would these work together?

Julianna

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Nov 11, 2021
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I am new to solar and have been doing my research and I think I've found a good set up for me using the growatt 3000w 24v all in one system ( https://watts247.com/product/spf-3000tl-lvm-24p/ ) with a a JA solar 530w half cell mono solar panel with these specifications:
  • Rated Maximum Power (Pmax): 530W
  • Open Circuit Voltage (Voc): 49.65 V
  • Maximum Power Voltage (Vmp): 41.84 V
  • Short Circuit Current (Isc): 13.43 A
  • Maximum Power Current (Imp): 12.67 A
  • Maximum System Voltage: 1000V or 1500V DC
  • Maximum Series Fuse: 20A
would these work well together? Also could I use this system with 2 12V 100AH Lithium Iron LIFEPO4 BMS Low Temp batteries even if it says it must be charged with a Lifepo4 compatible charger? would that be easy to add onto this system if i needed too? I was also thinking about using Renogy Deep Cycle AGM Battery 12 Volt 100Ah, what other batteries would you guys suggest that's on the cheaper side? Any advice is much appreciated!!!
 

sunshine_eggo

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Yes. You could put up to 2 in series and then parallel up to 4 groups of 2 panels in series.

You can customize the way the Growatt charges for any common battery type.

AGM batteries can only use half their capacity on a regular basis, or they will degrade. For lead-acid (flooded, sealed, AGM, Gel) you treat them as though they only have half the rated capacity, so that 100Ah AGM is really 50Ah. For LFP, you assume 80%, so the LFP battery is 80Ah.

100Ah of USABLE battery capacity would only allow the unit to operate at full power (3000W) for about 45 minutes or 240W for 8 hours.

Before you invest in a system, you should determine your needs. The resources section has a spreadsheet for you to conduct an energy audit.
 

Julianna

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Yes. You could put up to 2 in series and then parallel up to 4 groups of 2 panels in series.

You can customize the way the Growatt charges for any common battery type.

AGM batteries can only use half their capacity on a regular basis, or they will degrade. For lead-acid (flooded, sealed, AGM, Gel) you treat them as though they only have half the rated capacity, so that 100Ah AGM is really 50Ah. For LFP, you assume 80%, so the LFP battery is 80Ah.

100Ah of USABLE battery capacity would only allow the unit to operate at full power (3000W) for about 45 minutes or 240W for 8 hours.

Before you invest in a system, you should determine your needs. The resources section has a spreadsheet for you to conduct an energy audit.
I think I will go for the LFP batteries then especially if they can work with the Growatt without any additional setup.

Im building this system to mount on a converted shuttle bus, so will probably only use one panel at the moment, and try to keep my consumption low but i will definitely have to check that resource out!

i was wondering if maybe i would need more batteries but what would be the best way to connect multiple batteries to still be 24v? should i find batteries with lower voltage that would still add up to the 24v and connect them in series or find 24v batteries and connect them parallel?

thank you so much!
 

sunshine_eggo

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I think I will go for the LFP batteries then especially if they can work with the Growatt without any additional setup.

You must setup the charge parameters in the unit, but you do not need any special hardware.

Im building this system to mount on a converted shuttle bus, so will probably only use one panel at the moment, and try to keep my consumption low but i will definitely have to check that resource out!

Best to do it now.

The solar panels determine how much energy you can use in a day and keep your batteries fully charged. Your battery capacity determines how much energy you can use without charging.

An unplanned system ALWAYS disappoints.

Note that these units are not particularly efficient and have a high idle power draw, i.e., they use juice converting DC to AC even if no AC is used. Just sitting there turned on, it will use 50W. 50W * 24hr = 1.2kWh/day even if you use NO power.

That's about HALF of your battery capacity just to turn it on and not use it.

i was wondering if maybe i would need more batteries but what would be the best way to connect multiple batteries to still be 24v? should i find batteries with lower voltage that would still add up to the 24v and connect them in series or find 24v batteries and connect them parallel?

