Characters Transformerless with three level topology Max efficiency up to 98.6% Dual MPPT inputs accommodating wide voltage range Compact structure design Complete protection function such as anti-islanding, short circuit, overload Easy installation and free maintenance WiFi or GPRS (optional) communication Component brands Specification Model No ST17KTL ST20KTL ST25KTL DC side/Input parameters Max. DC power [W] 18500 22000 25000 Max. DC voltage [Vdc] 1000Vdc. 1000Vdc. 1000Vdc Min. System start/Shut down voltage [Vdc] 250 250 250 MPPT voltage range[Vdc] 250~850 250~850 250~850 Max. input current [A] 25A*2 25A*2 25A*2 Number of MPP trackers 2 2 2 Strings per MPP tracker 2 2 2 AC side/output parameters Nominal output power [W] 17000 20000 25000 Maximum output power [W] 18500 22000 27000 Nominal output voltage/range [V] 400V/ 280-490V（adjustable) AC grid frequency/range [Hz] 50Hz,60Hz(auto-selection) / 44Hz-55Hz; 54Hz-65Hz Maximum output current [A] 25 30 36 AC connection(with PE) 3W/N/PE 3W/N/PE 3W/N/PE Current distortion(THDi) [%] <1.5 <1.5 <1.5 Power factor [%] >99.95 >99.95 >99.95 Efficiency Maximum conversion efficiency[%] 98.5 98.6 98.8 European efficiency[%] 98.1 98.2 98.3 MPPT efficiency[%] 99.9 99.9 99.9 Safety and protection yes DC reverse-polarity protection yes Anti-islanding / Overvoltage protection yes Short circuit protection yes Leakage current protection yes Grid monitoring / Ground fault monitoring yes DC/AC side varistors(thermally protected) yes General Parameters Dimension(L/W/H)[mm] 505*525*245 Weight (kg) 37 Embedded DC Switch Optional Night power consumption[W] <0.2 Isolation type Transformerless Protection degree IP65 according to IEC60529 Operation temperature[ºC] -25 ~ 60 Cooling concept Natural convection Acoustic noise level[dB] <25 Operating altitude[m] <2000 without power derating Display Graphic LCD Communication Interface Standard WIFI; GPRS(optional) Certificates and Approvals CE-(EMC/LVD) : EN(IEC) 61000-1/-2/-3/; EN(IEC) 62109-1/-2;IEC 61727/62116;G83-3/G59-3; EN50438;VDE-0126-1-1;VDE-AR-N4105;AS4777.2;AS4777.3 Projects