How to create and apply a battery control scheme

Summary:

This article explains how to create, configure, and apply battery control schemes in OpenSolar to manage how batteries charge and discharge based on system behavior and time schedules. It also covers available pre-built strategies designed to optimize energy usage, savings, and grid interaction.

Accessing Battery Control Schemes:

All battery control schemes can be accessed by navigating to Control > Design & Hardware > Battery Control Scheme.

To edit an existing control scheme, click the pencil icon next to the scheme you wish to modify.
To create a new scheme, click + Add Battery Control Scheme.

Creating a new Battery Control Scheme:

In the Create Battery Scheme window, you will be prompted to complete the following fields:

Title: The name of the scheme, which will appear in the Battery Control Scheme drop-down menu during project design.
Description: An optional field to describe the scheme.
Strategy: Defines the battery behavior.

Configuring the strategy:

Within the Strategy section, you can define how the battery charges or discharges using the following checkboxes:

Charge from the system: Enables charging using energy generated by the PV system.
Charge from the grid: Allows charging from the electricity grid.
Discharge to the load: Enables the battery to supply energy to the project’s building or household load.
Discharge to the grid: Allows energy discharge back to the electricity grid.

You may select any combination of these options to create a customized battery behavior strategy.

Adding the charge information:

Field	What does it do?
Minimum stage of charge (%)	Set the minimum state of charge (SOC) that the 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 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 abtetry can charge or discharge at that is less than or equal to the batteries' "Max Continous Power". This field is useful if we want to limit the rate at which the battery can charge/discharge.

Assigning a time period:

Important: Assigning a time schedule is mandatory. If no schedule is assigned to a time period, the battery will remain inactive during that time

To assign a time-based schedule:

Click + Set Time of Use Schedule.
Select the Start Date and End Date for which the strategy will be active.
Choose the days of the week and hours of the day the strategy should apply.

Example:
To apply a schedule from January 1st to April 30th, select those dates as the range.
To restrict battery operation to Monday through Friday from 4 PM to 9 PM, highlight that portion of the application schedule.

Once the configuration is complete, click Save.

Applying the Control Scheme to the project:

To apply a battery control scheme:

Navigate to the Design tab of your project.
Select the Battery tab.
Use the Battery Control Scheme drop-down to select the desired strategy.

Note: OpenSolar provides several pre-built battery control schemes that can be used.

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 the 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	Description of Applied Logic
✔	✖	✖	✖	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.

Pre-Built Battery Control Scheme:

Battery Control Scheme	Description
Self-consumption (Also known as load-following)	In most cases, you would want to select this battery control scheme. This control scheme gets the battery to: Charge from any excess solar generation remaining after offsetting the load until the battery is full. This occurs when generation > load. Discharge to meet any load after self-consumption until the battery is empty. This occurs when load > generation. Due to the logic that applies by this battery control scheme, it will be the best control scheme to maximize self-consumption with a battery.
Minimize Grid Import Cost	This battery control scheme is designed to maximize electricity bill savings of a Time-of-Use electricity bill by withholding capacity to offset the usage during peak electricity pricing. Note: most cases using the "Self-consumption" control scheme will result in similar savings since the battery discharge period generally coincides with the peak pricing periods. There are also some occasions when "Self-consumption" may have a higher bill saving than this battery logic due to the fact that the battery must withhold capacity for peak TOU periods, and hence the battery may not be fully utilized to increase self-consumption.
Maximize Savings	This battery control scheme is designed to maximize customer bill savings by smartly charging/discharging the battery based on time-of-use cost of electricity and generation and energy usage characteristics. It achieves this by identifying optimal periods to: Conserve energy to ensure that the usage during the highest pricing periods gets offset first before prioritizing cheaper time periods. It will discharge the full battery capacity to the grid to try to achieve energy export during time periods with favorable export rates (i.e., export rates that are greater than the peak cost of electricity). It will charge the battery during off-peak pricing periods (generally, this would be at night-time) to ensure the battery has sufficient capacity to offset the load during the next day. The optimization is smart enough to know not to fully charge the battery to 100% capacity at night-time in order to reserve some capacity to charge from excess solar the next day. (For California) This battery control scheme enables your project to take advantage of the high export rates in August/September put in place as part of the NEM 3.0 transition. Note: OpenSolar does not currently validate the system's battery control capabilities to optimize for favorable export rates. We recommend pros to continue using the "Self-consumption" battery control scheme if you are unsure.
Peak Demand Shaving	This battery control scheme is designed to maximize savings for a bill that includes demand charges. When a utility tariff includes demand charges, these can make up a significant portion of a customer's monthly spend. A key benefit of installing storage is enabling the customer to limit exposure to demand charges by discharging at points of highest demand. The Peak Demand Shaving control scheme prioritizes reducing peak demand (kW), thus reducing demand charges. By default, the control scheme will seek to reduce the peak demand to the average demand per month. Note that this control scheme is most effective when: The battery is sufficiently sized such that it is able to effectively reduce the peak demand There is enough solar generation to adequately top up the battery each day. It does try to charge from the grid in these scenarios where the system is not large enough, but it will never draw more energy from the grid such that it will create a new peak demand.
NZ Optimized (New Zealand Only)	This battery control scheme is generally not optimal for most system designs and is very specific for a niche use case in New Zealand. The battery will do the following: Charge the battery from the grid between 1-5 AM (low electricity prices) and 3-5 PM (to top up the battery before peak electricity pricing in the evening) Battery can ONLY charge from excess solar generation between 11 AM - 5 PM All other times, the battery will charge when there is excess solar generation or discharge to offset the load. Note: Given the niche use case of this battery logic, in most scenarios, it does not result in improving electricity bill savings.

Articles in this section

Summary:

Table of contents:

Accessing Battery Control Schemes:

Creating a new Battery Control Scheme:

Configuring the strategy:

Adding the charge information:

Assigning a time period:

Applying the Control Scheme to the project:

Battery control logic:

Pre-Built Battery Control Scheme:

Comments

Articles in this section

Summary:

Table of contents:

Accessing Battery Control Schemes:

Creating a new Battery Control Scheme:

Configuring the strategy:

Adding the charge information:

Assigning a time period:

Applying the Control Scheme to the project:

Battery control logic:

Pre-Built Battery Control Scheme:

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