Off-grid

This page describes my off-grid solar system in Norway, based on practical experience from designing, building and operating three independent solar power and battery installations. The systems use different battery technologies, Victron inverters, solar charge controllers and monitoring equipment. I also explain how I use my own Python software to monitor system performance and analyse operating data.

Living off-grid means producing and managing your own electricity without relying on the public electricity grid. For a modern home, this requires more than installing a few solar panels. It involves combining solar energy production, battery storage, inverters, charge controllers and monitoring equipment into a reliable and efficient energy system.

For several years, I have operated an off-grid property in Norway, where connection to the public electricity grid is not economically practical. The nearest power lines are too far away, making the cost of a conventional grid connection prohibitively expensive.

What initially began as a practical necessity gradually developed into a long-term technical project and a valuable learning experience.

Today, my off-grid installation consists of several solar panel arrays, three independent battery banks, multiple inverters, solar charge controllers and an extensive monitoring system. I have also developed my own Python-based software to collect and analyse operational data from the Victron Energy monitoring environment.

The system has evolved over the years as I have gained experience with different battery technologies, equipment manufacturers and energy management strategies.

Contents – Off-Grid Solar System in Norway

Select a topic below to jump directly to that section.

 

1. How My Off-Grid Solar System Works
2. Living Off-Grid – Advantages and Limitations
3. My Three Independent Solar Power Systems
4. Main House and Victron Installation
5. Vestwoods LiFePO4 Battery Bank and Charging
6. Victron Cerbo GX and MPPT Charge Controllers
7. My Three Battery Banks and Solar Panel Arrays
8. Solar Panel Installation and Charge Controllers
9. Annex – Solar Power and 230 V AC Distribution
10. My Inverters – Victron MultiPlus and EPEVER
11. Practical Electricity Use and Operating Instructions
12. Essential Electrical Formulas and Calculations
13. My Python-Based Victron Monitoring Application
14. Further Reading – My Books on Solar Energy

 

How My Off-Grid Solar System in Norway Works

My property combines several independent energy sources and systems to provide electricity, heating, hot water and water supply.

Electricity and Solar Power

Solar panels generate electricity that is stored in battery banks for use during the day, at night and during periods of limited sunlight. The batteries supply direct current (DC), while inverters provide 230 V alternating current (AC) for household appliances and other electrical equipment.

Battery Storage

My installation includes three separate battery banks using different battery technologies. This arrangement has given me practical experience with lithium iron phosphate (LiFePO₄) batteries and valve-regulated lead-acid (VRLA) batteries, including their charging characteristics, maintenance requirements and performance under Norwegian conditions.

Heating and Hot Water

Space heating is primarily provided by wood-burning stoves, using firewood from my own property. Gas is used for domestic hot water and cooking, while electric heating is available when sufficient battery capacity is available.

Private Water Supply

The property has its own water supply, with water pumped from approximately 120 metres below ground. The pump requires electrical energy, making water management another important consideration when planning and operating the system.

Monitoring and Energy Management

Effective monitoring is essential in an off-grid installation. I use Victron monitoring equipment together with my own Python applications to analyse battery status, solar production, electricity consumption and system performance.

This is particularly useful during the Norwegian winter, when solar production is limited and energy consumption must be managed carefully.

From Practical Experience to Technical Books

My experience with off-grid and on-grid solar installations has also contributed to my work as a technical author.

In 2026, I published Solenergi og energisystemer, a comprehensive Norwegian-language guide to solar energy and modern energy systems. The book covers solar panels, battery banks, charge controllers, inverters, off-grid, on-grid and hybrid installations, electrical safety, system design and emergency preparedness.

An expanded British English edition, Solar Energy and Energy Systems, is planned for publication in 2027. This edition will include additional technical explanations, practical examples and information relevant to the United Kingdom.

On this webpage, I describe the equipment, system architecture, technical solutions and practical experiences behind my own off-grid installation.

The following illustration provides an overview of a typical off-grid property before I introduce the components of my actual system.

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The Trade-Offs – Living Off-Grid in Practice

Living off-grid brings both freedom and responsibility. The initial investment can be substantial, particularly when it comes to battery storage, which may account for a significant proportion of the total system cost.

It also changes the way you think about electricity. In a conventional home, most people rarely consider how much energy is available. In an off-grid house, the available battery capacity and expected solar production become part of everyday decision-making.

During a rainy week in October, for example, I know roughly how many hours I can watch television before the batteries reach a level where I need to reduce consumption. Such decisions gradually become second nature.

For me, one of the greatest rewards is the satisfaction of producing and managing my own electricity. Knowing that the energy powering my refrigerator, lighting and other electrical equipment comes from solar panels on my property gives me a genuine sense of independence.

I also value the resilience of an independent energy system. When the public electricity grid experiences an outage, my off-grid installation continues operating, provided sufficient stored energy or alternative generation is available.

I believe that off-grid living particularly appeals to people who value self-sufficiency, environmental responsibility and a greater degree of control over their energy supply.

For my part, reducing my environmental impact and avoiding ongoing electricity bills are important motivations. However, I have also learned that genuine energy independence requires realistic expectations, careful planning and a willingness to adapt daily consumption to the available resources.

My Off-Grid Solar Energy Solution in Norway

My off-grid property combines several independent energy systems to provide the electricity and essential services required for everyday living.

The following sections focus on the technical infrastructure behind my installation, including the three independent solar power systems, battery banks, charge controllers, inverters and monitoring equipment.

I explain how these systems are configured, how they operate in practice and what I have learned from maintaining and improving them over the years.

My Off-Grid Solar System in Norway – Three Independent Installations

My off-grid installation has gradually developed into a relatively sophisticated energy infrastructure consisting of three separate solar power systems, each with its own battery bank and associated equipment.

Two of these systems supply electricity to the main house, while the third provides an independent electricity supply to the annex.

One of the main reasons for having two separate systems serving the main house is redundancy and ease of maintenance. This arrangement allows me to carry out servicing, inspections, repairs or upgrades on one system while continuing to supply electricity from the other, provided the necessary loads are connected to the operational system.

This is particularly valuable in an off-grid property, where there is no public electricity supply available as a backup.

The three systems also provide flexibility in managing electricity production, battery storage and consumption. Rather than depending on a single large battery bank and inverter, I can operate and maintain the installations separately.

Over the years, this arrangement has also allowed me to gain practical experience with different battery technologies, charge controllers, inverters and monitoring equipment.

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System 1 – Main House (Battery Bank 1)

The following technical diagram illustrates the electrical infrastructure of my first off-grid system, including its principal components and their interconnections.

This is one of the two independent installations supplying the main house. The diagram provides a detailed overview of how solar electricity is generated, regulated, stored and converted into usable power.

The other two systems are described separately further down this page.

Main System  – The Installed Equipment

The photograph below shows the actual equipment installed in my first off-grid system (Battery Bank 1), corresponding to the technical diagram above.

The installation includes a Victron MultiPlus inverter/charger, a Victron Cerbo GX monitoring and communication unit, Victron MPPT solar charge controllers, and a Vestwoods lithium battery rack.

The photograph also shows the associated electrical cabling, connections and supporting installation equipment.

