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Small Cabin Forum / Off-Grid Living / sos new solar system
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bc thunder
Member
# Posted: 23 Aug 2021 19:16 - Edited by: bc thunder
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Hope you solar guys can tell me if everything seems ok to you......
1 60 watt light--less than 1 hr per day
1 8o watt small mobicool frig-- 10hrs want ( 24/7)
1 150 watt tv --3 hrs
1 internet --50 watts 3hrs
4-5 good hrs of sun
24 volt 2.4kw all in one system
440 watts panel
8 6 volt golf cart batteries series/parralle 230 amp hrs

I thought i would have power to spare, but run down to 24.4volts before 10 pm. Only seems to charge up to 26.1, i thought it would be higher ?
It,s pretty new and im still learning whats what...

Any thoughts apperiated, Thanks

ICC
Member
# Posted: 23 Aug 2021 19:30
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Quoting: bc thunder
24 volt 2.4kw all in one system

Need more info on that.
Need to know the CC and the bulk, absorb, float settings, etc.

Have you actually calculated the theoretical watt-hours use vs the usable capacity of the batteries?

440 watts of solar seems undersized for the listed battery bank

ICC
Member
# Posted: 23 Aug 2021 19:34
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Quoting: bc thunder
Only seems to charge up to 26.1

That would seem to indicate insufficient pv panel capacity or faulty CC settings

bc thunder
Member
# Posted: 23 Aug 2021 19:38
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mpp all in one solar
bulk 29.2
float27 vdc
i just added the 4 more batteries as it seemed to fully charge the first four with lots of sun to spare

bc thunder
Member
# Posted: 23 Aug 2021 19:40
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there are so many settings and to be honest i dont understand many of them yet, i am cramming hard though. thanks ICC

bc thunder
Member
# Posted: 23 Aug 2021 19:44
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I think the cc is 60a ?

ICC
Member
# Posted: 23 Aug 2021 20:19
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Quoting: bc thunder
mpp all in one solar
bulk 29.2
float27 vdc


webpage link?

bc thunder
Member
# Posted: 23 Aug 2021 21:21
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www.mppsolar.com/manual/

sorry i have no idea how to link lol

ICC
Member
# Posted: 23 Aug 2021 21:46
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That did not lead anywhere useful... a 403 error was all I got. The mppsolar site itself lists lots of equipment.

Model numbers, names, complete list of equipment, etc. is needed if anyone is to be able to offer more than conjecture.

ICC
Member
# Posted: 23 Aug 2021 22:03
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Quoting: bc thunder
60 watt light--less than 1 hr per day


? A true 60 watt load or an led equivalent of something like a true 10 watts?

Brettny
Member
# Posted: 24 Aug 2021 08:08
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I something is wrong with your system. But how many watt of pannels do you have?

Also with 8 batteries at 230ah you have just under 1,000ah of max useable power from the batteries. You will also get loss through the inverter.

gcrank1
Member
# Posted: 24 Aug 2021 10:14 - Edited by: gcrank1
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Did the bat bank ever get completely properly fully charged Before hooking up to the solar?
I do my 12v bats individually, if I had 6v in series Id do each pair as a 12v (unless I had a 24v grid charger)
If they have not been fully charged you are likely running them down from whatever level the less than optimum array can put back in each day.
Btw, dont count on the array putting out the max rated watts, use 70% of that for losses, and you est. of 4-5hrs/day 'good sun' may be optomistic.
One thing I would be tempted to try right off is disconnecting (and grid full charging) half of your bat-bank and running the other 4 as you have been only reducing/conserving on your power use. Your array may be able to pump up those 4 to a higher level than it can get the whole 8.
Fwiw, I have 612w of array at 24v into the mppt 50w scc which steps the 24vdc down to 12 into my 200ish AH of bat-bank (2 x 12v). I have considered 4 of those GC 6v as a replacement (I wouldnt even try 8) with my array. My sun is basically over by 1pm (tall trees shading) so I have them oriented S-SW for early sun.
With our usage the bats typically are recharged by mid-morning to noon and anything we are running in the morning is off the excess solar while they are charging the bats. This means that about our only depletion of storage is in the evening. We have no fridge (Yeti clone ice chest) making a constant drain overnight, but when we tried one I unplugged it overnight. We werent getting into it so no loss of cold and the interior temp was still fine come morning. For us, at a normal 2 day stay and not leaving the fridge running while not there, it didnt make sense to spend 1/2 day or more to bring it down to fridge temp, it was a power hog.

