Autonomous Energy System for a Garden House or Remote Property – Designed for Long-Term and Reliable Operation
The Figure 1 illustrates a system where the inverter can handle a continuous load of 1300 W, with a peak load capacity of up to 3000 W. This power output is more than sufficient for most common needs such as running a refrigerator, lighting, or charging power tools. If you plan to use a kettle, it’s recommended to choose a lower power model (not exceeding 1000 W) to keep a power reserve for other systems.
Figure 1 – Autonomous Power System for a Garden House: 1600 VA, 1200 Wh
The amount of energy generated depends on the size, quantity of connected solar panels, and the charging controller used. The average daily energy production of the solar panel “TSM-450NEG9R.28A”, depicted in the diagram, is shown in Figure 2.
Figure 2 – Average Energy Output from a 450 W Solar Panel in Kaunas
This is not a guaranteed energy output, but if energy is stored throughout the week, a 100 Ah battery will certainly be charged. It's important to consider the maximum charging current for the battery: for AGM lead-acid batteries, the typical max allowable charging current is 0.3 C. For example: 100 Ah × 0.3 = 30 A. With a 200 Ah battery, the max charging current can be 60 A. To improve system stability, it's advisable to increase battery capacity. This can be done by: connecting a second CSB-GPL121000 (100 Ah) battery in parallel or using a 200 Ah gel battery (NPG12-200 Ah) directly. Note: Gel batteries typically allow 0.2 C as the max charging current.
How to Get More Energy?
If the solar panels do not provide enough energy, the simplest solution is to connect an additional TSM-450NEG9R.28A panel in series with the existing one. Without any other changes, the charging current will remain limited to 30 A, but you will benefit during lower sunlight conditions. When using two 450 W panels in series, a different solar charge controller is required, such as VICTRON ENERGY SmartSolar MPPT 100/50 (SCC110050210) or reconfigure the system to operate at 24 V, keeping the same SmartSolar MPPT 100/30, but using an inverter that supports 24 V input. Possible 24 V inverter options: phoenix Inverter Compact 24/1600 230 V (CIN241620000) or more powerful: Phoenix Inverter 24/3000 230 VE.Bus (PIN243020000). A higher-power inverter provides more flexibility and allows you to run more powerful loads. If the inverter is not in use for a longer period, it should be disconnected from the battery, as it consumes a few watts even in standby mode (the higher the power rating, the more power it consumes when idle).Less energy is consumed when the inverter is switched to “ECO” mode. More details can be found in the user manuals:
Battery Balancing for Multi-Battery Systems
When connecting lead-acid batteries in series, internal characteristics (like resistance) gradually diverge. For example, in a 24 V system with 2x 12 V batteries in series, one battery may be overcharged while the other remains undercharged. To equalize charging voltage: periodic high-voltage charging or use a battery balancing device, which actively levels voltages and prolongs battery life.
Figure 3 – Typical Battery Balancer Connection
In this diagram, two 24 V battery strings (each 12 V + 12 V) are connected in parallel. More strings can be added if needed. To connect the balancer, 1–1.5 mm² wires are sufficient since balancing currents are low. The midpoints of each battery string should also be connected. For inverter connections, use thick and as short as possible cables. Choose cable thickness based on the maximum current: 1500 W inverter @ 12 V → ~150 A or 3000 W inverter @ 24 V → ~150 A. In both cases, at least 35 mm² cables are recommended.
When using lead-acid batteries, it is important to keep them consistently charged and avoid leaving them deeply discharged for extended periods. It is recommended that the minimum charge level does not drop below 30%, or approximately 11.75 V. Short-term higher loads can discharge the batteries further, but once the load is removed, the voltage tends to recover slightly. The critical threshold is 10.5 V—once this level is reached, the battery must be immediately disconnected and recharged (for 24 V systems, these voltage values should be doubled).
Information about the battery’s state of charge, real-time charging or discharging current, and estimates of how long the energy will last is provided by the BMV-712 Smart monitoring device. The same data can also be obtained by using the VICTRON ENERGY SmartShunt (SHU050150050) instead of a standard shunt and the BMV-712 Smart monitor. The information is accessible via Bluetooth once the SmartShunt is paired with your smartphone. The VictronConnect app must be installed on the phone: https://www.victronenergy.com/victronconnectapp/victronconnect/downloads. The BMV-712 device can also be accessed via Bluetooth.
How to protect batteries from deep discharge?
- Inverters are equipped with built-in protection against deep battery discharge – the inverter automatically shuts off when the battery reaches a critical discharge level.
- Energy savings are supported by LED strips used for lighting, which are powered directly from the batteries.
- The “BP-65” device is designed to disconnect DC loads when the battery voltage reaches a critical level.
- The “CHR0006” is a compact converter with USB-A and USB-C ports, intended for charging and powering various devices.
- The “DDR-120A-12” is a DC/DC converter that stabilizes the output voltage for the lighting system (battery voltage fluctuates depending on the discharge level, and without this converter, light intensity would vary). If a 24 V battery is used, the “DDR-120B-24” should be used for voltage stabilization along with 24 V LED strips. LEMONA electronics specialists recommend choosing LED strips that generate the highest luminous flux per watt of energy and selecting the light color temperature based on your needs: 3000 K for a cozy atmosphere, 4000 K for work environments.
The most important installation tips for a garden cabin power system
- When installing the system, the battery must be connected to the MPPT-100/30 charge controller first, and only then the solar module. When disconnecting, the solar module should be disconnected first, followed by the battery.
- Since the environment in garden cabins is often humid, it is recommended to install a residual current device (RCD) in the output (230 VAC) circuit and to ground the inverter.
