System Design for Dock Lights

[Datech]

Have your added up all of your loads and how long each will run to get a total daily watt hour usage?

I picked out some bulbs on Amazon to make it simple, so we'll use this going forward:
- 4x 14W (100W eq) LED floodlights, total of 1 hour a day since they'll mainly be security lights: 56W
- 4x 14W (60W eq) accent lights, probably brighter than I need, for 5 hours at night: 280W
- 2x 9W (65W eq) overhead lights, for 4 hours at night: 72W
- 1x 450W vacuum for 15 minutes: 112.5W
- 1x 100W fan for 8 hours (overkill): 800W

That adds up to 1320.5W, which would be the very high end of use. Since I would be very surprised if we ran the fan for 8 straight hours, I feel like that's a pretty safe estimate for 50% DOD for sizing. I'm considering just closing off the receptacles and saying lights-only in order to keep costs down.

So your batteries, panel wattage, inverter should work if you use a true 60A MPPT type CC.

I didn't mention it, but I originally had a 45A MPPT charge controller. Did I miss something that would tell me I should get the 60A? Also, since this is a boat dock in Georgia that will almost exclusively be used during the swimming season (or at least 55 degrees and up), could I generate some cost savings by going PWM?

[SunEagle]

You may have an issue with what you have picked out but lets go through the math.

Have your added up all of your loads and how long each will run to get a total daily watt hour usage?

If not then looking at your 2 x 12v 220Ah batteries, if you connect them in parallel you have a 12v 440Ah system which can get you about (12v x 440Ah x 25% = 1320watt hours) a day.

And a pv system with 4 x 160watt = 640watt. With a 60amp MPPT charge controller you can get up to 53amps (if you get a few hours of uninterrupted sun) which is fine for that 440Ah system.

The 1000 watt inverter should work but can easily drain those batteries if you do not pay attention.

So your batteries, panel wattage, inverter should work if you use a true 60A MPPT type CC.

But the question is, will 1320 watt hours be enough for you when you end up using that vacuum system along with all your lights and that fan on a day that does not get you much sun?

[Datech]

I've been trying to design a solar system for my in-laws' dock, but I've been running into some issues and wanted to make sure I've got the calculations right.

Background:
- Off-grid system to provide power for lights on a boat dock
- Dock already has electrical appliances (listed below) as it used to be hooked up to land power
- Dock is a two bay, two story with a top sun deck, and the edges of the sun deck has a slightly sloped tin roof angled toward the sun that are about 3'x25' (hopefully will mount panels here)
- Primarily need power for lights at night (4-5 hours)
- Will also use power for vacuuming the boat and maybe powering a fan or a speaker
- Since this is a boat dock we won't be using it much, if any, in the winter, so the calculations below should cover the maximum need

Current Appliances:
- Two motion sensor flood light fixtures with two bulbs each (4 bulbs total)
- Four accent lights on top deck (4 bulbs total)
- Two general purpose lights over each bay (2 bulbs total)
- Four total standard receptacles

In order to make this work, we can change the bulbs to anything. I'm thinking 11W CFLs for the accent lights, some low wattage LEDs for the flood lights, and probably some 15-20W CFLs for the general purpose lights. I don't have specifics on the vacuum, but from a quick Google search it seems the average is around 450W (probably no more than 15 minutes for a boat). A fan seems to be about 100W, and to be safe that could be up to 8 hours continuous run. Other stuff like iPhone or Bluetooth speaker charging will hopefully be negligible.

With all of that info, I keep coming back to 4x 160W panels, a 1000W inverter, and 2x 220Ah 12V batteries minimum. I know I can cut some off by keeping the fan and the vacuum out of the calculation, but I figured I'd start high.

Questions:
1. Am I even close on the calculations?
2. If I'm close, is there any where I can reasonably cut back?
3. Any reason I should go with 24V instead of 12V?
4. Should I piece the design together myself, or order a kit?
5. Should I worry about loss at the panels since they'll be mounted on a tin roof on a dock?
6. Aside from dropping components into the water and general electrical safety, anything I should worry about with a solar system on a dock?
7. Any reputable suppliers that you guys prefer over others?

Thanks!