Battery
The page lets you define your battery strategy by choosing between self-consumption, autonomy, and arbitrage operating modes, and automatically calculates the appropriate battery size for the project.
Purpose of This Page
This page is used to add and configure a battery system within a PV project.
It allows you to define the battery’s role in the system, either to increase self-consumption or to provide backup power during grid outages.
Based on the selected use case and preference inputs, solarVis automatically calculates the required battery capacity and proposes suitable battery systems.
The results are based on an hourly simulation that compares solar production and site consumption and determines when the battery should charge or discharge.
Battery calculations express state of charge limits, efficiency losses, and charging/discharging power constraints to reflect realistic system behavior.
All inputs on this page directly affect:
Required battery capacity (kWh)
Self-consumption and grid dependency
Backup performance during outages
Energy flow outputs and system behavior simulations
Electricity cost savings and bill reduction
Long-term financial metrics such as return on investment
Recommended battery products and system configuration
What You Can Do Here
On this page, you can:
Enable or disable a battery system for the design
Select the battery operating mode: Self Consumption, Autonomy, Arbitrage
Adjust your target values, such as self-consumption rate and autonomy level
Configure how an arbitrage battery charges and discharges against the time-of-use tariff
Reserve part of the battery capacity for backup with Enable Backup Reserve
Include battery pack replacement in the long-term financial calculation
Add an AC-coupled battery with a Power Charge Controller (PCS) when the inverters cannot host one
Let solarVis automatically size the required battery capacity or choose the battery manually
Review the recommended battery system and select a matching product
Battery Preferences
Battery sizing and behavior are defined through a set of preferences that depend on the selected use case.
Use Case Selection
You should select one of the following battery operating modes:
Self Consumption (On-grid projects)
Autonomy (Zero injection projects)
Arbitrage (On-grid projects with a time-of-use tariff)
The selector only lists the modes that fit the design's grid connection type. A mode that exists but cannot be used, for example, Arbitrage on a design with a zero-injection connection type, is shown disabled with a tooltip explaining the reason.
The selected use case determines:
Which input fields are shown
How battery capacity is calculated
How the battery is operated in simulations
1. Self Consumption Mode
This mode focuses on increasing the share of generated solar energy that is consumed directly at the facility.
In this mode, the battery stores excess PV production during the day. It discharges the stored energy later when on-site consumption exceeds solar generation.
It will be seen on On-grid projects.
Targeted Self-Consumption Rate (%)
Set the percentage of self-consumption you want to achieve with a battery system.
The panel displays:
Current self-consumption rate without a battery
A slider to define the desired target
SolarVis calculates the battery capacity required to store surplus production and reach the selected target.
2. Autonomy Mode
This mode is designed to increase the level of energy independence by maximizing how much of the total consumption is covered by solar production and battery storage.
It will be seen on Zero injection projects.
Targeted Autonomy Rate (%)
Set the desired autonomy level for the project.
The panel displays:
Current autonomy rate without a battery
A slider to define the target autonomy rate
Autonomy represents the percentage of total electricity demand that can be supplied by the PV system and battery without drawing energy from the grid.
SolarVis calculates the required battery capacity to reach the selected autonomy target, considering:
PV production profile
Consumption profile
Daily and seasonal energy balance
3. Arbitrage Mode
Arbitrage mode uses the battery against the electricity tariff: it charges when electricity is cheap and discharges to serve the site or sell to the grid when it is expensive.
It will be seen on On-grid projects whose tariff has time-of-use period prices.
Strategy
Defines how the charge and discharge decisions are made:
Optimal dispatch
A rolling-horizon optimiser decides when to charge and discharge based on tariff prices, production, and consumption. You can set the Forecast horizon (2–48 hours, default 8) and optionally enable Include opportunity cost, which adds a per-kWh wear and opportunity cost to grid charging so the battery only charges from the grid when the arbitrage benefit exceeds this cost.
TOU-based
You mark the charge and discharge hours yourself on a 12-month by 24-hour grid with separate Weekday Schedule and Weekend Schedule tabs, using the Charge, Discharge, and Erase paint tools. The tariff's period prices are shown on the grid so cheap and expensive hours are easy to spot. A suggestion is auto-filled from the tariff, and Auto-fill from tariff re-derives it at any time; editing the grid switches the schedule to manual.
Max Grid Import Power and Max Grid Export Power
Optional caps on the AC power the battery draws from the grid and exports to the grid. Leaving a field empty uses the battery's maximum power.
Backup Reserve
Backup power is configured with the Enable Backup Reserve switch, available in the Self Consumption and Arbitrage modes.
When enabled, the Backup Percentage (%) slider (10–90%, default 50%) reserves that share of the battery capacity as a minimum state of charge:
The battery does not discharge below this level while connected to the grid, so the reserve stays available for outages
The remaining capacity is used by the selected operating mode
Battery Replacement Cost
Turn on Enable Battery Replacement Cost (available in the Self Consumption and Arbitrage modes) to include battery pack replacement in the 20-year simulation and in the battery payback calculation.
Replacement cost
The total cost of one replacement event for the whole battery pack, with its Currency. Required when replacement is enabled.
Replacement trigger
Choose what triggers a replacement:
Fixed year: Replace the pack once at the start of the chosen Replacement year (1–20, default 10)
Cycle count: Replace the pack when it reaches the set number of Equivalent full cycles (default 4000); this may trigger multiple replacements over 20 years
Capacity threshold: Replace the pack when its state of health falls to the set share of nominal capacity (10–100%, default 70%)
Selected System
After defining battery preferences, solarVis calculates the required battery capacity and displays suggested battery systems.
