Input requested 24v Four Panel Four Battery System

Nebiros

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Ok just signed up here and glad to be here, I have been wanting solar for a good long while and have finally started pulling the trigger on some parts to a system. I have almost everything I need and ready to start hooking up soon and I just want to make sure I am wiring correctly.

This will be a moderately temporary system. Well let me give a little more background first, I have 4 off grid cabins on 10 acres and have been powering everything through generators for quite a long time. I’m tired of hauling fuel and filling cans.

So back to this system, I have decided to get my feet wet on my cabin 3 to replace a 2k watt generator, highest load devices would be 1000 watt microwave or vacuum cleaner. It also has a tv, fan, and small propane / electric refrigerator. It is heated with an oil drip non electric stove.

Ultimately I intend to have all 4 cabins on their own individual systems this is just my starter set up for a single cabin.


Ok back to the system

4 x 250 watt solar panels trina solar
4 x 12v group 31 deep cycle Duracell
1 mppt 24v charge controller epever model4210
Need input on 24v inverter

I had a 1000 watt inverter already someone gave me but it’s only 12v and I’m committed to 24v system so I will buy a new inverter. I was looking for input on what wattage and brand I should buy for the system.

I intend on hooking up the batteries series parallel as per diagram below.

I will try to attach a diagram, sorry for my bad handwriting.
 
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Nebiros

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I can’t see my diagram but I attached it twice. If y’all can’t see it please let me know. My reception out here can be spotty.FBBE1960-07CF-4E16-B9CA-03B9007B3544.jpeg
 

Nebiros

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It was my understanding the inverter should be wired in between the charge controller and the batteries so that the panels could power the inverter without batteries at times.

The panels are spaced that way as they are wall mounted and I have it to catch the sun from multiple angles given my site. The distance between the panel sets is about 24 feet.

The charger controller and inverter will be within 4 feet of the battery bank, the batteries will be in their own vented shed style room on part of my deck outside. The wires will come through my wall to the charge controller and inverter.

The wiring from the inverter to my main panel will be approximately 30 feet, I have some really heavy gauge cable I used to run power at my home from my house to a 100 amp panel in a shed, I figured this was overkill on sizing but I already had it and I didn’t think it would hurt anything to be too big of wire from inverter to panel.

I currently only have 1 50amp fuse on the system near the battery and no circuit breakers. The solar store person said I didn’t need them since this is a moderately temporary system.
 

rmaddy

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Welcome. It's too bad you chose to seek help after buying stuff. Before doing anything you should do a full energy audit so you know how much power you need. Then you can start working out the inverter size, the amount of battery, and the amount of solar.

See:


Post the results of filling that out.

Just a few comments on your current diagram. First, update the diagram with your proposed wire size and lengths so those can be validated. Next, you will want bus bars between the batteries and everything else. Then you can connect the charge controller to the bus bars. You can connect the inverter to the bus bars. And of course you can connect the batteries to the bus bars. Everything needs to be fused properly, temporary or not. No sense burning down a cabin even if the system is not permanent. The 50A breaker is way too small for a 2000W inverter on a 24V system. 2000W / 24V / 0.85 = 100A. Your wire choice must handle 100A. Then the fuse would be about 25% bigger than that. So you need a 125A fuse. Your battery wiring is all wrong but that can be worked out later. You can't wire the solar panels in 4S if they are going to be angled differently. You must wire them in 2S2P for that to work well.

Post the specs on the solar panels and your charge controller.
 

OffGridInTheCity

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First thing - your batteries are wired as 'dead short' in the diagram - e.g. you show + connected to -
1637460806848.png

The following would be better :)
1637460116592.png
It was my understanding the inverter should be wired in between the charge controller and the batteries so that the panels could power the inverter without batteries at times.
Yes

The panels are spaced that way as they are wall mounted and I have it to catch the sun from multiple angles given my site. The distance between the panel sets is about 24 feet.
4 x 250wat. You show 4s1p (4 in series) and they're probably 35v * 4 = 140v string. Make sure this is OK with max voltage you're charge controller will accept. You could do 2s2p for 70v strings in parallel as well - this would let each string have a bit of shade and not bring down the other string. But either way is OK if your charge controller can accept the voltage - check the VoC on your panels.

1000w PV will generate 'in the ball park' of 6-8kwh/day in spring/summer which means it will be more like 2kwh/day in winter (averages) - some days 0 when cloudy/rainy. Is this enough for your expectations?

The charger controller and inverter will be within 4 feet of the battery bank, the batteries will be in their own vented shed style room on part of my deck outside. The wires will come through my wall to the charge controller and inverter.
No problem - very short distances.