Together, these components form the core of my first off-grid system, managing solar energy production, battery charging, electricity storage, power conversion and system monitoring.

The photograph provides a practical view of how the individual components shown in the technical diagram are arranged in the actual installation.

Figure: The actual installation of off-grid System 1, showing the Victron MultiPlus, Cerbo GX, MPPT charge controllers, Vestwoods battery rack and associated electrical equipment.

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Battery Bank 1 – Vestwoods LiFePO₄ Battery Rack

My first battery bank is based on six Vestwoods VT48100E lithium iron phosphate (LiFePO₄) battery modules, installed together in a dedicated battery rack.

Each module contains 16 lithium iron phosphate cells connected in series, providing a nominal voltage of 51.2 V and a capacity of 100 Ah. This corresponds to approximately 5.12 kWh of nominal energy storage per module.

With six modules, the battery bank has a total nominal storage capacity of 30.72 kWh (approximately 30.7 kWh).

LiFePO₄ technology is particularly suitable for stationary energy storage because of its long cycle life, thermal stability and relatively low maintenance requirements compared with traditional lead-acid batteries.

Each battery module incorporates a Battery Management System (BMS), which monitors and protects the battery against conditions such as excessive charging, deep discharge, excessive current and temperatures outside permitted operating limits.

A modular rack arrangement offers several practical advantages. Individual battery modules can be monitored and serviced according to the manufacturer’s instructions, and the system architecture allows for expansion where supported by the battery manufacturer and inverter configuration.

In everyday operation, the battery bank stores electricity generated by my solar panels and supplies energy to the Victron MultiPlus inverter/charger. The inverter converts the stored DC energy into 230 V AC electricity for household use.

An important distinction is that 30.72 kWh represents nominal capacity, not necessarily the energy available for daily use. The usable capacity depends on the permitted depth of discharge, battery condition, operating temperature and system settings. Conversion losses in the inverter must also be considered.

In my experience, understanding these limitations is essential when designing an off-grid system intended to operate reliably throughout the year, particularly during the Norwegian winter.

Further reading and technical documentation

The Vestwoods VT48100E-P2 technical documentation provides additional information about the battery modules, their electrical characteristics and operating limits.

For a more detailed explanation of battery technologies, series and parallel connections, battery management systems and the dimensioning of battery banks, see Chapter 6, Battery Banks, in my Norwegian book Solenergi og energisystemer.

These subjects are also covered in greater detail in my forthcoming British English book, Solar Energy and Energy Systems, planned for publication in 2027.

Technical Specifications – Vestwoods Battery Bank One

Note: Electrical current limits are specified per battery module. The total nominal capacity assumes six identical modules connected in parallel. Actual charge and discharge settings must comply with the battery manufacturer’s instructions and BMS limits.

Battery Communication and Rack Configuration

The six Vestwoods VT48100E battery modules are installed in a rack and connected in parallel to form my first battery bank, providing a total nominal energy storage capacity of 30.72 kWh.

In addition to their electrical power connections, the battery modules are interconnected using communication cables with RJ45 connectors. This allows the individual Battery Management Systems (BMS) to exchange information and coordinate battery operation.

A 120 Ω terminating resistor is installed in the RJ45 communication port at the end of the battery communication chain, on the module furthest from the inverter connection. This termination helps prevent signal reflections and ensures reliable CAN bus communication between the connected battery modules.

The battery modules also have individual addressing settings, allowing them to be identified within the communication network.

It is important to distinguish between the battery communication cables and the main DC power cables. The RJ45 connections are used for communication, while the heavier DC cables carry the charging and discharging currents.

The photograph below shows my actual Vestwoods battery rack, including the six LiFePO₄ modules and their associated connections.

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Victron Cerbo GX – The Brain of My Off-Grid System

The central monitoring and communication unit in Battery Bank 1 is the Victron Cerbo GX. I consider it the brain of my off-grid installation because it brings together information from the different components and provides a central interface for monitoring and system management.

The Cerbo GX communicates with compatible equipment, including the Victron MultiPlus inverter/charger, MPPT solar charge controllers and battery monitoring devices. Depending on the equipment and configuration, communication takes place through interfaces such as VE.Bus, VE.Direct and VE.Can.

This allows me to monitor important operating parameters, including solar energy production, battery voltage, charging and discharging currents, battery state of charge and electricity consumption.

One of its most useful features is integration with the Victron Remote Management (VRM) portal. With an internet connection, I can monitor the system remotely, review historical data, examine performance trends and investigate alarms without being physically present at the property.

As a software developer, I have also taken advantage of the Victron monitoring environment to develop my own Python-based applications for collecting and analysing energy data. This gives me additional flexibility when examining system behaviour and evaluating performance over time.

For an off-grid installation, reliable monitoring is particularly important during the Norwegian winter, when limited solar production makes battery management and energy consumption critical.

Check the Victron documentation.

Victron SmartSolar MPPT Charge Controllers – Battery Bank 1

My off-grid installation uses several Victron SmartSolar MPPT (Maximum Power Point Tracking) charge controllers of different sizes, depending on the solar panel configuration, array capacity and required battery charging current.

The smallest controller in my installation is the Victron SmartSolar MPPT 150/35, which supports a maximum PV open-circuit voltage of 150 V and a maximum battery charging current of 35 A.

For larger solar arrays, I use more powerful models, including the Victron SmartSolar MPPT 250/60. This model supports a maximum PV open-circuit voltage of 250 V and a maximum battery charging current of 60 A.

Some of my larger solar panel strings consist of six 450 W panels connected in series, providing a total nominal peak power of:

6 × 450 W = 2,700 Wp (2.7 kWp)

The panel voltage is approximately 42 V per panel. However, the exact open-circuit voltage (Voc), maximum power voltage (Vmp) and temperature coefficient must be considered when evaluating the electrical configuration.

When panels are connected in series, their voltages add together, while the current remains approximately the same as that of a single panel. Since open-circuit voltage increases as panel temperature decreases, the maximum expected string voltage must remain within the charge controller’s limits under the coldest anticipated conditions. A string must not be connected to a controller if its calculated maximum open-circuit voltage exceeds the manufacturer’s rating.

How the MPPT Controllers Work

Solar panel output changes continuously with sunlight intensity, temperature, cloud cover and seasonal conditions.

The MPPT controllers automatically adjust the operating voltage and current of the solar arrays to extract the maximum available power. They then convert this energy into a suitable voltage and current for charging the battery bank.

This is particularly important in Norway, where solar energy production varies considerably between the long summer days and the much shorter winter days.

Using several MPPT controllers also provides greater flexibility. Different solar arrays can operate independently, allowing me to monitor their performance, expand the installation and carry out maintenance more easily.

Charging the Vestwoods LiFePO₄ Batteries

Correct charging settings are particularly important for lithium batteries.

The MPPT controllers must be configured according to the specifications of the Vestwoods VT48100E LiFePO₄ battery modules and their Battery Management System (BMS).

Charging voltage, charging current, temperature limits and the permitted charging profile must all be considered. Generic settings intended for lead-acid batteries should not be used without appropriate adjustment.

