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[Tonopah solar]

I have a mpp 3000 watt 48v hybrid system. Running 2 sets of 4 lead acid batteries in series to parallel. So I was told that’s 200ah.
My panels are sun power 305 watt 52v panels.
Im running 4 sets of 2 in series to parallel. So getting about 104 volts going in and suppose to be 2400 watts.

im so new at this. Im running my rv out in the desert while im waiting to build. Im just not sure if this is the best way to set it up.

i also have 49 more panels in my storage shed so I can add more but not sure how as they say that would be to many volts.

help.

 

[snoobler]

Welcome to the forum.

Tonopah? How in the hell are you keeping cool?

Assuming 2S2P 6V batteries, ea at 200Ah, that's 400Ah of 12V storage or 4800Wh, half of which is usable, 2400Wh. This is enough energy to power your absorption fridge on AC for 1/2 a day. Yes, run the fridge on propane.

This is not very much capacity.

IIRC, the MPP 3kW is 80A, and it has a published kW limit. 80A*24V = 1920W, probably limited to something like 2000W. You can over panel a bit, and I wouldn't worry about 2400W. You won't get it, but you'll get 2000W for as long as a 2400W array can produce it.

You could opportunistically position additional panels, i.e., East facing 2S for more morning power and West facing 2S for more evening power.

Without adding additional SCC, more PV may not offer much.

 

[Tonopah solar]

Heat not to bad yet. 117 next week.
So do I just need more batteries. I have a 38 foot trailer and I have not been using propane for the fridge. So I will get on that. And at the main part of the day it runs everything. But towards the end it starts to drag my batteries. I don’t let it get under 50%. Honestly I don’t let it go under 60%. It also controls the input of power. Like if I turn on the fridge in the after noon the watts it’s bringing in from the panels goes up to compensate. But building 48v battery banks is expensive for only 100 more watt hours. Just so new at this I get lost in the numbers. This is completely off grid as well.

 

[Wibla]

Assuming 2S2P 6V batteries, ea at 200Ah, that's 400Ah of 12V storage or 4800Wh, half of which is usable, 2400Wh. This is enough energy to power your absorption fridge on AC for 1/2 a day. Yes, run the fridge on propane.

I have a mpp 3000 watt 48v hybrid system. Running 2 sets of 4 lead acid batteries in series to parallel. So I was told that’s 200ah.

I would guess he's running 4s2p with 100 Ah 12V batteries, so that would give him 200Ah/48V and about 4.8 kWh usable?
@Tonopah solar , can you take some photos of your battery bank? Just so we can make sure of the sizing, this is important for giving further advice.
How are your current solar panels setup?
What other heavy loads are you running? I assume you've got an AC running at least part of the time, those use a fair bit of power, too.

What are your long-term thoughts for the house power-wise?

But building 48v battery banks is expensive for only 100 more watt hours.

The "quick and dirty" solution is to add another set of 4x100Ah 12v batteries to your existing bank, as long as the existing batteries are relatively new, that'll give you another 2.4 kWh of storage, which is a significant upgrade. I wouldn't necessarily recommend that you do that though, it would be better to try to conserve power for now while you research and plan a larger, permanent 48V lifepo4 battery bank, that will be a lot cheaper in the long run.

 

[Tonopah solar]

Yes on the batteries. The panels are 8 split into 4 pairs of two wired I. Series to parallel.

I’m too the point of buying another mpp and adding more panels. And yes I run the ac almost all day.

Future plans for the system is it will go in the house we are going to build

 

[schmism]

IIRC, the MPP 3kW is 80A, and it has a published kW limit. 80A*24V = 1920W, probably limited to something like 2000W.

Nope, rated for 4000w solar. as its a 48v unit.

 

[Wibla]

Yes on the batteries. The panels are 8 split into 4 pairs of two wired I. Series to parallel.

You can add more solar to that controller - at least 4 more panels before you start getting close to the limits on the MPPT, I would do that first, before doing anything else.
I would probably have setup that battery bank differently myself, but it does the job, there's even a fuse!

What kind of AC is it, and how much power does it use?

 

[snoobler]

Nope, rated for 4000w solar. as its a 48v unit.

