How to use your Sofar ESI hybrid inverter? Complete guide to modes

Your Sofar ESI hybrid inverter: an intelligent brain for your solar energy

Have you just installed a Sofar ESI hybrid inverter with a BTS battery ? Congratulations! You now have an intelligent system capable of automatically managing your solar production, consumption, and energy storage. But how does it actually work on a daily basis?

Imagine your inverter as the conductor of your photovoltaic system . Depending on your needs and consumption habits, it can adopt different strategies to optimize your self-consumption, reduce your electricity bills, and even protect you in the event of a grid outage.

In this comprehensive guide, we'll explore the 5 main operating modes of your Sofar ESI inverter, without complicated technical jargon. Whether you're in Belgium or France, a homeowner or a business, you'll know exactly which mode to activate for your situation.

The 5 operating modes explained simply

Mode 1: Self-Consumption (Self-Use Mode) – The “fully automatic” mode

Who is it for? Ideal for 90% of users who want to maximize their solar self-consumption without complicating their lives.

"Self-consumption mode is like having a personal assistant that manages your energy 24/7. You don't have to do anything, everything happens automatically!"

How does it work in practice?

• In the morning , when your solar panels start producing electricity, the inverter first powers your operating devices (refrigerator, Wi-Fi, computers...).
• If your production exceeds your consumption , the surplus automatically goes into your BTS battery to recharge it.
• Once the battery is full , the remaining energy is injected into the electrical grid (unless you have activated the "anti-reflux" function to block the injection).
• In the evening or at night , when your panels are no longer producing, your inverter automatically draws from the battery to power your home.
• If the battery is empty , the inverter takes over with electricity from the conventional grid.

Benefits :

• ✅ No programming required
• ✅ 24/7 Automatic Optimization
• ✅ Maximize your energy independence
• ✅ Perfect for beginners

Configuration: This mode is usually enabled by default during installation. No additional settings are required.

Discover the Sofar ESI 5 kVA inverter

Mode 2: Peak/Off-Peak Hours (Time-of-Use Mode) – The “smart savings” mode

Who is it for? Perfect if you have a day/night electricity contract in Belgium or a peak/off-peak hours contract in France.

The principle: Take advantage of reduced rates at night to recharge your battery from the grid, then use this "cheap" energy during the day when electricity costs more.

"Imagine being able to charge your battery at 7 cents per kWh overnight, then use that energy during the day when the price climbs to 30 cents. That's what Time-of-Use mode is all about!"

A concrete example in Belgium:

Configuration: You can program up to 4 different time slots (called "rules" 0, 1, 2, and 3). For each rule, you define:

• The start and end time (example: 2:00 - 4:00)
• The desired charge percentage (example: charge to 100%)
• The maximum charging power (example: 2500 W)
• The days of the week concerned (Monday to Sunday)
• The time of year (example: from October to March for winter)

Tip: Outside of scheduled operating hours, the inverter automatically functions in self-consumption mode. This combines the advantages of both modes!

Discover the Sofar BTS 5K battery

Mode 3: Advanced Programming (Timing Mode) – The “custom control” mode

Who is it for? Experienced users who want total control over their battery's charging and discharging schedules.

The difference with Time-of-Use mode? Here, you program not only when to charge , but also when to discharge the battery, with precise power levels. This is the "expert" mode.

Typical use case: advanced pricing optimization

Imagine you have a contract with 3 pricing levels in Belgium:

• Night rate (2h-6h): €0.06/kWh
• Normal day rate (6 a.m. to 5 p.m. and 9 p.m. to 2 a.m.): €0.25/kWh
• Peak rate (5 p.m. to 9 p.m.): €0.40/kWh

Your strategy with Timing Mode:

1. Scheduled charging (2h-4h) : Recharge the battery from the grid at 2500W during the cheapest hours.
2. Scheduled discharge (5pm-9pm) : Automatically drain the battery during peak hours to avoid peak rates.
3. Self-consumption the rest of the time : Let the inverter intelligently manage the other periods.

