Yacht hybrid system

[Glenn_A]

I will soon retire and plan to spend a lot of time on our new boat cruising the Bahamas and the carribbean, I have been waiting patiently for the release of free energy technologies waiting in the shadows. For the time being, I want to know how to design the following.
The boat currently has 2 50KW generators is more than enough to run everything on the boat. They are loud and burn a lot of diesel. On previous boats I have installed a smaller, quieter, night generator that is just large enough to run refrigeration, air conditioning and a few lights. My first thought was to install about solar panels and a large battery bank to take the place of the night gen but after further study I think I want to start with a large battery bank and add the panels later. My goal is to have enough battery to run the boat all night. I would like help calculating the size of lithium battery bank and how much energy output needed from current generator to charge this bank every day. I am estimating approximately 80 amp draw during the night time 8 -10 hours. Then figure how many solar panels to charge the system daily.

 

[RCinFLA]

"two 50 kW generators" !!, not a yacht, its a ship.

Likely dominated by air conditioner. Find out its startup surge power requirement, run power, and nightly duty cycle.

My whole house central A/C is 4 ton (48K btu). It's starting surge is 120 amps for 400 msecs, and run current is 18 amps with fan and blower at 240 vac. Duty cycle at night is about 20% in summer in FL, about 80 degs F at night with thermostat set at 74 degs F. Run time is about 25 minutes each run time cycle which is dependent on thermostat temp setting and on/off temp hysteresis of thermostat. Total cumulative run time during night is about one and half hour to two hours. That is about 7 to 9 kWH's at night. With 90% inverter efficiency, that is about 200 AH's of battery capacity from 48v battery system. Dominate item is finding an inverter that does not cave in and shut down on high starting current of A/C compressor. I have 1000 AH's of batteries and two old Trace SW5548 plus inverters, just for A/C, that can handle the startup surge current.

Startup surge current is usually slightly higher then compressor LRA (locked rotor amperage) as the LRA is spec'd at lowest AC voltage, typ. 205 vac. My A/C compressor name plate shows an LRA of 105 amps versus measured startup current of 120 amps @ 240 vac.

If you have an inverter A/C compressor the startup current is only slightly higher then run current.

 

[Ampster]

I am estimating approximately 80 amp draw during the night time 8 -10 hours. Then figure how many solar panels to charge the system daily.

I assume its a 12 volt system. Although 50kW is is 4000 Amps at 12 volts. Can you clarify?

 

[scott harris]

Do you have electric motors in mind to move the boat, or are you just looking for house (boat) power?