International Journal of Electrical and Computer Engineering (IJECE) Vol.
No.
October 2015, pp.
ISSN: 2088-8708
A Review of Solar PV-Grid Energy Cost Parity in Akure.
South-West Nigeria Melodi A.
Famakin S.
Department of Electrical and Electronics Engineering.
Federal University of Technology.
Akure.
Nigeria
Article Info
ABSTRACT
Article history:
The abundance of solar energy in Akure.
South-West Nigeria and its feasibility as an alternative energy source has been proven.
However, cheap.
Government subsidized but unreliable grid electricity and high cost of solar equipment are considered the major hindrances to deployment of solar energy for improved power supply and environmental sustainability.
earlier work pointed out realistic pricing of electricity, reduced cost of solar equipment and reduction in solar cell degradation factor as major factors capable of speeding up parity hence, motivating solar energy consumption.
showed that parity is attainable within 14 years.
Documented significant improvements in these factors in recent times are the motivations for this This review cost-comparatively re-assesses both sources of energy under the prevailing National electricity policy and market realities using simple mathematical and graphical modeling techniques.
This is with a view to determining a new timing for parity of solar energy with grid supply.
Results showed that solar PV-grid energy cost parity is now attainable within 6 years in the study region.
It was also observed that sustained improvement in grid energy unit cost and reduction in cost of solar equipment and accessories may accelerate solar-grid energy parity to less than three years.
Received Feb 13, 2015 Revised Jun 9, 2015 Accepted Jun 24, 2015 Keyword:
Electricity policy Grid parity PV-grid Solar cell degradation Solar energy Copyright A 2015 Institute of Advanced Engineering and Science.
All rights reserved.
Corresponding Author:
Melodi.
Department of Electrical and Electronics Engineering.
Federal University of Technology.
PMB 704.
Akure.
Nigeria.
e-mail: melodiadegoke@yahoo.
INTRODUCTION
Inadequate and unreliable power supply has been a very significant constraint to socio-economic development in Nigeria.
Generous government subsidy on the inadequate available power has been one of the major problems militating against the development and deployment of unconventional energy resources such as solar energy.
Though solar energy is abundantly available in Akure ( 7o 15Ao N, 5o 11Ao24AoAo E) and may be easily deployed to meet daily simple energy needs in areas such as transportation, recreation, domestic and industrial lighting and heating, mobile charging etc .
, the equipment and accessories for harnessing it are quite expensive.
The recent privatization of the Nigerian power sector has led to systematic increase in the unit cost of electricity, which was a major incentive to early solar PV-Grid energy cost parity.
The concept of parity is a major selling-point for renewable energy sources such as solar whose initial costs of procurement are often prohibitivecompared to traditional energy sources, though considered cheaper on the long run on account of little or no operational cost.
As cheap energy is naturally attractive to consumers, it is important to assess the progress made by solar energy in approaching parity with grid supplied energy since .
this is the objective of this review.
The aim of this work is to assess the progress made towards grid parity between 2011 and 2014.
an earlier assessment by .
, the timing of parity for an installation carried out in that year was found to be 3years or 57% of the useful life of a solar module.
This review becomes necessary in view of the rapid Journal homepage: http://iaesjournal.
com/online/index.
php/IJECE A ISSN: 2088-8708 changes in the following indices earlier identified in .
as key to achieving early solar-grid electricity parity in the study location:
Rapidly falling price/watt of solar modules, inverters and other accessories .
Upward review of electricity tariff in Nigeria .
New information and data on solar cell degradation in literature Between 2011 and 2014 the average price of solar modules has reduced from $4.
18 to $0.
66 per watt .
, the Multi-Year .
Tariff Order (MYTO) introduced by the Nigerian Electricity Regulation Commission (NERC), in 2008, which was designed to establish a cost-reflective electric energy pricing within five years.
2008-2012 has experienced two reviews giving birth to the MYTO 2 .
and MYTO 2.
Each version of the policy portrayed varying but progressive upward review of the electricity tariffs across all sectors of NigeriaAos socio-economy.
In addition, .
had proposed 0.
71% annual solar cell degradation for crystalline silicon modules.
However, emerging results from field tests on solar modules spanning over forty years carried out by the National Renewable Energy Laboratory (NREL) and covering a wide range of module technologies has put the figure averagely at 8% per annum and are now available in literature .
Consequent upon the foregoing, it is opined that the above combination of factors would have significantly affected earlier results obtained.
Hence, there is need to investigate the new solar PV-grid energy cost parity scenario.
RESEARCH METHODOLOGY
1 Energy and Power Demand Estimation Adopting a typical three room apartment in the study area, a demand estimate is carried out from first principles based on common and regular home appliances.
The power ratings of each were determined from the ratings of similar commonly available appliances in the open market.
Table 1 shows the details of compiled and applied demand assessment data.