Configuration: Via the inverter's LCD menu or the mobile app, you define:

• Start time of charging / end time of charging
• Charging power (in Watts)
• Discharge start time / Discharge end time
• Discharge power (in Watts)

⚠️ Warning: This mode is for experienced users only. Incorrect programming can reduce your savings. If you are a beginner, use the Time-of-Use mode, which is simpler and just as effective.

Mode 4: Emergency Power Supply (EPS / Backup Mode) – The “anti-failure” mode

Who is it for? Essential if you have critical equipment to protect (freezer, alarm system, home office, medical equipment...).

"Power outage? Don't panic! In EPS mode, your Sofar UPS automatically takes over in less than a second. Your essential devices continue to function as if nothing happened."

How does it work?

Emergency Power Supply (EPS) mode is an automatic backup function that activates as soon as a power outage is detected. Your UPS instantly switches over to power your loads from:

• Your solar production (if the sun is shining)
• Your BTS battery
• Or a combination of both

Operating logic in Backup mode:

• If PV production > consumption : The inverter powers your appliances AND recharges the battery with the surplus
• If PV production equals consumption : The inverter only powers your devices, the battery remains stable
• If PV production < consumption : The inverter completes with the battery to cover all your needs

⚠️ Important: The "Backup" output of your ESI UPS is a separate outlet . During installation, only connect your priority equipment to it (not your entire house):

• ✅ Refrigerator / freezer
• ✅ Internet and telephone box
• ✅ Essential lighting
• ✅ Alarm system
• ✅ Computers / servers
• ❌ Avoid: electric heating, oven, washing machine (too energy-intensive)

Activation: EPS mode can be enabled/disabled in the UPS system settings. Once enabled, it will automatically activate in the event of a power outage without any intervention on your part.

Consult the complete setup guide

Mode 5: Passive Mode – The “external control” mode

Who is it for? Very advanced users wishing to control their inverter from an external home automation system (Home Assistant, Raspberry Pi, MQTT server...).

The principle: Instead of letting the inverter decide on its own, you control it remotely via a communication protocol (Modbus TCP/IP). This allows you to create custom automation scenarios.

Examples of use:

• Trigger battery charging when the electricity price falls below a certain threshold (via dynamic tariff API integration)
• Program complex scenarios based on the forecasted weather
• Synchronizing multiple inverters in a professional installation
• Integrating the inverter into a company's energy management system

⚠️ Warning: This mode requires advanced technical skills in home automation and programming. The complete communication protocol is available upon request from Sofar Solar or your Wattuneed installer.

Bonus Feature: Anti-reflux control (Zero Export)

In addition to the 5 modes, your Sofar ESI inverter has an anti-backflow function which is very useful in Belgium and France.

What is it for? This function allows you to limit or completely block the injection of electricity into the grid . Why? Several reasons:

• 🇧🇪 In Belgium : If you don't have a meter that runs backwards, feeding electricity back into the grid doesn't earn you anything. You might as well store it all in your battery!
• 🇫🇷 In France : If your installation exceeds 3 kWp without purchase obligation, limiting injection can save you from complex administrative procedures.
• 💰 Financial optimization : In some cases, the buyback rate is so low that it is more profitable to store your surplus for later use.

Configuration:

In the inverter's advanced settings, you can define the maximum injection power :

• 0 kW = Zero injection, everything is consumed or stored
• 1 kW = Maximum 1000 W can be injected into the grid
• 5 kW = Free injection up to 5000 W

Wattuneed tip: If you have a battery, we generally recommend setting the backflow preventer to 0 kW to maximize your self-consumption and energy independence.

How to choose the right mode for your situation?

How to change modes? Step by step

Changing modes on your Sofar ESI inverter is very simple, whether via the LCD screen on the inverter or via the mobile application .

Method 1: Via the inverter's LCD screen

1. Press the "Menu" button (☰ icon) on the touchscreen
2. Navigate to "System Settings "
3. Select "Energy Storage Mode "
4. Choose your preferred mode from the list:
   • Self-Use (Self-Consumption)
   • Time-of-Use (Off-peak hours)
   • Timing Mode (Programming)
   • Passive Mode (External Control)
5. Confirm your choice by pressing "OK"
6. Wait for the "Success" message which confirms the change

⚠️ Golden rule: If you no longer want to use a mode, remember to deactivate it AND do not leave it highlighted . Otherwise, the inverter may no longer function correctly.

