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maxtosea avatar image
maxtosea asked

Why PV only produces during high loads?

I have a 2600w solar array all on separate 100/50 MPPT's. On average it's producing around 800w even if my batteries are from 60-90%. But if i turn on a high load it jumps to 1500w. My question is why doesn't it charge at 1500w even when my battery are at 60%?

MPPT ControllersSolar Panel
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·
More informations about your system are needed.

What components do you have? Settings? Some screenshots?

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maxtosea avatar image maxtosea Matthias Lange - DE ♦ commented ·

I have 4 330ah life-po4 ,smart shunt ,two 12/2000 Multi in parallel, 2 battery Protect 2 Orion 12/30 DC DC charges for alternators, four 545w panels each on own 100/50 mppt, two 160w panels in series on own 100/30 mppt. All my settings are set to life-po4. My mppt setting are 10-14v

But for some reason my PV watts doesn't exceed 8pp-1000 unless I'm using a large load even if the batteries aren't at 100%

Cerbo GX

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maxtosea avatar image maxtosea Matthias Lange - DE ♦ commented ·

screenshot-20230417-041710.png

Here's some

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5 Answers
snoobler avatar image
snoobler answered ·

Always worth triple checking connections.

Is Cerbo DVCC enabled?

If so, do you have a charge current limit set? If so, that's a charge limit, and the GX will not permit charging to exceed that TOTAL value from all connected sources, i.e., if set to 50A, it will prevent all the MPPT and the MP charging from AC-in from sending more than 50A to the battery. Period.

That value does not affect loads. If loads pull battery voltage down, the Cerbo will only restrict charging. The chargers can supply as much as they're able to power the loads.

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maxtosea avatar image maxtosea commented ·

Thank you i did have it set to 50 . What would you recommend the setting be at?

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snoobler avatar image snoobler maxtosea commented ·
There you go. That's why it wouldn't pull more for charging.


50A means 50A * 14.5V = 725W into the batteries. Only loads can force more PV power.


If you do not need to restrict charge current, and with 1470Ah of LFP battery capacity, I would say you don't - you're good to 500A+, turn that feature off unless you want to restrict charging.


The most common reason for this is batteries that can't safely accept the full output of all attached chargers. Lead-acid batteries typically can only take 0.1-0.2C where LFP can typically take 0.5C+, so it's common to use this feature to ensure the lead-acid batteries do not receive excessive charge current. With LFP, this is more often a concern due to a BMS limitation.


If your full PV output + your two MP at full charger output would exceed your battery charge rating, I would limit it to that value.

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maxtosea avatar image maxtosea snoobler commented ·
What about shore power DC chargers and I also have a 5k generator

The Max charge rating for victron 330ah are 400amps. Should I keep it at 300 just to be safe?

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snoobler avatar image snoobler maxtosea commented ·

Isn't each MP only capable of 80A charging for 160A total?

60A on the Orions

2136W in solar for 167A@12.8V

So assuming all chargers are operating at max possible output (They NEVER will)...

387A

1681711498408.png

With 4 in parallel, theoretically you could go to 1600A (minus a little for uneven current sharing).

Even with the recommended charge current of < 150A, 4 of them puts you at 600A.

You are certainly free to limit it however you like, but your equipment can't even deliver the maximum charge current for a single battery, let alone 4 in parallel.


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1681711498408.png (38.9 KiB)
maxtosea avatar image maxtosea snoobler commented ·
Thank you so much. I was going crazy trying to figure this out. We're charging around 1800w now about 90-105 amps
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snoobler avatar image snoobler maxtosea commented ·
You're welcome. I had to use it for the stated purpose - lead acid batteries. My batteries could only handle about 30A input while my array could provide up to 50A.
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maxtosea avatar image maxtosea snoobler commented ·
I have 1 more question. Life-po4 is supposed to go down to 10v correct. I have mine set for 10.5 but whenever it reaches around 11.7 the inverter shuts down saying low battery alarm. I've checked all my settings and even the configuration in the inverters and they all say 10.5.
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snoobler avatar image snoobler maxtosea commented ·

"supposed to"... not really. They "can" but that requires that all 4 cells in each 12V be perfectly balanced and hit 2.5V at the same time. Most batteries are top balanced to favor trouble free charging and will disconnect somewhere above 10V during a discharge.