For each suggested option, you can review:
Total battery capacity
Expected self-consumption rate
Expected autonomy
Backup duration with solar energy support
You can:
Accept the suggested battery system
Manually select a different battery model
Compare alternatives before applying the system
Power Charge Controller (PCS)
A battery normally connects through the project's inverter, which means the design needs at least one Hybrid or Off-Grid inverter. When it has neither, solarVis reports that the battery is not compatible with the inverters in the project and offers a Power Charge Controller (PCS) instead.
A PCS is an AC-coupled unit that sits alongside the existing inverters, so an on-grid design can take a battery without replacing them.
PCS Conversion Efficiency
The one-way AC/DC conversion efficiency of the controller, entered as a percentage.
This loss is applied to both charging and discharging in the simulation, on top of the battery's own round-trip efficiency, so the energy and financial results reflect the real cost of the AC-coupled configuration.
Battery Impact Overview & Performance Visualization
After a battery is selected, the platform provides a visual performance summary to illustrate how integrating a battery system affects energy usage, backup capability, and electricity costs when compared across different system configurations.
The project connection type can be set to on-grid, and zero injection to see these charts.
Key Performance Indicators
At the top of the page, summary indicators provide a quick overview of system performance based on the selected battery strategy.
Yearly Average Self-Consumption
This indicator shows the proportion of solar energy that is consumed directly on-site over the course of a year.
It reflects how effectively the system minimizes electricity exported to the grid.
The value increases as battery storage allows excess solar energy to be used later.
It is influenced by load behavior, PV production, and battery operation strategy.
Backup Time (With Solar Energy Contribution)
This metric represents the estimated duration during which the system can supply power to critical loads during a grid outage while solar generation is available.
The value is derived from battery capacity, critical load definition, and expected solar energy contribution.
Backup Capacity
This indicator reflects the energy (kWh) available from the battery's backup reserve during a grid outage.
When Enable Backup Reserve is on, it follows the configured backup percentage.
Otherwise, a typical battery management reserve of about 10% of the total capacity is assumed.
Payback Period
This indicator shows how long it takes for the battery investment to be recovered through bill savings, displayed as years and months.
The battery investment includes replacement costs when Enable Battery Replacement Cost is configured.
Savings are the difference between the bill with solar only and the bill with solar and battery.
The value is capped at 20 years when the investment is not fully recovered within the simulation horizon.
Annual Energy Estimation Chart
This visualization highlights how battery storage enhances both self-consumption and cost efficiency.
The visual chart comparison of electricity cost behavior across the year. Each month is displayed with three comparative values:
Cost without solar energy
Cost with solar energy only
Cost of both solar energy and battery
This view allows users to understand how energy generation and storage influence grid dependency and financial outcomes over time.
Monthly Utility Bill Comparison
For each month, a detailed breakdown is shown for the different system configurations.
Before Solar
This scenario represents full reliance on the grid, with no on-site generation or storage.
All electricity is purchased from the utility
No surplus energy is produced
With Solar
This scenario shows the effect of adding PV generation.
Grid consumption is reduced
Excess energy may be exported
Costs change depending on seasonal production
With Solar + Battery
This scenario demonstrates the added value of energy storage.
A larger share of solar energy is consumed on-site
Grid usage is minimized both outside solar production hours and by storing solar surplus in the battery instead of exporting it to the grid.
Financial performance becomes more stable across the year
Daily Energy Usage Chart
This section visualizes how energy is produced, consumed, stored, and supplied throughout an average day of the selected month.
The chart shows the selected month's average day: each hour is the average of that hour across all days of the month for both production and consumption, and the battery is simulated on these averaged profiles with the design's operating mode. This makes the daily curves representative of the whole month instead of one sampled day.
The chart combines multiple energy indicators to illustrate system behavior at each hour:
Production
Represents the solar energy generated during the day.
Consumption
Shows the site’s electricity demand throughout the day, reflecting typical usage patterns such as daytime activity and evening demand.
Autonomy
Indicates whether the site is being supplied by on-site energy sources (solar and battery) rather than the grid. Higher autonomy means lower grid dependency at that hour.
State of Charge
Displays how full the battery is over time. It increases when excess solar energy is stored and decreases when the battery supplies energy to the site.
Monthly Selection
The month selector allows you to view how daily energy behavior changes across different seasons.
This helps illustrate:
Seasonal variation in solar production
Changes in battery usage patterns
Energy Flow
The Energy Flow tab shows an annual energy-flow diagram between Solar PV, Grid, Site, and Battery, together with an Energy Flows table listing each flow with its yearly value and a short description:
Solar to Site, Solar to Grid, and Solar to Battery
Grid to Site and Grid to Battery; grid charging typically happens during cheap tariff hours in arbitrage operation
Battery to Site and Battery to Grid: battery energy sold back to the grid when export is allowed
The Grid node is hidden for off-grid designs.
Cashflow
For on-grid designs, the Cashflow tab plots the battery's financial performance over 20 years: per-year net cashflow, the battery's upfront costs, replacement costs for the years the pack is replaced, and the accumulated cashflow line.
Key Insights from the Charts
Shows when solar energy is consumed directly, stored in the battery, or supplied back to the system on an hourly basis
Illustrates how grid dependency increases or decreases throughout the day and across the year
All values are based on the same hourly simulation used for system sizing, savings calculations, and performance analysis
Makes backup readiness and system resilience clearly visible
Shows how energy storage improves both operational performance and financial outcomes
Related Pages
For more assistance, don’t hesitate to get in touch.
Last updated
Was this helpful?