I'm sure I've mentioned it a couple times, I bought a couple shipping containers which are amazing price vs value for their usable size. I live out in the country so I have land area and don't have to have the prettiest house on the block to please the city ordinance overlords.
Anyway, one issue I have is lighting. My house is around 150-200 feet away from them and being 40ft long even in the day time it can be hard to see stuff near the back. I figured I'd document what I do so other's with sheds or similar type of lighting needs can follow along. It's not super cheap, but it should end up being cheaper than running power all the way out. Of course being off grid, you have limits, like you can't leave the lights on 24/7 or you'll kill the battery in a hurry.
Here's my plans currently.
12v 20ah sealed lead acid battery
~100w solar panel. Harbor freight has one for $75 but the website says they can't deliver to my store. I'll have to go in there some time and ask them about it.
LED light strips, day light (~6000k color temp) lights using the 5050 SMD LED's and 12v design.
14-2 gauge outdoor wire to be more than plenty heavy enough for all planned loads.
Solar/wind charge controller
Here's a little math to see how well (or bad) my balance is for the parts. The battery really could be a bit larger but I don't plan to work in the shipping container light at night time for too long normally.
Sun hours for my area is about 4, so 100w rating * 4hr = 400wh per day of perfect sunlight. 400wh/12v = 33ah charging capacity roughly (the battery should be around 80% efficient), so even if I completely drain the battery, it should recharge in one day of sunlight. I think the solar panel is probably about twice as much as I really need but having the extra output is nice. The other spec to check out is the max charge rate, listing says 10-20% of battery capacity, so up to 4 amps (48w). I guess that means I can't get the battery to charge 100% in one day, but real close at around 16ah that the battery will take. Seems like the 50w solar panel size is a little more ideal for this small setup.
Now for the battery sizing calc. I'm kind of doing this a bit backwards from what you should really do it, like figure out your needs (my case lighting) and size the battery, then size the solar panels. Anyway, the LED light strips I'm using should be 36w per strip (around 16ft). I'm using two, but the one near the door will be controlled by the door and the rear one will be on a switch. Since it's pretty easy math, 36w/12v = 3 amps of draw, so the 20ah battery gives me 6.7hr of run time with one strip on and half of that with both on. That's more on the low end of what I should be targeting probably, but I expect in a 3 day span that I won't be in the shipping container long enough to drain the battery once and generally it's a good idea to target around 3 days of capacity for the battery size. I would double the battery size, but they add up in cost pretty fast. I didn't check what a golf cart battery would cost locally (120ah), kind of overkill for this project, but the 50ah ones are $110 online, worst case I could buy a 2nd 20ah battery to bump it to 40ah capacity for around $80 total. For a larger setup a "fork truck" battery is probably more ideal, I think the battery is a L-16 if I recall correctly and pretty sure they were 240ah rated. Anyway, 6hr+ run time I'd be pretty happy with, 90% of the time I'll probably be only using the lights for a few minutes and most of the time it will be during the day when the solar panel is making excess power.
The electrical I'm planning to make a plate to bolt some sort of framing to to hold the solar panel on the top corner of the shipping container. I don't like the idea of holes in the roof so I'll probably be poking through the wall and sealing the hole up. The battery will be in the same corner as the solar panel to keep the wire run nice and short. Clearly everything from then on will be going to the battery for the power source.
I plan to put a magnetic reed valve switch on the main door, so when it's open the front lights are on. I also want to have an override to turn the light off if for some reason I need the door left open but don't want the light on. Roughly half way back will be where the second switch should be located. Should be a solid layout since I'll already be heading that direction when the back lights would be needed.
I actually have two shipping containers, so the 100w solar panel and doubling up the batteries should get me in the ball park range I'd want to be for both systems tied to the same batteries. For now it's just a proof of concept. The shipping containers don't get a ton of sunlight during the day, so I might have to upgrade to two solar panels (or one larger one). At least on paper it seems to be reasonable. If all goes well, I plan to trench and pipe the power from one container to the other and poke through the floor in the corners.
Anyway, anything I'm missing? Also is my math off anywhere?
I've been looking at off grid setups for quite a while now, this is kind of the project to get my feet wet. Solar panels have dropped greatly in price since I first started looking, still kind of waiting for battery prices or tech to get more affordable and I might build a whole house system, something like 4kw solar panel array. That's defo for another time though since that system is around $10k investment and break even is something like 8 years or so and the batteries probably last around 10 years on average.