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How to create your own battery control scheme

OpenSolar Support
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A battery control scheme sets the logic on when the battery should charge/discharge, whether it should reserve capacity to offset load at a specific time (i.e. at peak electricity rate), and if the battery is allowed to charge/discharge to the grid. 

 

In OpenSolar, you can select a battery control scheme, which will alter the savings your customer sees in their proposal. See more on how OpenSolar models battery energy storage here. 

 

Creating a Custom Battery Control Scheme

In OpenSolar, admins can make a unique battery control scheme in Control > Design & Hardware > Battery Control Schemes. Note that OpenSolar has default battery control schemes that are robust and cover most Pro needs. Please check the defaults before creating your own.

 

1. Adding a New Battery Strategy

OpenSolar provides you the flexibility to create multiple different battery strategies that apply at a specified time-period. You can click on the "Add New Strategy" button to create more than 1 strategy. 

 

2. Customizing the Battery Strategy Logic

There are four battery control logic that you can apply given by the four check boxes. These control whether the battery is allowed to:

  1. Charge from the system (i.e. charging from solar energy generated by the PV system)
  2. Charge from the electricity grid
  3. Discharge to the load (i.e. household or building load of your project)
  4. Discharge to the electricity grid

You can also apply different combinations of these four control logic to create some more advanced behaviors. Please go to Battery Control Logic section to read more on this.

 

The two other fields set constraints on what the battery can do:

Field What does it do?
Minimum State of Charge (%)
  • Set the minimum state of charge (SOC) that battery must maintain. The lower limit of the minimum state of charge will always be given by the battery specifications (1 - Depth of Discharge).
  • This field is useful in making the battery to maintain some reserve capacity to meet an evening load when prices are high, or discharge to the grid to participate in services like Energy Arbitrage or Frequency Control Services in the Energy Markets.
  • Note that it is valid for the battery to start off below the minimum SOC set by this field, however the battery will not be able to discharge until it has been charged above the minimum SOC.
Maximum Charge/Discharge Rate (kW)
  • Sets the maximum rate the battery can charge or discharge at that is less than or equal to the batteries "Max Continuous Power".
  • This field is useful if we want to limit the rate that the battery can charge/discharge at.

 

3. Assigning a Time-Period to a Battery Strategy (This MUST be set)

IMPORTANT: 

  • If NO battery strategy is assigned to a particular time-period, then by default the battery will do nothing during that time-period.

All Strategies must have the Applicable Time-Period set. If a strategy applies to all time periods please set the Time-Of-Use Schedule to reflect this by setting the Date Range as 1st Jan to 31st Dec and selecting all Applicable Weekdays and Hours.

You can add multiple strategies that apply at different times throughout the year/month or weekday. If there is no strategy applying to particular time-period, then the battery will do nothing (i.e. does not charge or discharge).

When you edit an applicable time-period, you will open up a time-scheduler dialog shown below. The time-scheduler allows you to select:

  1. A start and end date in which the battery strategy applies,
  2. The applicable weekdays and hours

For example, the Scheduler below would set the applicable time-period of the battery strategy to apply between 1st Jan to 30th April, Monday to Friday between 4-9pm.

4. Apply your custom Battery Control Schemes to your system designs

Once you've added a battery a system designs, you can select a battery control scheme.

 

Access OpenSolar's default schemes or a custom battery control scheme in Project >  Design > Batteries. Here you can select from your entire list of control schemes. 

 

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Battery Control Logic

OpenSolar supports the following battery control logic combinations that can be set by the four tick boxes when creating a new battery strategy.

Note: the maximum charge/discharge rate of the battery is limited by lesser of the "Max Continuous Power" of the battery given by the battery specification (view in Control > Design & Hardware > Batteries), or the Maximum Charge/Discharge Rate set by the assigned battery strategy settings.

Allow Charging From: Allow Discharge To: Description of Applied Logic
System Grid Load Grid
✔ ✖ ✖ ✖

The battery will ONLY charge from excess solar energy generated from the PV system after offsetting the load.
✖ ✔ ✖ ✖ The battery will ONLY charge from the electricity grid.
✖ ✖ ✔ ✖ The battery will ONLY discharge to offset the energy load or usage of the household/building of the project.
✖ ✖ ✖ ✔ The battery will ONLY discharge to the electricity grid.
✔ ✔ ✖ ✖ The battery will FIRST charge from excess solar energy generated from the PV system after offsetting the load. If the battery still has remaining capacity to charge from the grid then it will do so.
✖ ✖ ✔ ✔ The battery will FIRST discharge to offset the energy load or usage of the household/building of the project. ONLY after offsetting the load will it discharge the remaining capacity to the grid.
✔ ✖ ✔ ✖

The battery will charge from any excess solar generation after the generation has been used to offset the load. The battery will discharge to meet the remaining load when solar generation is not enough to fully offset the load.
✖ ✖ ✖ ✖ If no battery control logic is selected, the battery will do nothing.

 

 

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