Over paneling a Growatt?

Working with a friend on a small off grid system way up north. Snow, clouds and short sun days. 39degrees latitude.
Need to over panel some for winter.
Thinking if a Growatt 3000tl all in one.
Will this be ok to overpanel like my Midnite Classic is? Will use bi-facials.
Thanks

We're gonna need a LOT more information than that. What panels are you thinking of? What's the VoC on those? How cold does it get, because that affects the VoC? How over-paneled are you thinking of? 10%? 1000%? There's a wide range there. What's the max PV input on that Growatt?

Yes, over-paneling is fine, however, you still need to do the math so you DON'T release the magic orange smoke (because that would suck) and live in the dark. What produces in winter may well fry the system in summer so you might want to think about disconnects of some sort. There's a lot to plan for before you spend any money on parts.

Ok,
Panels: 390w bi-facials Canadian Solar
46.9v, 10.19a
6 panels
2-s3 strings
Growatt rated for 2,000w
This would be 2,360w
With possible output of 560x6 or 3,360 peak watts.
Cold- 0f at times.
So percent of over panel could range from 20 to 70%?
May have to place two panels on second CC?

gray webber said:

46.9v

Click to expand...

Is that Voc or Vmp?

What is the max PV input voltage of the Growatt?

Better yet, post links to the exact model of Growatt and the solar panels.

Just napkin mathing here but I think the temperature of the panels is going to go over the max PV input on the Growatt (145V?), you might be limited to 2s strings, so you could probably get away with a 2s3p setup which would put you at about 100v @ 30.5a (napkin math) which even really, REALLY cold should keep you well under the MaxPV input voltage and amperage limits.

The simplest solution would be a 2s2p on the Growatt and a 2s1p on a second MPPT controller just to avoid any clipping in summer from the Growatt. Then when the sun really comes out and it's cold you're only over-paneling the Growatt by a little bit and the second SCC would be able to really run nicely.
I'm assuming that's the 24v version by the low wattage limit anyways.

Question: can you overpanel a Growatt 3000.
Answer: yes.

rmaddy said:

Is that Voc or Vmp?

What is the max PV input voltage of the Growatt?

Better yet, post links to the exact model of Growatt and the solar panels.

Click to expand...

Ok. I’ll try posting but I’m not good at this crap
In case-Voc
2,000w 145v CC

I found a crude way to get the info to you. I took screen shots and will attach.

timselectric said:

Question: can you overpanel a Growatt 3000.
Answer: yes.

Click to expand...

Is there a limit? 20-50%?
Is there info in a manual that supports this?
Hate to do it a fry the inverter.

Your name seams to bring a deep knowledge of these things. Experience is always a great teacher.
Thanks for your answer and any further info you may offer.

gray webber said:

Is there a limit? 20-50%?
Is there info in a manual that supports this?
Hate to do it a fry the inverter.

Your name seams to bring a deep knowledge of these things. Experience is always a great teacher.
Thanks for your answer and any further info you may offer.

Click to expand...

There's no limit. But, too much becomes wasteful.
As long as you keep the VOC below the max of the charger, you won't hurt anything. The panels don't push power into the charger. The charger draws power from the panels. More panels gives the charger more available sources to draw from.
Think of the solar panels as buckets. And solar energy as rain. In a heavy rain, you can collect a lot of water, with only a few buckets. But in a light rain, it will take a lot more buckets to collect the same amount of water, in the same time frame. You just have to find a balance. So that you can collect enough from a lower production day. Without having way more than you need, on a higher production day.
No point in paying for too many panels, if you are rarely able to utilize them.

timselectric said:

There's no limit. But, too much becomes wasteful.
As long as you keep the VOC below the max of the charger, you won't hurt anything. The panels don't push power into the charger. The charger draws power from the panels. More panels gives the charger more available sources to draw from.
Think of the solar panels as buckets. And solar energy as rain. In a heavy rain, you can collect a lot of water, with only a few buckets. But in a light rain, it will take a lot more buckets to collect the same amount of water, in the same time frame. You just have to find a balance. So that you can collect enough from a lower production day. Without having way more than you need, on a higher production day.
No point in paying for too many panels, if you are rarely able to utilize them.

Click to expand...

Got it! Thank you. It makes perfect sense?
I’m looking at adding 50% to compensate for bad winter times. Also tilting panels to near vertical during Dec and Jan so self cleaning of snow. I’m feeling better about my plan. Now to build design on my battery. Yikes!
Thanks again.