The wiring from the inverter to my main panel will be approximately 30 feet, I have some really heavy gauge cable I used to run power at my home from my house to a 100 amp panel in a shed, I figured this was overkill on sizing but I already had it and I didn’t think it would hurt anything to be too big of wire from inverter to panel.
Yea - we're talking 2000w/120v = 17a, so 12AWG (yellow romex) is OK / maybe 10awg (orange romex) if you have it.

I currently only have 1 50amp fuse on the system near the battery and no circuit breakers. The solar store person said I didn’t need them since this is a moderately temporary system.
Yikes - I would always recommend fuses / circuit breakers!!!
Between Battery and rest of the system. Even between the panels and the charge controller.
If you do fuses, an on/off between the battery bank and the rest is good :)
 

Nebiros

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Welcome. It's too bad you chose to seek help after buying stuff. Before doing anything you should do a full energy audit so you know how much power you need. Then you can start working out the inverter size, the amount of battery, and the amount of solar.

See:


Post the results of filling that out.

Just a few comments on your current diagram. First, update the diagram with your proposed wire size and lengths so those can be validated. Next, you will want bus bars between the batteries and everything else. Then you can connect the charge controller to the bus bars. You can connect the inverter to the bus bars. And of course you can connect the batteries to the bus bars. Everything needs to be fused properly, temporary or not. No sense burning down a cabin even if the system is not permanent. The 50A breaker is way too small for a 2000W inverter on a 24V system. 2000W / 24V / 0.85 = 100A. Your wire choice must handle 100A. Then the fuse would be about 25% bigger than that. So you need a 125A fuse. Your battery wiring is all wrong but that can be worked out later. You can't wire the solar panels in 4S if they are going to be angled differently. You must wire them in 2S2P for that to work well.

Post the specs on the solar panels and your charge controller.
The wiring on the batteries is 2/0 ga
the wiring batteries to the inverter is 6 ga
The wiring from the panels is 10 awg

I’m not super knowledgeable on what inverter size I need, I am unable to use that spreadsheet above at this time until I get home. I run everything very easily off a Honda 2000 so that was my intention to replace. I’m not sure if the inverter needs to be 2000 watts or if the 4 battery bank bridges the difference in load. So was hoping to get input on what size inverter would be correct.
 

Nebiros

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First thing - your batteries are wired as 'dead short' in the diagram - e.g. you show + connected to -
View attachment 73025

The following would be better :)
View attachment 73024

Yes


4 x 250wat. You show 4s1p (4 in series) and they're probably 35v * 4 = 140v string. Make sure this is OK with max voltage you're charge controller will accept. You could do 2s2p for 70v strings in parallel as well - this would let each string have a bit of shade and not bring down the other string. But either way is OK if your charge controller can accept the voltage - check the VoC on your panels.

1000w PV will generate 'in the ball park' of 6-8kwh/day in spring/summer which means it will be more like 2kwh/day in winter (averages) - some days 0 when cloudy/rainy. Is this enough for your expectations?


No problem - very short distances.


Yea - we're talking 2000w/120v = 17a, so 12AWG (yellow romex) is OK / maybe 10awg (orange romex) if you have it.


Yikes - I would always recommend fuses / circuit breakers!!!
Between Battery and rest of the system. Even between the panels and the charge controller.
If you do fuses, an on/off between the battery bank and the rest is good :)
Oh shoot yeah I drew that wrong my other diagram has correct battery wiring, just tried to make it look neater and missed that.
 

rmaddy

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Until you do the energy audit there is no way to know what size you need for anything. So that would be the best next step.
 

Nebiros

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Gosh dang it, I tried to make those pictures all readable, sorry about that, it’s the model 4210 at bottom
 

rmaddy

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The wiring on the batteries is 2/0 ga
the wiring batteries to the inverter is 6 ga
2/0AWG wire is much bigger than needed if you do end up with a 2000W inverter.
6AWG to the inverter is much too small if you do end up with a 2000W inverter.

2AWG would be a good choice for both.
 

Nebiros

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i mean I already know what size is needed for this cabin and it’s a maximum of 2000 watts. Based off using a 2k watt gen and never overloading.

Oh shoot yeah I drew that wrong my other diagram has correct battery wiring, just tried to make it look neater and missed that.
Until you do the energy audit there is no way to know what size you need for anything. So that would be the best next step.
 

rmaddy

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You may know that you need a 2000W inverter but that doesn't help knowing how much battery and solar you need. Without the audit you are just guessing which in the end will cost you time and money.
 

