SOLAR PHOTOVOLTAIC COST REDUCTION VIA EE APPLIANCES AND EFFECTIVE INSTALLATION

i . Wan Rahmah Mohd Zaki

Faculty of Architecture, Planning and Surveying, Universiti Teknologi MARA, Malaysia

E-mail:warazaki@yahoo.com

Abdul Hadi Nawawi Faculty of Architecture, Planning and Surveying

Universiti Teknologi MARA, Malaysia E-mail:hadinawawi@yahoo.com

Sabarinah Sh Ahmad Faculty of Architecture, Planning and Surveying

Universiti Teknologi MARA, Malaysia Sabrin63@yahoo.com

ABSTRACT

Despite being the likeliest alternative energy for houses, solar PV system is not yet economical from kouseholds' viewpoint due to its high capital cost. This paper deliberates on tlte relationship between Energy Effient (EE) appliances and effective PV array installation that can lower solar PVsystem cost without changing a houselrold's lifstyle. A local survey shows EE products namely refrigerator and air conditioning are not only cheaper tlran the non EE appliances from the same category, but also can effect for a significant reduction in the Operational Energy and subsequently PVsystem cost. This paper demonstrates tlrat by using EE appliances, a typical urban houselzold of a landed property can reduce tlze cost of solar PV system around 30% from tlze original price. In addition, it is found that EE appliances are clteaper than conventional products. Another measure tlzat can reduce the cost of PVsystem is to ensure tlre PV array receives maximr~m exposure from the solar irradiation so as to get high performance yield. In Malaysia, this is achieved by laying the PV array almostfInt on an area witltout obstruction. However, a plzysical survey ofprecedent PV Irouses in Putrajaya and Slzah Alamflnds tlzat this aspect is taken lightly and literature review suggests tlrat this may effect for a loss in performance yield and unnecessary high solar PVsystem cost.

Keywords: Refrigerator, Air Conditioning and Solar Irradiance

1.0 INTRODUCTION

1.1 Solar Photovoltaic (F'V) System

Solar photovoltaic (PV) has been recognised as a likely renewable energy for houses due to its simple system configuration. The main component of domestic solar PV system is the PV silicon cells. When exposed to sunlight, these cells generate electricity at atomic level and produce energy in the form of direct current. Using an inverter the direct current can be converted to alternating current for household's consumption. In an off-grid system, the excess solar PV electricity is stored in a battery and ready to be used as required. Otherwise, the recent on-grid PV system technology allows for excess PV electricity to be channelled to the national electricity grid. This

enables house owner to do away with the battery component, hence reducing the total PV system cost significantly (Figure I).

PV Array

isolation switch

Load

Meter Main fusebox \

Storage battery L

Figure. 1: Comparison of Schematic Grid-connected PV System (left) and Off-grid PV System (right) (Source: MEC, 2008b)

1.2 High Capital Cost of Solar PV System

Despite being technically viable, solar PV system is not widely applied in Malaysia. Many researchers attributed the low take-up of solar PV to its high capital cost (Haris, 2006a; Smith, 2005). Solar PV system is expensive mainly due to the silicon content of the PV cells. The production of silicon involves expensive technological procedure and consequently, the component makes up 60% of the solar PV system cost @EC, 2008a). In addition, there is no local manufacturer of PV parts in Malaysia. Li et al. (2008) in his study of PV system in Malaysia informed that all the key components of the system such as the PV silicon cells and inverters are imported fiorn foreign countries, namely Germany and Japan, thus inflating the transaction price when these products reached the local market.

For a house that uses 5,000 kwh (kilowatt hour) electricity per year, the capital investment of PV system (including parts and installation) is approximately (Ringgit Malaysia) RM120,OOO. On the other hand, mains electricity from the national grid requires a capital cost of only RM4,500. In this instance, the economic gap between the two products appears several thousand folds but this is greatly misleading because the capital cost of PV system includes its operational cost and it is a long term investment. However, the capital cost of mains electricity is purely contribution charges to the Electricity Company. A more appropriate approach to demonstrate the quantum of price difference is through relative price comparison between solar PV system and mains electricity on specific households. This can be done by deducing a hypothetical monthly "PV electricity bill" for certain households and compared it with their monthly mains electricity bills.

