How Much Solar Does a Liveaboard Boat Need?
Size marine solar panels from daily kWh use, Australian cruising conditions, battery capacity and backup charging.
Example 1: weekend cruiser
Daily use:
1.2kWh
Planning array:
400W x 4.5h x 0.8 = 1.44kWh/day
Example 2: coastal cruiser with Starlink
Daily use:
2.7kWh
Planning array:
800W x 4.5h x 0.8 = 2.88kWh/day
Example 3: full liveaboard
Daily use:
6kWh
A 1,600W array under the same simple assumption gives:
1,600 x 4.5 x 0.8 = 5.76kWh/day
That is close to the assumed load but leaves little room for poor conditions.
A serious liveaboard normally needs a recovery plan using some combination of more solar, alternator charging, generator, hydro generation, wind generation, load reduction or shore power.
Check the whole charging path
A charger setting is only one part of the result. On the boat, charging performance depends on the source, regulator, cable path, temperature, battery limits and what happens when the BMS asks the source to stop.
- Record sustained output after the alternator, controller or charger is hot—not only its nameplate rating.
- Verify voltage limits, temperature sensing and shutdown behaviour against the battery manufacturer’s instructions.
- Compare daily energy used with energy that can realistically be replaced in the available charging window.