bc thunder
Member
# Posted: 24 Aug 2021 14:02
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Thanks for the replies Guys......
I did not equalize the batteries...
I get sun from noon till 5, but at 430 its fading...
The fridge is the hog, but I'm here fulltime now....
I've been running the generator for 3 hrs a day and charging the batteries off, which works well....
My rough math tells me I need to double the panels.

gcrank1
Member
# Posted: 24 Aug 2021 17:40 - Edited by: gcrank1
Reply 


Sun 'noon till 5'....any shading on the array during in that time?, it can really compromise the output.
Is the array optimized for the sun position during those hours? Make amps not only when the sun shines but where the sun shines.
How far from array to scc? And how far from scc to bat-bank? What gauge wire between them for those distances? (ie, get all the amps you paid for, dont let wire losses kill you).
Use LED lights, the incandescents suck ah's, LED's are so little as to be almost inconsequential. Same with usb chargers for small devices. So little at our place that I dont even factor them in anymore.
Fwiw
You do know you really cant run FLA batteries down below 50% often or you are killing them?
The diff between fully charged and 50% on a 24v bat bank is a top of about 26v to only 24.1, but you have to keep the charge going in at an absorb voltage at the high end for quite some time or they never really are fully charged even if the voltmeter says 26v. If the bank sits for half a day disconnected from input/output what does the voltage sink to?
Are you checking the water levels and using a hydrometer? That is the best way, but if yours are AGMs/sealed you cant.
And, with that many batteries, you might have one or more that are already compromised or failed. LA bats like to be kept fully charged asap after being drawn down; if that doesnt happen they start to deteriorate.
I had two of 4 12v that went one following the other. They were pulling down the bank. As I got the worst one out things improved, then went bad again until I pulled #2 out. Ive been running all summer on the remaining 2 better than the 4 did last year.
What gauge wires are you bats tied together with? Good terminals? Solid bolting? Loose connections will do you no good.
What is the max 'C' rate those bats can be charged at? (check the manufacturer specs).
With LA bats think of them like an 8oz bottle of water that is mis-labeled as 16oz; ie, you think you have more than you do, and if it never gets topped up to full before the next 'use' you have a limited amount to actually use.

bc thunder
Member
# Posted: 24 Aug 2021 18:27
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perfect sun till 430, then a little shading till 5 and then its shaded at best....I think the wire is 10 gage, but the
guy at the solar shop put it on with the panels. the whole system is only a week old, so i'm feeling it out still.....its running between 26 and 24.4 volts, so I guess that's good too. panels are about 15 feet away.
I think after all this help and advise, that everythink is working as it should, but my expectaions are now becoming more realistic lol.
when I add up my usage it's about all this can handle, if I double my solar array and run the honda on cloudy days, that should be as good as I can expexct without going crazy $$$

bc thunder
Member
# Posted: 24 Aug 2021 18:32
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Gcrank your comment about the 26 volts helps, as I thought it shoud be closer to 28 fully charged. That was what was worring me most, that something was wrong charging wise. I think it just me on a real fast learning curve, not the system that's faulty lol.....

gcrank1
Member
# Posted: 24 Aug 2021 18:41 - Edited by: gcrank1
Reply 


Your thought was correct. The system has to put out more than 26v to charge bats to 26. It isnt putting out enough to charge them to top.
The 10ga. wire is fine for 15' and more at 24v.
Someone else here can best advise what that output needs to be, Im a 12v guy. My system is set to 14.5 bulk/13.4 absorb for AGM bats. I dont know if you just double those for 24v. I only get decent sun 8am'ish to 1pm and it works great.

