wanting 2000 watts or more in panels at under 250vdc total for Growatt 3000es HELP Please

[motomarc]

Well I am getting 1 day closer to purchasing everything I need going with the Growatt 3k lvm es unit will be the inverter with a max of 250vdc PV input.

I need advice on panels I would like to get 2000watts or more on the 39ft RV roof but have 250v max & 18amps max capable can I/should I series or parallel to get what I am looking for.
I know colder weather has to be taken into consideration when buying the panels so not to go over the 250vdc VOC.
Any panel recommendations please I need help want it close to the 250v as possible and 2000 watts.

thank you for your time. MM

 

[rmaddy]

Post a link to the Growatt so we can see the full specs.

For an RV roof you need to figure out what panels will physically fit on the roof and you need to worry about shading from all of the stuff sticking up on the roof.

Getting to 2000W while staying under 250Voc is easy. But doing so while dealing with the physical constraints of the RV roof and shading makes it much more of a challenge. You need to make a diagram of your roof with lots of measurements. Then start looking at various solar panels to figure out rough sizes that you can fit like a puzzle on the roof. Can you do it with 10 200W panels? Or maybe 8 250W panels? 6 330W panels? Or worse case, 20 100W panels (avoid that at all costs). Keep it at an even number or maybe a number divisible by 3 so you can put the panels in equal length parallel strings.

 

[motomarc]

Post a link to the Growatt so we can see the full specs.

For an RV roof you need to figure out what panels will physically fit on the roof and you need to worry about shading from all of the stuff sticking up on the roof.

Getting to 2000W while staying under 250Voc is easy. But doing so while dealing with the physical constraints of the RV roof and shading makes it much more of a challenge. You need to make a diagram of your roof with lots of measurements. Then start looking at various solar panels to figure out rough sizes that you can fit like a puzzle on the roof. Can you do it with 10 200W panels? Or maybe 8 250W panels? 6 330W panels? Or worse case, 20 100W panels (avoid that at all costs). Keep it at an even number or maybe a number divisible by 3 so you can put the panels in equal length parallel strings.

here is the Growatt it says 300vdc on front of the page but specs say 250VDC VOC https://www.growatt-america.com/show-42-641.html I will be calling them in morning for sure, wow just looked signature solar is there distributer in the USA. less then 4 hours from my house.
for sure going less panels more watts 330w or higher I was looking at these 365w https://solareverusa.com/wp-content/uploads/2021/06/Module-HC-60M-360-370w.pdf at signature solar. there 41.4voc each that puts me at 248.4 VOC just under the 250vdc VOC for the Growatt 3k. I know colder weather factor would send it over VOC limit.
could I simply disconnect 1 panel or toss a blanket over 1 to cut voltage down in cold weather?
thank you again ahead of time. I am a newb and learning. even after reading and research I am still confused on some of what people say are simple things.

 

[DaGoose13]

Here is a table I made for the 360 and 440 Solarever Panels.

​	​	​	​ 360W​ ​	​			440W​
C T​	F T​	VOC​	Pmax​	Isc​	​	VOC​	Pmax​	Isc​
-60​	-76​	51.36​	467.10​	10.70​	​	60.98​	570.90​	10.89​
-55​	-67​	50.76​	460.80​	10.73​	​	60.27​	563.20​	10.91​
-50​	-58​	50.16​	454.50​	10.76​	​	59.56​	555.50​	10.94​
-45​	-49​	49.56​	448.20​	10.79​	​	58.85​	547.80​	10.97​
-40​	-40​	48.97​	441.90​	10.81​	​	58.14​	540.10​	11.00​
-35​	-31​	48.37​	435.60​	10.84​	​	57.43​	532.40​	11.02​
-30​	-22​	47.77​	429.30​	10.87​	​	56.72​	524.70​	11.05​
-25​	-13​	47.17​	423.00​	10.89​	​	56.01​	517.00​	11.08​
-20​	-4​	46.58​	416.70​	10.92​	​	55.30​	509.30​	11.10​
-15​	5​	45.98​	410.40​	10.95​	​	54.59​	501.60​	11.13​
-10​	14​	45.38​	404.10​	10.97​	​	53.89​	493.90​	11.16​
-5​	23​	44.78​	397.80​	11.00​	​	53.18​	486.20​	11.19​
0​	32​	44.19​	391.50​	11.03​	​	52.47​	478.50​	11.21​
5​	41​	43.59​	385.20​	11.05​	​	51.76​	470.80​	11.24​
10​	50​	42.99​	378.90​	11.08​	​	51.05​	463.10​	11.27​
15​	59​	42.39​	372.60​	11.11​	​	50.34​	455.40​	11.30​
20​	68​	41.80​	366.30​	11.13​	​	49.63​	447.70​	11.32​
25​	77​	41.20​	360.00​	11.16​	​	48.92​	440.00​	11.35​
30​	86​	40.60​	353.70​	11.19​	​	48.21​	432.30​	11.38​
35​	95​	40.01​	347.40​	11.21​	​	47.50​	424.60​	11.40​
40​	104​	39.41​	341.10​	11.24​	​	46.79​	416.90​	11.43​
45​	113​	38.81​	334.80​	11.27​	​	46.08​	409.20​	11.46​
50​	122​	38.21​	328.50​	11.29​	​	45.37​	401.50​	11.49​
55​	131​	37.62​	322.20​	11.32​	​	44.66​	393.80​	11.51​
60​	140​	37.02​	315.90​	11.35​	​	43.95​	386.10​	11.54​
65​	149​	36.42​	309.60​	11.37​	​	43.25​	378.40​	11.57​
70​	158​	35.82​	303.30​	11.40​	​	42.54​	370.70​	11.60​
75​	167​	35.23​	297.00​	11.43​	​	41.83​	363.00​	11.62​
80​	176​	34.63​	290.70​	11.45​	​	41.12​	355.30​	11.65​