LOL... yep... he said it right there on the post. Sheesh.

 

[snoobler]

Supplementing /correcting my prior post due to the failed reading comprehension and general rectal-cranial inversion.

I'm in Mesa, so I know the heat of which you speak.

Absolutely max out the 4000W you have now. Even over-panel for more evening collection, i.e., put another 4-6 panels @30-45° tilt facing WSW. IMHO, morning doesn't matter nearly as much. I wouldn't hesitate to go 5000W total panels on the SCC especially if about 1kW is facing West-ish.

Our off-grid place is up north past Show Low, and with 3kW solar, we can run one A/C pretty much all day until about 5pm before we've dipped too far into the battery for comfort (array facing about 165° vs. 180° @ 30° tilt). Yes, we actually need A/C up there. It's going to hit 100°F this weekend at 6700'!

Get your main array tilt to about 10-15°. Flat on the ground isn't so great. Once we hit mid Sep, go for 30°. Dust those things off.

We run the absorption fridge on AC during the day and switch to propane once solar drops. 30# bottle will last a couple months like that. Consider that an absorption fridge's daily AC is the same as 3 hours of one A/C unit running, so the option of propane can ease your electric demand.

I too have 4S2P FLA. Using Trojan T-1275. You need to watch the 12V battery voltages to confirm that they're not wandering. This is particularly critical at absorption voltage. If one hits full charge before the others, you can toast it after several days of over-charging. I use 12V equalizers to keep the batteries balanced. The equalizers monitor each 12V and move charge from higher voltage to lower voltage batteries. Something like this:

Amazon.com: Battery Equalizer 48V - Battery Voltage Balancer,for 4×12V or 8×12V or more Battery Bank Extend Battery Life 1 Year and More, support Gel Flood AGM Lithium Battery HA02 Balancer(Battery Equalizer 48V): Industrial & Scientific

Buy Battery Equalizer 48V - Battery Voltage Balancer, for 4×12V or 8×12V or more Battery Bank Extend Battery Life 1 Year and More, support Gel Flood AGM Lithium Battery HA02 Balancer(Battery Equalizer 48V): Energy Controllers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Good luck with the build!

 

[Tonopah solar]

Adding 4 more panels in series so each group is 3 panels or add 2 more sets of 2 to keep the volts down. 3 makes it over 150.

 

[Wibla]

add 2 more sets of 2 to keep the volts down.

Do this. Ideally, follow this recommendation:

Absolutely max out the 4000W you have now. Even over-panel for more evening collection, i.e., put another 4-6 panels @30-45° tilt facing WSW. IMHO, morning doesn't matter nearly as much. I wouldn't hesitate to go 5000W total panels on the SCC especially if about 1kW is facing West-ish.

 

[Tonopah solar]

You can add more solar to that controller - at least 4 more panels before you start getting close to the limits on the MPPT, I would do that first, before doing anything else.
I would probably have setup that battery bank differently myself, but it does the job, there's even a fuse!

What kind of AC is it, and how much power does it use?

Not sure it’s a big trailer.

 

[Tonopah solar]

Not sure it’s a big trailer.

How would you have done the batteries.

 

[schmism]

think of parallel batteries as just one big battery. They are forced to share the same voltage.

so 4s and another 4s is just 2 batteries in parallel.

but if you had 2p -2p-2p-2p then that's 4 batteries in parallel.

The goal is to try and keep the 12v lead as close to each other in voltage as possible. The more you have in parallel the less work that is.

The other benefit of the 2p setup (as i understand it, i dont have a lead pack) is that when the 12v batts start to go out of balance, you can easily unbolt the second bat in the 2p and move them around (putting a 13v one with a 14v one to balance them back out)

 

[Wibla]

How would you have done the batteries.

I would have put them on some sort of shelf, arranged by string, with both strings of batteries going to common busbars for + and - using matched wire lengths throughout the whole battery setup, fuses between each string and busbar on the positive side, then add equalizers to each string (as linked by @snoobler a few posts up the thread). I would also add a shunt battery monitor to keep better track of SOC.

