
Installation and Operation Guide SOLECTRIA XGI 1000
DOCR-070733-F (2/22/2021)
Page 35 of 78
PV String Sizing
NOTICE !
DC Overload: Exceeding the recommended DC to AC ratio may damage the inverter and will void the warranty.
Size strings according to information in this section and all applicable electrical codes.
DC/AC Ratio and Current Limits: Both DC to AC ratio and I
sc
limits must be observed. Failure to meet these
requirements may result in damage and will void the warranty.
Each MPPT zone has four inputs, and each input has a positive and a negative side, both are fused. Connect the same
number of PV modules in each string landed in the same zone. The string sizing tool (
https://solectria.com/support/string-
) can be used as a guide to help determine appropriate string lengths. It is the responsibility of the system
designer to perform all string sizing calculations, and overall array sizing to ensure proper operation and code compliance.
3.5.2.1 Combined Mode
For factory configured Combined Mode installations, perform the calculations based on the total inverter nameplate
power rating. With a maximum DC to AC ratio of 1.5 at STC conditions (Equation 3.1), a user can connect up to 90 kW (XGI
1000-60/60 & XGI 1000-60/65), and 97.5 kW (XGI 1000-65/65).
NOTICE !
High Irradiance Installations: In applications that may experience higher than 1000 W/m
2
on a regular basis, it is
recommended to reduce the DC to AC ratio.
The Maximum Short Circuit Current (I
sc
rating of all strings multiplied by 1.25) must be less than 180 A for Combined Mode
(Equation 3.2).
𝑘𝑊
𝐷𝐶
𝑘𝑊
𝐴𝐶
≤ 𝟏. 𝟓 𝐚𝐭 𝐒𝐓𝐂
(3.1)
∑ 𝑰
𝑺𝑪
∗ 𝟏. 𝟐𝟓 ≤ 𝟏𝟖𝟎𝑨
(Combined Mode)
(3.2)
3.5.2.2 Independent Mode
For factory configured Independent Mode. The maximum DC/AC ratio in Independent Mode follows Equation 3.1 on a per
MPPT zone basis. Each zone’s maximum input power is 22.5 kW (XGI 1000-60/60 and XGI 1000-60/65) and 24.4 kW (XGI
1000-65/65).
NOTICE !
High Irradiance Installations: In applications that may experience higher than 1000 W/m
2
on a regular basis, it is
recommended to reduce the DC to AC ratio.
The Maximum Short Circuit Current (combined I
sc
rating of all strings in the MPPT zone multiplied by 1.25) must be less
than 50A (Equation 3.3).