The Vestwoods battery documentation specifies a float charge voltage parameter of 56.8 V for the 16S configuration. However, this does not necessarily mean that the batteries should be maintained continuously at this voltage. The actual charging profile must follow the manufacturer’s recommendations and the requirements of the installed BMS.

The BMS provides essential battery protection and monitoring, but correct configuration of the charging equipment remains equally important.

Monitoring Through Victron Cerbo GX

The Victron SmartSolar MPPT charge controllers are integrated into my monitoring system through the Cerbo GX, using compatible communication interfaces such as VE.Direct or VE.Can.

This allows me to monitor the performance of individual charge controllers, including solar power output, charging current and daily energy production.

The collected information is also available through the Victron Remote Management (VRM) portal, making it possible to compare solar production across different arrays and investigate changes in performance.

I use these measurements in my own Python-based monitoring application, which is described in detail later on this page.

Technical Documentation

Further information about these charge controllers, including electrical specifications, installation requirements and configuration options, is available from Victron Energy:

• Victron SmartSolar MPPT 150/35

• Victron SmartSolar MPPT charge controllers

For a more detailed explanation of solar charge controllers, MPPT technology, lithium battery charging and system design, see my Norwegian book Solenergi og energisystemer.

These subjects will also be discussed in the forthcoming British English edition, Solar Energy and Energy Systems, planned for publication in 2027. Check the Victron documentation.

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My Three Battery Banks and Solar Panel Arrays

The following table provides a consolidated overview of the three battery banks used in my off-grid installation.

The systems use different battery technologies and capacities, reflecting how my installation has developed over the years. Their separate configurations also provide useful practical experience with lithium iron phosphate (LiFePO₄) and valve-regulated lead-acid (VRLA) batteries.

Overview of My Battery Banks

Battery bank	Battery model and technology	Quantity	Nominal energy
Bank 1	Vestwoods VT48100E, LiFePO₄, 51.2 V / 100 Ah	6 modules	30.72 kWh
Bank 2	GNB M12V155, VRLA, 12 V / 155 Ah	12 batteries	22.32 kWh
Bank 3	Monbat 12MONBAT200, VRLA, 12 V / 200 Ah (stated rating)	4 batteries	9.60 kWh
Total	Three independent battery banks	22 units	62.64 kWh

The combined nominal storage capacity of my three battery banks is approximately 62.6 kWh.

This represents the energy calculated from the rated voltage and ampere-hour capacity of the batteries. It should not be confused with the usable electricity available to household appliances. Actual usable energy depends on the battery chemistry, permitted depth of discharge, operating temperature, battery condition and inverter efficiency.

In particular, lead-acid batteries generally require more conservative discharge limits than LiFePO₄ batteries when long service life is a priority.

Main Battery Bank  – Vestwoods LiFePO₄

My first and largest battery bank consists of six Vestwoods VT48100E LiFePO₄ modules connected in parallel, providing a combined nominal energy storage capacity of 30.72 kWh.

The battery rack, electrical specifications, charging requirements and Battery Management System (BMS) are described in detail earlier on this page.

This battery bank supplies my first Victron MultiPlus system in the main house and is an important part of my independent electricity infrastructure.

Battery Bank 2 – GNB VRLA

My second battery bank consists of twelve GNB M12V155 valve-regulated lead-acid batteries, each rated at 12 V and 155 Ah.

The combined nominal energy capacity is:

12 × 12 V × 155 Ah ÷ 1,000 = 22.32 kWh

VRLA batteries require appropriate charging settings and careful consideration of operating temperature. Charging voltage generally needs to be adjusted according to battery temperature to prevent overcharging or undercharging.

Unlike conventional flooded lead-acid batteries, VRLA batteries should not be subjected to routine equalisation charging unless this procedure is expressly permitted by the manufacturer for the specific battery model.

Further manufacturer information is available from GNB.

Battery Bank 3 – Monbat VRLA

My third battery bank consists of four Monbat 12 V VRLA batteries, with a stated capacity of 200 Ah per battery.

Based on these ratings, the combined nominal energy capacity is:

4 × 12 V × 200 Ah ÷ 1,000 = 9.60 kWh

As with the GNB installation, correct charging parameters are important for maintaining battery performance and service life. Charging voltage, temperature compensation and any manufacturer-approved boost or equalisation procedures must be matched to the specific battery model.

Further information is available from Monbat.

Charging and Temperature Compensation

One of the important lessons from operating different battery technologies is that charging requirements are not interchangeable.

The Vestwoods LiFePO₄ battery bank requires a charging profile compatible with its Battery Management System (BMS) and the manufacturer’s specified operating limits.

The GNB and Monbat VRLA battery banks require charging profiles appropriate to their particular lead-acid construction. For lead-acid batteries, charging voltage generally increases as battery temperature decreases and decreases as temperature rises.

However, the exact voltage settings and temperature compensation coefficients must be obtained from the documentation for the installed battery models.

Using incorrect charging parameters can reduce battery life, cause excessive gassing or overheating, and potentially damage the batteries.

Further Reading

My experience with these different battery technologies has contributed to my Norwegian book Solenergi og energisystemer, which explains battery chemistry, battery bank design, series and parallel connections, battery management and charging systems.

These topics will also be discussed in greater technical detail in my forthcoming British English edition, Solar Energy and Energy Systems, planned for publication in 2027.

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Info banks:

Bank 1	Vestwood VT48100E x 6
Bank 2	GNB (valve regulated lead acid) – M12V155 x 12
Bank 3	Monbat VRLA battery – 12MONBAT200 x 4

• Bank 2 – GNB (Batteries (gnb-nordic.com))

Temperatur	Equalization voltage
0	15.15
5	15:00
10	14.85
15	14.70
20	14.55

• Bank 3 – MONBAT (www.monbat.com)

Temperatur	Equalization voltage
0	15.45
5	15:00
10	14.85
15	14.70
20	14.55

Solar Panel Arrays for My Off-Grid Systems

The three battery banks are supported by separate solar panel arrays with different configurations and capacities.

Battery bank	Solar panel configuration	Number of panels	Nominal peak power
Bank 1	2 × 300 W + 6 × 450 W	8	3,300 Wp
Bank 2	9 × 300 W	9	2,700 Wp
Bank 3	5 × 450 W	5	2,250 Wp
Total		22	8,250 Wp

My complete solar installation therefore has a combined nominal peak capacity of 8.25 kWp, distributed across 22 solar panels.

The actual electrical output depends on sunlight, panel orientation, temperature, shading, wiring losses and the performance of the associated charge controllers.

The nominal peak rating should not be confused with continuous power production. During the Norwegian winter, solar energy production can be considerably lower than during the summer months.

The use of separate solar arrays and battery banks provides operational flexibility and allows me to monitor the performance of individual installations.

Practical Experience and Further Reading

Operating three different battery banks has given me valuable practical experience with both lithium and lead-acid battery technologies.

I have learned that selecting a battery involves much more than comparing its nominal capacity. Charging characteristics, cycle life, temperature sensitivity, monitoring, maintenance and the intended application are equally important.

These experiences have contributed to my Norwegian book Solenergi og energisystemer, which includes detailed chapters on battery technologies, battery bank configuration, charge controllers and complete off-grid energy systems.

My forthcoming British English edition, Solar Energy and Energy Systems, will also cover these topics in greater technical detail.