Intenlcitioriol Symposiin ~ , t Devcloi:iii&z igconortlies: Cornmonciiines Ainong Diversities ~.

1.3 Relative Price of Solar PV System

Tang (2005) in his study on Energy Efficiency (EE) in the local residential sector had deduced the amount of electricity consumption by households with income brackets from RM5,000 and below RM1,OOO. Based on Tang's data, and assuming the amount of electricity consumed by these groups of household are constant, the amount of electricity consumption for specific households can be ascertained by computing it with the relevant electricity tariff rate charged by the Electricity Company, i.e., Tenaga Nasional Berhad (TNB, 2009) (Table 1).

Table 1: Monthly Electricity Consumption for Household with Monthly Income Between RM5,000 to Below RM1,ooo

Calculation Description Note: RM is Ringgit Malaysia

Average energy used per household per year deduced by Tang (2005) (kWyear)

Household Income

RM.5000 I RM4000 I RM3000 I RMZ000 I RMlOOO RMlOOO

Average energy used per household per month deduced !?om Tang (2005) (kWyear)

2009 TNEi domestic tariff for &st

3268

@ RM0'218kwm0nth and for next 200kW @ RMO.334kWmonth (RMlmonth)

Capital cost of mains electricitv

--

Consequently, a hypothetical monthly "PV electricity bill" can be inferred for these households (Table 2). Haris (2006b) suggested that lkWp (kilowatt peak) of solar PV array in Malaysia can generate 1200 kWh of PV electricity annually. Generally, lkWp of solar PV system (of any type) costs RM26,OOO and has 30 years' service life. If the households in Tang's study were to be fitted with solar PV system, households with monthly income of RM5,000 to below RM1,000 will need solar PV system with capacity ranges from 2.72kWp to 1.17kWp. Converting this into monthly electrical consumption, the hypothetical "PV electricity bill" for households with monthly income of RM5,000 to below RM1,OOO varies between RM196.4 and RM84.5 per month, for 30 years.

272

&4,500) averaged for 30 anticipated building's life time (RiWmonth)

2754

RM67.65

230

RM12.50

2495

RM53.62

208

RM12.50

2130

RM46.27

178

RM12.50

1611

RM38.80

1409

134

RM12.50

117

RM29.21 RM25.51

RM12.50 RM12.50

Internationol.~vnipo.i.iurn it? Developing Ecoriomies: C~~~~~motitrl;~-iesi i t~to~~~t Diver.citit.s

Table 2: Hypothetical Monthly "PV Electricity BilP' for Households with Monthly Income Between RM5,000 to Below RM1,OOO

Calculation Description Note: Rh4 is Ringgit Malaysia

Average energy used per household per year deduced ftom Tang (2005) (kwyem)

Capacity of solar PV installation @ 1,200 kwyear (kWp)

Capital Cost of solar PV system installation @ RMZ6,OOOlkWp

The relative price of solar PV system and mains electricity in terms of their respective monthly electricity bill makes a fair comparison between the two products (Figure 2). Nonetheless, the apparent monetary gap makes it unlikely for solar PV system to be applied in households that are already enjoying electricity from a cheaper source, i.e., mains electricity supply.

