1. How to Design and Implement a Reliable PV System which could last 30+ years
ZAKI IQBAL
SENIOR R&D ENGINEER
RAK RESEARCH AND INNOVATION CENTER

2. Content
Current trends of Solar PV market
Electrical concept in Solar PV
Decoding I-V curve
Factors affecting the choice of components
Summary

3. Question
Why highly skilled PV designers and installers are required for the PV market today ??

4. Growing installed capacity of PV
Answer
Growing installed capacity of PV

5. PV Installed Capacity and Projection

6. Rise in Global investment in PV
Answer
Rise in Global investment in PV

7. Global investment in renewables

8. Question
What could be the consequences of poor PV design/ poor PV installation??

9. Lack of trust ( investors) Increase in system fail ratio
Answer
Lack of trust ( investors)
Increase in system fail ratio
Extra overhead in maintaining the system
Fire leading to injury and death
Loss of property

10. How to design and install a reliable PV system??
Question
How to design and install a reliable PV system??

11. Understanding the basics of Photovoltaic electricity
Answer
Understanding the basics of Photovoltaic electricity

12. V Voc Vmpp I Isc Impp Voltage Current Electric concepts in Solar PV
V ( Voltage) ~ Pressure
Voltage
V Voc Vmpp
Current
I (Current) ~ Flow
I Isc Impp

13. Basics of I-V Curve Voc Open circuit Voltage Isc Short circuit Current
@ V= 0, I= Imax ~Isc
@ I= 0, V= Vmax ~Voc
Isc
Impp
Current [A]
Voltage [V] Vmpp Voc
STC 1000 W/m2 25ₒC AM 1.5

14. I-V Curve interpretation
Solar Irradiation effects the Current
1000 W/m2
800 W/m2
600 W/m2
400 W/m2
Current [A]
Solar irradiation
Voltage [V]

15. I-V Curve interpretation
Temperature effects the Voltage
TIP : Design based on Cell temp and not ambient temperature !
0ₒC
25ₒC
50ₒC
75ₒC
Current [A]
Temperature rise
Temperature drop
Voltage [V]

16. Choosing the reliable components for Solar
Answer
Choosing the reliable components for Solar

17. PV Module Always look for Tier 1 manufacturers
Always analyse the datasheet of manufacturer carefully
Be careful analysing the Power Warranty
Look out for Power Tolerance
Tip : Always go for positive only power modules !
Module power at STC
+2%
-2%
250 W
255 W
245 W
300 W
306 W
294 W
Look out of TkVoc and TkVmp values

18. PV modules ( design consideration)
Cell ~ 0.5V
Cells in PV module are connected in series
Bypass diode are connected to reduce the effect of shading

19. Shading ( design error)
Loss of total or partial power output
Prolonged shading lead to failure of bypass diode
Can even lead to fire due to built up heat in module

20. PV module ( design consideration)
Site Survey and predictive design modeling is very important
Shading calculations are very important
Know the highest and lowest historical temperature data ( in the last 20 years )
Max.mod.Voc = Voc * [ 100% + [ ( Tmin – Tstc ) * TkVoc ]]
Particularly important for sizing the string
Higher voltage than the operating voltage of inverter can damage them

21. Inverter selection
Depends on the application and can change case-to-case
Module Level ( MLPE)
Microinveters
DC-DC Optimisers
String Inverters
Central Inverters
Operating DC voltage window of the inveter is an important constraint for design consideration
Must have ground fault protection
Newer version coming with Arc-fault protection

22. Inverter ( design consideration)
Temperature effects the inverter selection
600
Coldest Day voltage (Voc)
Inverter input voltage window
Voltage [V]
200
Hottest Day voltage (Vmp)
Time of the day
Source: SEI,US

23. Wiring conductors Choose correct wire size based on
Ampacity required for the design
Maximum ambient temperature recorded
Voltage drop
No of wires in the conduit
Heat dissipation
Installation/removal
Tip: The total number of bends in the conduit should not exceed 270 degree in each wire run !

24. Wiring ( design consideration )
Crimping of the lugs for the DC wires correctly
Source: Etco.com

25. Wiring ( design consideration)
Using Torque wrench and screwdrivers to torque each wiring terminations, installation as per manufacuter recommendation
Source: solarprofessional.com

26. Grounding
Ungrounded , Grounded , Grounding conductor, Ground Fault (GF)
Ensure proper equiment grounding has been done to bond all the non-current metal carrying enclosure, equipment
Module/racking should all be connected to ground via the inverter
Inverter checks for GF everytime it boots up. It would not be able to detect GF, it if the earlier is not bonded
Source: solarprofessional.com

27. Summary Inorder for a system to surpass its design life :
Design of the system should be spot on
Components chosen should be of high quality
Use of symmetric design pattern would help in troubleshooting
Wiring terminations should be torqued as per manufacturer torque setting
Proper labeling of the wires, breaker, distribution boards is a must
Overcurrent protection devices & disconnects has to be used adequately for the servicablility
Onsite and remote Monitoring of plant/system with timely manitence should be done

28. THANK YOU
FOR ATTENDING THE PRESENTATION