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New shed build help

Ockid

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Joined
Mar 31, 2022
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Good morning all! I'm looking for help that has probably been discussed already. But I'll go for it anyways. So please bear with me and or guide me to the right source.

I bought a shed, 12X18. I want to install two basic lights and a vent fan. Minimal usage for the lights and the vent fan would be small. As for the amps and usage. I get a bit lost here, but the bulbs are your basic 8w bulbs and vent fan would be 10-15 watt.

I've seen kits on Amazon and Harbor Freight, and I don't know which one would be the best. I have no desire to go and build a massive one. Just a basic panel or two, connect to a battery and then to an inverter. Excuse my ignorance if I missed a part or two, but nothing crazy.

I'd like the fan(s) to run on a constant, and the lights would be on for maybe 10-15 min at a time if I need to get something at night.

Any and all direction is wanted. And of course, I don't want to spend a lot of money. Thanks in advance.
 
Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the PVwatts.com or JCR Solar Uber-Sun-Hours calculator sites to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that. If you're looking at the All-In-Ones check for correct voltage outputs (120v or 240v Split Phase for North America, 220v Single Phase for European type areas) and make sure it has enough capacity for a little bit of growth and fudge factor.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. :) Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen 3000AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round :) ) and help figure out which parts and pieces you're going to want to get.
 
I bought a shed, 12X18. I want to install two basic lights and a vent fan. Minimal usage for the lights and the vent fan would be small. As for the amps and usage. I get a bit lost here, but the bulbs are your basic 8w bulbs and vent fan would be 10-15 watt.
You'll need to do a Power Audit. Knowing it's an 8w light doesn't help you if you don't know how long you're going to have it on. 1Hr a day? 10 hours a day? Try to get all your measurements in Watt Hours so the numbers stay straight. About the only time you need to worry about amps is when you calculate things like your battery capacity, which will be Amps * Volts = Watt Hours.

I.E. a 100Ah 12v battery gives you 1200Wh to play with. Once everything is in watt-hours the math gets a LOT easier to keep track of.

I've seen kits on Amazon and Harbor Freight, and I don't know which one would be the best. I have no desire to go and build a massive one. Just a basic panel or two, connect to a battery and then to an inverter. Excuse my ignorance if I missed a part or two, but nothing crazy.
The Fisher Price My First Solar Harbor Freight kits are absolute krap and will be nothing but waste of money. The kits you find on Amazon ffrom companies like Renology and HQST and such, while basic and simple, are a much better value. Especially for the beginner & small system ends.

I'd like the fan(s) to run on a constant, and the lights would be on for maybe 10-15 min at a time if I need to get something at night.
That's going to require a calculator and some math but is easily do-able.

Any and all direction is wanted. And of course, I don't want to spend a lot of money. Thanks in advance.
If you're working on a budget there are some things you can cheap out on and some things you really, REALLY shouldn't. The more limited the budget the more leg work you need to do.

Some things you can cheap out on for a smaller/beginner system:

Batteries. You can get Wally-World 120Ah FLA batteries for about $100 out the door. You'll get 60Ah or 720Wh of power out of them, but they're 1/3 the price of even the cheapest LFP comparable battery. If your needs grow, you can always replace it later.

SCC. If you can get a MPPT controller you'll gain upwards of 30% more efficiency out of panels than you'll get out of the PWM's most kits come with. The Victron fanboys will tell you that it's Victron or nothing, but those of us with cats to feed find that an EPEver or HQST or even Renology will do the job of turning solar panel DC into battery DC just fine for 1/4 the cost.

Panels. Search your local Craigslist, ebay, and online places for used panels. A 10-15 year old panel will still produce plenty of wattage compared to a new one but might cost you as little as $0.25/w compared to the almost $1.00/w of a new bog standard "100w Panel". The hardest part of doing that is that shipping a panel is usually more expensive than buying a new one unless you buy a LOT of panels at once. As an example, I bought a pallet of 23 used panels a few months back and the shipping was about $300. That made the panels about $53 each. If I had purchased a single panel, the shipping was the same so it would have cost me $360 for a single panel.

Number of fuses. Some people put a fuse into every single wire in their system. A fuse on every panel, a fuse from the panels to the SCC, a fuse from the SCC to the battery, a fuse from the battery to the inverter, etc. For a small system don't be afraid to just fuse the loads like the inverter and low power fuse blocks. If you want to add more fuses to feel better you're more than welcome to, just use quality trusted fuses.


Things you really, REALLY don't want to cheap out on:

Fuses & Wire. Get the correct type and quality of fuses and breakers. Chinese knock-offs and the tube-style "automotive" fuses look great until they catch fire. ANL is fine for FLA but you really want a Class-T if you step up to LFP. Remember, Fuses are cheaper than fires!

Inverters. Spend the extra to get a Pure Sine Wave inverter. Yes, that Modified Sine inverter is cheap and you can take all that money you saved and put it to new fans and lights and electronics that burned up because MSW is krap for those. When you plan out your system get the right inverter for the job. The basic rule of thumb is "No more than 250a" because around 300a that fuse becomes a flamethrower. Besides, there's no need to buy a 2000w inverter if you're only running 200w of load, that's just a waste of money and battery power.
 
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