Eousehold Income

3268

2.72

HY?'othetical monthly "PV electricity bill" for 30 years

a ~ ~ ~ o f l ~ e t i c d ~ o n t h l ~ PV Electdcity Bill

RM70,720

. ERaillS Supply Monthly Electdcity Bill Deduced fro111 Data byT<ang (2005)

2754

2.30

Rh4196.4

Househ~oIdsMonthh Income

RMlOOO RM2000 RM5000

RM59,800

Figure 2: Comparison of Hypothetical Monthly "PV Electricity Bill" and Mains Electricity Bill for Households with Income Brackets ftom RM5.000 to Below RM1,OOO

< RMIOM)

2495

208

RM166.1

Another reason for the wide economic gap between PV electricity and mains electricity is due to the subsidy embedded in the price of i&e latter. According to the Economic Planning Unit (EPU) (2008), natural gas intended for generating electricity for domestic consumption is being sold to the Electricity Company at RM6.40 per mmBTU (million British thermal units), whereas the actual market price is RM40.53 per mmBTU.

RM4000

RM54,080 RM46,280

RM3000

2130

1.78

RM150.2

RM34,840

1611

1.34

RM30.420

RM128.6

1409

1.17

RM96.8 RM84.5

Having said that, there are several policies being implemented to induce reduction in the price of solar PV system. Amongst others is the generous subsidy scheme known as SURSA 1000 whereby potential PV owners can bid for the amount of fund up to 75% off the total solar PV system cost (MEC, 2006). In addition, the present mandatory requirement for grid-connected PV system provides an opportunity for PV owner to "sell" excess PV electricity to the national electricity grid. When the selling rate is made more attractive in the future, PV owners with low electricity demand would enjoy a shorter payback period. The government has also allowed for companies providing "energy conservation services" to be exempted from import duty and sales tax on imported equipment for a certain period (Treasury, 2009). This is intended to affect for solar PV suppliers to reduce the price of equipments and components of the system which are mostly imported.

Nonetheless, all these actions are still too i n s i d c a n t to drive the domestic PV price down. The market response on PV is still low such that the end of December 2008, there were only 23 solar PV installations including 10 by housing developers (MEC, 2009). On the other hand, 536 high-end detached houses and 162 town houses were completed around the same time (NAPIC, 2008). It appears that the high-income households, presumably those who can afford to pay for the high capital cost of solar PV system are not receptive to the idea of using the product as an alternative energy source. Therefore, it is imperative to look at reducing the cost of solar PV system from basic common sense perspective. Since a major part of PV system cost goes to the PV module, a reduction in the element will have a significant impact in reducing the PV system cost. This paper deliberates on how PV system owner can reduce the quantity of PV module and subsequently PV system cost by using EE appliances and effective installation, without compromising their lifestyles.

2.0 ENERGY EFFTCIENT (EE) APPLIANCES

2.1 Basic Operational Energy (OE) Requirement in a House I

Building's OE is a necessary element of a house because most items that fulfil occupant's modem lifestyle and indoor comfortable conditions require some form of energy to function (Figure 3). Nonetheless, OE varies from one property to another depending on the house design and its occupants.

I Building Operational Energy

I I I I I - Rice Cooker I I - M e r Heater I I

Washing Machine I I - Td-OII I I I I I I - Vaamm Cleaner I I !

Figure 3: Demand for Operational Energy

Mainly, there are two reasons for OE: to provide comfortable indoor conditions and to fulfil the modern needs of the occupants. Although mechanical cooling and artificial lighting are required to create thermal and visual comforts, respectively, the use of these appliances is influenced by lifestyle due to the subjectivity of the term comfort itself. Nonetheless, it is a fact that using EE equipment will reduce the amount of OE in a building as found in several researches. A local study by Mahlia et al. (2005) on the cost-benefit analysis and emission reduction of lighting retrofits in residential sector affirmed that EE lights reduces OE and offers monetary savings to house owners. Meanwhile, Tang (2005) in his study on EE in the local residential sector claimed that using EE air conditioning unit can save up to 25% of electricity expenditure on cooling cost compared to the non EE unit.