 

[snoobler]

think of parallel batteries as just one big battery. They are forced to share the same voltage.

so 4s and another 4s is just 2 batteries in parallel.

but if you had 2p -2p-2p-2p then that's 4 batteries in parallel.

The goal is to try and keep the 12v lead as close to each other in voltage as possible. The more you have in parallel the less work that is.

The other benefit of the 2p setup (as i understand it, i dont have a lead pack) is that when the 12v batts start to go out of balance, you can easily unbolt the second bat in the 2p and move them around (putting a 13v one with a 14v one to balance them back out)

I don't object to this 2P4S concept at all, and I totally agree with the logic, but no battery manufacturer recommends this. They always recommend single element strings in series and then paralleling those strings. I'm not sure why.

I would actually gain capacity if I did this because my 8 T-1275 range in cap from 75-95%, so I treat the whole battery as a 75% rated battery. I could pair highs with lows and effectively have a bank with 85% rated capacity with 2P4S.

Instead, I've done as I was told... 4S2P with the 12V balancers, and my 12Vs were within .03V this last weekend. I can say the balancers have worked like magic in keeping the individual 12V balanced.

 

[Tonopah solar]

Supplementing /correcting my prior post due to the failed reading comprehension and general rectal-cranial inversion.

I'm in Mesa, so I know the heat of which you speak.

Absolutely max out the 4000W you have now. Even over-panel for more evening collection, i.e., put another 4-6 panels @30-45° tilt facing WSW. IMHO, morning doesn't matter nearly as much. I wouldn't hesitate to go 5000W total panels on the SCC especially if about 1kW is facing West-ish.

Our off-grid place is up north past Show Low, and with 3kW solar, we can run one A/C pretty much all day until about 5pm before we've dipped too far into the battery for comfort (array facing about 165° vs. 180° @ 30° tilt). Yes, we actually need A/C up there. It's going to hit 100°F this weekend at 6700'!

Get your main array tilt to about 10-15°. Flat on the ground isn't so great. Once we hit mid Sep, go for 30°. Dust those things off.

We run the absorption fridge on AC during the day and switch to propane once solar drops. 30# bottle will last a couple months like that. Consider that an absorption fridge's daily AC is the same as 3 hours of one A/C unit running, so the option of propane can ease your electric demand.

I too have 4S2P FLA. Using Trojan T-1275. You need to watch the 12V battery voltages to confirm that they're not wandering. This is particularly critical at absorption voltage. If one hits full charge before the others, you can toast it after several days of over-charging. I use 12V equalizers to keep the batteries balanced. The equalizers monitor each 12V and move charge from higher voltage to lower voltage batteries. Something like this:

Amazon.com: Battery Equalizer 48V - Battery Voltage Balancer,for 4×12V or 8×12V or more Battery Bank Extend Battery Life 1 Year and More, support Gel Flood AGM Lithium Battery HA02 Balancer(Battery Equalizer 48V): Industrial & Scientific

Buy Battery Equalizer 48V - Battery Voltage Balancer, for 4×12V or 8×12V or more Battery Bank Extend Battery Life 1 Year and More, support Gel Flood AGM Lithium Battery HA02 Balancer(Battery Equalizer 48V): Energy Controllers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Good luck with the build!

Thank you so much again.

 

[Tonopah solar]

You can add more solar to that controller - at least 4 more panels before you start getting close to the limits on the MPPT, I would do that first, before doing anything else.
I would probably have setup that battery bank differently myself, but it does the job, there's even a fuse!

What kind of AC is it, and how much power does it use?

So I had the mpp hooked to the computer and it went from 200 to 1900 watts when I turned on the ac. So pulling about 1700. I’m hooking up the other pa els tomorrow.

 

[Wibla]

So I had the mpp hooked to the computer and it went from 200 to 1900 watts when I turned on the ac. So pulling about 1700. I’m hooking up the other pa els tomorrow.

No wonder you've struggled! Is it a mini split or one of those mobile single/dual hose units?

@snoobler mentioned that you should should align further panels towards west/south west, try that and tell us how it goes

 

[Tonopah solar]

I’m trying now to figure out how my batteries are charging when I’m pulling more watts then putting in. I know it’s early but only getting 800 watts off 12 305s. Seems wrong.