Growatt SPF 3000TL LVM-24P

[KolobSolar]

I have the Growatt SPF 3000TL LVM-24P which I just purchased. I’m strictly off-grid and feed it with 4x100w Renogy panels. I store in 4 x 6v400ah (24v/400ah) Centennial AGM L16’s in series. I have a battery balancer on the 4 cells. My non-occupied load is 55 watts 120v AC constant rate. Starlink and security cams.

It’s monsoon season and afternoons are cloudy. There is theoretically 14 hrs of sun per day at my latitude right now. Batteries go to 25 % SOC overnight and struggle to get to 100% it’s clouds.

I’m planning to buy 3 x 450w panels. Do I need even more storage? My occupied loads only top out 170w, not continuous.

Any help would be appreciated.

 

[diysolarforumvpc]

Let's try to see if I can help and start the conversation

Production Before upgrade
Solar: 4*100[W]= 400[W]=>400[W/h]
400[Wh] * 14[h] = 5600 Watts per day

Production After upgrade
Solar: 4*100W + 3*450W = 400+1350=1750[W/h]
1750[Wh] * 14[h] = 24500 Watts per day

Consumption: 55*24=1320 W per day

I believe even without the upgrade you should be ok because you are loading 5600 [W] into your batteries and consume only 1320 [W]
but it seems you are not ok... I might be missing something here maybe the sun is not really good or the batterie is not taking the full charge, or the loss in the charger, wire, panel is horrible.g
I know here in NY state I have only5 hours of full sun during summer because of trees around... that would impact the results a lot.

Anybody else can chip in?

 

[acdoctor]

I am sure you don’t get 14 hours of stc sun. Probably closer to 5 hours.
The growatt has a self consumption of about 60 watts which needs to be added in. So 55+60=115 watt x 24 hours = 2760 watts + inefficiencies let’s round up to 3000 watts.

3000 watts / 5 solar hours = 600 watts of panels

Lead acid charging inefficiencies is about 20% though. You need enough solar to charge the batteries to the top of bulk 80% SOC and still have 2 hours of marginal charge current to fully recover the batteries daily. IF YOU DON’T do this at least 75% of the time you will be throwing the batteries out in a couple of years.

I have included a page from Rolls Surrett manual. Your manufacture charge voltage may very but the rest is very appropriate.