Site Design Rules

When you consider investing solar PV farm in your potential area, you need to fully maximize your designated area to get faster ROI by determining on how many solar modules/panels, how many and which type of power optimizers and inverters you need to buy, how many panels per string you need to set up and how many strings in one inverter. This solution will provide you on how you tailor your own solar farm.

In general:

  • Every 7m2 of your desired area, you can install 1 kW of solar panel
  • The dimension of panel is 1 m x 1.8 m (width x length)
  • Specification on each panel on average are 32V, 9.2 A, 295 W in 60 cells
  • Different inverters have different optimum range of DC input voltage
  • One power optimizer (P600) can hold 2 modules/panels

Procedures/steps to design your favorable solar farm:

1. Selecting the most compatible power optimizer and inverter with modules for your solar PV system
  P300 P350 P500 P404 P405 P600 P700
Compatible with module type 60-cell 60/72-cell 96-cell 60/72-cell Thin-film 2x 60-cell 2x 72-cell
Rated Input Power (@STC) 300W 350W 500W 405W 405W 600W 700W
Absolute Maximum Input Voltage (Voc at lowest temperature) 48V 60V 80V 80V 125V 96V 125V
MPPT Operating Range 8-48V 8-60V 8-80V 12.5-80V 12.5-105V 12.5-80V 12.5-105V
Maximum Input Current (ISC) 10A 11A 10.1A 10.1A 10.1A 10.1A 10.1A
Maximum Output Voltage 60V 60V 60V 85V 85V 85V 85V
Maximum Output Current 15A 15A 15A 15A 15A 15A 15A


  SE15k SE16k SE17k SE25k SE27.6k SE33.3k  
Rated AC Power Output 15000 16000 17000 25000 27600 33300 VA
Maximum AC Power Output 15000 16000 17000 25000 27600 33300* VA
AC Output Voltage - Line to Line / Line to Neutral (Nominal) 380 / 220 ; 400 / 230 480/277 VAC
AC Output Voltage - Line to Neutral Range 184 - 264.5 244-305 VAC
AC Frequency 50/60 ± 5 Hz
Maximum Continuous Output Current (per Phase) 23 25.5 26 38 40 40 A
Residual Current Detector / Residual Current Step Detector 300 / 30 mA
Grids Supported - Three Phase 3 / N / PE ;
230 / 400
3 / N / PE
(WYE with Neutral)
Utility Monitoring, Islanding Protection, Configurable Power Factor, Country Configurable Thresholds Yes  
Recommended Max. DC Power(1) (Module STC) 18750 20000 21250 33750 37250 44950 W
Transformer-less, Ungrounded Yes  
Maximum Input Voltage (Voc) 900 1000 VDC
Nominal DC Input Voltage 750 840 VDC
Recommended Max. DC Power(1) (Module STC) 22 23 23 37 40 40 ADC
Reverse-Polarity Protection Yes  
Ground-Fault Isolation Detection 1MΩ Sensitivity  
Maximum Inverter Efficiency 98 98.5 %
European Weighted Efficiency 97.6 97.7 97.7 98 98 98.3 %
Nighttime Power Consumption < 2.5 < 4 W
Supported Communication InterfacesSTC) RS485, RS232, Ethernet,
Zigbee (optional)
RS485, Ethernet, Zigbee
(optional), Wi-Fi (optional)
Safety IEC-62103 (EN50178),
IEC-62103 (EN50178),
IEC-62109, AS3100
Grid Connection Standards VDE 0126-1-1, VDE-AR-N-4105,
AS-4777, RD-1663, DK 5940
VDE-AR-N-4105, BDEW, G59/3, AS-4777, EN 50438, VDE 0126-1-1, CEI-021, CEI-016(2) BDEW,
Emissions IEC61000-6-2, IEC61000-6-3 ,
IEC61000-3-11, IEC61000-3-12,
FCC part15 class B
IEC61000-6-3, IEC61000-3-11,
Emissions Yes  
AC Output Cable Gland - diameter 15-21 mm
DC Input 2 MC4 pairs 3 MC4 pairs mm
Dimensions (H x W x D) 540 x 315 x 260 mm
Weight 33.2 45 kg
Operating Temperature Range -20 - +60
(M40 version -40 - +60)
-20 - +60 (-40 version available) ˚C
Cooling Fans (user replaceable)  
Noise <55  
Protection Rating IP65 - Outdoor and Indoor  
Bracket Mounted (Bracket Provided)

(1) Limited to 135% of AC power.

