48V system on a sailboat

[Sunking]

Victron energy does inverters,charge controlers specifically for marine use and they latest 250v 100A controller with a efficiency of 99% is not to shabby.

Raul that raises one huge RED FLAG. Victron is not known for quality equipment, and no other manufacture claims 99% efficiency. Midnight Solar and Morningstar are two of the best money can buy. I do not think 99% is even possible.

[Raul]

I use the earlier version. However the new models if you read they spec carefully is the mppt tracking eficiency referred to 99%. Conversion/ harvest I expect it to be max 97-98% max. But they are tuff , robust and built for marine use.

[kibi]

I understand that Victron may not be very well known in the US market, but in most parts of the rest of the world they have a very good reputation. It's a well known brand in marine and vehicle applications too. I have a Victron Multiplus (inverter / charger) which previously served in an ambulance. The ambulance has long since been decommissioned, but the Multiplus is still going strong to this day.

I have a Victron MPPT 150/35 too. It's a very good quality product. I currently have an over powered PV array connected to it's input, so it hits it's maximum power output on most days. It is also part of a system that is configured to export excess solar, so it maintains maximum power (often full power) despite the battery being full. I realize that this is not a good way to configure any charge controller, but it is a temporary setup.
Despite its daily hammering, it has not skipped a beat.

[Amy@altE]

Space is going to be the biggest consideration with what panels to get. If you have the space for them, you could use up to 1440W of 60 or 72 cell panels cell panels in series/parallel to a Midnite Kid charge controller (1440W / 48V battery = 30A output). (The configuration of how many in series versus parallel depends on which panels you get)

As far as the panels go, be sure to look for brands that are both tested for salt mist (IEC 61701) and have a warranty that will cover them on a boat. Kyocera used to be the favorite for boaters, but they stopped making them in North America, so they are hard to get now. I think Canadian Solar is a good option, and they have several sizes available. For example, you could do 2 parallel strings of 2 in series with the 24V (72 cell) 320W panels.