Solar Panel Installation – Orientation, Tilt and Mounting Options

The following illustrations show different ways of installing solar panels, including various mounting systems, panel orientations and tilt angles.

Solar panels can be installed facing south, east, west or north, depending on the location, available roof space and energy requirements. In the Northern Hemisphere, south-facing panels generally provide the highest annual energy yield under otherwise comparable conditions, while east- and west-facing installations can offer a more balanced distribution of electricity production throughout the day.

The optimal tilt angle depends on geographical latitude, seasonal sunlight, local shading and the intended use of the system. This is particularly important for off-grid installations in Norway, where solar production varies considerably between summer and winter.

The illustrations below compare different panel arrangements, roof and ground-mounted installations, mounting structures and tilt angles. They demonstrate how installation choices can influence solar energy production, especially under challenging weather and seasonal conditions.

 

EPsolar and EPEVER Solar Charge Controllers – My Installations

Over the years, I have used solar charge controllers from several manufacturers, including EPsolar and EPEVER, in my off-grid installations.

The following photographs show examples of these controllers installed as part of my solar energy systems, together with their associated wiring and electrical equipment.

Solar charge controllers play an essential role in regulating the energy transferred from solar panels to battery banks. Depending on the model, they use PWM (Pulse Width Modulation) or MPPT (Maximum Power Point Tracking) technology to manage battery charging.

Correct controller selection depends on the solar array voltage and power, battery bank voltage, charging requirements and operating conditions.

My experience with different charge controllers has been valuable when comparing equipment, evaluating system performance and planning improvements to my installations.

The photographs below illustrate how these components are integrated into practical off-grid systems, rather than simply showing individual products.

For a more detailed explanation of PWM and MPPT technology, charge controller selection and battery charging, see my Norwegian book Solenergi og energisystemer.

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Solar Panels and Battery Charging

The annex has its own solar panel installation consisting of five 450 W panels, divided into two separate strings.

The first string contains two solar panels, while the second consists of three panels.

The nominal peak power of each string is:

String 1: 2 × 450 W = 900 Wp

String 2: 3 × 450 W = 1,350 Wp

Together, the five panels provide a total nominal peak capacity of:

900 Wp + 1,350 Wp = 2,250 Wp (2.25 kWp)

Using two strings provides flexibility in the arrangement of the solar panels. The strings have different electrical characteristics because they contain different numbers of panels connected in series.

The solar energy produced is regulated by the charge controller arrangement and used to charge the annex’s 48 V Monbat VRLA battery bank.

The charging equipment must be configured according to the battery manufacturer’s specifications, including charging voltages, current limits and temperature compensation.

The actual electricity production depends on sunlight, panel orientation, tilt angle, shading and seasonal conditions.

During the Norwegian winter, solar production is considerably lower than in summer, making battery management and efficient electricity consumption particularly important.

The 230 V Electrical Distribution in My Annex

The following six technical sketches illustrate the internal 230 V electrical distribution system in my annex.

The annex is supplied by a Victron MultiPlus inverter/charger, which converts the 48 V DC battery voltage into 230 V AC for ordinary household use. The 230 V output from the MultiPlus is fed into the annex distribution board, which functions as the central point for the electrical installation.

From this distribution board, the installation is divided into four separate 16 A final circuits.

These circuits supply the most important parts of the annex:

1. Living room and kitchen

2. Bedroom

3. Dishwasher

4. Water pump

Each circuit has been separated to provide a clearer and more practical distribution of the electrical loads. This makes it easier to understand which appliances and sockets belong to each part of the installation and helps to reduce the risk of overloading individual circuits.

The sketches below show how the electrical supply is distributed from the inverter to the consumer unit and then onwards to the different 230 V circuits. They also identify the sockets, switches and electrical connection points associated with each circuit.

Together, these diagrams provide an overview of how the annex electrical installation is organised in practice, from the inverter output to the individual rooms and dedicated loads.

As with any 230 V installation, the detailed design, protection and wiring arrangements must be appropriate for the equipment used and should comply with the relevant electrical regulations and safety requirements.

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My Inverters – Victron MultiPlus and EPEVER

An inverter is one of the most important components in an off-grid solar energy system. Its primary function is to convert direct current (DC) from the battery bank into alternating current (AC) suitable for household electrical equipment.

In Norway, the standard household electricity supply is 230 V AC at 50 Hz. Off-grid inverters provide a similar AC supply using energy stored in batteries, typically operating at nominal DC voltages of 12 V, 24 V or 48 V.

My property has three independent off-grid electrical systems. Two supply the main house, while the third supplies the annex. Each system has its own battery bank and inverter.

Overview of My Three Inverter Systems

Location	Inverter	Battery bank	Battery configuration
Main house – System 1	Victron MultiPlus 48/5000/70	Bank 1 – Vestwoods LiFePO₄	6 × 51.2 V / 100 Ah modules in parallel
Main house – System 2	EPEVER 24/3000/50	Bank 2 – GNB VRLA	12 × 12 V / 155 Ah batteries, configured for 24 V
Annex – System 3	Victron MultiPlus 48/5000/70	Bank 3 – Monbat VRLA	4 × 12 V / 200 Ah batteries in series

The two installations in the main house operate independently. This arrangement allows me to carry out maintenance, inspections or upgrades on one system while continuing to supply electricity from the other, provided the necessary household loads are connected to the operational installation.

The annex has its own independent 48 V system.

Main System – Main House: Victron MultiPlus and Vestwoods LiFePO₄

My first system in the main house uses a Victron MultiPlus 48/5000/70 inverter/charger connected to Battery Bank 1, consisting of six Vestwoods LiFePO₄ modules.

The battery bank and its technical specifications are described in detail earlier on this page. Here, I focus on the inverter’s operation, power conversion and integration with the Victron monitoring system.

The Victron MultiPlus converts DC energy from the battery bank into 230 V AC electricity for the connected household appliances and other electrical equipment.

The MultiPlus designation 48/5000/70 refers to a nominal 48 V battery system, a 5,000 VA inverter rating and a battery charger rated at up to 70 A when operating from a suitable external AC source.

The distinction between volt-amperes (VA) and watts (W) is important. The continuous active power output depends on the particular MultiPlus model and operating conditions.

The MultiPlus also supports integration with the Victron Cerbo GX monitoring system, allowing me to observe inverter operation, battery conditions and energy consumption through the Victron monitoring environment.

System 2 in Main House: EPEVER 24 V and GNB VRLA Batteries

My second independent system in the main house uses an EPEVER 3,000 W inverter operating at a nominal battery voltage of 24 V.

The inverter is connected to Battery Bank 2, consisting of twelve GNB M12V155 VRLA batteries. These are arranged in six parallel strings, each containing two 12 V batteries connected in series.

This configuration provides a nominal battery voltage of 24 V and a combined capacity of 930 Ah, corresponding to 22.32 kWh of nominal energy storage.

The battery specifications and charging requirements are described earlier on this page. Here, the main focus is on the EPEVER inverter and its operation within the 24 V system.

The EPEVER inverter converts the DC energy stored in this battery bank into 230 V AC electricity for the household loads supplied by System 2.

One important difference between this installation and the Victron systems is the lower nominal DC voltage.