- The system shown in the diagram No. 4 includes the "Cerbo GX" communication center. This is the key difference from the system shown in diagram No. 1. This diagram also features light dimming through the LED controller "SR-2501NS".
Figure 4. Stand-alone energy system 3000 VA, 2400 Wh
Internet access is necessary for remote system monitoring. To ensure connection, LEMONA electronics specialists recommend using the "RUT-241" mobile router. It is convenient because it can operate over a wide voltage range. The router can be powered directly from the VBB115060020 power bus via a 1 A fuse, but it is crucial not to reverse the polarity. The router and the "Cerbo GX" device should be connected directly to the batteries (after the shunt), so that even in a critical battery discharge situation, the system can still transmit status information and remain controllable. For a stable connection and reduced energy consumption, it is advisable to use the directional GSM antenna "A7041". An additional screen can be connected to the "Cerbo GX", but it is not necessary if everything can be conveniently monitored on a mobile phone via the app. The "Cerbo GX" device can also be accessed via Bluetooth. With a GSM communication modem, the VICTRON ENERGY "VRM" platform can be used to monitor and manage the energy system of the cabin from anywhere in the world, as long as there is an internet connection. More information on "VRM": https://www.victronenergy.com/panel-systems-remote-monitoring/vrm
With internet access, it is possible to automate your garden cabin without major expenses by installing an automatic irrigation or security system. The key is to choose the components that best meet your needs and provide the greatest benefit.
Figure 5. Security and irrigation components for the garden cabin
Diagram No. 5 shows several essential components needed for typical tasks in the garden. The core component of the system is the TUYA gateway "GW16-BLUE", which links all other components. These components do not use direct wired communication: they communicate wirelessly using the secure Zig-Bee protocol. Furthermore, the devices retransmit messages to one another, thereby increasing range and reliability.
The top part of the diagram shows the monitoring system:
- "NOUS-E3" sends a signal if the distance between the sensor and the main unit is increased – suitable for door and window protection;
- Two types of PIR motion sensors – designed for indoor security;
- A surveillance camera that can be installed outdoors and supports two-way voice communication. This enables intrusion alerts and real-time monitoring via the camera.
The lower part of the diagram shows components for irrigation automation and other device control:
The second part of the image shows components designed for irrigation automation and other technical control:
- R7060" – a valve with an actuator that allows automatic or manual opening of the water valve. This enables pre-filling of a water tank for intermediate irrigation (the tank can also be filled with rainwater collected from the roof). Automatic irrigation can be managed via a soil moisture sensor when a critical moisture level is reached, using the soil sensor "BSS-YC-STH-A-EN" or the environmental humidity sensor "NOUS-E5". To control other electrical devices, use the smart switch "NOUS-B2Z" (e.g., to activate a water pump from a pond and fill the water tank).
Energy Storage System (ESS)
If you want to save electricity in your home, the easiest way is to use the energy stored in batteries (also called an energy storage system or ESS) during the day. This type of system is most beneficial in a household where people live permanently. It allows you to take advantage of fluctuating electricity prices—buying electricity when it is cheap and selling it back when it is expensive. In addition, in case of a power outage, you will have a backup power supply.
What is ESS?
An energy storage system (ESS) is a specific type of electricity system that integrates a grid connection with a Victron inverter/charger, a GX device, and a battery system. It stores solar energy in batteries during the day so that the energy can be used later, once the sun is no longer shining.
ESS allows you to shift energy usage over time, charge batteries from solar energy, support the grid, and export energy back to it. When the ESS system generates more energy than can be consumed or stored, the excess energy can be sold back to the grid. When there is not enough energy or power, the system automatically purchases it from the grid.
What are the minimum ESS requirements?
The system must have at least one inverter/charger (MultiPlus or Quattro) and one GX device, such as Cerbo GX or Ekrano GX. Other components can be added based on individual needs.
When is ESS suitable to use?
ESS can be used in self-consumption systems, backup systems with solar energy, or hybrid solutions. For example, you can allocate 30% of the battery capacity for self-consumption and keep the remaining 70% as a backup energy source in case of a grid failure.
ESS can be configured either to optimize self-consumption or to keep the batteries fully charged at all times.
Self-consumption optimization:
When the PV system produces more energy than needed for loads, the surplus energy is stored in the battery. That stored energy is later used to power loads when solar energy is insufficient. The percentage of battery capacity used for self-consumption is configurable. If power outages are very rare, you can set it to 100%. Meanwhile, in areas where power outages are frequent or even daily (such as in some African countries), you might choose to use only 20% of the battery capacity and reserve 80% for the next outage.
Keeping batteries fully charged:
ESS can also be configured so that the batteries always remain fully charged. In such a setup, battery energy is only used in the event of a power outage. Once the grid is restored, the batteries are recharged either from the grid or from solar modules, if solar energy is available.
ESS system with a generator:
ESS can also be used in systems where a diesel generator serves as a backup energy source during prolonged power outages. In this case, it is essential to configure the grid codes carefully and specify how the system should behave when the grid is lost. In the GX device, go to Settings → System setup and select “Generator” as the AC input type. The system will then enable charging from the generator, ensure appropriate generator loading, and automatically shut it down once the preset parameters are reached.
When ESS should not be used:
- for off-grid systems (with or without a generator),
- marine systems,
- vehicle systems.
Paveikslas Nr. 6. Tipinė ESS sistema su integruotu On - grid inverteriu.
These are just a few simple and relatively inexpensive solutions that can be implemented in your home or garden. If you need a different setup, LEMONA electronics specialists are always ready to find the best solution to match your individual needs. More detailed information about ESS systems will be provided in the next article.
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