MPP Aio Now installed with new question!

[bignc]

First post so asking for forgiveness in advance but also don’t want to die or ruin nice equipment so give it to me straight!
I got the itch to keep my new shed off grid, so started reading, found Will on YT and ended up here. Lol.

I get hyper focused so quickly got in too deep mentally down the diy solar rabbit hole and backed off by ripping off the Band-Aid and buying the thousand watt MPP all in one and basically everything from Will’s suggested parts and associate links on his website for that beginner type of set up.

In preparing and acquiring supplies/ parts to begin setting it all up, I can’t tell if I need to put a mega fuse on the positive terminal of the battery or not. I’m just basically running 100 W (eventually multiples of that) of solar and wiring up the AC to charge the LiPo 12v 100ah with my generator if need be. I am probably mixing plans up since in the milk crate, and other DIY stuff I noticed battery block terminal type fuses, and fuse blocks and things that aren’t in the little 12 V beginner friendly set up he listed out- but didn’t know if that would be extra protection. Also, don’t know if I need to do an earth ground or some thing or not. I can wire household residential, but I am not an engineer so any and all input appreciated. The components are mostly purchased and on their way but I have some construction to finish on the shed first so I have a couple weeks. Thanks for your help in advance and thanks for a cool forum!

 

[Rednecktek]

In about 4 hours when I get home I'll post The Blurb to get you pointed in the right direction.

First and foremost, DON'T spend any money until you have a plan. Otherwise you're just setting yourself up for disappointment.

 

[Bud Martin]

1) Can you tell us in details what you already bought so far?
2) What is your power consumption each day and what kind of loads you will be using?
3) "buying the thousand watt MPP all in one and basically everything from Will’s suggested parts and associate links on his website for that beginner type of set up." Can you provide the link since he has so many example systems?

 

[Rednecktek]

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.

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.

As for where to get started, let me throw my standard blurb in here to help point you in the right direction. There's going to be a lot of math and research involved, but that's going to be a LOT cheaper than just buying parts off of someone's list and finding out that it doesn't do what you need.

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.

 

[bignc]

Sorry for the confusion and thanks for your responses! The thread title was supposed to be helpful but i didn’t get specific because I was really just curious about the fuses and protection and trying not to bog the forum with another “I can’t read or pay a pro so you guys do all the work for me and I’ll plug it in.)

Details coming:

 

[bignc]

1: The audit is the fun part. I literally started trying not to pull a permit to build a 12x12 shed- here I only permit if electricity or plumbing is run to the building. So I started thinking about $100 solar shed lights and then thought, “maybe I can charge my cordless tool batteries or run a fan too….”. I own a business and could write off more portable type stuff as emergency power for the office (why I already made the big purchases for the write-off) so I figured I’ll just buy enough to get a few laptops rolling possibly too.

1a: FLORIDA! Pretty ok on sun. December gets me 4.2 hrs of peak sun and May gets 5.24 hrs.


2: Parts…

All-in-One 12/24/48V Packages

MPP and a few other manufacturers now sell a "complete off grid system in a box" that has: AC Inverter Solar Charge Controller AC Battery Charger Automatic Transfer Switch (if grid power is...

www.mobile-solarpower.com

Here’s where I ended up. I bought basically from this list….

Got the 1000w 12v MPP All-in one, a LiTime 12v 100ah LiPo battery and one 100w 12 v panel from his links (HSQT or whatever it is lol. and the mounting brackets in case I decide to use them.) Also went to currentconnected and got PV cables to run from the panel to the AIO and a set of 1/0 inverter to battery cables. Also went ahead and got a 2-1 panel connector since I’ll add a panel, the mega fuse holder with 100a fuses since it was $18 and i’d rather have it and not need it.

I haven’t bought the extension cord to cut up for the AC in/out yet. I was wondering if i could just buy a surge protector to use instead so I always have multiple outlets.

So I think i’m really looking for clarification on protection IN and OUT of the MPP:
adding the mega-fuse to the battery / inverter line AND whether a fuse or some other ground from a bus bar or something should go on the AC in/ out side also. I am 100’ from a grid power outlet so would only likely use my 2000w psw yamaha generator to charge if needed….


Everything else: I figured this would be a good size/ system to learn on. I can add panels and batteries later if I want to grow capabilities….

ANY thoughts appreciated!!!! Thanks again!

