Now that we have solar
and are liveaboards, it would seem the obvious thing to do is turn off the shore charger
and power 12v loads from solar
as much as possible, turning on the shore charger
only say once a week.
But I've realized while solar is a pure win while cruising, it's not clearly superior to using a shore power
charger while living aboard
(in a marina). Using solar instead of a shore charger you're basically trading potentially shorter battery
life for lower shoreside electrical
usage. Electricity is cheap
and relatively earth friendly here (hydro-electric), and my batteries
are also relatively cheap
- but a hassle to replace. So it's not clear which to favor, and I'm wondering what approach others have taken.
- Solar only: batteries
cycle between partially discharged and fully charged states.
- Shore charger + solar: batteries are happiest, fully charged all the time (equivalent to non-solar liveaboard
situation), but we'll pay a bit more for electricity and won't be as earth friendly.
If we do solar only, each night the batteries may discharge to about 90% (the fridge is our only significant DC usage) and get charged to 100% the next day. But, if there's an overcast day, we may have some 90% -> 95% -> 85% -> 100% cycles, and my understanding is those shallow recharges are what can reduce a battery's capacity pretty quickly.
We're already used to timing our fridge use manually - we turn it up while motoring, and super-chill it at dock
prior to a cruise
. Our ice box is pretty efficient and the fridge only needs to run about every 4-6 hours - but by cooling
it more to a higher setting we can forestall the next cooling
cycle to 8-10 hours.
So even while cruising, there's still a solar management question - should we time when our fridge runs to be during the daytime (and sunny)? Does anyone else do that or do you feel it's not worth the effort? I suppose I could make it easier by hooking a timer device into the switch.