Sunsynk 8k and String Sizing
HI All,
Newbie to the solar world and just about to hopefully get solar installed in UK. Would appreciate if anyone could help me with clarifying situation.
Was looking at getting following:
SUN-8KSG05LP1-EU
Max. DC Input Power 10400W
Full Load DC Voltage Range 200~425V
PV Input Current 26A+26A
Max. PV Isc 34A+34A
No. of MPPT / Strings Per MPPT 2/1+1
Panel Spec
Nominal Max. Power (Pmax) 400 W
Opt. Operating Voltage (Vmp) 30.8 V
Opt. Operating Current (Imp) 12.99 A
Open Circuit Voltage (Voc) 36.8 V
Short Circuit Current (Isc) 13.85 A
Temperature Coefficient (Voc) -0.26 % / °C
Voc @ -10 °C 40.1 V
plus either 2 or 4 x Sunsynk 5.12kWh batteries.
I had thought that I could get 26 panels installed using both mppts in a MPPT1 = 2S7P East Facing and MPPT2 = 2S6P West/South Facing configuration. Giving me the max 10400w of production (not actually achievable due to roof facing).
I am being told that the actual PV input current for the 8K is only 20A per MPPT so I cant parallel the strings using these panels and would be better off running 10 or 11 panels in series into each MPPT (giving me max 8000/8800w production, again not actually achievable due to roof facing)
Is this correct? and what would anyone suggest on setup?
Thanks.
Why not 2 strings of 13 in series? Sum of Vmppt is 400.4V which is less than the 425V inverter Vmppt limit. Sum of Voc is 478.4V which (from memory, check the data sheet) is less than the 500V PV input Vmax. Running at high voltages also increases inverter efficiency at low light levels and reduces % of power lost in PV cables at high power, compared to parallel strings.
Im surprised you go for 400W panels. Every time Ive looked recently, the 455 to 540Wp panels were better value £/Wp. But maybe you've got a bargain somewhere or get a better geometrical fit that way.
Just some ideas.