To Next Page

To Previous Page

String Sizing continued…

Finally, calculate the maximum current of the string so as not to exceed the Inverter’s MPPT circuit ratings.

Double check if the calculated Vmp range is within the 230-500 VDC optimal MPPT circuit operating range.

Consult a solar designer if needed.

FOR ALL MODULES, THE CALCULATIONS NEED TO BE PERFORMED OR VERIFIED BY USING A STRING CAL-

CULATOR OR CONSULTING A PROFESSIONAL.

The inverter has three MPPT PV charging circuits. MPPT #1 will use up to 25 amps which means two strings

can be paralleled for any modules having less than a 12.5 A (Imp) rating. MPPT #2 and MPPT #3 will use up

to 15 Amps each so they are usually limited to one string. (Unless you have a module with < 7.5 Amps)

Each string ideally should contain the same model, brand, and quantity of panels for ease of design, racking

and wiring. However, varying string sizes can be used for unique MPPTs. If two strings are used for MPPT

#1 they MUST be the same model, brand and # per string. MPPT#2 and MPPT #3 could differ in model,

brand and # per string (same make/model per string) on condition that each string complies with the low-

est temperature (maximum string number) and maximum amperage calculations above.

All panels on a series/parallel string should face the same orientation and hopefully be exposed to roughly

the same shading across the string. Consideration should be placed on string location and wiring order on

the racking to minimize shading effects. One shaded module can disproportionately reduce output for the

entire string so avoiding linear strings in favor of rectangular strings can increase output. Optimizers can

also achieve this.

The inverter will limit the total MPPT current to 25 A for MPPT #1 and to 15 Amps for MPPT #2 and 15

Amps for MPPT #3.

Note: The array can have a higher Imp than the 25A/15A specified, but the MPPTs will not make full use of

the extra current. Having an array that can produce more current than the MPPTs will bring in is useful for

increasing morning, winter or cloudy day solar production.

Other manuals for EG4 18KPV

Questions and Answers:

Need help?

Do you have a question about the EG4 18KPV and is the answer not in the manual?

General