question

Nils Ihlen avatar image
Nils Ihlen asked

Solar panels with different spec on MPPT RS 450/100 PV-strings

How similar must the spec of the PV-panels be when connecting two different PV-strings to the 450/100? What are the limitations?

Could I have 6 x 500W (60,4V VOC, 9,84A) panels on PV-string 1, and 6 x 360W (46,45V VOC, 9,23A) panels on PV-string 2?

Best regards, Nils

MPPT Controllersmppt rs
2 comments
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

mike avatar image mike commented ·

NO this is not a good idea, the 360watt panels will limit the 500w panels to 360watts

you will need to install multiple mppt's if you are going to mix and match solar panels.


0 Likes 0 ·
baxter avatar image baxter mike commented ·
I dont think so. He is talking about two different strings and as the 450/100 has two MPPT trackers you should be able to have two different string settings
0 Likes 0 ·
3 Answers
snoobler avatar image
snoobler answered ·

It's not that the 360W would limit the 500W to 360W it's that the 6S Voc of each string does not line up. Performance of the 500W might even be worse than 360W or they might perform like 500W panels, and you get nothing out of the 360W.


6*60.4V = 362V

6*46.45 = 279V


The two strings perform optimally at different voltage levels. Thus the MPPT would likely find a sub-optimal voltage for both arrays. If the MPPT settles on a voltage above the Voc of the 360W panels, the 360W panels won't produce anything.


IF THESE TWO GROUPS OF PANELS MUST BE USED TOGETHER, THIS IS THE OPTIMAL WAY:


Their Isc is pretty close. Panels in series always work at the lowest current. Thus the 500W panels would be force to work at 6% lower current/power if placed in series with the 360W.


In this case you would want each string to be 3 panels from each group, i.e.


3S 500W in series with 3S 360W - two groups of those in parallel forming 2 strings or:


6S(3S 500W + 3S 360W)2P


This would decrease the 500W panel performance by approximately 6%, so 500*.06 = 30W.


You would then have 500W panels that perform like 470W panels and 360W panels that perform like 360W panels, total wattage:


(470 + 360) * 3 * 2 = 4980W

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

louvre avatar image
louvre answered ·

hallo nils-ihlen,

da 450/100 zweit Tracker sterben unabhängig von einander arbeiten, dürfte Ihr Vorhaben nicht im Wege stehen, solange Die Spezifischen Daten der beiden Tracker einhalten. (max. 18 Ampere pro Tracker)

Sie sollten nur sterben 500er Module und sterben 360er Module NICHT untereinander mischen.




2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

basil katakuzinos avatar image
basil katakuzinos answered ·

The 450/100 has two MPPT Trackers, you will experience no adverse effects.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.