Nebiros

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You may know that you need a 2000W inverter but that doesn't help knowing how much battery and solar you need. Without the audit you are just guessing which in the end will cost you time and money.
I’m not trying to come off rude but I have 4 cabins with all different power demands so ultimately nothing will be wasted. I’m trying to base this system off replacing a 2000 watt generator. I don’t know about inverters so was asking if a 2000 watt inverter is appropriate for a 4 panel 4 battery system.

I already have the 4 solar panels 250 watt each, I already have the batteries 4 group 31 deep cycle which I got free, brand new.

I’ll grab some 2/0 for all the rest of the connections.

I appreciate your help and knowledge.
 

rmaddy

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No rudeness was perceived. All good. I'm happy to help. Just trying to make sure you don't end up with an inappropriate setup.

So let's work out all of the nitty gritty assuming your existing charge controller, batteries, solar panels, and a 2000W inverter.

I’ll grab some 2/0 for all the rest of the connections.
As I stated, 2/0AWG is much bigger than needed. It will work if used between the batteries and to the inverter. But 2AWG is sufficient. 2AWG and 2/0AWG are very different in size (2/0 is a lot thicker).

You do not need 2AWG between the charge controller and the batteries. For that, as shown in the manual, you only need 6AWG to handle the 40A output from the controller. This is where you can make use of the 50A fuse. That can go between the charge controller and the batteries.

The batteries should have a 150A fuse. The inverter should have a 125A fuse.

Your panels need to be in 2S2P. Your charge controller can easily handle that arrangement. The 1000W of panels at 24V works well with the 40A max output of the controller.

You will want a disconnect breaker between the solar panels and the charge controller.

One thing I forgot to ask for earlier is the capacity of your batteries. How man amp-hours (Ah) is each battery?
 

Nebiros

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No rudeness was perceived. All good. I'm happy to help. Just trying to make sure you don't end up with an inappropriate setup.

So let's work out all of the nitty gritty assuming your existing charge controller, batteries, solar panels, and a 2000W inverter.


As I stated, 2/0AWG is much bigger than needed. It will work if used between the batteries and to the inverter. But 2AWG is sufficient. 2AWG and 2/0AWG are very different in size (2/0 is a lot thicker).

You do not need 2AWG between the charge controller and the batteries. For that, as shown in the manual, you only need 6AWG to handle the 40A output from the controller. This is where you can make use of the 50A fuse. That can go between the charge controller and the batteries.

The batteries should have a 150A fuse. The inverter should have a 125A fuse.

Your panels need to be in 2S2P. Your charge controller can easily handle that arrangement. The 1000W of panels at 24V works well with the 40A max output of the controller.

You will want a disconnect breaker between the solar panels and the charge controller.

One thing I forgot to ask for earlier is the capacity of your batteries. How man amp-hours (Ah) is each battery?


Perfect that helps a lot, I didn’t realize the difference between 2 and 2/0

The batteries are group 31 Duracell marine and rv deep cycle, I think they said 100 or so amp hours. Specs on batteries say

Max @ 32 degrees 800
Cca @ 0 degrees 650
Min @ 25 amps 190

I know that isn’t amp hours but they aren’t listed on battery, later down the road I’ll run t105 or something better but these were free so I took them. I’ll looking into the busses and pick some of those up as well as the larger fuses and breakers. — just checked, 105 amp hours

I’m ok with lots of trial and error because I have so many places to utilize equipment as I adapt and change. Money isn’t a super big issue but I also don’t mind pricing together slowly over time.

I still have 5 2000 watt generators, a 5500 watt diesel gen, and a 7200 watt gas gen in case I find things are inadequate I will scale up. Mostly trying to learn as I go without ruining equipment and ultimately add some wind turbines as it’s very windy.

I got twice the amount of panels they recommended because I’m in petersville Alaska and it can be pretty dark in winter. I had originally intended to do series parallel on the panels but they solar store made me cables that were series only so I’ll just go get more cables to it can be series parallel.

These are recreational cabins for me currently but will be retirement home in a few years so trying to get the whole compound self sufficient as I go.

Would you all recommend i get stuff on Amazon or keep at the local store.
 
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Nebiros

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Of the four cabins this one is more a lounge for me, it is the second highest energy demand cabin of the four so if things end up too small I’ll just move that equipment to a smaller cabin like the bar where I don’t use much electricity.

The main living cabin has electric incinolet and will be a much much larger system as it has a well pump too but that is for way later down the road, that also will have a wind combo and many many more batteries.
 

Nebiros

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732E8509-C3CD-4C59-BCA4-75656FD0E1EA.jpgLooking at these two inverters based off talking in here unless there is something else that is better.
 
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