Expected daily household energy consumption ( ) is obtained with consideration for diversity as in Equation 1:
represent energy consumption, unit appliance rating, quantity, and daily hours of use for appliance respectively.
Household peak load ( .
) is obtained with consideration for divesity as in Equation 2, assuming power factor of unity:
is load diversification factor of appliance .
, .
, and From table 1 obtained .
is approximately 3,335 W.
However, average household load:
IJECE Vol.
No.
October 2015 : 879 Ae 886 istotal household connected load.
IJECE
ISSN: 2088-8708
Table 1.
Compiled Demand Assessment Data and Estimation for a typical Household in Region CFL lamps Television Cable TV decoder DVD player Computer Fan Freezer Blender Wash Machine Pressing Iron Water Pump Hair clipper Mobile Phones Electric kettle 3,200.
, .
2,520
1,200
1,920
2,000
3,334.
2 Estimation of Deep Cycle Battery Capacity Needed At sun-up, the load is served from the solar modules via the inverter.
If inverter output terminal is regulated to 220V, then, average AC drawn by load in a day is given by:
43 through the DCAt sun-down or during heavy cloud covering, the battery supplies between the AC/DC AC converter.
If battery terminal voltage quantities may be stated as:
Consequently, average battery current drawn by load in a day:
If sun-up hours = 5.
21 hours .
, then sun-down hours .
is given by:
Minimum battery capacity needed to cover this period is given by:
is battery efficiency.
80-90%).
is valued at 85% (For deep cycle batteries, average .
varies from A standard overall battery capacity of 300AH is adequate for this application.
3 Estimation of Solar Array Capacity Within the sun-up hours of 5.
21hours, it is required that the battery be charged up.
For the battery to charge up in charging time of 5hours, then, charging current .
is given by:
Applyinganalogy in Equation 5.
A Review of Solar PV-Grid Energy Cost Parity in Akure.
South-West Nigeria (Melodi A.
ISSN: 2088-8708
Overall equivalent ac current drawn from the solar array is:
Hence, total power drawn by battery and load through inverter is:
1,755.
Average efficiency of domestic inverters is 95% .
Power delivered by solar array is given by:
1,848
A system of 8 solar modules amounting to 2000W solar array capacity may be adopted for the 4 Inverter Capacity Estimation For any solar-electric power application designed to power appliances, if individual appliance (KW), total connected load is denoted by .
, (KW),
power rating is is inverter rating (KW), then the capacity of inverter needed for any application should satisfy the condition:
From Equation 13, considering peak load and starting current effect of motorized appliances, 3500W inverter capacity is selected, which could have a peak capacity of up to 4000 W.
5 Utility Grid per Unit Energy Cost Energy billing history for residential load category (R.
from 2000-2007, were obtained from the system's energy and billing records.
Akure.
Nigeria.
Also, the stipulations of energy cost for the same consumer category, spanning ten years .
, were extracted from the NERCAos MYTO documents.
With these two sets of data, an eighteen year energy cost trend spanning 2000 to 2018 was obtained.
This cost variable is denoted , being year index.
6 Solar PV Energy Cost Per Unit .
Equipment Costing Table 2 shows, the current cost of solar power equipment as obtained from ebay on-line store as of Januar2015.
This has been used as the basis for the costing in Table 3.
Total cost of solar PV system .
nnotated as ) is evaluated as in Equation 14.
, and , , are costs of solar panels, cost of inverter, cost of battery, cost of supporting steel structure, cost of cabling and terminations, and cost of labour respectively.
Obtained values for these cost components and entire system are as shown in Table 3.
Table 2.
Solar Equipment Price Index Ae January 2015 .
Equipment Average Price/unit (USD) 250W Solar 230/Module Module modules Sampled Manufacturers.
Unisolar.
Sunware.
Sanyosolar.
Sharp Corporation.
Suntech Power 3000W Inverter 800/Unit Deep Cycle 88/Amp-hour Battery Solarix.
Soltek.
Powersine.
Sharp.
Electronics.
Powerpro Varta AG.
Exide.
Optima.
Dyno,Trojan Battery.
Deka IJECE Vol.
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IJECE
ISSN: 2088-8708
Table 3.
Bill of Estimate for the Installation of 2.
0KW Solar PV System
S/No Solar PV System units 250W, 12/24V Crystalline Silicon Solar module Inverter capacity Deep Cycle Battery Solar modulesAo supporting steel structure Cabling and terminations Labour
TOTAL
At NGN168/1.
0USD exchange rate Source of Exchange Rate: .
Quantity/ Capacity Unit Lot Lot Lot Rate ($) Costs Notations Cost ($) 1,840.
$3,714
N623,952
Estimation of Annual Energy production Annual energy produced by the system is given by:
3,803.
