I have an rs450/100 with 2 strings of 7 x JA SOLAR JM60S20 380/MR and 3 x Longi 385w.
Looking at the capacity 7400wp can I make the 2 strings into 1 and for string 2 add 10 x 450 longi in series or would 8 be the maximum?
thanks
specs
LONGi Solar 425WP Full Black Solar PV Module LR5-54HTB-425M
Ja solar
380W
VOC 41.62 V
VMP 34.77 V
ISC 11.47 A
IMP 10.93 A
CLASS II
MAX SYS 1000V
MAX AMP 20
You can try the calculator on:
The calculator does not allow panel mixing in 1 string. I would be hesitant to mix panels on 1 string. But if the V are really close you could. You haven’t mentioned the Longi 385 specs.
Don’t forget to enter your float Voltage.
This a factor of 8 of your float voltage to the maximum of 450v at min temps. (So use the calculator.)
You can parallel 2 strings on one tracker, if you go over the ISC though, don’t make a mistake. Reverse polarity over the ISC is not covered by warranty.
And you have to use even strings on one tracker.
Also, while doing parallel it is important to remember that the maximum power per tracker is not really fixed, because there is a current limit also. Example, if I remember correctly (this is just an illustration): 4kW at 400V is 10A, which is fine, but 4 kW at 150V is not fine as 18A is the maximum current per tracker: 150x18 = 2700W, far less than 4000. I.e. even with the calculator it is important to read and remember the key variables from the technical spec doc.
Correct there is a limit to each tracker in production (max is 4kw per tracker), however i think @druist is aiming to over panel due to poor irradiance.
There is definitely no advantage to doing it if you have good solar conditions, it would be a total waste.
Max array size per tracker for the RS 450/100…
Max. 450 Voc result in appr. 360 Vmpp, therefor the maximum PV array is appr. 360V x 20A = 7200Wp
Thanks.
Do you know (I am new in the field) why they have slight variations in technical spec of the “same” product but in different documents? I.e. your link talks about 16A tracker current as maximum, while in the fragment I attached it says 18A (unless one is for MC4 version and the other one for non-MC4 - apart from the connector are they the same or not?)
Yes there was TR version which has been discontinued. And as models have had hardware revisions as well there have been some changes.
Thanks for your advice. Do you mean each string has to be the same 7 and 7 or one can be 7 x JA 380w and 7 x 450W? I will check the calc.
Sorry the garden strings 2 x 5 (3 older longi and 2 JA on one string, the other is 5 ja. This works ok, but with 3 different wonder if best to lose these given amperage.
I thought i had to make this into one string of 10, then the new 425w as the other - I have 5 mounted of the latter (have 10 in total)
Any thoughts on what configuration would work best
I am having problems with mppt calc when i put 2 strings for the older panels.`
older longi
You can do 1 string of 10x Longi @ 425W (depending on your float V)
Another string of 7x JA Solar 380W
The remaining 3x Longi 370W panels you can connect to a separate SmartSolar MPPT 150/35
Thanks Skippper,
not sure about float charge as intend to use more kw/h with an electric boiler purchase to lose gas utility
I have a bank of pylontech batteries = 32kw with lynx’s / Multiplus II 10k, for most of the year I wouldnt need the extra panels just 3 months winter but with an electric boiler I will consume much more electric- but planning on an electric boiler to lose the gas utilithat kw this will consume, but atm it is about 8 - 15kw per day.
on ESS/off grid mostly and dont use feed-in tariffs - not sure if this affects anything?
thanks
From what I’ve read, the Pylontechs have 15 cell 48V batteries. I assume your float V will be more around 51V. Please check your manufacturer specs sheet. The RS max input PV V is 8x the float V of your batteries. If it’s 51V * 8 = 408V. This is max Voc on the coldest expected conditions.
If that’s the case you can’t do 10x 425W panels on one string. 9 will be your max.
You could potentially add the 10th panel to the 3x 370W Longi’s. You need a 250/60 MPPT in that case.
I take it the mppt cant be separated from an easysolar gx 48v 250/70 as got one s/h but standalone, I would need a battery 100a costly and complicated things.
Or i perhaps sell the 3 old longis - then with 7 ja in series and 10 425w longi on the other tracker 425W (series) to the rs450/100, as I cant get to the roof to add to the other RS450 which are the same - does that make more sense for winter and electric boiler?
