Adding different types of batteries to your project

Summary

OpenSolar now allows you to add multiple different types of batteries to the same project. This allows for more complex battery configurations to be modeled and calculated accurately. 

NOTE:  Multiple types of batteries are modeled together within the system. If you need to model these separately, just create multiple proposals or systems.  

How to add multiple batteries

To achieve the addition of multiple types of batteries, please follow these steps:

• Go into the battery tab of the design
• select the + Battery icon
• Follow the battery selection pop-out to select the battery you want to use for your design.

Once you have the first battery selected, follow the same steps to add all the other batteries you need for your project. 

How multiple batteries impact energy calculations 

When designing with multiple batteries, key metrics like energy and power capabilities are aggregated for a comprehensive overview:

• Total Energy (kWh Charge, Optimal, Optimal Degraded)
• Power Metrics (Peak Power, Continuous Max Power)
• Warranty kWh (1 Cycle Per Day)

Weighted average: For parameters that vary based on battery performance, we calculate a capacity-weighted average, ensuring accurate reflection of each battery’s contribution, these parameters include

• Battery Aging Factor
• Depth of Discharge Factor
• Efficiency Factors (Total and One-Way)
• End-of-Life Capacity
• Usable Capacities (Standard and Degraded)

Note for installers:

Given that the battery voltage doesn't directly impact the battery simulation, it is acceptable to add a  range of batteries with different voltages, regardless of the installation implications this adds.

This structured approach ensures the combined battery model delivers accurate, actionable insights while maintaining the integrity of individual battery data.

Detailed Calculation Steps

After combining the multiple battery specifications, OpenSolar simulates battery performance hourly, tracking capacity, and lifetime throughput.

Four key input areas influence battery modeling:

1. Battery Specifications: Defines charge/discharge rates, degradation profile, and efficiency. Configured via Control > Design & Hardware > Batteries.
2. Battery Control Scheme: Determines charge/discharge logic, reserved capacity for peak times, and grid interaction. Custom schemes can be created.
3. Connection Type: DC-coupled vs. AC-coupled impacts PV oversizing.
4. Load-offset Settings: Specifies the portion of the load the battery can offset.

Based on these inputs, OpenSolar models:

• Usable Capacity: Total capacity adjusted by the battery’s depth of discharge (DOD).
• Charge/Discharge Rates: Limited by maximum rates; excess solar is exported if charging capacity is exceeded.
• Efficiency Losses: Accounts for energy losses during charge/discharge using round-trip efficiency.
• Degradation: Tracks lifetime throughput to calculate reduced usable capacity over time.
• Charge/Discharge Timing: Controlled by the selected scheme, defaulting to a basic load-following strategy.

For more information relating to how OpenSolar models battery energy storage, see this article.