(2) For all standards refer to Certifications category in Downloads page

* 33.3k requires separate 480V-MV transformer

2. Keep in mind that each string has to follow one of these rules (only optimizers from the same row can be mixed within one string):
3. Understanding your oversizing condition based on the location you are at (Oversizing is only allowed for inverter with the maximum oversizing up to 135%, but oversizing for power optimizer as well as string are NOT ALLOWED)
A. Example of power optimizer oversizing:

From this picture, we can see that P600 has to be set into series and NOT parallel. It is due to the maximum current (ampere) that exceed its limitation.

*Remark: if it is series, the current (ampere) is the same; if it is parallel, the voltage (volt) is the same

B. Example of string oversizing:

C. Oversizing exceptions:

  • Inverter over-sizing is up to 135% (37.25 kWp DC)
  • Maximum string power: 11.25 kW

D. String over-sizing of up to 13.5 kW per string allowed, if:

  • P600 or P700 are used
  • And 3 strings are connected to the inverter
  • And maximum power difference between strings: 2000W and maximum panel difference between strings: 6 panels

Case Example 1:

Oversizing (%) in Taiwan
Region Perfect angle Non-perfect angle
North/East 110-115% 120%
South 105-110% 110-115%
If the condition is 20 kW of inverter with 2 MPPTs and your optimum range of inverter is 550V-800V
  1. Oversize the 20 kW inverter based on the location you are at
  2. Since there are 2 MPPTs, there are 4 strings of panels. Each string has 10 kW (20 kW/2)
  3. Calculate the number of panels you need for each string
    • 10000 w / 295 = 33.8 panels = 34 panels
    • Each string needs 34/2 = 17 panels
  4. We need to install more panels to reach the minimum voltage of operating inverter. This phenomenon is called oversizing.
  5. Take as an example that the oversizing is 118%. Therefore, the oversized inverter is 20 kW*1.18 = 23.6 kW
  6. Each MPPT has 23.6 kW/2 = 11.8 kW
  7. To know the how many panels we need is by calculating 11.8/0.295 kW = 40 panels, so each MPPT needs 40 panels and each string needs 20 panels.
  8. The optimum range of MPPT is 550-800 V, so if we calculate 40 panels x 32 V (each module) = 640 V in each string
  9. In conclusion, we need 40 panels for each MPPT in this condition.

Case Example 2:

Take as an example of 50 kW inverter with 1 MPPT, oversizing 110%, how many panels do we need?
  1. Calculate the number of panels you need for each string
    • =50 kW*1.1 = 55 kW
    • =55 kW/0.295 = 186 panels
  2. Since the maximum of voltage of inverter is 550-800 V. Thus, maximum panel in each string is ranged from 17-25. It is suggested to have 19-23 panels on each string in this condition
  3. Take an example 23 panels per string, so 186 kW / 23 = 8 strings

Case Example 3

You have certain potential rooftop areas that you have decided to invest for solar PV system. You have 382.32 kW that can be generated from your rooftop. There are several inverters of SolarEdge provided (three-phase) : 33.3 kW, 27.6 kW, 25 kW, 17 kW, 16 kW, 15 kW, 12.5 kW, 10 kW, 9 kW, 8 kW, 7 kW, 5 kW, 4 kW. Oversize is 110-115% How many and which inverters are recommended for you to buy?
  1. Ideally, the higher power of inverter, the cheaper price will be per watt.
  2. 33.3 kW is considered as the cheapest inverter per kWh (the higher AC power output, the cheaper inverter per kWh). It is different from other inverters.
  3. Oversizing your inverter depending on the location you are at.
  4. Let's say we are in the Southern part of Taiwan and we want to apply the cheapest price per kW: 33.3 kW
  5. 382.32 kW of potential ground or rooftop you want to install solar farm
  6. Calculate the number of panels you need for each string
    • = 382.32/ (33.3 x 1.1)
    • = 382.32/36.63
    • = 10.44 = 10 inverters of 33.3 kW