Integrel – An Alternative to a Generator

Integrel Solutions has spent a decade of research and development and over $10m in grant money to create a new smart electrical generating device. The device, dubbed “Integrel” generates and controls up to 9 kW of electrical power directly from the boat’s own propulsion engine without compromising any of the power needed for the propeller.

Editor's Report by Capt. Nick Martinez


Integrels’ Lithium Ion batteries.


Nigel Calder, the famous boating author of multiple books on cruising, including the Boat Owner’s Mechanical and Electrical Manual, in the Integral lab describing the benefits and workings of the system. Calder has thoroughly tested Integrel over a ten-year period.


The picture shows a MerCruiser engine with an Integrel generator (pink dot) and a standard alternator (right). Standard alternators put out approximately 1 kW, but not enough to run home appliances like AC units.

Brief Summary

Integrel Solutions has spent a decade of research and development and over $10m in grant money to create a new smart electrical generating device. The device, dubbed “Integrel” generates and controls up to 9 kW of electrical power directly from the boat’s own propulsion engine without compromising any of the power needed for the propeller. The smartness lies in the Integrel control system.

It makes real-time decisions about the difference between how much power the propeller needs and how much power the engine can produce to bring it into its own efficient operating power zone. It then takes this remaining (almost free) power and turns it into electrical energy. It stores this energy in a 48 volt Li-Ion DC battery bank for use when needed by the boat’s own normal electrical systems such as the refriegerator and air conditioner, as well as charging the boat’s house bank and engine battery bank. It is completely automatic, working in the background with no direct input from the operator. It requires no maintenance other than a periodic belt change, offering substantial savings on fuel and maintenance costs across its lifetime.

The standard Integrel system consists of:

  • A 9 kW engine-mounted Integrel generator which is much the same shape and size as an alternator
  • Engine mounting kit
  • Solid state Integrel system controller
  • 48v battery sensor
  • Integrel 600W 48v to housebank DC to DC battery charger
  • 5” touchscreen user information system
  • Wiring looms and fuses

How It Works

The boat’s existing inboard engine has a significant amount of spare horsepower capacity most of the time. Integrel uses this spare capacity to generate electrical energy either for immediate consumption or to charge the battery banks. As that spare capacity increases and decreases with engine revs, the Integrel automatically adjusts its power generation accordingly. If the boat needs full power to the propeller for an emergency operation, Integrel instantly ramps down. The energy generated is stored in a 48volt battery bank that also charges the boat’s own battery banks.


Battery and circuit setup are compact and easily accessible. Integrel has worked hard to make the system predictive rather than reactive and the installation easy.

power efficiency

Calder explains the power-efficiency curve and the theory behind how Integrel works.

Effectively, the Integrel generator is like an alternator on steroids. Permanent magnets embedded in the rotor improve the internal magnetic coupling, delivering exceptionally high power and efficiency. But such high power needs to be controlled carefully or it could damage the engine or battery bank where the energy is stored. Integrel’s smart system controller is programmed with information about the engine (maximum power output and maximum rpm as well as the engine’s efficient operating zone) and the boat’s battery bank systems. This allows the controller to calculate in real-time exactly how much additional load can be added to bring the engine to its most efficient operating point at any given engine speed.


Power from the engine is stored in batteries for later use in onboard (household) devices.

What are the Benefits?

With sufficient battery capacity, Integrel will deliver enough silent, emissions-free power to run all of the boat’s electrical needs, including air-conditioning, refrigeration, icemakers, hair dryers etc... Most of the time, this will be generated during normal cruising using minimal extra fuel, with no effect on boat speed and no increase in running hours. Many times, operating the  engine during simple short operations like raising the anchor and getting out of the bay to set the sails will create enough energy for the entire day’s electrical  requirements.

With no need for a separate generator, there are no additional servicing costs to worry about either and no need for any additional through-hull fittings. And depending on the number and type of battery banks, it often takes up less space and weight of a traditional generator. Integrel prefers batteries like Li-Ion that can withstand high charge rates (1C) but is designed to work with any other battery type such as AGM.