You may be experiencing the BMS in the batteries cutting off the inverter due to a single cell in the battery dropping below 2.5V. Can you track cell voltages?


FWIW, between 12V and 10V, there's only about 7-8% capacity.


IMHO, I think you're pushing the batteries too low.


Victron ratings:

1681792920634.png


80% DoD is going down to 20%. You're going down to 0% (100% DoD). That means you're going to get LESS than the stated 2500 cycles.





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1681792920634.png (21.4 KiB)
klim8skeptic avatar image klim8skeptic ♦ snoobler commented ·
@snoobler @MAXTOSEA Victron Lithium Smart Batteries & BMS will shut down when the first cell drops below 2.8v, approx 11.2v.

I would not set the inverter / chargers low volt cut out any lower than 11.6v (??).

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maxtosea avatar image maxtosea klim8skeptic ♦ commented ·
I've read all over this forum that everyone sets their low voltage to 10v even on the battery Protect one of the default settings for life-po4 is 10.5
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snoobler avatar image snoobler maxtosea commented ·

I certainly don't have that impression. If it's true, everyone is doing it wrong UNLESS they have other primary means of disconnect - based on SoC, etc.


What are you using the battery protects for?

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maxtosea avatar image maxtosea snoobler commented ·
I believe 1 battery Protect is for the mppt and the other is for DC to DC. So in theory from what you're saying I would never be able to go below 50-60%. Because my 220v shuts down and only able to use 12v
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maxtosea avatar image maxtosea snoobler commented ·
Hey so yesterday I got a high temperature alert from the battery Protect. One of the reasons said the load may be too high for what the bp can handle. Do you think that i might need a bigger battery Protect? Mines is 12/100 but when we are charging now we get to about 160-170amps
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maxtosea avatar image maxtosea snoobler commented ·
Yes I'm able to see each cell. The inverters alarm usually comes on around 60%

The 330ah doesn't come with a built in BMS. I'm using VE bus BMS


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klim8skeptic avatar image klim8skeptic ♦ maxtosea commented ·

@MAXTOSEA @snoobler I've read all over this forum that everyone sets their low voltage to 10v even on the battery Protect one of the default settings for life-po4 is 10.5

You can only draw your battery down until the first cell goes under 2.8v (or 2.6v if you want to push your luck)

Have a look at the Lithium Battery Smart manual.

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maxtosea avatar image maxtosea klim8skeptic ♦ commented ·
I'm understanding that now. I was just going by what other users were saying how they had theirs set to 10.5. right now all my 220v shuts down when i reach around 60%
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kevgermany avatar image
kevgermany answered ·

We need to know your MPPT settings, batteries, how you get the state of charge and any other devices in the system.

First guess is MPPT settings.

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maxtosea avatar image maxtosea commented ·
Moth setting is algorithm 1 10-14

Using the smart shunt for SOC please see comment below. I posted all my devices

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maxtosea avatar image
maxtosea answered ·

I have 4 330ah life-po4 ,smart shunt ,two 12/2000 Multi in parallel, 2 battery Protect 2 Orion 12/30 DC DC charges for alternators, four 545w panels each on own 100/50 mppt, two 160w panels in series on own 100/30 mppt. All my settings are set to life-po4. My mppt setting are 10-14v

But for some reason my PV watts doesn't exceed 8pp-1000 unless I'm using a large load even if the batteries aren't at 100%

Cerbo GX



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maxtosea avatar image
maxtosea answered ·

screenshot-20230417-041728.pngImage Caption


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maxtosea avatar image
maxtosea answered ·

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