For the same electrical power, a 24 V inverter generally draws approximately twice the DC current of a comparable 48 V inverter. This makes appropriate cable sizing, protective devices, voltage drop and connection quality particularly important.

The GNB VRLA batteries also require charging settings appropriate to their chemistry, temperature and manufacturer specifications.

System 3 – Annex: Victron MultiPlus and Monbat VRLA Batteries

The annex has its own independent off-grid installation, powered by a Victron MultiPlus 48/5000/70 inverter/charger.

The inverter is connected to Battery Bank 3, consisting of four Monbat 12 V / 200 Ah VRLA batteries connected in series.

This configuration provides a nominal battery voltage of 48 V, with a capacity of 200 Ah and a total nominal energy storage capacity of 9.60 kWh.

Unlike the GNB battery bank in the main house, which uses both series and parallel connections, the Monbat batteries form a single series string.

The battery specifications and charging requirements are described earlier on this page. Here, the focus is on the Victron MultiPlus inverter and its role in supplying electricity to the annex.

This battery bank supplies DC energy to the Victron MultiPlus, which provides 230 V AC electricity for the annex.

Having a separate installation means the annex can operate independently of the two systems in the main house.

Why I Use Three Independent Inverter Systems

My decision to use three independent inverter systems was primarily motivated by reliability, flexibility and ease of maintenance.

In practice, this arrangement allows me to maintain or upgrade one installation without necessarily interrupting electricity supplied by the others. However, each system supplies its own connected loads, and one inverter does not automatically take over the circuits supplied by another.

Over the years, this configuration has also made it easier to experiment with different technologies and improve individual systems without rebuilding the entire electrical infrastructure.

Inverter Efficiency and Standby Consumption

Inverter efficiency is an important consideration in an off-grid installation.

Some energy is lost when DC electricity from the batteries is converted into AC electricity. Inverters also consume power when operating with little or no connected load.

For systems that operate continuously, these losses can become significant over time.

During the Norwegian winter, when solar production is limited, reducing unnecessary consumption is particularly important.

When selecting an inverter, I therefore consider not only its rated output but also its efficiency, standby consumption, reliability, monitoring capabilities and compatibility with the battery bank.

Technical Documentation and Further Reading

Additional information about inverter technology and the equipment used in my installations is available from the manufacturers:

Victron Energy – MultiPlus Inverter/Chargers

EPEVER – Solar Energy Equipment

For a more detailed discussion of inverters, battery configurations, electrical system design and complete off-grid installations, see my Norwegian book Solenergi og energisystemer.

The forthcoming British English edition, Solar Energy and Energy Systems, planned for publication in 2027, will also cover these subjects in greater technical detail.

The photographs below show examples of the Victron MultiPlus and EPEVER equipment used in my installations.

You will find the manual for the Victron product here. If you want to build your own solution this link from Victron will help you.

 

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Using Electricity in My Off-Grid House – A Practical Guide

Living in an off-grid house does not mean giving up modern conveniences. We can use lighting, televisions, computers, refrigerators, washing machines, dishwashers and many other everyday electrical appliances.

However, there is one important difference compared with a house connected to the public electricity grid: the available electrical power is limited by the inverter supplying each installation.

My property has three independent off-grid systems, each with its own battery bank and inverter. Two systems supply the main house, while the third supplies the annex.

Understanding these limitations is important for anyone staying at the property, particularly when using appliances that consume substantial amounts of electricity.

Recommended Inverter Operating Limits

Location	Inverter	Recommended continuous load
Main house – System 1	Victron MultiPlus 48/5000/70	3,500 W (3.5 kW)
Main house – System 2	EPEVER 3000 / 24 V	2,500 W (2.5 kW)
Annex – System 3	Victron MultiPlus 48/5000/70	3,500 W (3.5 kW)

These are my recommended operating limits for normal use, rather than the absolute maximum ratings of the inverters.

The systems operate independently. Their power ratings cannot simply be added together when determining how much power is available from an individual socket or electrical circuit.

Understanding Power and Energy Consumption

Electrical power is measured in watts (W) or kilowatts (kW).

1,000 W = 1 kW

Power tells us how much electricity an appliance requires at a particular moment.

Energy consumption is measured in kilowatt-hours (kWh), which takes both power and operating time into account.

For example:

1,000 W operating for one hour = 1 kWh

2,000 W operating for 30 minutes = 1 kWh

This distinction is important in an off-grid system. The inverter determines how much power can be supplied at once, while the battery capacity determines how long the connected appliances can operate.

Typical Household Appliance Power Consumption

The following values are approximate examples. Actual consumption depends on the appliance, operating programme and whether heating elements or motors are active.

Appliance	Typical power consumption
LED television	50–150 W
Laptop computer	30–100 W
Refrigerator	50–200 W while running
Microwave oven	1,000–1,800 W input
Vacuum cleaner	500–1,200 W
Washing machine	500–2,500 W, depending on cycle
Dishwasher	1,000–2,400 W during water heating
Electric kettle	1,500–2,200 W
My water pump	1,800 W

Many appliances do not consume their maximum power continuously. Washing machines and dishwashers, for example, may have relatively low consumption during part of a programme but draw considerably more power when heating water.

My Water Supply – A 180-Litre Pressure Tank

My off-grid property has its own private water supply. Water is pumped from a well approximately 120 metres deep into a pressure tank.

The electrical water pump consumes approximately 1,800 W (1.8 kW) while operating.

Under normal conditions, the pump takes approximately six minutes to refill the 180-litre pressure tank.

The electrical energy consumed during a six-minute pumping cycle is approximately:

1.8 kW × 0.1 hours = 0.18 kWh

Although this represents a relatively small amount of energy, the pump places a substantial electrical load on the inverter while running.

For example, if the water pump operates at 1,800 W while a washing machine is heating water at 2,000 W, their combined power consumption would be:

1,800 W + 2,000 W = 3,800 W

This exceeds my recommended continuous operating limit of 3,500 W for the Victron systems.

For this reason, I always refill the pressure tank before starting the washing machine or dishwasher.

This reduces the possibility of the water pump starting while one of these appliances is drawing a substantial amount of electricity.

It is a simple practical precaution that makes everyday off-grid living more predictable.

Can the Washing Machine and Dishwasher Run Together?

In principle, simultaneous operation depends on the available inverter capacity and the instantaneous power demand of the appliances.

However, in my installation, I have adopted a straightforward rule:

Never operate the washing machine and dishwasher at the same time.

Both appliances contain electrical heating elements, and their power consumption can increase substantially during water heating.

The same precaution applies to the vacuum cleaner. I avoid using it while either the washing machine or dishwasher is running.

These rules help prevent unnecessary inverter overloads and make electricity consumption easier to manage.

Washing Machine – Operating Instructions

Before starting the washing machine, the pressure tank must be refilled.

Step 1 – Prepare the water supply

1. Set the inverter selection switch to Inverter 1/2, with the switch facing Battery Bank 1.

2. Switch the control labelled Water Pump to ON, following the property’s normal operating procedure.

3. Allow the pump to operate for approximately six minutes, or until the pressure tank has reached its normal operating pressure.