The Talking Points of the System

  • Propulsion is always prioritized, and the electrical power is ramped up slowly to avoid any shock loading on the engine.
  • Integrel is fully automatic and almost no user intervention is required. Simply start the main engine and it will start generating power. All of the information regarding your boat’s energy system is available on the dedicated user interface. Much like a modern car shows the miles remaining given the fuel tank status, the touchscreen shows  the amount of time to fully charged batteries or the amount of time remaining at current discharge rate.
  • When the engine is not running, all of the boat’s electrical systems automatically continue to be supported by the energy stored in the 48v battery bank through a Integrel Solutions invented 600 watt DC to DC converter charging the house bank; the more batteries, the greater the boat’s electrical autonomy.
  • When the batteries need recharging, a reminder appears on the screen indicating the battery level and advising that the engine should be started. Because the Integrel generator is so powerful, the engine only needs to be run at idle, or a little above, to recharge the batteries very rapidly. 


This picture shows the Integrel charging at 6.5 kW. The engine RPM at the time was 1100 RPM.


The system’s 5” touchscreen provides real-time power monitoring with sensors on the battery bank and output levels on the charging system. When operating an appliance such as a microwave, the system can even predict “time to go” based on draw rate and existing charge level.

The Integrel system is much more than just a generator; it is a complete power generation, control, storage, conversion, and distribution system.

  • The Integrel generator will deliver its rated power continuously. For example, with an ambient temperature of 25C (77F) the generator will deliver a constant 8.3 kW.
  • The coupling of the magnetic flux between the rotor and stator has been dramatically improved to give very high generation efficiency.
  • The windings have been changed to give the specific voltage range needed and to provide unusually high-power output at low revs. With a suitable engine, up to 3.5 kW of output DC power is available at engine idle of 800 RPM.
  • The generator itself has no embedded electronics and much improved cooling airflow to cope with the higher power output. The solid state electronic control box is mounted in a separate area from the engine compartment.
  • The customized engine mountings are specifically designed to minimize side loads on the engine, to eliminate shock loading and to maximize belt life.

The Integrel generator is manufactured specifically for Integrel Solutions Ltd, a U.K. based company and is distributed in North America by Integrel Solutions, LLC.

catamaran owner

This Lagoon 46 catamaran owner wanted autonomy, flexibility, and comfort when using the vessel. With lots of electronic equipment and high house loads to deal with, an effective battery bank was designed using 20 kWh Victron batteries that, in conjunction with the Integrel system, could be charged quickly and offer enough power to run air conditioning overnight – without the drone of a diesel generator.

Additional Options

  • Additional battery storage can be added in 5 kWh increments. Lithium-ion batteries are available as an option.
  • An inverter/charger is also available in 5 kW, 8 kW, 10 kW and 15 kW sizes.
  • The Integrel battery-to-battery charger is upgradable in 600W increments up to 2400W.
  • Further battery sensors are available to monitor the house and engine start batteries.
  • A 3 kW 48v inverter/charger is available for shore power charging as well.

Where Integrel really shines is the quiet running of the air conditioner all through the night. An average 40' (12.19 m) boat in warm Caribbean waters will use about 12 kW hours of energy through the night just for the air conditioner. If during the day, the user stores this up by running the propulsion engine for a little over an hour, on-board boaties can get a full quiet night’s sleep without the constant thrumb of a generator all night. And feel a whole lot better about the environment.

Technical Specifications



The basic Integrel generator package starts at $15k, but to determine specifics for each vessel, Integrel supplies a cost estimator that will take into account both the vessel’s equipment, other power generation contributors such as solar, and area of operation.



Energy efficiency and independence is a goal of Integrel. For instance, the lithium-ion batteries in this Torqueedo outboard can be charged off the system, possibly eliminating the need for gasoline.

Yachting guru Nigel Calder and the Integrel U.K. team have brought a game-changer to the marine world. This system replaces generators in power and sailboats alike, doing away with the noise, smell, and maintenance of a standard onboard generator.

With efficiency and the environment as a high selling point of this product, the Integrel system uses every last bit of energy from the boat’s engine and wastes nothing.

Determining energy consumption and making sure the battery banks are sufficient to store the energy derived from Integrel while underway will lessen the need for operating the engine for electrical reasons alone.

Grant Headifen, Global Director of Education for NauticEd, who, also heads up the introduction of Integrel into the North American markets says “Yacht charterers must typically run their engines for 4 hours per day to generate the 4kW.hrs needed for daily electrical consumption. Now, with Integrel, that virtually disappears. And, so does the need for a generator running all night. That’s a big win for the environment”.

Drawing power from an existing engine is not new, but producing 10 times the output of an alternator, then controlling, storing, and reusing it in a safe effective way is new. Power is not free – but Integrel is a smart investment to a more efficient and sustainable future.