Roberto,
Here is some additional info regarding the simple system I installed on the Far Reach.
First, I have a modicum of skills in this area. So, I can describe what I have on my boat. I researched it. I installed it. I am responsible for it. Your boat and your set up may be different. I provide this info as a start point for you to develop your own plan. I will tell you that I was anxious about it as I just don't have much background with electrical system. I read a few books to get the basic idea but RC Collins site was the most useful to me as I suspect it has been for many others. So I read his info very carefully--and made a donation to his site. I did my home work, wrote down the components I planned to use then made a written plan to execute. I purchased the tools and supplies I needed, made a few practice crimps, melted a few heat shrinks in my shop, stripped some wires with the new tools in my shop before I started. I ran my written plan past my mentor and proceeded. I did not document the install on my website (though I took pictures) as I was just out of time. I was a couple weeks from sailing for the West Indies and I had to prioritize.
With that said, You have two batteries, I have one. I have no other charging system to contend with where as you have an engine driven alternator. You may also have shore power. I do not.
I found the folks at emarineinc to be very helpful and knowledgeable. I recommend you discuss your requirements with them so they can better advise you.
The Far Reach:
1. I installed a Gantz GSP 30 solar panel. I did not purchase the Gantz "ez install kit" that comes with its own controller, just the panel because I purchased a separate more capable controller. The basic panel does, however, come with a 10' tinned copper power cable. I like the semi flex panel. It's very thin but it is not really flexible. But, it has, so far, worked well. You can see in the photo above I have lines tied to the grommets in each corner and I can tie the panel to wherever it gets the most sun--on top of the dinghy, on the side of the dinghy, to the base of the mast, etc. To my way of thinking, by having an easily moveable panel, I can capture the same amount of sunlight as someone with a larger fixed panel because I don't have to contend with shading issues. I move the panel all the time. Someone can argue they have their panels on special davits or arches and blah blah blah fine. But I did not want any towers or arches or stuff like that on my boat. Nice simple clean is what I wanted so that informed how I proceeded. If I wanted more watts of panels I would have had to do it another way. But, I digress . . . back to the panel. I like the fact I can disconnect it and it can lay flat in the wardrobe locker or under a bunk cushion if that is ever required. Keep in mind some of the panels have two separate cables on each panel. I think maybe one cable is pos and the other neg. But that means two deck connectors and it just took me down a path I did not want to go. So, the Gantz fit my requirements as both pos and neg where sheathed together. There is a good argument for installing a simple 15-30 watt hard frame panel off the stern pulpit. In which case maybe the two cables is not such a big deal as by all intents and purposes it becomes a fixed mount system. Or maybe you can do that with a single cable system. Others with more experience can advise you accordingly if you want to go that way.
2. I wanted to be able to remove the solar panel when necessary. So, I needed a deck fitting that allowed me to disconnect the panel's 10' cable from a deck connector fitting. Surprisingly there are not many suitable connectors out there. I went with a two prong chromed brass hella marine deck connector. It works perfectly for me. There are other ways to make a detachable connector but this is the way I chose to do it. There are special solar power connectors but I could never determine if they were really weatherproof and if they would be easy to remove. You can check into that if you like. I actually do have some of them installed inside my boat because of the way I chose to route my cable but it is not germane to the discussion.
https://www.jamestowndistributors.com/u ... nd+Sockets
I used tinned copper duplex marine cable from the connector on the inside of the boat to connect the connector to the the solar controller.
3. I installed a Genasun GV 5 MPPT Controller, per RC Collins (Compass Marine) instructions and by the instructions that came with the controller (they were the same). The compass marine site details the installation of the slightly more capable Genasun GV 10 MPPT Controller (it can handle more incoming amps from the solar panel). But, since I have a very small panel and no desire to expand beyond the one panel that I currently use I did not need the slightly more expensive GV 10. The GV 5 had the capability to handle my 30 watt panel. More is not always better. But, for all intents and purposes they are the same controller as far as installation goes. I also believe the Genasun controller is the same for lead acid and AGM batteries. I think it might be the same for gel cell as well but you should ask if that is an issue. I do know they have a different controller for lithium batteries. re, the "Peukert formula." I am not going to address it. I learned about on RC Collins site and he does a very good job of explaining it. I think he describes it on his post about the BV 700 controller. You can read about it there. The long and the short of it is that my monitor allows that issue to be address and RC Collins explains how to do it.
4. The solar controller is wired to my 100aH Lifeline AGM battery per the instructions contained with the controller and per RC Collins site.
I then installed a Vectron BV 700 monitor as recommended by RC Collins and that was essentially the entire system. The monitor is important as it has some programmable features in it that allow for some loss of battery capacity over time. Since I had no 12v panel or distribution of any kind I had to build one and install it and all the wiring and a battery switch and connect it to the battery and I had to buy the tools for wire crimps and heat shrinking, etc. Sounds complicated but it turned out to be a pretty simple event.
I purchased the panel for emarineinc. I don't remember where I purchased the Genasun controller as emarine did not carry it. I think you can purchase it from RC Collins though you can find it a little less expensive elsewhere. But, he has done a lot for our community and the little price difference is a small thing given the great info he provides to so many sailors.
I learn new stuff all the time. It's just fascinating. Most if it is pretty simple stuff really but you got to read, make some notes, roll up your sleeves and get started. Or . . . you can pay a competent marine electronics professional to make the installation. That is certainly a reasonable way to go.
I hope this helps Roberto. Good luck and keep us posted.
If possible I would like to avoid having to install a controller/regulator but will do so if necessary.
Everyone on this board can attest to my lack of knowledge, especially when it comes to anything electrical.