Brettny
Member
# Posted: 24 Aug 2021 19:16
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O see now 440w of pannels. You have a good amount of sun on your pannels for 4.5hrs so I would add more pannels right off the bat, your charge controller can defenatly handle it. I would double the pannels you have now.

In the mean time amazon sells cheap $12 programable timers that use there own battery. Over night set your fridge to 1hr on/off, or 1hr on 1.5hr off. This made a noticeable difference in my system that only sees 3hrs of sun. I'm so shaded I get more sun in the fall/winter when the leafs are off the trees.

bc thunder
Member
# Posted: 24 Aug 2021 19:35
Reply 


I think that timer is a good idea, I hate to just unplug it for the whole night. on/ off would be a good inbetween. The system is rated for almost 2000watts, but I might double the pannels and call it a day......
Fridges seem to be a real solar achiles heel!!!

bc thunder
Member
# Posted: 24 Aug 2021 19:39
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gcrank I believe it is just doubled for 24v, but are agm and flooded the same volts?

gcrank1
Member
# Posted: 24 Aug 2021 19:56 - Edited by: gcrank1
Reply 


Yes, both come in the common nominal volts.
You may want to look online at batteryuniversity.com
for more info than you can take in a night.

bc thunder
Member
# Posted: 25 Aug 2021 19:23
Reply 


Well, added another 440 watts and it looks a lot more like what I was expecting!!! I'll still have to run the genny a few hrs every other day I think, but this should work well for now.
I was bringing in 804 watts at one point and there was a few light clouds here and there.....
Next the fridge condrum; my little 80 watt cooler/fridge pulls 80 watts constantly, maybe a real, bigger fridge pulls more watts but less hrs. Or what about a small chest freezer and make ice blocks for a good cooler???

Nobadays
Member
# Posted: 25 Aug 2021 21:27
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We have a 10.1cuft Magic Chef that is rated at 297kw/year, about .81kw/day. The big box store near our home in AZ has it for $328.00. Another forum memeber says his in actuality uses .50kw/day. That might help. Keep in mind that refrigerator only actually runs ~8 hours per day.

gcrank1
Member
# Posted: 25 Aug 2021 21:42
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You can have my Heier 4.5cf for $50 if you come pick it up

Brettny
Member
# Posted: 26 Aug 2021 05:34
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Those cooler fridges can fiddle with the wattage draw spec. I had family who went though this too but it was on a boat in another country before they figured it out.

We are running a 4.5cuft dorm fridge with separate top freezer on a 12v 615ah(useable). I only get 3hrs of sun and will generaly run the generator only to charge the batteries on the second day. I dont use my fridge timer any more either as I dont really need it.

bc thunder
Member
# Posted: 26 Aug 2021 06:02
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Yes, definately want rid of this little power hog. I think the 4.5 would be the smallest I would go (full time), and the 10.5 would be ideal, bigger, faster, better than before.......

bc thunder
Member
# Posted: 26 Aug 2021 17:59
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Nobadays, I just picked up a 10.1 magic chef. there are three cold settings for both fridge, and freezer, which do you find best. id like to go with the lowest, but they recomend the mid setting.
So far im loving it. It's using about 55 watts, with periods of nothing at all and its hugh

Nobadays
Member
# Posted: 26 Aug 2021 18:12
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BC.... ours is set at the middle setting- recommended- in the fridge and a little to the colder side on the freezer. We close the vents on the crisper and most of the time it won't freeze veggies. We tried to go to the warmer side in the fridge but just doesn't stay as cold as it should. It is a great little fridge though!

As crazy as it might seem, a freezer/fridge will use less power the fuller it is. If you can't fill the freezer, put water jugs in there, same in the fridge. Takes a lot of power to cool air. Once contents are cool/frozen doesn't take a lot to keep them that way.

bc thunder
Member
# Posted: 26 Aug 2021 18:20
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great info, thank you very much

bc thunder
Member
# Posted: 29 Aug 2021 19:29
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I'm finding my lights are a bit blinkey when the fridge kicks in or tv or whatever. Anyone else have that???

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