Energy on board: inverter or generator, that is the question

inverter-vs-generatorFor 220-volt power, on a boat, is it better to use an inverter or a generator? Let’s start with the definition of these two facilities.

An inverter is a device connected to the electrical system that transforms the voltage from 12/24 volts to 220 volts. It uses the power reserve of the on-board batteries to power the consumers at the latter voltage. The generator is an actual engine that works, as a rule, at a low RPM. Connected to it is a powerful alternator capable of delivering electrical “energy” with a voltage of 220 volts. Similarly, the alternator also serves to recharge the batteries.


Premised on the differences in running your own 220-volt utilities, you need to evaluate a number of parameters that will be able to make the choice, as far as on-board power supply is concerned, fall on an inverter or a generator:

Available space on board: a generator takes up more space than an inverter and must be installed in a convenient location that allows it to be connected to the cooling (water) circuit and outboard exhaust.

– Energy requirements : you have to calculate the energy requirements for everything on board operating at 220 volts. The unit of measurement to be considered is the Watt, and it is also the distinguishing parameter of various models of inverters and generators. To size them consider, for example, that if you use two 600 W consumers on board simultaneously, you need to calculate a 1200 W system. This power translates into a draw of about 100 ampere-hours (Ah) at 12 volts (i.e., using the batteries and thus the inverter). If you have a 200 Ah battery bank, halve its capacity in one hour. With the generator, on the other hand, there is no time limit on its use (as long as its power is greater than the sum of that of the utilities, in this case 1200 W).

Type of utilities: If you use 220-volt utilities for a long time and at the same time, your choice should fall on a generator. Imagine a microwave oven, hair dryer, phone charging, and so on. On the other hand, if the requirement becomes less, you will only need an inverter.

compact size, ease of installation, existence of models capable of developing great power.
Cons: Use limited to the scope of the battery bank.

continuous and stable electric supply, reliability.
Cons: large size, noise

coverThis, and many other useful tips, can be found in the special issue of Sailing devoted to Practice and DIY: a volume, this special one, designed to keep on hand, at home and on the boat, to take away doubts or brush up on your knowledge at any time. You can find it on newsstands or at




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