field test

PV Modules

A real world comparison between Mono, Poly, PERC and Dual PV Modules.

Realtime data
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Installation date: 09-03-2020


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* This is a field test and the results are specific for this installation on this location, please research which is the best solution for your own situation as the results can be different based on environmental influences.

Sailing Yacht

Sail away in comfort

Motor cruisers are masterpieces of engineering. They pack the comfort of a home into the compact space of a yacht. Wherever you go, you want to enjoy this hard-earned luxury to the fullest. Victron provides an intelligent power grid that adapts to any challenges you may sail into. So you can sit back in a deck chair.

How much energy do you need for your trip?

Whether you’re taking the family island hopping for the weekend or if you anchor at a beautiful bay for a week, it’s your holiday and you do whatever you want. This makes the optimal energy solution will vary from yacht to yacht and from owner to owner. With Victron you can power just about any plans, but as an example we illustrated ‘normal’ and ‘heavier’ power profiles in the below for the ‘average’ motor cruiser.

Let's take a look at your Optimal Energy Plan that makes it all happen.


How much do you need?

A motor cruiser wouldn’t be complete without a lot of electrical equipment. Most things used to run the boat usually use DC, bigger (household) appliances need AC. How much power does this add up to? Don’t just look at the Watts. A microwave might use 1000 Watts, but only for 4 minutes. A fridge/freezer combo might consume as little as 100 Watts, but is turned on 24 hours a day.

For inspirational purposes we’ve outlined 2 system examples based on ‘normal’ and ‘heavier’ use.

2.4 - 4.8 kWh / day

'normal' and 'heavier' energy consumption profiles. Lue lisää

Lue lisää

Example 1

The microwave uses 1000W an hour but is only on for 4 minutes
1000W / 60 x 4 = 0.67 kWh / day

Example 2

The fridge/freezer combo uses 84W an hour but is on the entire day (normally cooling ½ the day).
84W x 24hrs/2 = 1 kWh / day

Storage & conversion

How much energy should be stored?

A motor cruiser needs good energy storage and powerful conversion to 230V. Charging a battery bank from the engines means you don’t have to turn on that noisy generator when you’re anchored off-shore for the night. Since you might not move for a few days, your house battery should have a generous capacity. As a rule of thumb, we’re calculating energy storage with 48 hrs on board without shore/engine/generator/solar power.

x 2

The storage capacity of a lithium battery should be two times the daily power consumption.

x 4

Due to its ±50% smaller discharge capacity, the storage capacity of a lead-acid battery should be four times the daily power consumption.


The inverter(s) should be sized to handle the average load continuously and should match the expected peak power current of the loads, which our inverters handle very well (on average 2 x their continuous current).


Where does the power come from?

All that energy must be generated one way or the other. Victron lets you combine multiple sources into one steady flow of energy. In the marina, you will plug into shore power. On the water you can use an (additional) alternator on the boat’s engines. Or turn on a generator if you’re anchored off-shore. Finally, you can install solar panels on the roof for free, green, energy.

Sources of power

33A - 40A(or higher, battery capacity depending)
2x 50A - 80A(engine depending)

Power profile

Normal and heavier power profiles in kWh, based on the daily energy consumption, which should be in balance with the generation.

Storage batteries in Ah, double the capacity using lead-acid batteries.

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Complete system

A closer look

How does the power profile translate into a system? Here is our recommendation for an average motor cruiser.

House battery:


Everything you would expect in a home can also be found on a motor cruiser. All these devices need AC to run. Think of:

  • Entertainment suite
  • Television(s)
  • Laptop(s)
  • Phone chargers
  • Fridge and freezer
  • Coffeemaker
  • Breadmaker
  • Dishwasher
  • Microwave
  • Mixer
  • Wine cooler
  • Washing machine


The Cyrix BatteryCombiner is the only safe way to connect the house battery to the starter battery (to start your boat’s engines). With a BatteryCombiner you can charge the house battery from the alternator without running the risk of draining the starter battery (which always should be ready to go). When other sources of power are available (eg. shore/solar/generator power), the Cyrix BatteryCombiner will allow bi-directional charging from the house battery to the starter battery.

When the Voltages of the starter and house batteries are the same, use a Cyrix: its current rating should be equal or bigger than the current rating of the alternator.

If the house battery is Lithium and the alternators Amperage is smaller than the house battery, or when the Voltages of the starter and house battery are different: use a DC-DC converter or Buck-Boost.


Discharging your battery too far will damage it. Adding a Victron BatteryProtect will disconnect the boat’s electronics when the battery voltage drops below a pre-set level. It will also automatically reconnect everything when the battery is sufficiently recharged.

There is more to a Victron BatteryProtect. The built-in shutdown delay ensures that vital electronics aren’t disconnected in error, i.e. when starting the engine causes a short drop in battery voltage.

