1. Techno Economic Analysis of On Grid PV System in AN Najah University Hospital
Supervised By:
Dr. Emad Breik
Hiba Abu Issa
Bara’a Surakji Dania Alabed

2. Introduction

3. In recent years, there has been a huge worldwide movement to use renewable energy in both residential and commercial uses. And the solar energy is the most important source.
We need to point the renewable energy sources that our country Palestine have Authority strategy in Palestine predicts that by 2020, 10 % of our total consumption will be from renewable source.
And this is the reason why we choose this topic to be our graduation project.

4. Photovoltaic Background
Photovoltaic system is comprised of photovoltaic cells, devices that convert light energy directly into electricity.
The word photovoltaic comes from “photo” meaning light, and “voltaic” which refers to producing electricity. Therefore, the photovoltaic process is “producing electricity directly from sunlight”.
Photovoltaic are often referred to as PV.

5. How PV Cell Work
PVcells are made of at least two layers of semiconductor material. One layer has a positive charge, the other’s negative. When light enters the cell, some of the photons from light are absorbed by
the semiconductor atoms freeing electrons from the cell’s negative layer to flow through an external circuit and back into the positive layer. This flow of electrons produces electric current.

6. How PV Cell Work

7. Types of PV Cells
Single Crystalline The most efficient sunlight conversion technology available - about 10% to 12%.
Polycrystalline or Multicrystalline Module efficiency about 10% to 11%.
String Ribbon Module efficiency about 7% to 8%.
Amorphous or Thin Film Module efficiency about 5% to 7%.

8. Theory of I-V Characterization
PV cells can be modeled as a current source in parallel with a diode. When there is no light present to generate any current, the PV cell behaves like a diode. As the intensity of incident light increases, current is generated by the PV cell, as illustrated in following Figure :

9. Standard Test Condition
Standard Test Conditions (STC) they are:
Cell temperature is 25 oC .
Solar irradiance (intensity) = 1000 W/m2 (often referred to as peak sunlight intensity, comparable to clear summer noon time intensity).
Solar spectrum as filtered by passing through 1.5 thickness of atmosphere .

10. Factors Affecting Module Output Power
Temperature & irradiance.

11. Factors Affecting Module Output Power
Mismatch and wiring losses.
Module mismatch.
Power lost in resistance in the wiring system.
These losses should be kept to the minimum.
DC to AC conversion losses.
Some power is lost in the conversion process.
Additional losses in the wires from the Roof top array down to the inverter and out to the house panel.

12. Photovoltaic Systems Types

13. Photovoltaic System Types
Grid tied system
Off Grid system

14. Off Grid System Types
It is the most common in remote locations without utility grid service, off grid solar electric systems can work anywhere. They are generally designed and sized to supply DC and/or AC electrical load.

15. 1. Direct Coupled System Drawbacks in this type are:
It can only be used in the day to supply load as there is no battery for storing energy.
It can not be used with AC load .

16. 2. Off Grid System With Inverter
In this type we use an inverter to convert voltage from DC to AC at appropriate voltage level.
Drawback in this type is:
The lack of storage unit, so it will not supply load at night.

17. 3. Off-grid System With Battery With DC Output
The problem of no electricity generation in the night is eliminated with the inclusion of storage unit (batteries) as backup energy in the night.

18. 4. Off-grid System With Battery Without DC Output

19. 5. Off Grid System With Engine Generator

20. Grid Tied System Types (On Grid System)
Grid tied systems are designed to operate in parallel with and interconnected with the electric utility grid.
Grid tied system with no battery for storing energy.
Grid tied system with batteries for storing energy.

21. Grid Tied vs. Off Grid Systems
Grid tied advantages:
There is no need for a battery system to store the energy.
Less expensive than off grid systems (less equipment and less time to install and require very little maintenances).
More efficient and environmentally friendly.
Off grid advantages:
When we have no grid, there may be no option other than to go with an off grid system.
Although it requires more care and maintenance, but it can give the homeowner a strong sense of independence.
Homeowner is no longer subject to the risk of a loss of power from the grid.

22. Grid Tie Inverter (GTI)
It is a special type of power inverter that converts from DC to AC and feeds it into an existing electrical grid.
Properties of Tie inverter:
The technical name for a grid tie inverter is "grid interactive inverter". typically it cannot be used in standalone applications where utility power is not available.
During a period of over production from the generating source, power is routed into the power grid, there by being sold to the local power company. During insufficient power production, it allows for power to be purchased from the power company.

23. Grid Tie Inverter (GTI)
It must synchronize its frequency with that of the grid and limit the voltage to no higher than the grid voltage.
GTI has a fixed unity power factor, which means its output voltage and current are perfectly lined up.
It has an on board computer which will sense the current AC grid waveform, and output a voltage to correspond with the grid.
It also designed to disconnect quickly from the grid if the utility grid goes down.