4. Switch the Water Pump control to OFF, according to the property’s operating procedure.

Step 2 – Start the washing machine

1. Press the red power button on the power cable connected to the washing machine.

2. Select the Quick Wash programme.

3. Start the washing machine.

Step 3 – After washing

1. Wait until the programme has finished completely.

2. Switch off the red power button.

Important: Do not use the dishwasher, vacuum cleaner or other high-power appliances while the washing machine is operating.

Dishwasher – Operating Instructions

As with the washing machine, the pressure tank should be refilled before starting the dishwasher.

Step 1 – Prepare the water supply

1. Set the inverter selection switch to Inverter 1/2, with the switch facing Battery Bank 1.

2. Switch the control labelled Water Pump to ON, following the property’s normal operating procedure.

3. Allow the pump to operate for approximately six minutes, or until the pressure tank has reached its normal operating pressure.

4. Switch the Water Pump control to OFF, according to the property’s operating procedure.

Step 2 – Start the dishwasher

1. Select the Quick or Fast programme.

2. Start the dishwasher.

Important: Do not operate the washing machine, vacuum cleaner or other high-power appliances while the dishwasher is running.

Short-Term Power Surges – My Log Splitter Example

An inverter’s continuous power rating should not be confused with its ability to handle brief power surges.

Some electrical equipment, particularly appliances with electric motors, requires considerably more power during start-up than during normal operation.

A practical example from my own property is my electric log splitter, which I use when preparing firewood for heating.

When the log splitter starts, its power demand briefly reaches approximately 5,000 W (5 kW).

My Victron MultiPlus is able to handle this short starting surge under normal operating conditions. Once the motor is running, its power demand falls to a lower level.

This illustrates an important distinction:

Continuous power is the amount of power an inverter can supply for an extended period.

Surge power is the higher power that some inverters can provide for a very short time, typically when starting electric motors or other demanding equipment.

The Victron MultiPlus is designed to handle short-duration peak loads, although the available surge capability depends on the exact model, battery condition, DC voltage, temperature and other operating factors.

A brief 5,000 W starting surge is therefore very different from operating a 5,000 W electrical load continuously.

This does not mean that several powerful appliances should be started together. High start-up currents can still cause an inverter to overload or shut down if the combined demand becomes excessive.

Practical Rules for Comfortable Off-Grid Living

In everyday life, living off-grid is relatively straightforward once the basic principles are understood.

Low-power appliances such as lighting, televisions, computers and mobile phone chargers can generally be used together without difficulty.

The main restrictions concern appliances that heat water, produce heat or use powerful electric motors.

At my property, I follow a few simple principles:

1. Refill the pressure tank before operating the washing machine or dishwasher.

2. Never run the washing machine and dishwasher simultaneously.

3. Avoid using the vacuum cleaner alongside other high-power appliances.

4. Keep normal electrical consumption below the recommended inverter operating limits.

5. Consider the available battery capacity, particularly during periods of limited solar production.

During sunny summer days, the solar panels may generate substantial amounts of electricity. During autumn and winter, energy management becomes considerably more important.

In my experience, these habits quickly become second nature. The objective is not to avoid using electricity, but to use the available energy intelligently.

With appropriate planning, an off-grid house can provide much of the comfort and convenience expected from a conventional home while remaining independent of the public electricity grid.

 

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Understanding Electricity – Essential Formulas for Off-Grid Living

Understanding a few basic electrical principles makes operating an off-grid energy system much easier. You do not need to be an electrician or an engineer to understand how electricity is produced, stored and consumed.

In my experience, a basic knowledge of voltage, current, resistance, power and energy is particularly valuable when living off-grid. These concepts help explain why some appliances can operate together, why others may overload an inverter, and how long a battery bank can supply electricity.

What Is Electricity?

Electricity involves the presence and movement of electric charge. In an electrical circuit, an electric current exists when charge flows through a conducting path.

In metal wires, this movement is primarily caused by electrons. However, by convention, electrical current is described as flowing from the positive terminal towards the negative terminal in a DC circuit.

For a basic understanding of electricity, it is useful to distinguish three quantities:

Voltage (V) is the electrical potential difference between two points. It provides the driving force that can cause current to flow.

Current (A) is the rate at which electric charge flows through a circuit. It is measured in amperes.

Resistance (Ω) describes how strongly a component opposes the flow of electric current. It is measured in ohms.

One simple analogy is to imagine water flowing through a pipe. Voltage is somewhat like the pressure difference, current resembles the rate of water flow, and resistance is similar to the restriction caused by a narrow pipe.

This analogy is not perfect, but it provides a useful starting point.

Ohm’s Law – Voltage, Current and Resistance

One of the most important equations in electrical engineering is Ohm’s Law:

V = I × R

Where:

V = Voltage, measured in volts (V)
I = Current, measured in amperes (A)
R = Resistance, measured in ohms (Ω)

The same equation can be rearranged to calculate current or resistance:

I = V ÷ R

R = V ÷ I

For example, consider a 12 V battery connected across a 6 Ω resistor.

The current flowing through the resistor is:

I = 12 V ÷ 6 Ω = 2 A

This means that a current of 2 amperes flows through the resistor.

Ohm’s Law is useful when analysing electrical circuits, calculating voltage drops and understanding how voltage, current and resistance are related.

It applies directly to ohmic components under suitable conditions. Inverters, batteries and electronic equipment often have more complex electrical behaviour.

Electrical Power – Watts and Kilowatts

Electrical power describes the rate at which electrical energy is transferred or consumed.

For a DC circuit, the fundamental power equation is:

P = V × I

Where:

P = Power in watts (W)
V = Voltage in volts (V)
I = Current in amperes (A)

For example, an electrical device drawing 10 A from a 24 V battery consumes:

P = 24 V × 10 A = 240 W

The equation can also be rearranged to calculate current:

I = P ÷ V

This is particularly useful when comparing 24 V and 48 V off-grid systems.

Suppose an inverter requires 2,400 W of DC input power.

At 24 V:

I = 2,400 W ÷ 24 V = 100 A

At 48 V:

I = 2,400 W ÷ 48 V = 50 A

The 48 V system requires approximately half the current for the same DC input power.

This is one reason why higher-voltage battery systems are often preferred for larger off-grid installations. Lower currents can reduce voltage drop and resistive losses and may allow more practical cable sizing, subject to the complete electrical design.

These examples assume fixed voltages and do not include inverter conversion losses.

For AC systems, the relationship between voltage, current and active power can be more complex because power factor must also be considered.

Electrical Energy – Kilowatt-Hours

Power and energy are closely related, but they are not the same thing.

Power is measured in watts (W) or kilowatts (kW), while electrical energy is commonly measured in watt-hours (Wh) or kilowatt-hours (kWh).

The basic relationship is:

Energy (kWh) = Power (kW) × Time (hours)

For example, a 1,000 W appliance operating continuously for two hours consumes:

1 kW × 2 h = 2 kWh

A 2,000 W appliance operating for 30 minutes consumes:

2 kW × 0.5 h = 1 kWh

This distinction is especially important when living off-grid.

The inverter determines the amount of electrical power that can be supplied at a particular moment, while the battery bank determines how much energy is available over time.