A study of 50 urban househoIds in Petaling Jaya, Selangor by the Centre for Environment, Technology and Development (CETDEM) Malaysia in 2006 found that the top two household appliances that consumed the most electricity are air conditioning and refigerator, forming 44.2% and 21.5% of the surveyed household total average electricity consumption, respectively. Based on these findings, and taking lifestyle as a constant, it makes sense to use EE air conditioning system and refrigerator in the quest to reduce the amount of OE demand and subsequently the PV module.

2.2 Energy Efficient (EE) Refigerator

A physical survey on EE product was carried out at a popular shopping mall in Kuala Lumpur in April 2009. Although several manufacturers claim to offer EE refigerators, only six models were found to provide evidence of Energy Star certificate issued by Energy Commission that validate the

lnfernfrtioitill Svi~tposit~l f f t Devi?lo~)ifg Econoittie.5: Cornmnnfrlities Airtong Diversities

claim and they all accorded with 5-star energy rating. A comparison of prices for the six EE refrigerator models with the others of similar capacity reveals that the former is cheaper than the latter (Table 3). As such, financial comparative study namely Life Cycle Cost (LCC), Payback Period or Return on Investment for EE and non EE refrigerator is futile and unnecessary. Assuming the household is indifferent to the style and design of refrigerator, it can be said that investment decision in EE refrigerator by PV system owner is a matter of choice, or otherwise.

Table 3: Price Comparison of EE and Non EE Refrigerators of the Same Capacity in the Local Market

On the average, the Energy Star certificate on the EE refrigerator stated that it saves 25% of annual energy consumption compared to the non EE refigerator of the same capacity.

5-star Energy Star

No

No

Yes Yes No

No

No

No

Y cs No

No

Yes No No No

No

Yes No

No

No

No

Yes

No

No

2.3 EE Air Conditioning

Similarly, another physical survey was conducted for air conditioning unit at the same shopping mall. It was found that most air conditioning manufacturers offered both EE and non EE units. 'Inverter' technology in air conditioning industry has resulted for a smart product that does not need much power during start-up. It reduces the fluctuation in power requirement to suit the set point temperature regardless the variation in the room temperature. A well known manufacturer claims that inverter EE air conditioning unit of 1.5 hp (horsepower) can saves up to 52% of energy cost compared to the non EE unit of the same capacity (Table 4).

Brand

Hitachi Panasonic

Sharp

Toshiha Hitachi

Electrolux

Samsung

Hitachi

Toshiba Samsung

Samsung

Sharp Panasonic Panasonic

LG

LG Toshiha Samsung

Hitachi

Hitachi

Hitachi

Hitachi Hitachi

Electrolux

Model

RZ48OAM NR-B403V

SJPTSORSL GR-MG43MD R-Z55OAM

ETM-4400DA

RS-HI KLMR R-Z65OAMX

GR-MG48MD RS-2ONRPS

RSZOBRHS

SJPT66RHS NR-D5 12X NR-B651G

GR-B2 17LGQ GR-C2 17LG.J

GR-Y G73MDA RT77SBSM

R-SSOOGM(GS)

R-S800GM(GWH)

R-SSOOGM(GBK)

R-M8000EM(GBK)

R-SSOOEM(GS)

ERE6100SX

Capacity Q

395 395

397 400

435 440

506

508

510 510

510

510 512 521

58 1 581

587 588 589

589

589

600

605

606

Price (RM)

1659 2469

1799 1699 1959

2649

7999

2559

1999 3299

3699

2549 5649 3049 5999

7599 2899 2899

6299

6299

6499

5699

4699

7599

Table 4: Comparison of Monthly Elechicity Cost between Non EE and EE Air Conditioning Units as Claimed by a Local Manufacturer

However, unlike the EE refrigerator as discussed in section 2.2, the price of EE air conditioning unit is higher by 28% to 37% compared to the non EE unit (Table 5).

