Solar Panel ? (novice Needs Help)

Q: I will need to figure out how to charge my sailboat bateries this season. I have 2 maint free wet deep cycle bateries connected in paralell (12 v). Each about 100 Ah. The boat will be used during weekend only and probably 2 weekends per month or so. I don't have to crank any engine. (Elbow grease is used) I would like to ask the following to those who know. What solar pannel setup should work to charge my bateries (1.9, 2.5... Ah/Day)? How should I set them up. Would I need a charge controller? Can I set it up in a way that the overcharge will never happen, avoiding the controller? Can I keep the bateries in parallel while charging? Will 2 small pannels connected to each separate batery work better than having one large one connected to the system? (If possible) What kind of pannel would you recommend that will accomplish this? Do I have to break the paralel connection at all? Basicaly, I'm not sure if I can hook one solar pannel to a batery "system", since the charge is so low and takes so much time, I don't know if it will work charging 2 bateries at the same time. Am I complicating too much something that can easily be configured? How?

A: The size of the battery bank doesn't matter. It is just like you are using a very small hose to fill a reservoir. It doesn't matter if you are filling a gallon bucket or a swimming pool, every cup of water you put in is a cup you can take back out (OK, it doesn't quite work that way, but if the currents are small, it's close). Now, that cup of water in the swimming pool won't look like much, but it will be every bit as useable as a cup in the gallon bucket. Plus, if you have a nice stretch of sunny weather, you won't be as likely to reach capacity with the larger reservoir. You didn't say how many amp-hours you use when you take the boat out. If you are trying to run refrigeration, then I would expect you to use all the 200 amp-hours of your capacity. Without refrigeration, I wouldn't expect you to use more than 50 amp-hours. If you need to replenish 50 amp-hours in 14 days, you will need about 4 amp-hours a day (always round up!). Since you will be wanting to just lay the panel flat, use the 25% figure, which shows that you will need a 15 watt panel. If it is often cloudy where you boat, you may want to double that, and get a 30 watt panel. With only a 30 watt panel, you won't need a regulator. You may wish to double this figure again, just to keep more options open (like using the boat on back to back weekends), or reduced output (due to bird droppings, dust, stretch of cloudy weather, etc).

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