Battery storage for industrial sites: an introduction

Solar has become a familiar part of industrial energy in Tamil Nadu. Battery storage is the next step many facilities are considering. A battery can store energy when it's cheap or plentiful and release it when it's expensive or unavailable. Whether that pays off depends on what the battery is asked to do, and on the facility's tariffs, load and reliability needs.

What batteries can do

Solar shifting

Store midday solar surplus and use it in the evening. Valuable where exports earn little or are not allowed. See net metering vs gross metering.

Peak shaving

Discharge during short periods of high demand to reduce the maximum demand recorded, potentially lowering demand charges. See reading your industrial electricity bill.

Time-of-day arbitrage

Charge during off-peak periods and discharge in peak periods, where time-of-day tariffs create a price difference.

Backup power

Supply critical loads during grid outages, reducing reliance on diesel generators and avoiding production losses.

Power quality

Fast-responding battery inverters can support voltage, smooth fluctuations and provide reactive power. See power quality and solar at industrial sites.

Stacking services

The strongest business cases usually combine several services. A battery used only for one may struggle to pay back; the same battery providing backup, peak shaving and solar shifting may make sense.

Key terms

• Power (kW) — how fast the battery can charge or discharge
• Energy (kWh) — how much it can store
• Duration — energy ÷ power; how long it can discharge at full power
• Round-trip efficiency — share of energy put in that comes back out
• Depth of discharge — how much of the capacity is used in each cycle
• Cycle life — number of cycles before capacity falls to a specified level
• Degradation — gradual loss of capacity over time and use

Technologies

Lithium-ion

Dominates new stationary storage, with different chemistries:

• Lithium iron phosphate (LFP) — widely used for stationary storage, generally regarded as having good thermal stability and long cycle life
• Nickel manganese cobalt (NMC) — higher energy density, used widely in vehicles

Lead-acid

Long used for backup (UPS). Lower upfront cost but shorter cycle life and lower depth of discharge.

Others

Flow batteries and other technologies exist for specific applications but are less common at industrial sites.

Sizing a battery

1. Define the services — what should the battery do?
2. Analyse interval data — load, solar generation, tariff periods. See matching solar to your load profile.
3. Size power for the largest required discharge
4. Size energy for the required duration
5. Allow for degradation over the battery's life
6. Model value of each service under current tariffs

The business case

Value comes from:

• Avoided energy cost (shifting, arbitrage)
• Avoided demand charges (peak shaving)
• Avoided production losses (backup)
• Avoided diesel cost
• Avoided power quality penalties

Costs include:

• Battery, inverter and control system
• Installation, civil works, fire safety and cooling
• O&M and monitoring
• Replacement or augmentation over time

Test the case under different tariff assumptions.

Safety

Large batteries store substantial energy and must be designed and installed safely:

• Fire safety — detection, suppression and separation distances as per applicable standards and insurer requirements
• Thermal management — cooling to keep batteries within operating temperature, important in hot climates
• Ventilation where required
• Battery management system — monitoring cell voltages, temperatures and state of charge
• Emergency procedures and staff training

Discuss the design with your insurer and fire safety advisers.

Regulatory context

Rules on behind-the-meter storage, interaction with net metering and any grid services are set by regulators and utilities. Check the current position with the distribution company and the regulator.

Questions to ask suppliers

• What chemistry, and why?
• What warranty — years, cycles, retained capacity?
• What round-trip efficiency, including auxiliary loads?
• How is the system cooled, and what is the fire safety design?
• How is degradation managed — augmentation or replacement?
• What monitoring and reporting will I receive?

Common mistakes

• Sizing for one service when value comes from several
• Ignoring degradation in the business case
• Underestimating cooling needs in hot climates
• Treating fire safety as an afterthought
• Assuming current tariffs will stay the same

Where batteries fit with solar

For many facilities, the practical sequence is to install solar first, measure how its output matches the load for a year, and then decide whether a battery adds enough value. Real operating data removes much of the guesswork in sizing, and space, cabling and inverter choices made for the solar system can allow for a battery later.

How we help

Through our C&I solar work with industrial consumers, we help assess whether storage adds value alongside solar, define the services needed and coordinate specialist partners for design and installation.