Table 5: Comparison of Capital Cost between Non EE and EE Air Conditioning Units as published by a Local Manufacturer

% Monthly Saving

51.6%

In addition, the installation cost for EE air conditioning unit at RM220 is 25% more than non EE unit that averages at RM180 due to the extra plumbing works required by the former. In this instance, a hancial viability study for EE air conditioning unit is necessary to make economic sense of investing in the product. Taking the effective service life of a typical air conditioning unit to be 10 years, Table 6 and Table 7 show the total LCC for non EE and EE air conditioning unit, respectively.

Monthly Electricity

Bill

39.24

18.97

1.5hp Non EE Air Conditioning Unit

1.5 hp EE Air Conditioning Unit

Saving

20.27

No. Of

Days Used

30

30

Percentage Difference

37.41%

33.10%

29.72%

27.70%

Electricity Rate

0.2 18

0.218

Model

CS- PC12JKH

CS- S13m

-

Horsepower

1

1.5

2

2.5

Power Consumption

per day

6.0 kwh

2.9 kwh

Difference (RM)

370

430

600

670

EE Air Conditioning Non EE Air Conditioning

Panasonic Model

CS-SIOJKH

CS-S~~JKH

CS-S15JKH

CS-S18JKH

Panasonic Model

CS-PC9JKH

CS-PCI2JKH

CS-PCl8JKH

CS-PC24JKH

Price @m

1359

1729

2619

3089

Price @'Q

989

1299

2019

2419

Table 7: 10-year Total Lie Cycle Cost of 1.5hp EE Air Conditioning Unit

Table 6: 10-year Total Life Cycle Cost of 1.5hp non EE Air Conditioning Unit

LCC exercise shows that for any number of 1.5hp EE air conditioning units, the product costs less in the long term approximately by 33%, compared to non EE unit; hence a worthwhile investment (Figure 4). As such, it can be established that investment in EE air conditioning unit is a matter of desire, or otherwise.

1.5hp non EE Air Conditioning Unit Model Panasonic

CS-PC12JKH

No. of Air Conditioning Unit in a House

Capital Cost (RM)

Installation Cost (RM)

Operation Cost at RMO.28lkWh (RM) (see Table 5)

Maintenance Cost at 10% of (0) (RM)

Salvage Cost (RM)

Total Life Cycle Cost (C+I+O+M-S) (RM)

EE Air Conditioning Unit Model Panasonic CS- S13JKA

1

1,299.00

180.00

4,708.80

470.88

20.00

6,638.68

(C)

0

(0)

0

(s)

(LCC)

NO. of Air Conditioning Unit in a House

Capital Cost (RM)

Installation Cost (RM)

Operation Cost at RM0.281kWh (RM) (see Table 5)

Maintenance Cost at 10% of (0) 0

Salvage Cost (RM)

Total Life Cost (C+I+O+M-S) (RM)

1,729.00

220.00

2,276.40

227.64

20.00

4,433.04

(C)

0

(0)

N

(s)

(LCC)

2

2,598.00

360.00

9,417.60

941.76

40.00

13,277.36

2

3,458.00

440.00

4,552.80

455.28

40.00

8,866.08

3

3,897.00

540.00

14,126.40

1,412.64

60.00

19,916.04

3

5,187.00

660.00

6,829.20

682.92

60.00

13,299.12

4

5,196.00

720.00

18,835.20

1,883.52

80.00

26,554.72

4

6,916.00

880.00

9,105.60

910.56

80.00

17,732.16

5

6,495.00

900.00

23,544.00

2,354.40

100.00

33,193.40

6

7,794.00

1,080.00

28,252.80

2,825.28

120.00

39,832.08

5

8,645.00

1,100.00

11,382.00

1,138.20

100.00

22,165.20

6

10,374.00

1,320.00

13,658.40

1,365.84

120.00

26,598.24

Non EE Air Conclitioning Unit

EE Air Conditioning Unit

No. of Air ConclitioningUnits in a House

Figure 4: Comparison of 10-year Total Life Cycle Cost of 1.5 hp EE and non EE Air Conditioning Unit of the Same Brand

