diy solar

diy solar

Planning power for a shed

Xue

New Member
Joined
Dec 10, 2023
Messages
4
Location
California
Are there any differences in using multiple lower AH batteries vs fewer higher AH batteries? I have four 400W panels coming and am looking to get either two 100Ah or one 200AH LiTime batteries. This will likely expand to double in the coming years so just planning ahead.

Plus, any advise on long term continuous running of a system? What do I need to know? I've only run stuff like lights on100W kits. The plan is to run a shed with fish tanks and other man stuff. Heaters are 100-150W each by themselves so that will be a problem.

Additionally, I have EcoFlow power stations and what if I just plugged those into the panels and skip all the other components I'd need? I already have them so might as well find a use for them. I've used them for week long power needs but nothing over maybe 7 days.

Again, my experiences are with power stations and light load 100W kits.

This is what is planned to be in use:

-400w panels (4 @100 ea)
-Victron MPPT 100-30 controller
-Ampeak 2000W pure sinewave power inverter
-LiTime batteries
 
Well, it all comes down to the math. It looks like the biggest consumers are going to be the fish tanks, but you'll have to start collecting more data points (numbers) before you can do a proper power audit. Just to run some example math with what you've listed so far:

Fish tank heater 150w * 24hrs = 3600Wh / 12v = 300Ah Per Heater Per Day!
3600Wh / 4 sun hours per day = 900w Of Solar Panel Per Day Per Heater!

and other man stuff.
Cordless tool chargers are pretty small, TV's aren't bad if you're only using them for a couple hours at a time, but 1 football game with pre and post shows is an easy 500Wh, or half a 100Ah battery. You'll need to get more exact numbers to get more exact answers, but if your system can handle fish tanks, it just needs extra capacity for everything else.

Honestly, if you're looking at feeding the whole man cave, you're going to want to think about a 24v or 48v system so you can get larger inverters involved for power tools. Anything over about 1500w on a 12v system starts getting sketchy, plus the cost of the charge controllers to feed a 12v system start adding up quick.

I think I really need to dust off my Blurb... ;)
 
Blurb time!

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.

2: 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.

3: 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.

4: 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.

5: 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.

6: 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.

Well that's the thing about solar systems, there is no 1-Size-Fits-All answer. Your system will need to be designed to fit YOUR needs. When you design and built the system, it's not going to be the perfect system for me, or Will or 12vInstall or anyone else, but it Will be the right system for You and that's the goal.

Don't panic on the Power Audit, you'll actually be doing that a few times. When you do the first pass put in ALL the Things that you might want. AirCon? Sure. Jacuzzi? Why not. MargaritaMaster-9000? Go for it.

The second pass will be the "I Absolutely Need This To Survive" list that isn't going to have much on there.

The third pass will be the "This is what is realistic" audit that you'll use to design the rest of the system.

The Power Audit is going to tell you 3 primary things: 1: How big does your inverter need to be to power your loads? 2: How much battery bank do you need to last $N number of days with krappy weather? and 3: How much solar panel will I need to install to refill those batteries in a 4 hour day (the average usable sun hours rule-of-thumb).

Once you know what you Want and what you Need and what your budget can Afford there will be somewhere in that Venn diagram where those three things meet.

After that, THEN you can start looking at parts.

Yes, it's a long drawn out process, but it's worth it in the end. Not every house has the exact same floorplan, not every vehicle is the same make & model, and not every solar system is designed the same.
 
12V.

The start will be at least 200ah on 400W panels.

Why 12V? If you have power hungry anything go higher in voltage. Keeps the current lower, less losses, smaller wire, etc.
 
No TV's, no charging or tools. Will mainly run lights and heaters for fish and reptiles. I knew the heaters would be a problem because they use a lot. I also have heat pads which uses far less but the load may still end up rather high.

I'm already discouraged, haha.

12V is because I already have components and wasn't intending to put in more than about $1500. I'm thinking any more than that and I might as well plug it into the grid and use the funds to buy another power station.

I have the Victron 30 controller already. I have several off brand 1500 inverters but want to purchase the Ampeak 2000.

Live in CenCal.

Would these main components be a good start even if it's limited, or advise what I need to mix and match with 400w panels because that's what's going up. I can run what they produce then add as needed.

-400w panels (4 @100 ea)
-Victron MPPT 100-30 controller
-Ampeak 2000W pure sinewave power inverter
-LiTime batteries, 200ah total
 
400w panels (4 @100 ea)
-Victron MPPT 100-30 controller
-Ampeak 2000W pure sinewave power inverter
-LiTime batteries, 200ah total
So 400W of panels will offer up to 33 Amps of charging at 12V nominal less inefficiencies so even if we guess at 30A that SCC will not even recharge + usage in a long day - if we accept that:
Fish tank heater 150w * 24hrs = 3600Wh / 12v = 300Ah Per Heater Per Day!
3600Wh / 4 sun hours per day = 900w Of Solar Panel Per Day Per Heater!

So as suggested it don’t matter no how because you can’t touch your loads.
 
Heaters never sound like much until you multiply it by 24 hours and then it adds up right quick. The most cost effective method is likely a grid connection and using the solar system to offset the power consumption, but it's only going to do that for a few hours with the limited battery capacity and panels you've got to work with. :cry:
 
So, I have the majority of my components in except for the wire and AC shutoff. I need advise on the gauge of wire between the components. The way it sits in the photo is how it'll be set up. The shunt will be mounted on the right somewhere. All can be easily moved if need be.

I have 10 AWG PV cables, 12V system. Total distance from panels to the charge controller will be approximately 12 ft.

Components used in build:

Solar panels are HQST 4 @100W
Battery is LiTime 200ah
Charge controller is Victron 100/30
Inverter is Vevor 3500
Shunt is Victron 500A
DC shutoff is 63A
AC shut off: need advise on amperage before I buy one.
Fuse between battery and inverter is Victron 300A
Fuse from battery to charge controller is 40A
Solar panel fuses: I have 15 and 30A. Need advise on which one to use. It'll be 2s2p. I will likely add 2 more 100W panels if the 400W isn't enough for my intended needs.

I'm not positive if all these can work together. Nothing is hooked up and no wire have been purchased other than PV.
 

Attachments

  • image3.jpeg
    image3.jpeg
    337.1 KB · Views: 3
Back
Top