The typical math is wattage times 5 hours up north or 6 hours if you're in a sunny part of the world.so if I employ 4 kyocera panels above my bimini each 135KW how do you back into what that would supply to the batteries for power on a daily basis.
That would give you 135W x 4 = 540W. Figure about 5 hours/day x 540W for fixed panels (probably less when you're actually sailing, since the boat is swinging around), and you get 2700 Wh(watthours). If you divide that by 15 (remember, charging voltages are higher than 12V; and you have to account for inefficiencies in the charge controller -- even an MPPT controller ain't perfect), you get 180Ah/day. I would round that down to 150 Ah/day, since there are all sorts of other inefficiencies involved in such a system, and that gives you a pretty good estimate of the maximum charging capability of your panels. If you are going to go with that sized PV system, I would try to keep your daily usage somewhat below that (maybe 25%, or 112.5 Ah) to give you enough charging capacity to bring you batteries back up after a few cloudy days in a row. Your battery bank should be large enough to last at least 4 or 5 days w/o any charging (unless you want to run the engine, or have a wind turbine), so you'll have to have four or five pairs of golfcart batteries (or the equivalent capacity). If you want to go with your original 500 Ah estimate (which I still think is way too high) you need to scale everything (panels, batteries, controller, et cetera) up by a factor of four or five.so if I employ 4 kyocera panels above my bimini each 135KW how do you back into what that would supply to the batteries for power on a daily basis. I would guess you would apply the amount of KW in the panels against your most demanding 24 hour period of need. I am trying to measure what the boat can handle conservatively with panels vs. worst and then average amp hour needs.
Not sure how you could be using that many amp-hours. What does your auto pilot draw? If it averaged 6 amps X 24 hours, that is 144 and I can't imagine it would use 6 amps. Fridge should be no more than 150. So if take those two at 300 a/h there is a lot more to be found.With my 46 Beneteau I am guessing most demand on electrical system is a full day of sailing using auto pilot, fridge, nav system, running lights etc. coud produce a 24 hour day that could potentially require 500+ amp hours. Does that audit sound way off?
Does your boat currently have an amp meter on the panel (would show total amp boat draw)? If not, you should add one- gives a good indication of power use- check west marine for a selection. Once your panels are added, you can add an amp meter to the panels to indicate how much amps the panels are producing at any instant. This information will give a good indication of your energy balance.Thanks for the good ideas regarding the led lighting. Another big amp draw while cruising would be the nav system usage. I am Trying to plan for the days with the most energy draws. I think the need for some energy austerity on these big draw days is a big part of the answer. Thanks again