Looking for help understanding what I need for fuses/breakers etc

[eriemountain]

Highly technical drawing. The cables connecting batteries to each other and to the inverter are 4/0(0000)awg. Any insight into what I need for breakers/fuses or anything else would be greatly appreciated. I'm a total newb, so eli5 please!

 

[John Frum]

First issue, a 3000 watt inverter at 12 volts is a lot of current.

 

[MisterSandals]

4x 200W panels in parallel seems odd. What is the panel Voc and your SCC max input voltage?

2S2P is often a better solution if you SCC will accept 2x Voc.

 

[camelCase]

You'll want to use a busbar if you parallel that many batteries.

 

[John Frum]

5 LFP batteries in parralel should not be paralleled as shown.
Especially at those current levels.
The outer batteries get more wear and tear and the middle ones get less.

 

[camelCase]

More than 2 panels in parallel require inline fuses, too.

 

[eriemountain]

So series would be better, or a combo of series and parallel? What is the optimal voltage?

 

[rmaddy]

Are you planning on more solar panels in the future? 100A is much more than the 60A you need with 800W on a 12V system.

You need a fuse or breaker between the SCC and the batteries. It should be 125% of the charge current of the SCC. If you stay with the 100A controller then you need 125A fuse or breaker.

With 5 batteries in parallel you should fuse each one individually between the battery and the bus bar (that need instead of the current parallel setup). Then you will need a 400A main battery fuse at the end of the bus bar. A 3000W inverter at 12V can pull 300A so you need 4/0 wire between the batteries, bus bars, and inverter.

 

[camelCase]

Some more details would be helpful. Panels, charge controller, ect.

 

[eriemountain]

Are you planning on more solar panels in the future? 100A is much more than the 60A you need with 800W on a 12V system.

You need a fuse or breaker between the SCC and the batteries. It should be 125% of the charge current of the SCC. If you stay with the 100A controller then you need 125A fuse or breaker.

With 5 batteries in parallel you should fuse each one individually between the battery and the bus bar (that need instead of the current parallel setup). Then you will need a 400A main battery fuse at the end of the bus bar. A 3000W inverter at 12V can pull 300A so you need 4/0 wire between the batteries, bus bars, and inverter.

Yeah we want to be able to add more to it. We are completely off grid and currently use a gas generator for power.
Would you agree that a series parallel combo would be better for the batter bank? How about the panels?
Thanks kindly for your help!

 

[John Frum]

Yeah we want to be able to add more to it. We are completely off grid and currently use a gas generator for power.
Would you agree that a series parallel combo would be better for the batter bank? How about the panels?
Thanks kindly for your help!

Unless this is a mobile application you should think about going up to 48 volts and using server rack batteries.

 

[rmaddy]

Would you agree that a series parallel combo would be better for the batter bank?

You can't put the batteries in series parallel. One, you have 5 batteries. Two, you (presumably) have a 12V inverter.

Is this for a home? RV? Van?

How about the panels?

It all depends on the full specs of the panels and the SCC. As much series as you can is typically best unless you have lots of shading issues to deal with. Just make sure the panel array's Voc, adjusted for the coldest temp you could possibly encounter, is less than the max PV input voltage of the SCC.

 

[John Frum]

What components have you already purchased?

 

[eriemountain]

Some more details would be helpful. Panels, charge controller, ect.

Panels: https://ca.renogy.com/200-watt-12-volt-monocrystalline-solar-panel/
Controller: https://ca.renogy.com/rover-100-amp-mppt-solar-charge-controller/
Batteries: https://ca.renogy.com/100ah-12-volt-smart-lithium-iron-phosphate-battery-w-self-heating-function/
Inverter: https://ca.renogy.com/3000w-12v-pure-sine-wave-inverter/

 

[eriemountain]

What components have you already purchased?

Batteries, panels, controller, inverter, 4/0 cables

 

[eriemountain]

You can't put the batteries in series parallel. One, you have 5 batteries. Two, you (presumably) have a 12V inverter.

Is this for a home? RV? Van?