Method 2: Via the SofarSolar mobile application

1. Open the SofarSolar app on your smartphone
2. Log in to your account
3. Select your installation
4. Go to "Settings" > "Operating Mode"
5. Choose the mode and schedule your time slots if necessary
6. Confirm and synchronize

Need help? Contact our technical support

Optimize even further: additional settings

Beyond the choice of mode, several parameters allow you to fine-tune the performance of your installation:

1. Depth of Discharge (DoD)

This setting defines the maximum amount your battery can drain . For example:

• DoD at 10% = The battery stops discharging when 10% of its capacity remains.
• DoD at 5% = The battery can drop to 5% remaining

Wattuneed Tip: We generally recommend leaving a 10-15% charge reserve to extend the life of your BTS battery . Lithium LiFePO4 batteries last longer when complete discharges are avoided.

2. Maximum charging power

Depending on your ESI inverter model (3 kVA, 5 kVA, 6 kVA), you can adjust the maximum battery charging power:

• Fast charging (2500 W) = Faster battery charging, but slightly increased wear
• Slow charging (1500W) = Preserves battery life, ideal if you're not in a hurry

3. Enabling Grid Tie mode (network connection)

This setting determines whether your inverter is authorized to feed power into the electrical grid:

• Grid Tie ON = Injection allowed (with or without backflow limit)
• Grid Tie OFF = No injection, energy island operation

Frequently Asked Questions (FAQ)

Can I change modes at any time?

Yes, absolutely! You can switch modes as often as you like, without risk to your system. For example, use Time-of-Use mode in winter when solar production is low, then switch back to Self-Consumption mode in summer when the sun is strong.

Which mode consumes the least electricity from the grid?

Self-use mode with backflow prevention activated and a properly sized battery. In this configuration, the inverter maximizes the use of your solar production and battery before drawing power from the grid.

Does EPS mode work at night without sunlight?

Yes! In EPS mode, if a power outage occurs overnight, your BTS battery automatically takes over to power your critical loads. The operating time depends on your battery capacity (5 kWh, 10 kWh, 15 kWh, etc.) and your energy consumption.

How long does a battery last in Backup mode?

Example with a Sofar BTS 5K battery (4.75 kWh usable) :

My inverter does not switch to EPS mode during a power outage, why?

Several possible reasons:

• EPS mode is not enabled in the settings (check "System Settings" > "EPS Mode" = ON)
• The devices are not connected to the dedicated "Backup" output of the UPS.
• The battery is empty or below the minimum discharge threshold
• A network configuration problem (contact your installer or Wattuneed support)

Can multiple modes be combined?

Not exactly a "combination," but the operation is clever: if you activate Time-of-Use mode , the inverter will automatically operate in Self-Consumption mode outside of the programmed time slots. It's the best of both worlds!

Does the Time-of-Use mode work with the Belgian capacity tariff?

Yes! Capacity-based pricing (which bills you according to your monthly peak consumption) in Belgium works perfectly with Time-of-Use mode. By charging your battery at night and using it during peak hours, you reduce your daily peak consumption, which lowers your capacity bill.

Need help configuring your Sofar ESI inverter?

Configuring your hybrid inverter may seem technical at first, but with this guide, you now have all the tools you need to optimize your installation according to your needs .

Our final recommendations:

• 🔰 Beginners : Start with the Self-Consumption mode, simple and efficient
• 💰 Off-peak hours contract : Switch to Time-of-Use mode to maximize your savings
• 🛡️ Sensitive equipment : Activate EPS mode for your peace of mind
• 📊 Advanced users : Explore Timing Mode for customized optimization

The Wattuneed team is available to assist you with setting up your installation. Feel free to consult our online resources or contact our technical support.

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About Wattuneed SPRL
Wattuneed, the Belgian leader in photovoltaic and battery storage solutions, has been supporting individuals and professionals in their energy transition for over 10 years. We offer technical expertise, responsive customer service, and a complete range of Sofar Solar inverters, BTS batteries, solar panels, and accessories for self-consumption and energy independence in Belgium and France.