24. Off Grid Inverters
always work in a system that uses batteries, but sometimes they work with generators too. Some inverters can charge the batteries with the extra energy from a generator.

25. Components of On Grid System

27. Component Of On Grid PV System
PV array
A PV array is the complete power-generating unit,
Dc-Ac inverter
Combiner Box
It gathers all the solar panel connections at one location, providing a neat, clean looking installation.
Metering
This includes meters that provide indication of system performance. Some meters can indicate energy usage.
other components
In most cases, the grid will require a transformer to step up the voltage from the solar inverter to be connected to the grid.

28. Component Of On Grid PV System
Balance of system equipment (BOS)
The BOS equipment that used to integrate the solar modules
into the structural and electrical systems of the home are:
Mounting systems.
Solar panel mount They are important to provide proper directional and latitudinal orientation, maximize production, and to provide the stability needed to protect your investment.
A solar tracker is a device for orienting a solar panel or solar array toward the sun.
Wiring systems, which include:
Disconnects for the dc and ac sides of the inverter.
Ground fault protection, and overcurrent protection for the solar modules.
Fuses for each module source circuit.

29. Designing The PV in An Najah Hospital

30. Our project is going to use PV system to generates electricity to feed An-Najah University Hospital.
The Hospital intends install solar cells and connect them with the grid lines of the Northern Electricity Distribution Company.
According to the financial possibilities that are available for the University , they decided to install a 100 kwp PV system.

31. The Energy Authority in Palestine tracking a feed in tariff policy In which the government buys one kilowatt that has been generated from a solar cell for 1.07 Nis, this price is set by PERC (Palestine electrical regulator council), as it is known, the price of one kilowatt we buy from the Northern Electricity Distribution Company is 0.55 Nis.

32. Choosing The Elements Of The PV System
In this research we will display our calculation that show:
Number of modules & inverters that are needed for this size of PV system.
The suitable fuse that we can used to protect module circuit (Dc side).
The suitable cables that are needed for connection between module circuit and a junction box, at the same way we choose a suitable cables are needed for connection between junction box and inverters.
In order to protect an AC side we choose the circuit breakers that are needed for our PV system.
And after of all we’ve calculated the space area that is needed to install 100 kwp PV system.
We’ve also designed calculator that help us sizing any ON Grid system.

33. Choosing The Elements Of The PV System
Select the type of PV module
We’ve used a Kyocera 140watt module.
Number of modules we need
100 kw / 140w = 714 module.
From the data sheet of this module we have:
Pmax = 140 watt
Vmpp = 17.7 V
Impp = A
Voc = V
Isc = A
Max system DC volt = 600V

34. Choosing The Elements Of The PV System
We need 384 DC volt (this value must be in the range of inverter‘s dc voltage).
Number of modules in series = system Dc volt / module Vmmp
384 / 17.7 = 22 modules.
Number of modules in parallel
714 / 22 = 33 modules.

35. Choosing The Elements Of The PV System
Select the inverter (DC/AC)
In our project we’ve used a 10 kw MAC inverter
From the data sheet, the DC volt range for this inverter is ( ) volt.
S inverters ≥ 1.1 Ppv peak
So we will need a 110 kw tie inverters
Number of inverters
110kw / 10k = 11 inverters
Number of Modules are connected to each inverter
22 * 33 /11 = 22 * 3 modules

36. Choosing The Elements Of The PV System
Cables, protection device & earthing system
Modules require fusing for each module source circuit.
In order to have a successful design we must achieve the following relationship
Irated fuse ≥ 1.25 Isc for module
The 140 watt module have a 8.86 A short circuit current So we use a 15 A fuse for each module circuit.
The cross sectional area for wire must be chosen according to this relationship
Irated cable ≥ Irated for fuse

37. Choosing The Elements Of The PV System
The suitable cable that is connected between junction box and inverter will be D 3-XLPE 16 mm2 cross sectional area. Now we select the C.B to protect the AC side ICB ≥ 1.25 * #of string of module * Isc for each module Icable ≥ ICB We’ve selected a 50 A C.B to protect the AC side of inverter & the suitable cables that connect between inverter and main power supply will be D 3-XLPE 10 mm2.

38. The Elements Of The PV System

39. Area Calculation Of PV Array
Dimensions of Kyocera module
Length = cm
Width = cm
Depth = cm
In Palestine the array of PV solar system placed diagonally at an angle 32 in degrees.

40. Area Calculation Of PV Array

41. PV Calculator

42. PV System Calculator
We designed a calculator that it help us to calculate the suitable elements for any on grid system.
The flow chart of the calculator

43. PV System Calculator

44. PV System Calculator
The following images show the module type that we used in our program and the inverter type.

45. PV System Calculator
After entering the PV System size in kw and DC volt system the program ask to choose a module and inverter that you want to use in PV system.
When you choose them, the data sheet will be displayed in the left side of the window.

46. Our Next Step Actual design on the roof of the hospital (location).
The Connection of the PV system with the grid (cables, transformers, protective devices).
Software Economical evaluation (calculating the total income from the PV system).
Environmental impact.