Battery Monitor

A battery monitor is like a "fuel gauge" for your battery. It records how much power is consumed and charged. The battery monitor calculates the state of charge, remaining capacity and time till empty. The battery voltage does not give an accurate indication of how full the battery is. A battery monitor does.

Victron battery monitors keep track of historical data, like the number of charging cycles, deepest discharge, highest voltage, lowest voltage and so on. It will alert you to critical conditions such as low voltage or low charge. The smart monitor can even shut down the entire power supply to avoid expensive battery damage.

Choosing a BMV:

  • Choose a BMV 700 battery monitor if you want to monitor the house battery and don’t need a Bluetooth connection.
  • Choose a BMV 702 battery monitor if you want to monitor both the house battery and the starter battery, and you don’t need a Bluetooth connection.
  • Choose a BMV 712 battery monitor if you want to monitor both the house battery and the starter battery via Bluetooth on a smartphone or tablet.

Boat Network

Keeping grips on all the systems on board can be a hassle. The solution: tie everything together in a single boat network using NMEA communication standards. Your boat network can include navigation equipment, tank senders, battery monitoring and much more. The status information can trigger alarms and shutdowns, adding to the safety on board. The Cerbo GX now supports the NMEA2000 out protocol, allowing you to monitor your boat’s network of systems from wherever you are.

Boat engines

Motor cruisers have one or two diesel engines to get from harbour to horizon. The engines are designed to run continuously, for days on end. They also come with high-output alternators to charge the engine batteries, drive fuel pumps, etc.

Once the starter batteries are recharged, the engines can also power the boat electrics and recharge the house battery. On motor cruiser you’ll find power hungry DC equipment such as anchor windlasses and bow thrusters. The engines have to be running before you can use them.

Boat Electronics

A motor cruiser is packed with dozens of electrical devices. These are all connected to the house battery. Think of:

  • Boat control panel
  • Log/depth sounder
  • Chart-plotter
  • Navigation / GPS
  • Navtex
  • Auto pilot
  • All-band Radio
  • Satellite comms
  • Maritime traffic identification systems
  • Navigation lights
  • Pumps
  • Windlass
  • Bow thruster
  • Fridge and freezer
  • Air conditioning
  • Blowers
  • Interior lighting
  • Music player


The Buck-Boost converter is used in dual battery systems, where the (smart) alternator and the start battery are used to charge the service battery (of equal or different voltages). The Buck-boost can be used in 12V or 24V systems and is suitable for both lead acid and lithium batteries.

Charging lithium batteries from the alternator

Alternators cannot be connected directly to most lithium batteries. A lithium battery will draw more current than the alternator can supply, which may result in alternator damage. A Buck-Boost DC/DC converter solves this problem: it acts as a current limiter between the alternator and the battery.

How to select a Buck-Boost? The current rating of the DC/DC converter has to be less than the alternator’s current rating. For example: pair a 50 Amps converter with a 60 Amps alternator. In the software the ideal throughput can be defined.

When the charging capacity exceeds the limits of the Buck-Boost, consider working with DC-DC generator(s) sized to the capacity of the battery bank.

Cerbo GX

The Victron Cerbo GX is the communication-centre of your boat’s installation, allowing you to always have perfect control from wherever you are and maximises its performance. Simply connect through our Victron Remote Management (VRM) portal, or access directly, using the optional GX Touch 50 screen, a Multi Functional Display or our VictronConnect app thanks to its added Bluetooth capability.

The Victron Cerbo GX is an easy to use visual system. Instantly monitor the battery state of charge, power consumption, power harvest from PV, generator, and mains, or check tank levels and temperature measurements. Easily control the shore power input current limit, (auto)start/stop generator(s) or even set quiet periods to avoid starting the generator in the middle of the night. Change any setting to optimise the system, follow up on alerts, perform diagnostic checks and resolve challenges remotely. The Cerbo GX turns any power challenge into an effortless experience.

Galvanic Isolator

A galvanic isolator prevents electrolytic corrosion. The isolator is mounted directly behind the shore power connector on board. It blocks DC currents that might leak through the shore power earth terminal. These currents can cause corrosion to all metal parts under water, like the hull, propeller, shaft, etc. The galvanic isolator should have the same power rating as the incoming shore power.

It’s a misunderstanding that galvanic corrosion occurs only in metal and aluminium hulls. In fact it can occur on any boat as soon as a metallic part (the shaft and propeller) is in contact with water. Galvanic corrosion will quickly dissolve your sacrificial anodes, and attack the shaft, propeller and other metal parts in contact with water as soon as the boat is connected to the shore-side supply. It might therefore be tempting not to connect the ground conductor: this is however extremely dangerous because Ground Fault Current Interrupters will not work nor will a fuse blow in case of a short circuit to a metal part on the boat.

