BatteryStorage¶

A BatteryStorage models a battery at a fixed, grid-connected site: a battery energy storage system (BESS), with a fixed capacity, charge and discharge limits, efficiencies and self-discharge. Closed-loop pumped hydro fits it as a first approximation, as long as you can leave out natural inflow, a minimum pumping or generating power, and start costs.

A battery storage has a Battery: the asset is what you own and name, and the battery holds all its physics. This page covers what the asset adds; the Battery page covers everything else.

Basic usage¶

Let's add a battery to the site: 50 MWh that charges and discharges at up to 25 MW, starting half full.

from odys import Battery, BatteryStorage, StorageInitialState

bess = BatteryStorage(
    name="bess",
    battery=Battery(
        capacity=50.0,  # MWh of storage
        max_charge_power=25.0,  # MW charge limit
        max_discharge_power=25.0,  # MW discharge limit
        efficiency_charging=0.95,
        efficiency_discharging=0.95,
    ),
)
starts_half_full = StorageInitialState(storage=bess, soc=0.5)

Add bess to your AssetPortfolio, and pass starts_half_full to the EnergySystem with initial_conditions=(starts_half_full,).

Fields¶

Initial and final state¶

A battery storage takes a StorageInitialState, which is required, and optionally a StorageFinalState. Both take the storage and its state of charge, soc, as a fraction of capacity. How they shape the plan, and their fields, are on the Battery page, under State of charge.

Results¶

A battery storage's results are in result.battery_storages: net_power, soc and charge_mode, one pandas.Series each. The Battery page solves the site with its battery and shows how to read them, under Results. The Storing Solar for the Evening example runs a battery through a full day of solar.

How it's modelled¶

A battery storage is a battery on the bus, with no rules of its own: the battery's B-1 to B-7. It charges from the power balance and discharges into it, and its wear enters the objective.

Next steps¶

Some batteries drive away. Next, see how an ElectricVehicle adds trips to a battery.