2.4 Effect of EE Refrigerator and EE Aii Conditioning on Total Solar PV System Cost

Findings in section 2.2 and 2.3 show that EE refrigerator and EE air conditioning unit save 25% and 52% of electricity consumption compared to non EE appliances of similar capacity, respectively. To demonstrate the relationship between EE products and solar PV system cost, a hypothetical solar PV requirement is deduced for the average landed houses in CETDEM's study (Table 8). Landed properties is chosen to demonstrate the case because they are likely to have solar PV system as shown by precedent PV houses (MEC, 2009). Based on CETDEM's (2006) data of OE requirement for the average bungalow, semi-detached, double storey terrace and single storey terrace, it is deduced that the annual electricity consumption varies from 21,000 kWh to 5,000 kWh. According to Tan (2009) the recorded annual energy consumption was fairly high at 21,000 kWh per year. It is not the agenda of this paper to scrutinise the quantum of electricity consumption, but from the appliances' individual electricity consumption figure, it is assumed that these houses used non EE appliances. Subsequently, the hypothetical PV cost for these houses can be ascertained using the same method in section 1.3. It is found that if CETDEM's houses were to use solar PV system, the system sizes are between 18 kWp and 4 kWp. By applying EE refrigerator and EE air conditioning units to CETDEM's houses, it is found that the solar PV capacity can be reduced by about 4.4 kWp in bungalow type houses and around 1 kWp in other type of houses. Consequently, this exercise shows EE appliances can reduce the total cost of solar PV system by about 30% in the case of CETDEM's landed houses.

inti!n?crtioirol Syrriposirt~ Irt Uewlopicig Econonlies: Cosrrmoniilities A~rtorr$j Diversities

Tnble 8: Hypothetical Solar PV System Cost and the Effect of EE Appliances in CETDEM's Houses (Landed Type of Properties only)

DERIVED FROM CETDEM'S STUDY

Bungalow

Monthly Refiigerator Consumption (kWh)

Monthly Cooling Consumption (kwh)

Total Electricity Consumption Annually (kwh)

Total solar PV Requirement (kWp)

Total PV System Cost (RM)

DERIVED FROM CETDEM'S STUDY AND BASED ON PHYSICAL SURVEY

BASED ON CETDEM'S STUDY

Semi D

311.47

845.37

21,319.32

3 .O EFFFCTIVE PV ISTALLATION

2x Storey

136.80

127.18

5,054.04

Saves 25% Annually if Use EE Refrigerator (kwh)

Equivalent Saving in PV Capacity (kWp)

Equivalent Saving in PV System Cost (RM)

Saves 52% Annually ifuse EE Air Conditioning (kwh)

Equivalent Saving in PV Capacity (kWp)

Equivalent Saving in PV System Cost (RM)

Total Savings in PV System Cost (RM)

Percentage of Savings in PV System Cost (%)

Effective PV installation can help to reduce the amount of PV module required in a PV system. Nevertheless, it must be noted that effective PV installation in the context of this paper does not mean efficient PV cell. The efficiency of PV cell describes the ratio of power output against PV input at cell level. For example, the efficiency of the PV cell is the highest in monocrystalline type, because less of such cell is required to generate the same amount of energy compared to polycrystallie PV cells which is less efficient (MEC, 2008b). Comparatively, since amorphous thin film is the least efficient, more of such cells are required to generate the same amount of energy as in polycrystallie. The efficiency of the PV cells can be deduced &om its price whereby monocrystalline being the most efficient commands a high price while amorphous being the least efficient is the cheapest and polycrystalline is somewhere in between. Subsequently, for the same amount of power output, the system cost for lkWp of polycrystalline or lkWp of thin film amorphous is approximately the same because more cells are required from the least efficient type of PV cell and less is required from the most efficient type of PV cell. Eventually, the price of any types of cells that offer the same effective service life, say about 30 years is the same, i.e., currently at RM26,OOO per kWp. As such, fiom Economics' viewpoint, the efficiency of PV cell makes no monetary difference.

