Hi everyone, please help a noob. I have a SNA5000 inverter and six Jinko 470w panels. I plan to connect them in a single serial string to one of the MPPTs on the inverter. Should be no problem, right? My problem is that since I have to build a mounting rack for the panels, I want to make provision for future possible expansion. I have been studying the inverter's manual and reading up on some of the treads here, and I am worried. The manual is not very spesific - I am trying to figure out if the figures in the manual refers to the total or are they per MPPT? If they are total figures, it looks like I will be limited to about 10 panels?

These are the specs for the panels

 

 

1 hour ago, eugenedp said:

Hi everyone, please help a noob. I have a SNA5000 inverter and six Jinko 470w panels. I plan to connect them in a single serial string to one of the MPPTs on the inverter. Should be no problem, right? My problem is that since I have to build a mounting rack for the panels, I want to make provision for future possible expansion. I have been studying the inverter's manual and reading up on some of the treads here, and I am worried. The manual is not very spesific - I am trying to figure out if the figures in the manual refers to the total or are they per MPPT? If they are total figures, it looks like I will be limited to about 10 panels?

These are the specs for the panels

 

 

The figures are 6400W in total. You can connect 7 in series on any MPPT as Voc will be below the maximum. 

This is how I see it. 

I thank you for the info, can you please share how you reached the conclusion? Am I correct in thinking you used the STC VOC of 52v X 7 = 364v?

6 hours ago, eugenedp said:

I thank you for the info, can you please share how you reached the conclusion? Am I correct in thinking you used the STC VOC of 52v X 7 = 364v?

Yes the Voc is at 364V at 25 degrees C. This leaves a lot of grace to 480V. Then the 7 in series using Vmp is below 385V which is the sweet spot for operation of the MPPTs. 

14x470W will be a bit higher than 6400W max but panels rarely give the STC value in operation. One normally only gets the STC during cloud edge lasting a few minutes before they drop in output. 

Edited December 27, 20222 yr by Scorp007

Great, thank you. That makes me feel much better. I have looked at the planned site again this morning and it seems I will only have space for max 2 more panels for a total of 8. In that case I will rewire for 2 series strings and will come nowhere near any limits. Thanks for the help. 

4 hours ago, eugenedp said:

Great, thank you. That makes me feel much better. I have looked at the planned site again this morning and it seems I will only have space for max 2 more panels for a total of 8. In that case I will rewire for 2 series strings and will come nowhere near any limits. Thanks for the help. 

Spot on. 

They say max PV power is 6400watts but that is over both strings so it is actually 3200watts per string. Therefore 470x6=2820watts so 6 panels is ideal on one string.

28 minutes ago, gdcarter said:

They say max PV power is 6400watts but that is over both strings so it is actually 3200watts per string. Therefore 470x6=2820watts so 6 panels is ideal on one string.

Not always the case. Some Lux power models have the spec for MPPT as follows. 25A total input into 2 MPPTs. 15A input into each MPPT. Also it is an assumption that each MPPT must have the same current/Watts/Volts. Most 2 x MPPTs are designed so that different direction strings can be used and then most times of the day the PV value would be different for each input. As long as the total allowed PV input does not exceed the max value at any point in time. 

Edited January 4, 20232 yr by Scorp007