 

[rmaddy]

That Growatt is a 48V AIO. You have a 48V system in your RV?

If you tried to put 6 panels in series with a Voc of 41.4V you would go over the 250V at about 73ºF. That's just not a good plan at all.

However, if you want to use a 365W panel then getting 6 and putting them in 3S2P would be 2190W and you would be well under the 250V. Having two strings in parallel will help with shading too.

Do you really have the physical space to fit 6 panels? They are 69.09"x40.87" each. Most RV roofs have a lot of things in the way. And make sure there is never any partial shading on both parallel strings at the same time or you will have terrible performance.

 

[motomarc]

That Growatt is a 48V AIO. You have a 48V system in your RV?

If you tried to put 6 panels in series with a Voc of 41.4V you would go over the 250V at about 73ºF. That's just not a good plan at all.

However, if you want to use a 365W panel then getting 6 and putting them in 3S2P would be 2190W and you would be well under the 250V. Having two strings in parallel will help with shading too.

Do you really have the physical space to fit 6 panels? They are 69.09"x40.87" each. Most RV roofs have a lot of things in the way. And make sure there is never any partial shading on both parallel strings at the same time or you will have terrible performance.

wow thank you so much the chart is fantastic. I am still learning the combinations of panels.
tons of room for panels on the roof even with 3 AC units & 3vents there all in center 39x8 roof , if I had nothing on sides IE bathroom vents, tv antenna I could fit 6 on 1 side alone? of course vents are always the issue on a RV but pretty sure could be above them if needed to.
I will be have them mounted for angle 4 ways. building this myself. https://www.4waysolar.com/ not buying it. very simple design my brother is a engineer as well.
so 3 in series would stay at 11amps and change voltage only is that correct? then go in 2p and get 22amps?
what about amp input on the Growatt???
I know it has a limit but can not find it now in any paperwork online manuals no place has it.
PV charging can do up to 80amps does this mean it can handle 80 amps input from the PV array??
pretty sure it was 18amps max input but could be way off as I have looked at many different units over the past months.

I will never see below -17.F degrees , that's the record low in Oklahoma currently.
so max 45volts per panel total 135v per series. then go 2p still at 135v?
I need minimum 120dcv to operate turn on the Growatt, 200v or more would be best according to Will.

from the downloaded manual it says "MPPT ranges 120V~250V, 300Voc"
but all over it says 250v max online.
when I watched the video again with Will testing the unit he had issues at 133v unit would not output AC power. needs to be higher he actually put 245v working voltage into the unit when testing it ran his AC unit and tesla charger? no battery.
200v or higher closer to 250v would be ideal working voltage from what he was saying without a battery. with battery it does way better still needs to be 200v or better for good battery charging.
what would you recommend to get to that point of voltage? I am open to any panels on the market that will make it correct.

again thank you so much any input is welcome and I am grateful for it. I just want to maximize the potential.

 

[sunshine_eggo]

The 18A max makes these inverters a real turd IMHO. Plus, you want the option for more parallel on an RV roof. The 145V 3kW version is superior in this regard.

Folks have claimed you can break the 18A limit by a little (24A?).

Pick panels with an Imp around 9-10A and get Voc around 200. Run an XS2P array.

Flat panels on an RV almost never push max power, so there's little real chance you'll ever break the 18A limit, and if you do, it will be rare.