On the other hand, effective solar PV system makes a significant economic impact to the PV system cost. The effectiveness of solar PV installation is reflected in the performance yield that measures the output against the input at system level (Eq 1).

lx Storey

Yield = Output PV Electricity (kwh) Input PV Capacity (kWp)

120.07

221.58

6,220.68

934.41

0.78

20,245.55

5,275.1 1

4.40

114,294.02

134,539.57

29.13

89.49

238.70

5,672.40

410.40

0.34

8,892.00

793.60

0.66

17,194.74

26,086.74

23.82

360.21

0.30

7,804.55

1,382.66

1.15

29,957.62

37,762.17

28.02

268.47

0.22

5,816.85

1,489.49

1.24

32,272.24

38,089.09

30.99

However, to make economic sense of the performance yield, Eq. 1 is modified to reflect the monetary value of the anticipated performance yield (Eq. 2).

Performance Yield = Output PV Electricity Generated to meet OE (kwh1 Input PV System Capacity planned for the OE (kWp)

(2)

Basically, the desired PV output electricity should meet the OE demand of a house. This means the installed PV system capacity, mainly the PV module, should produce the required PV electricity matching the OE demand. According to Hadri (2006b), lkWp of PV system in Malaysia would produce 1200kWh, annually. Therefore, if the OE demand of a house is 3,600 kwh per year, the PV system should be 3kWp. However, if the same house gets only 3,000 kwh of PV electricity, it can be said the 3 kWp PV system is under optimised. In this instance, the performance yield has dropped by 17% and despite paying for 3kWp of PV system, the PV owner actually gets electricity worth only 2.5 kWp. Effective PV installation in the context of the paper means that the PV owner should get the anticipated yield as what he had paid for. If the PV system is giving output below the predicted yield, the PV owner has to spend more on the PV system (such as increasing the no. of PV module) so as to match the required OE demand, making the total system costs more expensive than necessary.

This paper looks at how performance yield can be maximised with little effort, but also will reduce the total cost of solar PV system, thus making it more affordable. To demonstrate the point clearly, present PV precedents are compared against two obvious measures that can result for high PV performance yield, namely maximum and unobstructed exposure to solar irradiation.

3.1 Maximum Exposure to Solar Irradiation

A straightforward action to ensure the high performance yield &om the solar PV system is to position the PV array where it can capture the most of solar irradiance. This can be ascertained fiom the sun path diagram for the PV house locality. Sun path diagram shows paths of the sun at different times of the year projected fiom the sky dome onto the flat image (Figure 5). Autodesk (2008) suggests that the best way to conceptualise a sun path diagram such as in Figure 5 is to liken it to a photograph of the sky, taken whilst lying on the ground looking straight up towards the zenith with a fish eye lens. Each sun path lime represents the exact position of the sun as it passes through the sky at a specific time. The sun path diagram for Malaysia in Figure 5 shows the path of the sun is above the head almost throughout the year.

Intcrnutiottal Syrnposittt lit Uevelo(tirtg L'cononties: Cornmt~nalities ~lmorw Diversiiies

Figure 5: Sun Path Diagram for Kuala Lumpur (Source: IES, 2006)

As such, the best position for the PV array in Malaysia is on a flat surface (such as flat roof) where it receives the most of the solar irradiance (Figure 6). According to a solar PV supplier, since Malaysia is located at 3.12% of the equator, the maximum solar irradiance can be captured if the PV array is tilted 15' to face south (IPS, 2009).

Figure 6: Percentage Amount of Solar Irrandiance on a Building Facade in Malaysia (Source: Ruoss, D., 2006)

A physical survey was carried on the latest domestic solar PV development situated in Putrajaya, Malaysia. There are four detached houses with each having an average 5.25 kWp capacity of PV. It was observed that these houses have good orientation, i.e., east-west meeting the sun path diagram for Malaysia (Figure 7).

