It's been a few months since I purchased the boat and moved aboard, and am starting to get my head wrapped around all of the various systems. I've taken her out in Baltimore Harbor a few times for short trips, but mostly I'm using it as a condo. My goal is to eventually use it for more cruising in a few years, but for now I'll be attached to shore power most of the time. I pay $0.25 per KWH for electricity here in the marina, so reducing the amount of shore power I need will both save on the electric bill when I'm "home" and reduce the need to run the generator when I'm out cruising. BTW, my background is in residential energy auditing and building small boats.
What I've done so far:
Before I tackle the project of adding solar to the already complex electrical system of the big boat, I decided to start off small. I bought a wonderful little wooden dinghy that has a sail rig and rows like a dream (11' Shellback Dinghy). I mounted a 55 lb. thrust Minn-Kota motor-mount electric motor on the rudder, which is powered by a 50AH lithium battery that is my portable power station. I am charging that with a 100 W solar panel. I put together a nice little ammo box that holds the battery, charge controller, a circuit breaker, volt meter, and has various outlets to connect the motor, USB charging, and 12V accessories. I have a little 300W pure sine wave inverter to connect to it for powering small AC appliances. I can also use the DC power in the battery for charging my phone and my laptop, and for a 12V electric blanket. I haven't mounted the solar panel permanently yet, as I am still trying to figure out where and how to do that and if I need to add another panel. For now, I'm just trying to see how much energy I can create/store/use with this little mini system. (Well, technically energy cannot be created or destroyed, but you know what I mean.)
What I'm planning on doing:
I've ordered ten 3.2V 280AH lithium cells to make a 32V battery. I'll be replacing one of my 32V battery banks with those, while using the remaining lead acid bank to provide the 980CCA needed to get the engines started when it's cold out. Basically, I'll use the lithium to handle all of the 32V appliances other than the starters on the engines, because they can be charged and discharged many more times than the lead acid batteries can. I'm converting the water heater (19 gal.) from 240V AC to 32V DC by installing a 36V 1200W element (should work just fine). Once I get all of that installed, I'll keep track of my 32V system usage and size my solar system accordingly. To start off with, I'll use the shore power (or generator when out cruising) for large AC appliances and the solar for keeping the batteries charged and all of the DC needs. Then I'll see about adding a second solar system to handle the AC appliances as well. I like the idea of keeping the two systems separated, rather than one big system. I may even add a smaller third system for 12V.
As far as efficiency improvements go, I'm using an induction cook top, all EnergyStar appliances, I've replaced all of the incandescent bulbs for LED and wrapped the water heater. The new full-size fridge will be here next week. (I'll let you know how getting the old one out and the new one in goes.) I'm also installing a little diesel heater. I'm curious to see how it will compare to using the heat pumps (and electric space heaters) at various temperatures. I may add a second one at a later date. I'd also like to see how hard it will be to remove (then put back) the head liners in the salon, galley, and master state room to install insulation. (Any ideas?)
That's where I am for now with the efficiency upgrades and solar conversion. I'm anxious to hear people's thoughts on the project and am happy to hear about any ideas you may have.
Thanks for taking the time to read all of this.
Thom