Practical Example – My Water Pump

My private water supply provides a practical example of the difference between electrical power and energy consumption.

The water pump draws approximately 1,800 W and normally operates for six minutes when refilling my 180-litre pressure tank.

The energy consumed during one pumping cycle is:

1.8 kW × 0.1 h = 0.18 kWh

Although the energy consumption is relatively small, the pump represents a substantial instantaneous load on the inverter.

The practical operating procedures for the water pump, washing machine and dishwasher are described earlier on this page.

Calculating Battery Capacity

Another useful equation is the relationship between battery voltage, ampere-hour capacity and stored energy.

Energy (Wh) = Battery voltage (V) × Capacity (Ah)

To express the result in kilowatt-hours:

Energy (kWh) = V × Ah ÷ 1,000

For example, one of my Vestwoods VT48100E battery modules has a nominal voltage of 51.2 V and a capacity of 100 Ah.

Its nominal energy capacity is:

51.2 V × 100 Ah ÷ 1,000 = 5.12 kWh

My first battery bank contains six of these modules connected in parallel.

The combined nominal capacity is therefore:

6 × 5.12 kWh = 30.72 kWh

This is the nominal stored energy, not necessarily the usable energy available to household appliances.

The actual usable energy depends on factors such as the permitted depth of discharge, battery condition, temperature and inverter efficiency.

Series and Parallel Battery Connections

Understanding series and parallel connections is also useful when working with battery banks.

Batteries connected in series: Their nominal voltages are added together, while the ampere-hour capacity remains the same for identical batteries.

For example, four 12 V / 200 Ah batteries connected in series provide:

48 V / 200 Ah = 9.6 kWh

This is the arrangement used in my Monbat battery bank supplying the annex.

Batteries connected in parallel: The nominal voltage remains unchanged, while the ampere-hour capacities are added together for identical batteries.

For example, six 51.2 V / 100 Ah modules connected in parallel provide:

51.2 V / 600 Ah = 30.72 kWh

This is the configuration used in my Vestwoods LiFePO₄ battery bank.

These relationships explain how battery banks can be configured for different system voltages and energy storage requirements. Actual battery connections require compatible equipment, correctly designed protection and compliance with manufacturer instructions.

Calculating Inverter Load

Another practical calculation is the total power consumed by appliances operating simultaneously.

The total demand is approximately the sum of their individual input powers:

Total power = P₁ + P₂ + P₃ + …

For example, imagine the following appliances operating together:

Appliance	Power
Washing machine heating element	2,000 W
Refrigerator	150 W
Lighting	100 W
Television	100 W
Total	2,350 W

This would be within my recommended continuous operating limit of 3,500 W for the Victron MultiPlus installations, assuming no additional loads or significant motor starting surges.

However, if the 1,800 W water pump were to start at the same time, the combined running load would increase to:

2,350 W + 1,800 W = 4,150 W

This exceeds my recommended normal operating limit.

For this reason, I avoid using several high-power appliances simultaneously.

Summary of Essential Electrical Formulas

The following table summarises some of the most useful electrical relationships for understanding an off-grid installation.

Quantity	Formula	Typical use
Voltage	V = I × R	Ohm’s Law
Current	I = V ÷ R	Current through a resistance
Resistance	R = V ÷ I	Circuit resistance
DC power	P = V × I	Electrical power
DC current from power	I = P ÷ V	Estimating battery-side current
Electrical energy	E = P × t	Energy consumed over time
Battery energy	Wh = V × Ah	Nominal battery capacity
Battery energy in kWh	kWh = V × Ah ÷ 1,000	Battery bank sizing
Series battery voltage	Vtotal = V₁ + V₂ + …	Increasing battery voltage
Parallel battery capacity	Ahtotal = Ah₁ + Ah₂ + …	Increasing ampere-hour capacity

The accompanying illustration shows the relationships between the most commonly used electrical quantities and formulas.

Understanding these principles makes it easier to interpret inverter specifications, evaluate electrical loads, estimate battery capacity and manage electricity consumption in an off-grid property.

For a more detailed introduction to electricity, electrical calculations and energy systems, see my Norwegian book Solenergi og energisystemer.

The forthcoming British English edition, Solar Energy and Energy Systems, planned for publication in 2027, also includes a more extensive explanation of these subjects.

These equations allow you to calculate voltage, power, current and resistance depending on the available variables.

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My Victron Monitoring Application – Developed in Python

As a software developer with a background in Java, Kotlin and Python, I have developed my own monitoring and management application for my Victron-based off-grid energy systems.

The application includes both a Python back-end and a graphical front-end, providing a comprehensive overview of solar energy production, battery storage, inverter operation, electricity consumption and system performance.

Although Victron Energy already provides an excellent monitoring environment through its Victron Remote Management (VRM) portal, I wanted to develop a solution tailored to my own requirements.

My objective was to bring together technical information from the different Victron components, perform additional calculations, analyse historical performance and provide more detailed alerts and operational information.

The application communicates with the Victron monitoring environment and retrieves available data from the Cerbo GX and associated equipment using supported interfaces and API access.

Why I Developed My Own Monitoring System

Operating an off-grid property in Norway presents challenges that are very different from those of a conventional grid-connected home.

During the summer, my solar panels may generate substantial amounts of electricity. During autumn and winter, however, production becomes more limited, and managing the available battery capacity is increasingly important.

I wanted a monitoring system that would give me greater insight into how the installation performs, not only at a particular moment but also over longer periods.

My application allows me to examine solar production, battery charging and discharging, inverter operating conditions and electricity consumption in one place.

It also provides additional functions such as battery capacity calculations, weather-related information, geomagnetic activity warnings, configurable alarms and automated email reports.

This makes the application particularly useful when I am away from the property. Provided the monitoring equipment and internet connection are operating normally, I can check the status of the installation remotely and identify conditions that may require attention.

The application complements Victron’s existing monitoring tools rather than replacing the manufacturer’s battery protection, electrical safety systems or device control functions.

Main Features of the Application

The application is organised into eleven tabs, each focusing on a particular aspect of monitoring, configuration, diagnostics or system management.

1. Status Tab – Complete System Overview

The Status tab provides a consolidated overview of the most important operating parameters.

It displays available information from the Victron Cerbo GX, including battery status, solar production, electricity consumption and relevant system conditions.

The tab includes battery capacity analysis, external power information and comparisons between battery state-of-charge estimates obtained from a battery monitor and estimates derived from battery voltage.

I find these comparisons useful for identifying possible inconsistencies in battery measurements, although voltage-based state-of-charge estimates are inherently approximate and are strongly affected by battery chemistry, load, temperature and recent charging activity.

The Status tab also includes solar charger totals, production forecasts, error indications and weather-related warnings.

An additional feature is the display of geomagnetic activity information, including the planetary Kp index. This provides an indication of geomagnetic disturbance levels and helps me monitor space-weather conditions.

The tab also displays available network and gateway information, together with configurable system location coordinates.

A refresh function allows me to retrieve updated information whenever required.

2. Data Dump Tab – Raw API Information

The Data Dump tab displays raw JSON data retrieved from the Victron API.

This feature is particularly useful during software development, troubleshooting and verification of measurements.

