Tesla Motors Club

I am looking forward immensely to my upcoming retirement, not least because I intend to spend large chunks of the year exploring Europe on a boat - exactly which boat is yet to be determined, but it is going to be a flybridge cruiser in the 50-foot range. We will spend a few weeks on it at a time, and then it will be laid up doing nothing for a few weeks (possibly up to four or five months if weather is poor). What do you all think about installing a powerwall? It seems to me the advantages could be:

• Not having to run the generator at night to run the aircon, which will make life a little quieter and reduce vibration when we are trying to sleep
• Not having to hook up to shorepower (which can (a) be expensive and (b) cause issues with galvanic corrosion of the metal parts which are in the water) during the periods we aren't using the boat, yet still allow us to keep a couple of dehumidifiers and an alarm system running
• Potentially reduce running costs since we would be running the generator less
• Permit the main boat batteries to be kept topped up during the periods we aren't using the boat (as you all know, batteries discharge over time even when not being used, and deteriorate, potentially to the point where they are useless and have to be replaced)

Obviously we would have a couple of solar panels on the boat to top up the Powerwall when we aren't using the boat, although space limitations mean it will be nothing like a normal domestic solar array. Presumably we could also connect the generator's output to it, and perhaps also the engine alternators?

Meanwhile, the downsides seem to me to be:

• Weight, and accordingly increased fuel consumption when on the move
• Placement (the obvious place from the space and ease-of-connection perspectives would be in the engine room, but they get pretty hot when the engines are running - it's a fairly confined space and the engines are likely to be a pair of diesels of approximately 11-litre displacement (possibly more) so as you can imagine they generate a bit of warmth, and the space also includes the hot water tank and a generator
• It is common for boat systems to be a mix of 12-volt, 110-volt and 220/240-volt systems - although I imagine that tapping the Powerwall into the same output points as the generator would solve that since the onward power transmission systems would have all the necessary gubbins built in

Not yet owning the boat I can't give you much guidance on electrical demand other than to say that we will have an upgraded aircon system which means (according to our enquiries in relation to the hot favourite boat) that we need an upgraded generator, with a nominal output of up to 12kW and 15kVA, instead of the standard 8kW unit. At night (which is when we would particularly want to use the Powerwall) the main draw will be the aircon, which is a 74,000 BTU system.

As regards daytime load - some aircon use but not much as we will generally be in the fresh air, and otherwise similar to a small home (cooker, oven, kettle, washer/dryer, fridge, freezer etc) but less likely that we will use it for hot water, since we would expect that to come mainly from the engines (boats typically have the hot water tank "powered" primarily by a heat exchanger connected to the engine cooling system). The only unusual bit of kit we are likely to be running is a watermaker but would probably only use that during the day (when engines or generator can provide the power).

Anyway, I am no expert on any of these issues so would be really grateful for any thoughts this community might have!