Join Date: Jun 2009
Location: Riverside, CA
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I'm also looking into this- I use my 13.3" Macbook as a digital chart plotter/viewer on my Catalina 22.
There's just no practical way to fit enough solar panels on a C22 to use a macbook very often. You'll just need a lot of battery capacity, and a 110v charger, generator, alternator outboard, etc.
You get a lot less than the rated battery capacity with high drain rates, plus you should never really let lead acid batteries drain below 50%. If you're drawing 85 watts, that's about 7 amps from a 12v battery.
A group 24 is probably about 70ah, so it should run your macbook for about 5 hours down to 50% charge if it really draws 85 watts (I'd bet it's really about half that).
I think it would be cheaper/easier actually to just get a few batteries for the macbook, charge them at shore, and swap them out, if it's an older model with a replaceable battery.