Rednecktek said:

Just napkin mathing here but I think the temperature of the panels is going to go over the max PV input on the Growatt (145V?), you might be limited to 2s strings, so you could probably get away with a 2s3p setup which would put you at about 100v @ 30.5a (napkin math) which even really, REALLY cold should keep you well under the MaxPV input voltage and amperage limits.

The simplest solution would be a 2s2p on the Growatt and a 2s1p on a second MPPT controller just to avoid any clipping in summer from the Growatt. Then when the sun really comes out and it's cold you're only over-paneling the Growatt by a little bit and the second SCC would be able to really run nicely.
I'm assuming that's the 24v version by the low wattage limit anyways.

Click to expand...

I’ll have to check on that temp issue upping the VOC? If that’s the case then as you say, a second CC for on string will be just right. Just ran the numbers and when it’s -10f and this does happen each year the VOC can exceed 52v. Yup, needs a second CC to run 3 strings rather then two or run all three into the one CC and clip excess as it occures?
Yes-24volts

timselectric said:

Question: can you overpanel a Growatt 3000.
Answer: yes.

Click to expand...

I don't recommend it though, one member here did it and it fried eventually. It will clip some on amps, voltage on the other hand is definitely a hard spec.

I'd just add more separate SCC's if I had overpaneled.

gray webber said:

I found a crude way to get the info to you. I took screen shots and will attach.

Click to expand...

2S is the most you can run. VOC in cold temps will put you over.

Zwy said:

I don't recommend it though, one member here did it and it fried eventually. It will clip some on amps, voltage on the other hand is definitely a hard spec.

I'd just add more separate SCC's if I had overpaneled.

Click to expand...

So the Growatt is not as robust as the Midnite Classic. Thought so. Yes- a separate CC is in order. All great to know!
Even if the bi-facials pump out extra(which I have found they will). The max watts would be about 2100w and that’s only slightly over the rating and no issue with volts.
My test on the Canadian 445 bi-facials found that on a cold sunny day in Jan I got 640w from each! That ran just under the max for the MS Classic I have. Adding two deep winter panels means adding a nice EPEver 50a-150v CC. I can shut down that string if too much in summer season.
Crap! I may have to add another 300ah of battery? Never ends.

I'm doing both.
Over paneling and an extra SCC.
I hate to waste free electricity. And, can't stand to be inefficient.
When production is low, all strings feed the inverter SCC. So that it can go straight to the loads, without stepping through the battery. And on high production days, some strings will be diverted to a separate SCC. And, just charge the battery. Or be shed into a water heater, if the battery is full.

timselectric said:

I'm doing both.
Over paneling and an extra SCC.
I hate to waste free electricity. And, can't stand to be inefficient.
When production is low, all strings feed the inverter SCC. So that it can go straight to the loads, without stepping through the battery. And on high production days, some strings will be diverted to a separate SCC. And, just charge the battery. Or be shed into a water heater, if the battery is full.

Click to expand...

That a very involved design. I have an off grid cabin need and must use battery storage. During bad winter times I do not want to lose the ability to pop into cabin and have full batteries for a visit. My friend is at his place full time and will if needed run s gen to bulk up his batteries.
Esther way we have discovered the two months of crap will require added PV.
He uses about 1.8kwh per winter day and thus has about 3 days storage. Our target is no gen need. Every few days he pumps water but that’s about it.
This is an upgrade from a 4 year old 800watt PV plus wind turbine system into 400ah FLA batteries. Started to fail after first year. Pure crap. Deep dive has me finding out all the limits that killed that magical system. Did not help that he left during a -20 two week stretch after the first year—battery damage!

In any case, I now have land one mile away and am building an off grid camp this summer. We are both going to do a similar system so lots of extra learning. Now another friend with shunting camp saw the me testing the panels I have at my shop wants in on a system for his place.
Too much information? Just saying I’m in recovery from hip replacement, have lots of time to do figuring. I hope we all benifit???
I’m even leaning towards building my own heated battery from EVE cells. High risk but what’s life for if not to explore!
Just enjoy learning from so many informed forum members?

As long as you get quality cells, a diy battery is a great way to save money. I just don't have the time or patience. So, it's EG4 batteries for me.

Nice Batteries! Ok price.
Im retired and need to save a bit of $. On my system. At the price of building materials I’ll need plenty to do the cabin part of my project. The only risk in building the batteries that I see is getting good cells. The US outlet is pricy for them but low risk. The China outlet???? Alibaba? Not so sure.

Are any of these suppliers good?
18650
Docan
Alibaba
I’m shopping EVE cells-grade A. 280ah
Thanks members for your assistance!