I spent a lot of time designing and building the electrical system for 'Anomaly'. As a quick review, we have mostly a 24V system with a 440 AH (@24V) house battery bank, charged by four systems: a 280A Electrodyne crankshaft driven alternator, a 40A belt driven Balmar alternator, 420 watt Sunware solar array, and a Mastervolt 100A charger when plugged in. There is no genset. Any 12V systems (including the engine and charging the engine start battery) are sourced by DC-DC converters from the 24V buss. There is an extensive Raymarine instrument system that is running at all times underway (driving a Jefa autopilot servo), a Glacier Bay 24V refrigerator/freezer/air conditioner compressor, a Mastervolt 2500W inverter, and ITR diesel water boiler for domestic hot water and cabin heat, a Spectra Catalina watermaker, and Alpenglow CFL cabin lights as the major loads.

The philosophy of the design was to run the engine in the morning when necessary using the large alternator to take care of bulk charging needs, then let the solar cells finish off during the rest of the hopefully sunny day. When the batteries are well down (say 50% state of charge) they will absorb about 200A charge for a while, this tapers back to about 80-100A by the time they hit 80%, and then asymptotically to zero. The Electrodyne alternator came with a surprise, in that it makes a whining sound while energized. It isn't terribly loud but unpleasant enough that when the charge gets down to 40A or so I switch it off and turn on the Balmar. According to Electrodyne this is normal. The refrigeration controls are set up to top up the holding plates when there is a charging source. My intention was to have this happen during the engine run, as well as run the Spectra to make water. With these major loads taken care of during the engine run, the other loads are modest. The alternator has sufficient capacity to run these and charge the batteries simultaneously.

What has happened in practice: I had been in fresh water until mid last season and water was available most places after, so I have yet to commission the water maker. The refrig compressor must run about 40 minutes a day to freeze the plate the way we use it (which involves loading a lot of warm drinks daily), for reasons unexplained the freezer wants two runs of about 20 minutes each a day, vs. the one 100 minute run expected. In any case, the result has been it is hard to synchronize the refrig runs with a morning engine run, so I have not bothered and just run it when the batteries get low. I think if I had more discipline this could work, but I haven't shown the backbone yet. The solar cells are a significant contribution when the sun shines. It did so for the first half of last season (Great Lakes, St. Lawrence), but not so much for the second half (Newfoundland, Nova Scotia). With good sun, the Blue Sky MPPT controller will charge up to about 10 amps (@24V), with 7A being more typical. Underway with good sun, the solar will keep up with the mostly idling inverter (just keeping the laptops charged and the microwave clock alive), the Raymarine system (about 4A typ) and the operating autopilot (2-4A average depending). If conditions are good it will put a little back into the batteries too. If I want, I can shut down half the Raymarine system and get more charge. On an overcast or cloudy day there is a very small contribution from solar. I think as I go south, the solar will get better. Underway the largest draw is the Raymarine system, at 4A it represents about 100 AH a day at 24V (!) which seems excessive. They have not made it easy to conserve power either: one MFD complains if the other is shut down, no time out on backlights, etc. The latest software rev for the ST70 display heads at least lets you group heads so you can dim the backlights as a group, rather than one at a time. The backlights for the displays (E120, E80, and seven ST70) are over half the draw.

At anchor or in harbor, if the sun in shining and we are not being careful about our usage, I can go around 3-4 days before I really need to run the engine. The solar contributes about 40-50 AH, we use about 100 or 150 AH (the higher number from running the air con a little bit), and I only charge to 90% or so state of charge in this case. If I am very careful about usage, keep the freezer turned off, don't run anything not necessary, I have found that in reasonably sunny weather the solar will just keep up with the load at anchor.

In about 4 months last season, we plugged into the dock exactly once. The last couple of days I was also plugged in, doing decommissioning and running the electric heater (mid October in Maine!). We were plagued by light winds a lot of the time, so there was a lot of motoring, and so very few times was the motor run only to charge batteries. Like maybe 10 or 12 times in 4 months.

Things that have worked well:

The Alpenglow lights are really great.
The Electrodyne alternator has met its specs (and there isn't any real alternative) but it does whine a bit.
The Mastervolt inverter is FAR better than anything I have owned from Xantrex, idle draw is about 100 ma, I leave it on all the time now.
Lifeline AGM batteries have worked well, very high absorption rate for charging, after calibration battery monitors are set to 94% efficiency (!).
ITR boiler has been great, no maintenance (one heat exchanger failed and was replaced under warrantee), pretty much unlimited heat and hot water.
Blue Sky solar controller has been flawless.

Things I might not do again:

Glacier Bay refrigeration is efficient, but expensive (they don't make them anymore anyway); would try Danfoss hermetic compressors next time.
Raymarine system is not very power efficient, no great alternatives but someone should beat some sense into them.
Stupid Trident propane control - not sure what you do about it. Almost 2A when its on, doing basically nothing (until it failed a few months out of warrantee). Someone needs to make a bistable solenoid and a lower power sniffer.

Overall I'm pretty happy with how it came out. If there was anything fundamentally learned, it was that the big current draws where accounted for and can be managed. However the quiescent background draws made up of small things amounts to quite a lot and needs more press. 2A doesn't seem like much, but if it is present 24 hours a day, there goes 50 AH. The refrig compressor is a 20A draw, but only for 40 minutes (14 AH) and you can plan on it.