 

[John Frum]

Your system is a very simple topology.
If you want to add pure dc loads then you would need to add some busbars?
Will you have any pure dc loads?

dc_domain {
    positive { battery<->250A_fuse<->aio<-dpst<-pv_panel }
    negative { battery<------------->aio->dpst->pv_panel }
}

1000 ac watts / .85 conversion factor / 12 volts low cutoff = 98.039215686 service amps
98.039215686 service amps / .8 fuse headroom = 122.549019608 fault amps

You could go as low as 4 awg wire with a 125A fuse on the main circuit.

1/0 awg is overkill, but overkill is fine.
1/0 awg can be fused as high as 250amps which is what I recommend.

You don't need any over-current protection between the aio and the pv_panel but its good practice to use a double pole single throw switch to allow administrative disconnect.

The fuse goes as close as possible to the battery positive terminal to minimize the chance of an upstream short.
I like marine rated battery fuses because the are mounted on a carrier directly to the battery positive terminal.

Eaton's Bussmann Series CFBAR1-250BP Mounting Bar, 3/8 Mount | Waytek

Eaton's Bussmann Series CFBAR1-250BP (CBBF-MBC) MRBF Mounting Bars with 1/4"-20 stud and 3/8" mounting hole work with CBBF Series Fuses and available at Waytek.

www.waytekwire.com

Eaton's Bussmann Series CFCOVER-1R Single MRBF Red Cover | Waytek

Eaton's Bussmann Series CFCOVER-1R Single MRBF Red Cover used with CBBF Series Fuses available at Waytek. Order today!

www.waytekwire.com

Eaton's Bussmann Series MRBF-250 Marine Rated Battery Fuse | Waytek

Eaton's Bussmann Series MRBF-250 Marine Rated Battery Fuse, rated at 250A for 58VDC systems with bolt-down design are available at Waytek today.

www.waytekwire.com

 

[bignc]

Thanks, John. I wasn’t planning on any DC load but hadn’t really sorted out what LIGHTS to use. it may be cheaper to just plug ? in a couple LED shop lights to the outlet than to add more wire and a bus bar and run 12v lighting but i’ll do the math on that.

As for fusing the positive battery terminal, i ordered this:

MEGA Fuse Holder + 2 Fuse Bundle | Current Connected

Choose between LittelFuse or Victron Fuses in the MEGA Fuse Holder Bundle for reliable electrical connections and peace of mind.

www.currentconnected.com

I see now that i miscalculated. Dangit. lol. I did email to ask Paige at CC if it was too late to change to 125a.

Good idea for the PV admin disconnect too….

 

[John Frum]

A mega fuse doesn't have enough breaking capacity for the battery fuse.
"nterrupting Rating: 2000A @ 32 VDC" -- https://m.littelfuse.com/~/media/au...bolt-down-fuses/littelfuse_mega_datasheet.pdf

From that datapoint we could estimate the breaking capacity at 12 nominal volts to be ~4000 amps.
I estimate a 12 volt nominal LFP battery can dump ~10,000 amps into a dead short.
That is why I suggest MRBF fuses for 12 volt LFP systems.

 

[bignc]

Oh goodness/ i get it- the mega was for a separate application- for this application, you are saying, since i have the 1/0, 250a fuse is needed. Thank you!

 

[bignc]

Any switch recommendations from the same company?

 

[John Frum]

Oh goodness/ i get it- the mega was for a separate application- for this application, you are saying, since i have the 1/0, 250a fuse is needed. Thank you!

The smallest fuse you could use is 125 amps, the largest is 250 amps which is the max for pure copper 1/0 awg wire with insulation rated for 90c or better in free air.
I prefer to use the maximum fuse size because they have lower resistance.

 

[John Frum]

Any switch recommendations from the same company?

Assuming you want a dpst for the pv circuit.

Solar Isolator Disconnect

This solar isolator disconnect is installed between the solar array and the charge controller to disconnect both the positive and negative conductors simultaneously. This disconnect is rated for solar arrays up to 63A and 1,000VDC.

shop.explorist.life

 

[bignc]

Yes- thanks again!

 

[bignc]

I first have to say thanks again to everyone. Right to business-

NEW QUESTIONS :

The instruction manual and the “setup/ programming” on Will’s website were great- BUT I still have 2 questions….

1: In setup it gives 3 options for battery type: Agm, SLA and User defined. I have LiTime LifePo4 12v 100ah batteries. 1 in and one on the way. Which option should I choose/ and if user defined, what parameters for over/ under/ bulk, etc.

2: When I add the second (so i will have 12v @ 200ah,) do i need to change those parameters or are they good since battery voltage stays the same?