diy solar

diy solar

Overpaneling Growatt spf 3000tl lvm-24p

eXodus

Solar Addict
Joined
Jul 27, 2020
Messages
1,462
I got a Growatt spf 3000tl lvm-24p can handle 80A on 24V - which is right around 2000W of MPPT
How much panels can I safely?

The local 450W panels which are cheap are right around 50V OCV and 40V MPPT - the maximum input of the Growatt is 145V - so to play it safe from the voltage I would need to limit it to 2 in series.

So I can do a 4x 450w in 2S2P - which gets me to 1800W

Or I do 2S3P which would be 2700W @ 80V - would be around 33A
 
Last edited:
I got a Growatt spf 3000tl lvm-24p can handle 60A on 24V - which is right around 2000W of MPPT
How much panels can I safely?

The local 450W panels which are cheap are right around 50V OCV and 40V MPPT - the maximum input of the Growatt is 145V - so to play it safe from the voltage I would need to limit it to 2 in series.

So I can do a 4x 450w in 2S2P - which gets me to 1800W

Or I do 2S3P which would be 2700W @ 80V - would be around 33A

2S3P if I were you.


if unspecified, the PV input current limit is presumed to be the charge current, i.e., 60A in your case.
 
if unspecified, the PV input current limit is presumed to be the charge current, i.e., 60A in your case.
The input current limit is 80A according to the manual. Input Voltage limitation is 17V to 145V
My assumption would be that this high 80A current only applies when you got a low Panel Voltage.

With 2 panels in series and 3 of those strings parallel I'm never getting anywhere close to the input current limitations and or the voltage limit.

I currently have 2x 430w panels connected for testing and they hardly ever produce peak power (laying flat on the roof), Getting 600-700W from theoretical 860w. Which is normal from what I read. When I calculate the same 75% of peak for the 2S3P

2700W * 75% = 2025W

I'm trying to get more output throughout the day, So having some panels on the east and some on the west of the roof.

So the MPPT would just clip the excess power like it already does when the batteries are getting full ?
 
Last edited:
The input current limit is 80A according to the manual. Input Voltage limitation is 17V to 145V
My assumption would be that this high 80A current only applies when you got a low Panel Voltage.

I see that in the data sheet. It actually never would apply. It's essentially impossible to have a PV input current limit higher than the battery charge current as PV voltage must always be higher than battery voltage.

With 2 panels in series and 3 of those strings parallel I'm never getting anywhere close to the input current limitations and or the voltage limit.

I currently have 2x 430w panels connected for testing and they hardly ever produce peak power (laying flat on the roof), Getting 600-700W from theoretical 860w. Which is normal from what I read.

That's actually fantastic. During winter months you'll likely only get 40% of rated power due to horizontal mounting (depending on latitude).

When I calculate the same 75% of peak for the 2S3P

2700W * 75% = 2025W

I'm trying to get more output throughout the day, So having some panels on the east and some on the west of the roof.

That's a viable approach. If the panels aren't actually tilted, then they won't perform any differently than panels elsewhere on the roof. You'll want the two panels in each string at the same orientation.

So the MPPT would just clip the excess power like it already does when the batteries are getting full ?

Essentially. It helps to think of the MPPT as a load to the panels. The MPPT can never output more than 80A @ peak battery voltage or the published 2000W limit even if the array can produce more. Anything beyond that will be unused.
 
I think the max charger amps is the number for the PV charger and the AC charger, combined. I would agree with Eggo and do 2s3p because you will almost never get panel rating in watts. You will spend 95% of the time in less than ideal conditions. So on a cloudy day you get 150% with 6 panels over whatever you get with 4 panels.
 
Essentially. It helps to think of the MPPT as a load to the panels.
I was assuming the same thing. Thanks for the verification. I used to have experience with PWM and those things are not self limiting. They are just connecting input and output on/off - would burn them self up when you provide them with to much power.

You will spend 95% of the time in less than ideal conditions. So on a cloudy day you get 150% with 6 panels over whatever you get with 4 panels.

That is what I'm currently experiencing, During the winter months in Florida I got a really good yield out of my two panels. But now I'm getting clouds around mid day and not nearly producing as much - even with the sun much more direct.
 
I was assuming the same thing. Thanks for the verification. I used to have experience with PWM and those things are not self limiting. They are just connecting input and output on/off - would burn them self up when you provide them with to much power.



That is what I'm currently experiencing, During the winter months in Florida I got a really good yield out of my two panels. But now I'm getting clouds around mid day and not nearly producing as much - even with the sun much more direct.
(just venting)
I understand the PWM may not have current limit but MPPT should be current limited as it takes some type of logic to manage the MPPT process and why not throttle the power based on your charger design goals (as a manufacturer). The idea of stating "max PV watts" on an MPPT spec seems silly to me. The only time that would make sense is if the designer said, "Well they won't see perfect sun for more than 2.5 hours so if it runs at rated amps and don't get too hot in 3 hours, we are good", but the thing is undersized so it won't do rated amps for more than X amount of time. Only then would putting a max available PV watts make real sense.

I connected a little 10amp EPEver AN to an array about twice what it needed. It went to about 9.7amp output and just sat there, happy as could be. That is the way all of these systems should work.
 
The idea of stating "max PV watts" on an MPPT spec seems silly to me.
the 2000w are never mentioned in the manual. That was my calculation. 80A * 25v = 2000w

It shows maximum amps for the battery charger (140A from Grid and Solar), maximum amps for the solar input (80A) and corresponding voltages.

If I want to be really accurate and it's truly current limited - I can calculate 29.2V * 80A = 2336W - which gets me much closer to the panel rating of 2700W
 
the 2000w are never mentioned in the manual. That was my calculation. 80A * 25v = 2000w

It shows maximum amps for the battery charger (140A from Grid and Solar), maximum amps for the solar input (80A) and corresponding voltages.

If I want to be really accurate and it's truly current limited - I can calculate 29.2V * 80A = 2336W - which gets me much closer to the panel rating of 2700W
What is your battery capacity (amp hours)?
 
What is your battery capacity (amp hours)?
One 24v 100ah
One 24v 200ah

300ah roughly ,7.5. kWh considering replacing the 100ah with another 200ah. So the end stage of this system would be 400ah

Don't have more space in the RV
 
Back
Top