RS 450/100 Datasheet - Not sure how to interpret it

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run-the-race asked May 15, '24

RS 450/100 Datasheet - Not sure how to interpret it

I understand electricity theory well, but looking at RS 450/100 Datasheet confuses me.

I tried to use the Victron MPPT calculator but it does not support the RS450/100: https://mppt.victronenergy.com/

I understand that the total Voc and Isc must be less than 450V and 20A respectively.

But with regards to power, how to does check if one is connecting too many panels?

Question: How does one check the power is within limits?

I can choose 455W or 550W panels, and don't know whether to keep the total below power below 5760W or 2*4000W or 2*7200W? Example calculation below:

455W Panels:

Voc: 49.85V

Isc: 11.41A

450Vmax / 49.85Voc = 8 panels (9 is just too much)

8panels x 455W = 3640W. This is less than the 7200W per tracker

For 2 trackers = 2 * 3640W = 7280W total, but this is more than 5760W max DC output charging power. I imagine there are some looses when it takes in power and outputs to the battery, but I think it wont be this much??

Is 2 strings of 8 PVs in series okay for the RS450/100 or should I reduce the number of panels? If not why not?

PS I don't wish to push it to the absolute max, I prefer to be well within safety margins.

Bonus question: If the batteriesare are full, what does the MPPT do with the excess power?

Thanks so much for any help!

mppt rs

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Answer 1 · 2024-05-15T12:21:17Z

Duivert NL answered · May 15 at 12:21 PM

hi total max charging power is indeed 5760 (100A x 57.6V)

operational current on trackers is 18A MAX each and if you stay below 450V

then 8 panels in series per tracker is fine, panels almost never deliver peak power, but you always have to take VOC and ISC in account, so in your case thats 4550WP thats below the 7200WP per tracker

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Answer 2 · 2024-05-15T14:39:20Z

Alexandra answered · May 15 at 02:39 PM

@run_the_race

The mppt will only generate what is needed by the system no more. So it will park off if there is no demand.

Keep it below 4000w per tracker.

Max voc is actually battery float voltage x 8 up to a max of 450voc at min temps. So choose your battery wisely

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Answer 3 · 2024-05-16T04:36:01Z

run-the-race answered · May 16 at 04:36 AM

Thanks for the help! That is very comforting. So In the case of 555W panels that have a Voc of 50.85V and a Isc of 14A, that means 8*50.85 V=406.8W which is below 450W so that is okay, but 8*555 = 4440Wp which is below 7200Wp, but not below the 4000W per tracker that @Alexandra mentioned, so if I went with 555W panels then I would have to go for 2 strings of 7 ? (ie 14 panels in total) ?

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ejrossouw commented · May 16 at 07:32 AM

@run_the_race With 8 panels per string, the MPPT will still only ever ouput 100A max. Oversizing is not an issue as long as the parameters mentioned above are respected. The online calculator works for me. Check the system/float voltage settings and use the superb panel search function.

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kevgermany ♦♦ commented · May 16 at 09:06 AM

Yes 7x555W panels per tracker.

Don't forget the min temp voltage calcs.

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