It allows me to examine the underlying data structure, identify available parameters and investigate unexpected readings without relying entirely on the formatted information shown elsewhere in the application.

As a developer, I regard access to raw data as an important tool for understanding how the monitoring system operates.

3. Gateway Tab – Cerbo GX Information

The Gateway tab focuses on information associated with the Victron Cerbo GX.

It displays available gateway parameters such as system uptime, network status, device time and communication information.

Where available, it also shows local and external network addresses.

This helps me distinguish between problems affecting the electrical installation and problems caused by network or internet connectivity.

4. MultiPlus Tab – Inverter and Charger Monitoring

The MultiPlus tab presents information relating specifically to the Victron MultiPlus inverter/charger.

It includes available operating states, AC input and output measurements, power flows and other relevant device parameters.

The information is organised into a consistent format so that the inverter’s operating condition can be reviewed without searching through a large collection of unrelated system values.

This is particularly useful when investigating unusual power consumption, inverter warnings or changes in charging behaviour.

5. Battery Monitor Tab – Battery Performance

The Battery Monitor tab concentrates on battery measurements obtained from compatible monitoring equipment, such as a Victron BMV or SmartShunt.

Depending on the installed equipment and available data, it displays battery voltage, current, state of charge (SoC), estimated remaining operating time and other battery-related parameters.

The application also includes voltage-based battery capacity estimates.

These calculations are intended as supplementary diagnostic information rather than a replacement for the battery’s BMS or a properly configured battery monitor.

For off-grid operation, monitoring battery condition is particularly important because the stored energy must cover periods when solar production is insufficient.

6. Solar Charger Tab – MPPT Performance

The Solar Charger tab provides detailed information about the connected Victron MPPT solar charge controllers.

It displays individual controller data, solar charging performance, available daily energy yields and accumulated production totals.

Where supported by the retrieved data, it also includes maximum power statistics for the current and previous day.

Additional panel or array information can be included through the application’s configuration settings.

By comparing the performance of individual MPPT controllers, I can investigate differences between solar arrays, identify unexpected reductions in output and examine production patterns throughout the year.

7. System Overview Tab – VRM Data

The System Overview tab presents general installation information retrieved from the Victron monitoring environment.

The data is organised to make it easier to identify relevant system conditions and operating states.

Less useful or repetitive fields are omitted from the normal display, providing a clearer overview of the installation.

This is particularly helpful when reviewing the condition of the system without examining the full raw API response.

8. Commands Tab – Selected Remote Operations

The Commands tab provides access to selected control functions supported by my application and the connected Victron equipment.

These include a software-based inverter restart function and an interface for controlling the configured power output associated with Interface 2.

The application also displays command execution status and any reported errors.

These functions require appropriate permissions and compatible equipment. Sending a command does not guarantee that it has been executed successfully.

Because remote operations can affect electricity supply, they must be used carefully and should not replace appropriate local safety procedures.

9. Configuration Tab – System Parameters

The Configuration tab allows me to configure the information required by the application.

This includes the Victron installation identifier, authentication settings, solar panel specifications, battery characteristics and additional external power information.

Solar panel configuration includes the number of panels and their nominal power ratings.

Battery configuration includes the battery type and capacity used by the application’s calculations.

The application also supports access tokens for authenticated communication with supported API services.

Authentication credentials and access tokens should be stored securely and must never be published in screenshots, logs or publicly accessible configuration files.

10. Settings Tab – Alarms, Reports and Notifications

The Settings tab controls monitoring preferences, alert thresholds and reporting functions.

It allows me to define data update intervals and configure battery state-of-charge alarms, including low and high battery thresholds.

Additional voltage-based battery capacity alerts and power consumption thresholds can also be configured.

The application supports consumption monitoring over different time periods, including 24-hour usage and accumulated energy consumption.

Location settings can be configured for weather-related and other geographical information.

Email functionality allows the application to send notifications and scheduled reports using configured SMTP settings.

These features help me identify unusual operating conditions, monitor changes in consumption and receive information about the installation without continuously checking the graphical interface.

11. Help Tab – Application Reference

The Help tab provides an overview of the application’s main functions and explains the purpose of the different monitoring and configuration sections.

It also contains information intended to assist with basic troubleshooting.

Solar Production Forecasting and Space-Weather Monitoring

Two features I find particularly interesting are solar production forecasting and geomagnetic activity monitoring.

Solar forecasts can help me anticipate periods of reduced energy production and adjust electricity consumption accordingly.

For example, if several days of poor weather are expected, I may postpone non-essential high-power activities to preserve battery capacity.

The geomagnetic monitoring functions provide information about space-weather conditions, including the planetary Kp index and associated warnings.

Given my academic background in astrophysics, this is an area of particular personal interest.

Geomagnetic activity does not directly predict the performance of individual solar panels. Instead, this information provides broader awareness of space-weather conditions that can, during sufficiently severe events, affect parts of the wider electrical and communications infrastructure.

Monitoring, Fault Detection and Preventive Maintenance

One of the most valuable aspects of my application is the ability to combine information from different parts of the energy system.

A single battery voltage reading tells me relatively little on its own. However, when I compare battery voltage, current, state of charge, solar production, inverter load and historical measurements, I can develop a much better understanding of how the installation is operating.

Unexpected changes in charging behaviour, reduced solar production or unusual electricity consumption can provide early indications that something needs to be investigated.

Historical information is particularly useful when comparing performance between seasons or after changes to the installation.

In my experience, detailed monitoring makes troubleshooting more systematic and helps me identify potential issues before they become more serious.

However, software alarms depend on the availability and accuracy of the underlying data. They cannot guarantee detection of every equipment fault or replace physical inspections and electrical safety protection.

Application Troubleshooting

The application includes several diagnostic functions intended to simplify troubleshooting.

If location information is unavailable, I check the configured coordinates, relevant data sources and network connectivity.

If a remote command fails, I check permissions, supported device functions, communication status and the reported command result.

Raw API data and application logs are useful when investigating missing or unexpected parameters.

If battery state-of-charge readings appear inaccurate, I investigate the battery monitor configuration, synchronisation conditions and measurement history before making any changes.

Battery monitors should only be resynchronised or reset according to the manufacturer’s instructions and after the cause of the discrepancy has been understood.

Software Information

Application: Victron Monitoring System
Developer: David Elboth
Programming language: Python
Architecture: Front-end and back-end application
Documented version: 2.2
Version date: 17 June 2025
Copyright: © 2026 David Elboth

The software is provided as-is, without warranty. It is a personal monitoring and management application developed for my own installation, and its features depend on the connected equipment, configuration, permissions and availability of monitoring data.

Official information about Victron equipment and monitoring services is available from Victron Energy.

For developers interested in the underlying interface, Victron also provides VRM Portal documentation and API information.

Screenshots of My Victron Monitoring Application

The seven screenshots below illustrate different parts of the graphical user interface I have developed.

They demonstrate how I have organised the data into individual monitoring sections, bringing together information about solar production, battery storage, inverter operation, system status and other operating conditions.

My aim has been to create a practical application that gives me a clearer understanding of my off-grid installation and greater control over how I monitor its performance.

Developing this software has also been a valuable extension of my work with solar energy systems, combining my interests in programming, data analysis, renewable energy and astrophysics.