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Asking for feedback on my system

 
Posts: 57
Location: Corinth, KY
1
forest garden fungi homestead
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Hello! I am setting up a solar panel system on my property but I would like to get some feedback on my system. I have 4-100 watt panels=400 watts. From the solar panel to the charge controller (20 amp charge controller-that I still have to buy) is 10 gauge wire that is buried in a conduit. The panels will be on a mount facing south. From the charge controller to the batteries I"m unsure what gauge of wire I need. I have 2-12 volt marine deep cycle batteries wired in parallel. The wire that is connecting them is an 8 gauge. From the batteries to the 1000 inverter is also an eight gauge wire. From the inverter to the breaker box is the wire that came with the inverter. (I'm not sure of the size). I have a grounding rod with is connected to the breaker box.  

My questions:

1. What size of wire do I need from the charge controller to the batteries?
2. Is an 8 gauge ok to use even though i have a 10 gauge from panels to charge controller?
3. The pictures below show how my breaker box is set up with a jumper wire from one side of breakers to the other side. (one side is lights-other side is outlets). Any other suggestions to get the positive wire from the inverter to both sides of the breaker box?
4. Do you see anything wrong with my system.
5.  What type of charge controller do I need? (is 20 AMP ok)

I'm only using solar for lights and charging things and the igniter on tankless water heater and clock on stove.

I plan on adding more solar panels as time and money comes.  

Thanks in advance!!
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Diane Maldonado
Posts: 57
Location: Corinth, KY
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forest garden fungi homestead
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Sorry for the pictures. I thought I had changed them to look normal but I'm working from home and I'm still getting used to the different technology on this laptop.
 
pollinator
Posts: 2822
Location: Massachusetts, Zone:6/7, AHS:4, Rainfall:48in even Soil:SandyLoam pH6 Flat
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The wires are fine for your current setup. The smaller the wire gauge the more amps it can carry in the future.
14 gauge = 15A, 12 gauge = 20A, 10 gauge = 30A, 8 gauge = 40A, 6 gauge = 55A

Inverter
1000W = 24V x 40A, (8 gauge wire)

Charge Controller
20A means 480W of panel aka 24V x 20A (10 gauge or even 12 gauge)

Solar Panel
400W is already installed.
Your charge controller couldn't handle 600W aka 6 panels, so there is no room for growth.
I also wouldn't recommend installing 5 panels for 500W but you might be able to get away with it for a while (500W vs 480W)

Battery
How much AH does your batteries have?
Lets assume it is 20AH+ each for 24V x 20A = 480W
You would have to run your battery at 2C (twice it capacity) to get 1000W. In reality you want to run your battery at quarter capacity (0.25C). But its okay it will still work, at some point you want to get 24V and 160AH.

I would recommend getting a 50A charge controller
 
S Bengi
pollinator
Posts: 2822
Location: Massachusetts, Zone:6/7, AHS:4, Rainfall:48in even Soil:SandyLoam pH6 Flat
248
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You never want to discharge your 480Wh battery more than 50%, but even at a 80% discharge you can only get 380Wh out of it.

LED light = 10W/each, amount = 10, avg runtime each = 2hrs = 10x10x2=200Wh
Thankless Water Heater = 2W, runtime = 16hrs of no sun 32Wh
Clock = ??, lets go with 50Wh per day
Charging phones/etc = 50Wh per day
 
pollinator
Posts: 297
Location: Nomadic
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Hi,
I agree. I would buy a bigger than 20 amp charge controller if I was planning to add more solar panels later. And go with a 24 volt system if you plan to grow the system a little. Go with a 48 volt system if you plan on growing it a lot.
If the 12 volt batteries are wired in parallel as you stated in your OP then you have a 12 volt system not a 24 volt system. If so that inverter will draw 80 amps give or take from the batteries through those small 8 guage wires. Also those DC wires are rather long between the inverter and the batteries. Even if your loads are currently very small it really is best to install correct size DC wire for the inverter. I think 4 guage would be more appropriate. And not so long. Raising the batteries off the ground on a tall platform would shorten the wires.
 
pollinator
Posts: 401
Location: North central Ontario
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I would suggest a thicker wire from batteries to the inverter. Technically is should be 4 or 2 gauge... at least a multi strand 6 gauge to reduce losses through the wire. Where abouts are you? If you get cloudy periods of the year I would suggest you get an mppt charger so that you can run 2 strings of 2 panels each and get some charging on those cloudy days. As voiced above get more charger then you need right now. An mppt charger will also let you change the array without having to rewire to the batteries...
Cheers,  David
 
