Dr. Engr. Tajudeen Humble Sikiru Presentation at Power Nigeria 2018. Designing Mini-grid Systems. How to design a mini-grid system. Where to look for the necessary data during the planing stage. How to use financial model to determine tariff. Impact of smart meters to revenue generation in mini-grids.

1. Designing Mini-grid Systems
POWER NIGERIA 2018
Engr. Tajudeen Humble Sikiru (PhD)
Electrical Engineering Department, Ahmadu Bello University, Zaria.
Rana World Tech Engineering Limited, Kaduna, Nigeria
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 A mini-gridis a distributed network with a power source serving a load between1 kW and 1 MW.
 The Power source could be Fossil fuel or Renewable(Solar, Wind, SmallHydro or Biomass)
 Generallya typical Mini-gridmay be a combination of fossil fuel and Renewablesource
 Mini-grids could be grid connectedor off-grid
 Systemdesigncomplexityisa function of the load to be served
 Mini-gridsare fast to deploy and set up compared to grid expansion
 Mini-grid is best for servingrural and semi-urban communitieswheregrid expansion is expensive
Power Nigeria2018

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A power Source (Fossil or Renewable) + A distributed grid = Independent or national grid connected
Power Nigeria2018

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Understanding Government Policies and Framework on Mini-grid
 Site Identification
 Good Technical Design
 Mini-grid Tariff Calculation using Financial Modelling
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 Understanding Government policies and framework on Mini-grid
 Mini-grids 1 kW to 100 kW : no permit required before operation
 Mini-grids 100 kW to 1 MW : permit required before operation
 How to Benefit from Government grant (REA-Rural Electrification
fund)/other Donor agencies
 Site Identification
 Proximity of national grid (working with DISCO or from DISCO)
 Aggregating loads
 Commercial viability of a community
 Exclusivity agreement
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 Good Technical Design
 How to predict the size of a mini-grid
 Where to find the necessary data in the planning stage
 How to design an entire system
 Mini-grid Tariff Calculation and Financial Modelling
 Using Financial Modelling to determine Tariff and to select the best
Techno-Economic model
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Power Nigeria2018

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Power Nigeria2018

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 Site Assessment Framework
 What is the current Energy Access Level in this Community?
 What is the current and Future Energy Demand Level for this
Community ?
 What is the Potential User Profiles (Household, Commercial &
Productive)?
 What is the history of Socio-Political Factors within this Community?
 Which of the Regulatory Factor Applies to this Community (NERC
policies and the Distance to the grid, is there possibility of grid arrival
soon?)
 What Economic Factor may lead to better Productivity in this
Community ?
Power Nigeria2018

11.  Keys to Profitability:
• Select communities with large number of commercial
users
• Select communities whose activities depend on
electricityor can expand with the arrival of electricity
• Ensure that the community is willing to pay for the
electricity
• Involve State and Local Government during site
identification
• Avoid selecting sites based on politics expect State
Government is the off taker
• The most profitable Mini-grid operators are
those serving Underserved communities !!!
• Work with DISCO if possible to provide power
to semi urban communities
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Power Nigeria2018
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 Understand that the mini-grid business model is far different
from the telecommunication model in Nigeria
 Tariff rate without grants could be as high as N 250 /kWh and between
N 110 – N 170 / kWh with grant
 Your Source of financing is critical in determining the payback period
( Loan Versus Equity)
 Foreign loan versus Local loan (Could Hedge Financing Help?)
 Understand the technology to be deployed ( Renewable or fossil)
 Understand the right Design concept: AC coupled or DC coupled
Systems
Power Nigeria2018

13. Survey: Location and Load parameters
• Know your solar installation location
• Accurately determine the load size
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Source: REA Nigeria Mini-grid investment brief
Power Nigeria2018

14.  Survey: Technique to Predict Load Size
• Current Load
• Future Load growth
 Current Load
• Use survey questioner
• Divide users into two broad categories: Residential
and Commercials
• Model Residential loads
• Model Commercial loads
• Combine the load forecast of Residential and
Commercial Loads
• Use curve fitting techniques and Binomial and
Poisson Distribution to determine load duration curve
• Use Fuzzy time series technique
24-Sep-18 Power Nigeria 2017 14
Source: REA Nigeria Mini-grid investment brief
Power Nigeria2018

15.  Technique to Predict Load Size
Load Forecasting Keys Indices to Consider:
 Demand Factor = Max. Demand / Connected load
 Load Factor = Avg. Demand / Max. Demand
 Diversity Factor = sum of individual max. demands /
max. demand of mini-grid power station
 Utilization Factor = Max. demand of mini-grid power
station/ Rated capacity of mini-grid power station
The goal is have the utilization factor to be very high
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Source: REA Nigeria Mini-grid investment brief
Power Nigeria2018

