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Thread: Solar on a Boat, 2019 updated edition

  1. #1
    Join Date
    Apr 2017
    San Francisco, CA

    Default Solar on a Boat, 2019 updated edition

    The last solar thread is coming up on 10 years old, prices have come down, technology has improved. MPPT is now the standard rather than the exception, and panels are about $1.10/watt, shipped, chart plotters use 20W and your laptop might even use less, most people have converted to LED nav lights which sip amps.

    I have an 8500 lb 34' boat with two 90ah agm deep cycle batteries, looking to add autopilot to do longer trips and make single handing a bit easier

    As far as I can tell, autopilot has not changed significantly in power use since the early 2000s, something like 50-80ah/day, is that about accurate for building a power budget around?

    What is everyone doing for solar these days? Holouikani (40' J boat) has a 120w rigid panel mounted to the push pit feeding into an MPPT and claims to then make up the balance running the engine every couple of days. That seems like a not terrible compromise.

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    Looking through some of the old boats and threads people are running anywhere from 2x40 watt panels just to run the radio and lights, up to 400 watts feeding 390ah of batteries pushing an autopilot

    Where is the sweet spot these days? I ordered a Victron BMV battery monitor with bluetooth to start tracking power usage. Will be doing a longer passage next month should collect some good data then.

    Sort of thinking something like this

    • 160 watt rigid renology panel mounted to the pushpit ($180)
    • 150~ish watt flexible panel to move around the boat ($160)
    • Victron 75/15 MPPT to feed the solar into the batteries ($110)

    In terms of value per dollar on the boat, solar isn't quite free but it's cheap enough that places to safely mount solar rather than the price is the limiting factor

  2. #2
    Join Date
    Jan 2014
    Arnold, CA


    Take a look at "Nightmares Saga" page 3&4
    I ran the autopilot, gps, lighting, tracker, Sat phone, tablet 24/7
    2x100 watt panels, 2x110 ah deep cycle batteries, 2x 75-15 mppt controllers.
    Even on cloudy days the batteries were up by the end of the day.
    I brought a portable generator and never used it.
    Last edited by Daydreamer; 04-22-2019 at 10:44 PM.

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