Diane Maldonado
Posts: 57
Location: Corinth, KY
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Thanks for all the feedback. I actually had a 20 AMP charge controller that came with with the inverter. Let's pretend that I won't be expanding my system because I have bought everything already. I know I'll have to buy more batteries and upgrade the charge controller and inverter but for the time being, I'll stay with the 400 watts for now. The issue I am having now is energy is flowing to the inverter- I get the same reading going into the inverter as it is going out of the inverter to the breaker box and I'm not sure why. Any thoughts?  
 
Posts: 4
Location: Anderson Springs, CA USA
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Diane Maldonado wrote:20 amp charge controller-that I still have to buy!



I don't know if it has been covered yet or not, but last time I did any checking on chg-ctrls, there were two basic types.

1 - Standard Analog
2 - MPPT

As I understand it, the MPPT tech takes any voltage over and above the 13.8 - 14.2vDC that your batteries are being charged at and converts it into added amperage instead of wasting it in heat energy loss from the charging components, so the voltage output of your panels comes into play there.  I'm not sure of the conversion algorithms used or their actual efficiency ratings.
Depending of the Vo and Io of you panels it might behoove you to wire them in series/parallel rather than straight parallel, depending on the Vi capabilities of your controller.

If you've already plugged these factors into your design plan, I apologize for being redundant.

If you double the voltage of the storage medium, connecting the batteries in series @ 24vDC, you can use smaller gauge cables from the PV array to the controller, IF your controller is designed to also charge at that voltage (24vDC) as well.
I didn't notice if you were using any kind of 'Inverter' to get up to 110vAC for your control circuits/igniters, etc, or if you are staying at 12vDC for those devices.   Any time you can bring the Voltage up through the cables from PV to Controller, the amperage drops relatively, and you can get away with smaller gauge cables -  as long as your controller can handle the Voltage input.
And if you can double AGAIN the voltage of the storage to 48vDC, and have an inverter designed for that input, you'll notice a much better conversion efficiency.


I would also agree with Mr.Baker and Mr.Baillie re: the heavier cables.  They both have some other great ideas also.
I would suggest as close as you could get to 'ought' (0#) gauge interconnecting the batteries AND going to the inverter.  Max out on the size accepted by the terminal blocks of each device.

I realize you already have your DeepCycle storage at this point, but with the price of top end 12v DeepCycle batteries, you can probably pick up a couple flooded acid 'RE' grade 6vDC devices and bump your amperage reserve up quite a bit (380AH/device, 380AH-20%efficiency=~300AH@12v=3.6kw-50%rule=1800W usable), I doubt you'll get much better than 100AH each out of those 12v deeps with the same (or less)efficient ratings being calculated, and the 6vDC units are much more forgiving of excess discharging.   IMHO
I seriously doubt you'll get the amperage capacity you think out of those Marine Batteries.

I use one 280w panel though an old Xantrex CC into two flooded 6v@380Ah rated batteries to power the control circuits (water heater, propane fridge, central furnace) in my 5th Wheel, and take care of keeping the laptop and cell phone charged, plus a minimum number of 12v automotive LED lights, and a 12vDC ceiling fan in the Summer.   My goal is to add 3 more panels in the near future for a total of 1kw/h (5kw/d), and add another 6-6v batteries for a total capacity of 14.4kw (so I can bring my HF Transceiver back into Ops), of course that will NOT give me the 3-day reserve one should design into their system.

Thanks for reading my Ramble,

Bruce
 
Jeremy Baker
pollinator
Posts: 297
Location: Nomadic
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Hi again. I’m not sure what exactly you are asking? The inverter should have only slightly less energy coming out of it as is going into it. A little bit of energy is wasted and turned into heat in the inverter. Inverters generally range from about 88%-93% efficient if memory serves me.
 
Diane Maldonado
Posts: 57
Location: Corinth, KY
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When we hook up the meter to read the voltage it says there’s 12 volts going into the inverter and the output only reads 12 volts as well. Could I have a bad inverter?

Jeremy Baker wrote:Hi again. I’m not sure what exactly you are asking? The inverter should have only slightly less energy coming out of it as is going into it. A little bit of energy is wasted and turned into heat in the inverter. Inverters generally range from about 88%-93% efficient if memory serves me.

 
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