DaveNSueM
New Member
Leaning towards the NHX (vs the Growatt SPH) mainly for known SA compatibility. Have developed the following hypothesis and would love additional eyes on calcs and confirmation I am thinking about this correctly; did I miss anything. TIA...this forum/information has been amazing so far and my daily read for past few weeks!
Hypothesis
To minimize clipping given parameters below, the best string config would be four 6S strings (as opposed to three 8S strings). With four 6S strings can use up to 10% bifacial gain (assuming it exists) with no clipping. There will be clipping overall; working to determine config to minimize clipping.
Panel/Wire/Location Info
Grid tied; no battery to start, interconnect agreement obtained
24 - Adani 530w bifacial (specs below)
Ground mount
Already purchased 8awg to connect 4 strings plus 8awg ground; 150’ in 1.5” buried pvc
Record low -36c
8S is max string @ -36c (8 panels VOC @ -36c = 461v; <500v)
Inverter MPPT info
4 mppt @14a max IMP; 22a max ISC
Voc range 120v-500v max
Max pv 15000w
Based on above, it seems implied each mppt is 3750w (?);
@14a max per MPPT, V calculates to be 268v
If watts per MPPT is 4000w (Watts247 website note) then
@14a max per MPPT, V would be 286v
VMP Calc
Panel vmp is 41.49v;
6 panels=249v;
8 panels=332v
Startup Calc
Min vmp @ 6 panels = 41.49v * .8 * 6 = 199v; >120v (saw the .8 derate suggested in a post)
Min vmp @ 8 panels = 266v; >120v
Imp Calc
6 panels=249v * 12.79a = 3185w
8 panels=332v * 12.79a = 4246w (over max w MPPT)
Add bifacial gain
10% : imp 13.97a * 249 (6S) = 3478w
10% : imp 13.97a * 332 (8S) = 4638w (over max watts/MPPT)
15% : imp 14.61a * 249 (6S) = 3638w (will clip @ 14a)
15% : imp 14.61a * 332 (8S) = 4851w (will clip @ 14a)
Panel Data (entire PDF sheet was too large to attach)

Hypothesis
To minimize clipping given parameters below, the best string config would be four 6S strings (as opposed to three 8S strings). With four 6S strings can use up to 10% bifacial gain (assuming it exists) with no clipping. There will be clipping overall; working to determine config to minimize clipping.
Panel/Wire/Location Info
Grid tied; no battery to start, interconnect agreement obtained
24 - Adani 530w bifacial (specs below)
Ground mount
Already purchased 8awg to connect 4 strings plus 8awg ground; 150’ in 1.5” buried pvc
Record low -36c
8S is max string @ -36c (8 panels VOC @ -36c = 461v; <500v)
Inverter MPPT info
4 mppt @14a max IMP; 22a max ISC
Voc range 120v-500v max
Max pv 15000w
Based on above, it seems implied each mppt is 3750w (?);
@14a max per MPPT, V calculates to be 268v
If watts per MPPT is 4000w (Watts247 website note) then
@14a max per MPPT, V would be 286v
VMP Calc
Panel vmp is 41.49v;
6 panels=249v;
8 panels=332v
Startup Calc
Min vmp @ 6 panels = 41.49v * .8 * 6 = 199v; >120v (saw the .8 derate suggested in a post)
Min vmp @ 8 panels = 266v; >120v
Imp Calc
6 panels=249v * 12.79a = 3185w
8 panels=332v * 12.79a = 4246w (over max w MPPT)
Add bifacial gain
10% : imp 13.97a * 249 (6S) = 3478w
10% : imp 13.97a * 332 (8S) = 4638w (over max watts/MPPT)
15% : imp 14.61a * 249 (6S) = 3638w (will clip @ 14a)
15% : imp 14.61a * 332 (8S) = 4851w (will clip @ 14a)
Panel Data (entire PDF sheet was too large to attach)
