I upgraded our solar to 400 watts.
We now have our energy independence during boating season. I have seen as high as 27 amps going to the house bank from solar.
Being Pacific Northwest boaters, I wasn't a believer in solar before, I am now! We no longer require shore power when at a guest marina during boating season. We are seeing over 2,000 watt-hours a day (about 166 amps, daily). I've seen as high as 2,700 watt-hours in a day. Our normal daily consumption is around 1,200 watts-hours. In September, at Roche Harbor, it rained all day. We still captured 590 watt-hours.
It's also important to note that we are heavy heavy users of electrical. I work from the boat. We don't conserve electrical, we use what we want. We do, however, turn things off we aren't using.
I removed the factory 160 watt polycrystalline panel.
I installed a pair of Custom Marine products 200 watt 23.7% efficient (Sunpower mono crystalline) marine grade solar panels. (They are the same width as the factory panel, and about 3 inches shorter!)
I ran NO new wires for this upgrade.
I upgraded the factory PWM solar controller to a Victron MPPT SmartSolar 100/30 controller.
The 12volt red/yellow pair of wire that went from the solar controller to the engine battery are no longer used so I pulled the fuse on them and labeled the ends NIS "not in service" and taped off the ends. I also disconnected them from the engine battery. I don't want lose wires laying around waiting to short out.
I connected the port and starboard solar panels in series (not parallel). I have no shading problem up top, and I wanted the amps to remain low, and the voltage to go high (around 70 volts DC).
As an added bonus... the clamp-on stainless brackets I used (Gemini Products) look great and hold the panels up off the roof rack about 2 inches higher. This provides more clearance for opening the aft hatches. The solar panels cover the aft hatches entirely, so if it's raining out, we can still open those two hatches without water running in.
The big con to this upgrade, I have little room up on the roof rack for a kayak or anything else to store. Having enough power was more important to us.
I looked at a portable generator and decided against one. They are noisy in quiet anchorages. They present a carbon monoxide poising risk to all onboard. Running it on the transom, surrounded by saltwater, it would most likely prematurely rust. Plus, it's another piece of gear to carry around and perform maintenance on. Our 400 watt solar array is our generator.
If you're looking to upgrade your house battery bank, consider upgrading to solar first. You may find that you won't need as large of a battery bank.
The installation is mostly comprised of mounting the panels. The electrical work was minor.
I purchased the following:
(2) 200 Watt Custom Marine mono-crystaline solar panels. Part No. CMP22200S
Total cost of the upgrade was about $2,400 and was a full day of labor.