16.  Let Use Solar Power Station as an Example
 We will use a community in Mokoloki ( see load curve on
the right)
 Max. Peak Load 120 kW
 Avg. Peak Load 98 kW ( 14.00 – 20.00 hrs)
 Day time Avg. Load 50 kW ( 7.00 – 20.00 hrs)
 Night time Avg. Load 8 kW (20.00 – 6.00 hrs)
 What should be the optimal best size of the solar panels?
 What should be the best sizing for the battery bank?
 What is the right size of Generator?
 The right Business Sense Questions to ask:
 How many hours of power supply should the mini-grid
provide?
 What percentage of consumption would be met by the
Diesel generator ?
 What is the impact of battery bank on the tariff cost?
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Source: REA Nigeria Mini-grid investment brief
Peak load
Avg. peak
Avg. load
Power Nigeria2018

17.  Energy Consumption Analysis
 Step 1: Minimum energy supply per day
 50 kW * 14 hrs (6.00 – 20.00 hrs) = 700 kWh
 8 kW * 10 hrs (20.00 – 6.00 hrs) = 80 kWh
 Total Minimum consumption = 780 kWh
 Low Sun / Night time energy consumption = 8 kW *10 hr +
50*6hr = 380 kwh
 Minimum night load on battery 8 kW* 10 hrs = 80 kWh
 Step 2: Design for Battery Capacity
Option 1: Minimum Battery capacity = 160 kWh @ 50% DOD of
minimum night load
Option 2: Maximum battery capacity = 460 kWh @ 80% DOD of
low sun/night consumption
Because of high capex for batteries we select battery capacity
between 160 kWh and 288 kWh when we do the economic
analysis
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Source: REA Nigeria Mini-grid investment brief
Peak load
Avg. peak
Avg. load
Best Harvest
Power Nigeria2018

18.  Energy Consumption Analysis
 Step 2: Design for Selecting of PV capacity
 Location of Mokoloki: OGUN STATE
 1 kWp solar installation will yield = 3.2 kWh/day
 Solar capacity =Total Minimum consumption (780 kWh) /
3.2 kWh (energy per day from 1 kWp installation)
= 240 kWp (ideal solar size)
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Peak load
Avg. peak
Avg. load
Best Harvest
Mokoloki
204 kW (peak PV generation)
150 kVA Generator
(3 hours max. per day)
BatteryBank
suppliespower
Power Nigeria2018

19.  Energy Consumption Analysis
 Step 3: Adjusting PV capacity
 Because Diesel generator will run daily due to the time of
night of the peak load, scaling down the PV capacity may be
considered !!
 However, this requires a lot of considerations (will
cumulative cost of diesel fuel over 10 years + outweigh PV
cost?)
 PV can be scaled down to 150 kWp minimum! If PV
capacity is too low tariff increases due to high fuel
consumption
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204 kW (peak PV generation)
150 kVA Generator
(3 hours max. per day)
BatteryBank
suppliespower Fuel consumptionperiod 7 hours per day
156 kW
Power Nigeria2018

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 Modelling the load duration Curve using Odyssey Software
 Example of the softwaremodelling is shown below:
Power Nigeria2018

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 Modelling the load duration Curve using Odyssey Software
 Example of the softwaremodelling is shown below:
Power Nigeria2018

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Modelling the mini-grid system using HOMER Software
 Example of the softwaremodelling is shown below:
Power Nigeria2018

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 Selecting the right technology (AC Versus DC Coupled Systems)
Good for small mini-grids
With less loadsduring the daytime
Good for large mini-grids
With more loads during the daytime
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 Design of internal
distribution Network
 Should conform to National
grid standards, if
compensation must be
provided when grid arrives
 Distribution network could
be single or three phase
depending on the load type
and size being served
 Wooden or concrete poles?
20-33 meters span between
poles
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 Tariff Collection
(smart metering)
and Project
Monitoring
 Daily energy
production should
be monitored (faults
and increasing loads
could easily be
identified)
 Mobile money
payment is preferred
 Pre-paid payment
model is most
suitable for cash
flow analysis
Power Nigeria2018

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 Summary page:
 Enter company info
only
 Other data in the
Summary page are
auto generated if all
the entries are
correct
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 Input page:
 Enter all fields in
colouredwith
GREEN
 e.g. Diesel cost
 Exchange rate
 Tariff for 1 phase
user
 Tariff for 3 phase
users
 Percentage of
projectcost to be
coveredby grant
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 Input page:
 Enter all fields in
colouredwith
GREEN relatedto
Cash flow and
Project
Development
 e.g. Income tax
 cost of feasibility
 Costof EIA
 Staff salaries
 Travel and vehicle
cost
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 Input page:
 Enter all fields in
colouredwith
GREEN relatedto
REVENUES
 e.g. nos of 1
phase and 3
phase users
 Total energy sold
to these users
 Costof new
connections
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Must be positive
The higher the better
Zero if no debt funding
Break even cost
Average tariff with grant
Earning before tax and otherdeductions
Very important
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Power Nigeria2018

32. Designing Mini-grid Systems
THANK YOU FOR LISTENING
POWER NIGERIA 2018
Engr. Tajudeen Humble Sikiru (PhD)
Electrical Engineering Department, Ahmadu Bello University, Zaria.
Rana World Tech Engineering Limited, Kaduna, Nigeria
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