Inter.nutii~nul.):~n~p~tsi~itn it? Dfve1opir1.g Economies: Ct.1nrmot1trliti~'.s11nrutig L)i~:ef:?ir.ies - ~. . . ~ ~~ ~. ~~ ... .

Figure 7: Site Plan of PV houses in Putrajaya (Source: Putra Perdana Construction, 2009)

However, the Putrajaya houses are with pitched roof with the ridge running north-south. As a result, the PV array has to be fitted on the east side of the gable to catch the ante-meridiem sunlight and the west side to catch the post-meridiem sunlight (Figure 8). Thus at every moment of the day, apart of the PV cells is underutilised.

Figure 8: Under-optimised PV Installations on the West (left) and East (right) Side of the Roof at a House in Putrajaya.

3.2 Unobstructed Exposure to Solar Irradiation

Meanwhile, a precedent PV house in Shah Alam has got both the orientation and shape of the roof flat, rightly designed to get the most of the local solar irradiance. However, an oversight in the installation has caused for a portion of the PV module to be shaded by the adjacent smcture (Figure 9).

Figure 9: Site Plan (left) and Flat Rooftop (right) of an Almost Perfect Solar PV Installation in Shah Alam

Small shading on PV module, say by a leaf or antenna, is detrimental to the performance yield of solar PV system. According to Sick and Erge (1996), shading of PV cells affects the performance yield because these cells perform best when they are homogeneously illuminated. Apparently, shadow on PV cells decreases the available output power due to that fact that the cell with the lowest illuminance determines the operating current of the whole series of PV strings. Sick and Erge demonstrated this effect as being comparable to a water hose which is pressed tight at one point preventing the flow of water in the whole hose (Figure 10). In addition, Sick & Erge suggested that under certain circumstances a partially shaded PV cell may even be forced into a load mode. This can lead to a thermal destruction of cell and the respective PV module.

Figure 10: Minor Shading Can Cause Energy Loss Compamble to Pressing Water Hose (Source: Sick and Erge, 1996)

It can be said that the poor PV orientation and shaded PV module as demonstrated by the above precedents have caused for the PV system to be less effective, as far as performance yield is concerned. In the case of PV house in Putrajaya, more of PV modules have to be fitted in the system to make up for the original OE demand of the house, hence more cost to the solar PV system. Meanwhile, despite the almost perfect PV installation in the Shah Alam PV house, the shaded PV array induces energy loss and makes the system less effective. Based on Eq. 2, the performance yield is low in the Putrajaya precedent due to the increase of the total PV system cost and in the Shah Alam precedent due to the drop in energy output. Theoretically, more PV array needs to be added to both cases to meet the OE requirement of the houses. As a result, the total solar PV system costs more than necessary.

4.0 CONCLUSION

Yeang (2006) noted that there is much misconception about "energy-cautious" houses. He pointed a "popular perception that if we assemble in one single building eco-gadgetry such as photovoltaic ... we will instantaneously have ecological architecture." This paper echoes Yeang's concern and provides evidence that EE can effect for low OE and can help to reduce the cost of the solar PV system. In fact, this paper has demomated that by using EE appliances, a typical urban household such as the CETDEM's house can reduce the cost of solar PV system by 30%. In addition, the paper found that EE refrigerator and air conditioning units are also cheaper to run compared to non EE products; as well as cheaper to buy in the case of EE refrigerator.

Literatures by experts in the field of solar PV have deliberated on the critical measures for effective PV system. However, precedents in Putrajaya and Shah Alarn with poor PV position and blocked PV installation, respectively, may effect for low performaace yield. Made worse by not using EE household appliances, the total PV system cost may be unnecessary high. This paper shows that good understanding on the relationship between OE, EE and effective PV installation can help to reduce the total solar PV system cost.

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