The safe option is to use a Galvanic Isolator for non-metal smaller boats, or use an isolation transformer for metal boats or boats with bigger systems.


The generator provides energy when shore power is not available and the boat’s engines aren’t running (or can’t supply enough power to meet the demand). The generator is usually supplemented with a inverter/charger and a battery bank. The batteries act as a back-up and allow for quiet periods at night.

Thanks to Victron’s PowerAssist, the generator doesn’t have to be sized for the maximum load. You can use a smaller generator which is cheaper to install, uses less fuel and produces less noise. The inverter automatically bridges the potential gap between supply and demand with support of the battery bank.

GX GSM Dongle

The Victron GX GSM is a 3G cellular modem that enables GX devices with mobile internet for the system and connection to the VRM Portal, allowing you to monitor your system from remote. When the boat is in range of a 3G network, it will send data to the VRM website and you can monitor the boat from your smartphone. The GSM module adds tracking the boat, recording your trips and putting up a geo-fence around the boat. You will get an alert via mail when the boat travels outside the geo-fence area.

House battery

The house battery stores power for the boat’s electrical system. Motor cruisers typically have large power demands and the house battery should have a generous capacity.

For a house battery you can choose from two types: lead-acid and lithium. There are various reasons to favour one over the other. Here are a few common ones:

  • Choose Lead-Acid when:
  • Use occasionally
  • Lower purchase cost
  • Weight and space are not an issue
  • Normal charging
  • Choose Lithium when:
  • Use daily
  • Lower cost per cycle
  • Weight and space considerations
  • Fast charging

House battery

The house battery stores power for the boat’s electrical system. Motor cruisers typically have large power demands and the house battery should have a generous capacity.

For a house battery you can choose from two types: lead-acid and lithium. There are various reasons to favour one over the other. Here are a few common ones:

  • Choose Lead-Acid when:
  • Use occasionally
  • Lower purchase cost
  • Weight and space are not an issue
  • Normal charging
  • Choose Lithium when:
  • Use daily
  • Lower cost per cycle
  • Weight and space considerations
  • Fast charging


On motor cruisers you’ll need an intelligent inverter/charger that automatically switches between various sources to cater for all power needs.

In the marina shore power will be used to feed the boat’s AC grid and charge the batteries. When no shore power is available, the batteries will power both the DC and the AC grid. Power can be drawn from the boat’s engines while sailing. If the power demand gets too high or the batteries get low, the generator will kick in to power the load and charge the batteries.

  • Victron inverter/chargers come with a handful of outstanding features:
  • PowerControl: automatically manage battery charging to prevent an overload of the generator or shore power.
  • PowerAssist: uses the battery as a buffer to assist the shore power during peak power demand.
  • Perfect power: even sensitive devices run flawlessly on the pure sine wave power.
  • High peak-power: use motorised equipment without overheating.
  • Low self consumption.

Thanks to PowerAssist, the generator doesn’t have to be sized for the maximum load. You can use a smaller generator which is cheaper to install, uses less fuel and produces less noise.

If you don’t have a generator on board, a Multiplus is all you need. With a generator on board a Quattro is the better choice.

We strongly recommend 24 Volts for new boats. The higher voltage is simply a better choice when it comes to meeting the power demands of a motor cruiser. If your boat’s system is based on 12 Volts, select a 12 Volts unit instead. If you have dissimilar battery banks, consider charging them using a DC-DC converter, or have it power several dissimilar appliances with a different voltage than the house battery.

Generally speaking, a 3 kVA unit will be big enough, unless the power consumption is higher than average. For example: when you have an air conditioner on board. If this is the case, choose a 5 kVA unit.

MFD GX Integration

The Marine MFD GX integration enables you to easily connect a Multi Functional Display (MFD) to the heart of your power system such as the Cerbo GX, or the GX enabled Multiplus-II GX. Once connected you can easily monitor and control your boat’s power system, right on your Glass Bridge. Now available on the industry’s best MFDs, such as Raymarine, Garmin, Simrad, B&G and Lowrance.

Shore Power

Usually shore power is available in the marina; it is used to run large AC equipment on board and recharge the batteries. Larger boats need a three phase supply. Sometimes shore power can’t provide enough power to cater for the total AC load of the boat. It might also just be single phase.

Often shore power is limited in how much power you can draw, i.e. just 10 Amps. Berths with higher ratings might not always be available. Victron inverter/chargers allow you set a maximum shore power current. Now you can charge your batteries and turn on any equipment without blowing a fuse. Thanks to Victron’s PowerAssist, the generator and batteries can automatically bridge the gap between supply and demand.

Sometimes shore power is less than perfect. You might run into voltage drops if you’re at the far end of the harbour. There could also be power surges, which could harm sensitive equipment on board. Victron’s inverter/chargers smooth out these problems and turn bad power into perfect power.

