery Storage
1. Residential Segment
For residential consumers, depending on the connected load, solar systems of up to 5 kW capacity are installed. Solar systems of 1 kW and 2 kW capacities can meet the electricity demand of average households and are frequently encountered installed. Residential segment is dominated by tubular flooded lead acid batteries and a small fraction of households also use VRLA batteries.
Now, Lithium batteries are also emerging rapidly. 12V batteries with 150Ah rating are predominantly used.
2. Industrial and commercial segment
This segment is dominated by industrial consumers where solar systems of up to a few Megawatt (1-3 MW) have been deployed on roof-tops which were otherwise unused
Industrial Segment – Industrial units are large consumers of electricity and thus have potential for large scale solar systems from few hundred kilowatts to few megawatts.
Commercial Segment – Commercial entities who are either highly dependent on diesel generators or lack the access to power are potential consumers for battery based back-up system. Telecom towers, petrol pumps, academic institutes, medical centres, rural banks etc are predominantly using solar systems with battery backup.
- Petrol Pumps Solar systems with a capacity in the range of 10kW to 15 kW with battery backup of 96V and 150Ah are installed along with a 6.5 kVA inverter to cater to the entire station load in urban areas.
- Telecom Towers Telecom towers without access to grid can be operated on battery based backup system. Telecom towers have an average load in the range of 1 – 4 kW, depending on installed Base Transceiver Station (BTS) equipment.
- Academic Institutes Solar systems with a capacity ranging from few kilowatts to few hundred kilowatts have been deployed for diverse consumer groups depending on the energy requirements. Battery backup in this segment is only preferred for critical loads instead of 100% backup. Battery bank of 12V and 600Ah capacity is installed for 1 kW system for academic institutes.
3. Microgrids/Mini Grids
Batteries are a critical component of micro/mini-grid systems. In absence of commercial consumers that could act as anchor loads for these micro/mini-grids, 100% of the total energy generated from solar PV is stored in batteries to supply the power during evening and night hours to rural consumers
4. Application of Batteries in Indian Railways
Batteries for the Indian Railways are primarily used for the following applications:
– Traction Applications
- Train lighting and air-conditioning
- Locomotive Starting
- Signaling and telecommunication
– Renewable Applications for non-traction applications
Key industry drivers for battery adoption
1. Power outages Availability of grid electricity and power-cut durations has been key driver for adoption of battery based backup systems in residential segment.
2. Cost of grid vs. solar Solar systems have now become cost competitive or even cheaper than grid tariff for commercial & industrial consumers and residential consumers as well.
3. ‘Time of Day’ Tariff In the time-of-day regime, consumers tend to install battery backup to supplement their energy demand from batteries during peak hours. Addition of time-of-day charges in electricity bill will result in increased demand for batteries
4. Grid scale storage With increasing share of renewable energies in national grid, will provide opportunities for advance battery technologies in areas such as ancillary services, peak shaving, grid stability, renewable integration to the grid and forecasting.
- Frequency Regulation – When power generation is equal to power usage, the frequency is stable. If usage is higher than generation, the frequency drops: brownouts and blackouts. When power generated exceeds the demands of the grid, the frequency rises: this can damage the grid and connected devices. Battery Storage technologies are widely used to maintain frequency regulation due to their millisecond fast response time.
- Voltage Support – Battery Storage, and in particular distributed energy storage , can be located extremely close to end users, making them an increasingly attractive option for voltage support.
- Peak Shaving – Peak shaving involves proactively managing overall demand to eliminate short term demand spikes, which set a higher peak. This process lowers and smooths out peak loads, which reduces the overall cost of demand charges. Solar + Battery energy storage is the best way to peak shave.