47. Technical Analysis Of Integration Of PV system

48. Integration of PV systems with distribution networks could bring a number of benefits as well as technical issues.
The benefits could be the reduction in maximum demand charge and energy losses. However, it creates voltage rise issues.
After we analyze the quality of supply that’s come from NEDCO company we take a LV network of An- Najah University Hospital , then we take another residential network to show the impact of PV system on networks.

49. Najah University Hospital Distribution Network (suggestion project)
This network supplies An-Najah University Hospital with a length of 200 m and 400 kVA transformer.
This network consists of 3 phase loads , 3 distribution lines.
The load related to the hospital is 274KVA.
The parameters of the cable and transformers are :
Type of equipment or cable
Resistance(at 50 Hz)
Reactance(at 50Hz)
400 KVA transformer
x/r = 3.09
Z% = 4
Cable (95 mm2)
.273 ohm/km
.330 ohm/km

50. For the photovoltaic system, we identify 140 wp PV modules of 17. 7 V
For the photovoltaic system, we identify 140 wp PV modules of 17.7 V. The PV generator that we want to install it on each bus will consist of 16 photovoltaic modules in series and 15 module in parallel.
The whole constituting a branch of 283 V DC to be connected to an inverters of 36 kW.

51. The network before installing a PV generator.
After installing a 33 kwp PV on a bus 3.

52. Another 33 kwp PV generator was installed on bus 4.
Finally a 33kwp PV
on bus5.

53. Residential network

54. Result before install PV on the network

55. A 5kwp PV on a bus 12 was installed.

56. Result after adding the PV from bus (12 to 4).

57. Impact of the connection of pv on the grid voltage
Number of bus
Bus Voltage befor install PV
Bus Voltage after install PV on bus 3
Bus Voltage after install PV on bus 4
Bus Voltage after install PV on bus 5
Bus 2
392.5
393
393.4
393.9
Bus 3
376.2
381.1
381.5
382
Bus 4
376.7
Bus5
377.1

58. Residention Network Number of bus V beforeinstall PV
after install PV on bus 12
after install PV on bus 11
after install PV on bus 10
after install PV on bus 9
after install PV on bus 8
after install PV on bus 7
after install PV on bus 6
after install PV on bus 5
Bus 2
393.1
393.2
393.3
393.4
393.5
393.7
393.8
393.9
394
Bus 3
386.6
386.8
387
387.2
387.4
387.6
387.8
388
388.2
Bus 4
381.1
381.4
381.6
381.9
382.2
382.5
382.8
383
383.3
Bus5
376.4
376.7
377.1
377.5
377.9
378.2
378.6
378.9
379.3
Bus 6
372.3
372.8
373.2
373.7
374.1
374.6
375
375.4
375.8
Bus 7
368.9
369.4
370
370.5
371
371.6
372.1
372.5
Bus 8
366
366.7
367.3
367.9
368.5
369.1
369.6
370.1
370.4
Bus9
363.8
364.5
365.2
365.9
366.6
367.2
367.7
368.1
368.4
Bus 10
362.1
362.9
363.7
365.8
366.3
367
Bus 11
361
361.9
362.8
363.5
364.2
364.8
365.3
365.7
Bus 12
360.4
361.4
362.3
363.1
364.3
365.6

59. These results shows the compensation of the voltage drop in line.

60. Impact of The Connection of PV Systems on The Power Losses in Distribution Network
Installation of PV systems on the distribution network changes the load profile of customers and hence energy losses on the networks.
In the first distribution network The procedure of the PV system increases from 0 to 100kWp. The reduction of power losses is about 54.5% .
Electrical losses Before install PV
8.4 KW
Electrical losses after install PV at bus 3
6.8 KW
Electrical losses after install PV at bus 4
5.3 KW
Electrical losses after install PV at bus 5
3.9 KW

61. And also in the residential distribution network the procedure of the PV system increase from 0 to 40 kwp, the reduction of power losses is about 19%.
Losses befor insert PV
37.1 KW
Losses after Insert PV at bus 12
36.2 KW
Losses after Insert PV at bus 11
35.5 KW
Losses after Insert PV at bus 10
34.4 KW
Losses after Insert PV at bus 9
33.4 KW
Losses after Insert PV at bus 8
32.7 KW
Losses after Insert PV at bus 7
32 KW
Losses after Insert PV at bus 6
31.3 KW
Losses after Insert PV at bus 5
30.8 KW
Losses after Insert PV at bus 4
30.5 KW
Losses after Insert PV at bus 3
30.1 KW

62. If the energy losses on the network can be reduced, any premature defect of network equipment caused by thermal heating could be minimized. Hence, utility companies may avoid or defer the needs of upgrading their networks. This can help the utility companies to minimize the cost of maintenance for their networks.

63. Is there Any Other Question ?

64. Thanks For your Attention