This represents original or nominal Energy Generation Capacity (EGC) of the solar module in the installation 7 Mathematical Model for the Cumulative Energy Produced in the InstallationAos nth Year Due to the phenomenon of cell degradation, the efficiency of solar modules drops with age.
According to .
, the mean degradation rate of solar modules is 0A8% per year.
For an installation effected in 2015, if the overall electrical energy produced that year is denoted by E n A1 .
, where n indicates year, then energy produced in the following year may be denoted by E n .
Therefore, on account of cell degradation.
EGC of solar modules at any year can be modeled as:
1,2,3 A
If 2015 is the base year of installation, then, 1,2,3, .
O 2016, 2017, 2018, .
, hence.
Let Cumulative energy produced by the n year, be denoted by U Let the constant 0.
992 be denoted by k hence.
U is solar cell degradation factor .
8 Estimation of the Unit Cost of Solar Electricity Maintenance of solar installation and the accompanying accessories are negligible.
Hence, if unit cost of energy produced by a PV in year is represented by (N/kW.
and total cost of equipment by (N), then, from first principles .
Au Cost per unit of energy in the first year of installation ( .
yields: 165.
38/KWh RESULTS AND DISCUSSION The result of implementing Equation .
is shown in Table 4 followed by a graphical comparison of the two scenarios, presented in Figure 1.
A Review of Solar PV-Grid Energy Cost Parity in Akure.
South-West Nigeria (Melodi A.
ISSN: 2088-8708
Table 4.
Comparison of Solar PV-Grid Energy Cost Per Unit , kWh , kWh , kWh 3,514.
N/kWh Energy cost (N/kWh.
Solar PV-Grid Energy Cost Comparison Year C_g.
C_PV.
Expon.
(C_g.
) Expon.
(C_PV.
) Figure 1.
Comparative cost analysis of solar PV system and Grid supply From Figure 1, it is observed that initial cost of energy from a solar PV system is very high but falls exponentially with the years since operation and maintenance cost is negligible.
Trend line analysis of these graphs using Microsoft Excel chart wizard shows that the graphs may be described by:
are unit cost of solar electricity and grid supplied electricity in At the point of convergence .
of the two curves:
IJECE Vol.
No.
October 2015 : 879 Ae 886
IJECE
ISSN: 2088-8708
Reckoning from year 2015 inclusive, the 6 year comes to the year 2021.
This implies that a solar PV system installed in 2015 will be able to attain grid parity and subsequently, profitability above grid supply within 6 years after its installation.
This is about 24% of the way into the 25 years average useful life of the As suggested in .
, the following combination of factors is needed to speed up parity:
Fall in the price of solar modules and inverters and reduction in the value of solar cell degradation factor are factors which will speed up grid parity.
An energy production cost reflective tariff for utility grid supply Table 5 reflects the trend of the above indices between 2011 and ending of 2014.
As may beobserved, the suggested aids to early parity have played out resulting in the condition becoming achievable in the medium term as defined in .
Research and development efforts on solar modules to combat module defects that results in cell degradation such as module solder joint .
, losses .
, corrosion and interconnect breakage .
etc are in progress.
Table 5.
Summary of Changes in Solar PV-Grid electricity Indices since 2011 S/No Indices Change Utility energy Cost/Unit (NGN) Solar Module Price/Watt ($) Inverter Price per watt ($) Deep cycle battery Price/watt-hour ($) Degradation Factor Time of Parity (Year.
Time of Parity as percentage of SystemAos average useful life of 25years As more success is recorded in research and development activities resulting in efficient and less degradable modules, more power per module square meter will be made available and useful lifespan will be Also, with increased interest in solar energy deployment, competition among manufacturers of modules, inverters, batteries and other accessories will be engendered resulting in considerableprice The on-going deregulation of the Nigerian power sector is expected to result in improved power generation and cost reflective tariffs over time.
These combinations of factors, when fully in place, are expected to aid earlier achievement of parity.
CONCLUSION
From the above analyses, it can be observed that the following factors have significantly affected the approach of solar energy to grid parity in terms of unit cost in the study location:
Rapidly falling price/watt of solar modules, inverters and other accessories .
Upward review of electricity tariff in Nigeria The review showed that parity can now be achieved in the medium term .
-6 year.
in typical Nigerian residences instead of the long term earlier predicted by .
due majorly to improvement in energy tariff and drop in costs of solar power accessories.
Sustained improved pricing of energy from the Distribution Service Providers (DSP) will further hasten parity.
Also, further breakthrough in research and development efforts in the area of solar module energy conversion efficiency, weather resistance and nondegradable solar cell products are other factors needed to achieve early parity.
Finally, with increased improvement and competitiveness in the inverter and deep cycle battery market, parity may even be achieved within the next three years.
The implication of this scenario is that deployment of solar energy as on-grid or stand-alone Distributed Generation will become economically more feasible .
This will improve power availability for domestic, commercial and industrial applications.
REFERENCES