It all depends on the full specs of the panels and the SCC. As much series as you can is typically best unless you have lots of shading issues to deal with. Just make sure the panel array's Voc, adjusted for the coldest temp you could possibly encounter, is less than the max PV input voltage of the SCC.

It's for a fully off grid home.
See my reply to camelcase for component specs.
Are you saying series would be better but that it would require a different, non 12v inverter?
Sorry, I'm still pretty dense on this stuff.

 

[rmaddy]

Are you saying series would be better but that it would require a different, non 12v inverter?

Things in series add voltage. Things in parallel add amperage.

5 batteries is difficult. It's a prime number. You either put them all in parallel for 12V or all in series for 60V. No one does 60V.

As was stated, for a home you want 48V. You should buy 48V batteries. You could make a 48V with 4 of the 12V that you have. You will likely need 3 more so you can put them in 4S2P. That will give you a 48V 200Ah battery. But that's a pain and difficult to do right. Return the 12V batteries. Return the 12V inverter. Go with 48V batteries and a 48V inverter. You will be so much better off with a home system setup that way.

Will posted some videos recently showing some 48V server rack batteries and an all-in-one inverter/charger/solar charge controller. Super simple and easy.

Having said all of that, you can use what you bought. It may or may not work for your needs.

The proper first step, before buying stuff, is doing an energy audit. Have you done a full energy audit yet? If not then there is no way to know if what you are planning will even meet your needs or not.

 

[eriemountain]

Things in series add voltage. Things in parallel add amperage.

5 batteries is difficult. It's a prime number. You either put them all in parallel for 12V or all in series for 60V. No one does 60V.

As was stated, for a home you want 48V. You should buy 48V batteries. You could make a 48V with 4 of the 12V that you have. You will likely need 3 more so you can put them in 4S2P. That will give you a 48V 200Ah battery. But that's a pain and difficult to do right. Return the 12V batteries. Return the 12V inverter. Go with 48V batteries and a 48V inverter. You will be so much better off with a home system setup that way.

Will posted some videos recently showing some 48V server rack batteries and an all-in-one inverter/charger/solar charge controller. Super simple and easy.

Having said all of that, you can use what you bought. It may or may not work for your needs.

The proper first step, before buying stuff, is doing an energy audit. Have you done a full energy audit yet? If not then there is no way to know if what you are planning will even meet your needs or not.

Can you post a link to that video?
I'm okay with the system not covering all of our power needs right off the bat. We have a gas generator we can supplement with, and scale up (or rebuild) the system as we learn. I just want to get something going that's not going to fry itself or burn the place down.
I was thinking of using one of the batteries for a cabin up the hill, so if I went down to four in parallel, would there be any safety issue? What size of breakers/fuses would be required?
Thanks again for your detailed replies. I have trouble wrapping my head around how volts and amps work together, no matter how many times I read explanations and analogies!

 

[rmaddy]

Can you post a link to that video?

This one:

and this one are a good start:

I was thinking of using one of the batteries for a cabin up the hill, so if I went down to four in parallel, would there be any safety issue? What size of breakers/fuses would be required?

The only difference between 1 or more batteries in parallel is mostly how long you can run your system. But there is also the discharge current needed by your system and how much each battery can support. If you stick with your current stuff, a 3000W inverter on a 12V system can pull up to 300A out of the batteries. The batteries you have support a max of 100A continuous discharge current. If you actually try to power 3000W of loads at once, you need at least 3 batteries to support the 300A discharge current. Using 4 will be fine. Do keep in mind that 4 12V 100Ah batteries is about 5120Wh of power. If you actually had a 3000W load then your batteries would last about 90 minutes. So obviously you don't want to have such a high load too much.

My first response above explains what size fuses and breakers you need.

I have trouble wrapping my head around how volts and amps work together, no matter how many times I read explanations and analogies!

Just remember W = V x A which is watts equals volts times amps. For a given amount of wattage, raise the voltage to lower the amperage. That's why a 48V system is better suited to a home system. Higher amps means much thicker wire which is a lot more expensive.