Solar charger

Solar panels won’t be able to cover all the power needed, but they can reduce the running time of the generator and fuel costs.

A solar charger - also called MPPT controller, harvests the power from the solar panels to charge the house battery. Solar chargers have the same charging cycles as our regular, fully automatic, battery chargers. When your boat is moored without shore spower, solar power is a great way to keep the batteries charged.

In a marine environment, the performance of solar panels changes constantly. Victron’s solar controllers use ultra fast maximum power point tracking to squeeze up to 30% more power out of your panels.

See our Solar Calculator to size the solar panels and select a MPPT charger

Solar panels

Solar panels won’t be able to cover all the power needed, but they can reduce the running time of the generator and fuel costs. Victron offers a wide range of highly efficient solar panels that are just perfect for marine use.

Starter Battery

The starter battery is needed to start your boat’s engines. These batteries are different from house batteries and engineered to deal with a large discharge current. The starter batteries should be ready to go. Always use a BatteryCombiner to connect the starter batteries to the rest of the electrical system; it prevents an accidental drain of power.

GX Touch

The GX Touch 50 display allows you to have an instant overview of your system and adjust settings in the blink of an eye. Simply connected to the Cerbo GX with one cable, its super slim 5 inch waterproof design and its top-mountable setup bring a lot of flexibility when creating a crisp and clean dashboard.


The VE.Bus BMS is a dedicated battery management system (BMS) that protects lithium batteries against deep discharges, overcharging and high temperatures. When critical values are exceeded, the BMS acts immediately and will have the 230V loads disconnected by the inverter and the 12V/24V loads by the BatteryProtect in case of a deep discharge. Charging is stopped when there is a risk of overcharging. High temperatures trigger an immediate end to both charging and discharging.

The VE.Bus BMS can be used in 24, 24 and 48 Volt systems. The BMS does not physically disconnect the like other BMS do, but sends a signal that will turn the load or charge off. The VE.Bus BMS should always be paired with a BatteryProtect. There is no limit on the size of the connected inverter. The VE.Bus BMS comes standard with a mains detector, so the BMS is able to control the rest of the system when these parameters change: for instance, stopping the charging process of the inverter/charger when shore power is unplugged.


All Victron products on your boat can be monitored and controlled from the palm of your hand. Just connect the VictronConnect App via Bluetooth and you’ll have direct access to values like battery voltage and current. You can also turn devices on or off, as well as change their settings.

See what the VictronConnect app can do
System examples

Power consumption will vary from yacht to yacht and from owner to owner. The Optimal Energy Plan should always be designed with the cruisers specifics in mind. However, to get you started, here are two examples - with a normal and a heavier daily energy consumption - of Optimal Energy for a motor cruiser.

Please note that many more factors come into play when designing and installing your optimal solution: your Victron Professional will gladly help you with that.

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Motor cruiser from 33 - 46 ft
4 persons
Same boat but used more intense: longer away from home, more comfort, equipment and people on-board.
Daily energy consumption
2.4 kWh
4.8 kWh
Total power batteries and generator
± 8 kVA
± 10 kVA
Peak power batteries and generator
± 16 kVA
± 20 kVA
Peak power batteries only
± 6 kVA
± 10 kVA
Storage & inverting
Victron Quattro
House battery
2x 220Ah 12V
or 4 x 165Ah 12V AGM
4x 220Ah 12V AGM
or 25,6V/200Ah Lithium
Cyrix 120A (alternator depending)
2x Cyrix 120A (alternator depending)
or for Lithium: 2x Buck-Boost 100A (/24V = 50A) when alternator is Lithium-Proof, or adjust Amps to safe zone for Normal Alternator.
2x 80A (24V)
2x 80A (24V)
Shore power rating 230V
or 1x25A
Galvanic Isolator
16A (non-metal boats)
or Isolation transformer 3600W (metal boats or bigger systems)
16A or 32A (non-metal boats)
or Isolation transformer 3600W or 7000W (metal boats or bigger systems)
not essential for this profile
ideally more if possible
Solar Charger
(Smart) MPPT 100/35
Adjust according to combined panel voltage
Battery Monitor - akun valvonta
BMV-712 Smart
BMV-712 Smart
Available extensions
Cerbo GX and GX Touch 50
Cerbo GX and GX Touch 50
GX GSM module
GX GSM module
Show full list

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Dive into the world of marine energy

Find your local dealer

Our well established global network of local Victron Professionals is dedicated to help find an optimal solution for your challenge.

Count on our worldwide service

At Victron we find it essential that customers are serviced and supported quickly and competently. This is why our global network of Victron Professionals pack the highest level of technical know-how and are committed to deliver repairs as fast as possible.

So you can start or continue your journey, wherever you’re headed.