When building a battery bank, it's best to stick with the same or highly similar elements. If you buy 2X AmpereTime 100Ah batteries to make 24V, you should continue with those or highly similar batteries. You want to avoid a "Frankenpack" if you can.

There is "Wiring Unlimited" in Resources. YOu need to understand those resources - wire sizing, fusing, wiring batteries together, etc.
 

cotswoldstony

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I clicked on the link in your thread.
You must be in America because that unit is a 60hz cycle 120 volt hybrid unit.
The unit can handle up to 145 volts DC input so 2 solar panels can be wired in series and double panels in parallel to the manufacturers maximum solar array input.
Hybrid inverters need to be as close to maximum solar array as possible to work well.
Batteries need to be all the same and same age and equalised before connection to the hybrid inverter.
My experience of hybrid inverters is you must check they will charge all types of batteries and you can adjust charging to match battery manufacturers spec.
LVD (low voltage disconnect) recommended to protect battery bank incase inverter is not turned off.
 

sunshine_eggo

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I clicked on the link in your thread.
You must be in America because that unit is a 60hz cycle 120 volt hybrid unit.

Yep

The unit can handle up to 145 volts DC input so 2 solar panels can be wired in series

Thanks for the confirmation.

and double panels in parallel to the manufacturers maximum solar array input.

Nope. One can safely over-panel these units as long as you stay within PV input current/voltage limits.

Hybrid inverters need to be as close to maximum solar array as possible to work well.

Completely false. The larger the DC-DC conversion, the LESS efficient. They need to be notably above battery voltage and within the MPPT operating range, which is clearly indicated to be 85-115V. Go higher than 115V, and performance drops.

Batteries need to be all the same and same age and equalised before connection to the hybrid inverter.

Again, thanks for confirming.

My experience of hybrid inverters is you must check they will charge all types of batteries and you can adjust charging to match battery manufacturers spec.
LVD (low voltage disconnect) recommended to protect battery bank incase inverter is not turned off.

The manual (and the bajillions of forum users who have them) indicates this inverter can be configured to properly charge LFP.
 

SignatureSolarUS

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Jul 1, 2020
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series does not work as well as BMS comms you can make it work as long as you temper voltage to 28.2 max, at this rate you get 96% of rated capacity. if you push this higher you could fully charge a battery, forcing the BMS off and hard disconnecting DC from the inverter (bad idea)

the EG4 Lifepower 24v 200ah is designed for Growatt and we have found i to work well, see the will prowse video:
 

Julianna

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Nov 11, 2021
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Yep



Thanks for the confirmation.



Nope. One can safely over-panel these units as long as you stay within PV input current/voltage limits.



Completely false. The larger the DC-DC conversion, the LESS efficient. They need to be notably above battery voltage and within the MPPT operating range, which is clearly indicated to be 85-115V. Go higher than 115V, and performance drops.



Again, thanks for confirming.



The manual (and the bajillions of forum users who have them) indicates this inverter can be configured to properly charge LFP.
Thank you so much for sharing all the info and recourses, it is greatly appreciated. I was also wondering if growatt has a power saving kind of mode? I was also looking at the MPP LV2424 and I read it had such an option.

I am now thinking of getting 4 12v 100ah LIFEPO4 batteries. Using the resources you suggested I'm guessing that would give me 200ah and 4,800wh if I wire them both parallel and in series to still get 24v.

Thanks again for your time!
 
Last edited:

Julianna

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Nov 11, 2021
Messages
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series does not work as well as BMS comms you can make it work as long as you temper voltage to 28.2 max, at this rate you get 96% of rated capacity. if you push this higher you could fully charge a battery, forcing the BMS off and hard disconnecting DC from the inverter (bad idea)

the EG4 Lifepower 24v 200ah is designed for Growatt and we have found i to work well, see the will prowse video:
That is good to know thank you very much for the information!
 
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