Solar Energy

International Conference on Modelling, Simulation and Control (ICMSC - 2015)

Solar Energy: A Solution for Street Lighting and Water Pumping in Rural Areas of Nigeria Orville Damso Cota

Nallapaneni Manoj Kumar

Renewable Energy Intern Atiode Solar Systems Ltd. Goa, India [email protected]

M.A. Environmental Economics Annamalai University Chidambaram, Tamil Nadu, India [email protected]

Abstract—Among all the renewable energy sources, solar energy has become more attractive and popular in Nigeria due to its non-exhaustible nature, less maintenance, no fuel cost etc. In recent years the use of solar energy in rural areas of Nigeria has grown drastically and it has become a sustainable solution for lighting and for pumping water. This paper clearly discusses the design, installation and economic viability of solar energy utilization with a case study on street lighting and water pumping. In addition to this maintenance of solar energy utilization systems is discussed. Keywords— Renewable energy; solar energy; street lighting; water pumping.

I.

resources, the use of solar energy is much feasible as it is easy for installation and maintenance. On other hand solar energy is freely available. As per C. N. Ezugwu [4], the daily average solar radiation potential for Nigeria is around 3.5-7 kwh/m2. Global horizontal solar irradiation map from Solar GIS [5] shown in Fig. 1. shows the feasibility of using solar in Nigeria. This clearly shows that the use of solar energy is most suitable for the locations in Nigeria where the people don’t have power lines etc. In this paper, the design, Installation and economic viability of the solar energy utilization for street lighting and water pumping application is discussed.

INTRODUCTION

Energy has become one of the essential needs of human life like food and water in the present generations and it is the most vital part for socio-economic development and the economic growth of any nation. Energy might be in different forms such as electrical energy, light energy, heat energy, mechanical energy, chemical energy etc., in our case we consider the electrical energy, and this can be used in residential applications and industrial applications for meeting the needs of human life. As we know that in most of the countries, energy needs were met by the power taken from nearest power grid which is of mainly from fossil fuels. Even though we have power grid systems, we could not connect all the locations to the grid. Still such areas are in darkness. In order to light up these locations we can opt diesel generators and other renewable energy technologies. Not only the remote locations, we can use all the renewable energy technologies for power generation in the cities too. But most of the countries in African continent are still in darkness. Considering Nigeria, one of the countries in Africa blessed abundantly with fossil fuels mainly crude oil and natural gas. Apart from these fossil fuels, it has enough renewable energy resources. [1] Even though Nigeria is blessed with energy resources, the power stability and power outs are the major problems [2] and this is more effecting the life of people lives in rural areas where they don’t have the street lights and community water supplies. However the use of fossil fuel is slightly declined due to climate change problems. As a result of danger posed to the environment with the use of fossil fuel, Nigeria is shifting to other alternative sources for meeting the countries energy demand. [3] Among other renewable energy

Fig. 1. Global horizontal irradiation of Nigeria. (Source: SALAR GIS) [5]

II.

DESIGN OF SOLAR ENERGY UTILIZATION SYSTEM

A. Solar Street Lighting System A solar street lighting system basically consists of a solar photovoltaic (PV) panel which converts the light energy from the sun to electrical energy, a charge controller which takes care of charging and safety of the batteries and also providing power to the load at required voltage and current ratings, a battery which would be used to store the electrical power during the day and provide it to the load during the night as and when required, and finally the lighting load itself. Here for lighting loads LED lights were used for improving the energy efficiency in the solar street lighting system. LED lights are energy efficient and consumes very less power when

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International Conference on Modelling, Simulation and Control (ICMSC - 2015) compared to other lighting devices like CFL, fluorescent lamps and incandescent lamps. [6]

shine hours of the location as 8.0 hr.,[9] charge required from the PV panels is calculated as 25 Amperes. Now our PV panel array should supply 25 Amperes of output current and 12 V of output voltage. Considering the available PV panels of 175 Wp, now connect two of each 175 Wp PV Panels in parallel to get 23.52 Amperes and 12 V as output voltage from PV panel array. Charge controller used in this case is different from other solar installations. In this case we used an automatic timer sensing controller which would on exactly evening 6 PM and off on 6 AM in the morning. Current rating of the charge controllers should be more than 30 Amperes. With this configuration all the 22 LED solar street lights were installed and few of those installed street lights are shown in Fig. 3. and the design specifications were tabulated in Table. 1.

Fig. 2. Design procedure for solar street lighting system

Fig. 3. Atiode LED solar street lights at Igbelaba Village, Nigeria. [10]

The actual operating time provided by the batteries is given by the ratio of battery energy (W.hr) to street light load (W) i.e. 4080/150 which is 27.2 hr. of backup time on full charge. Actual backup time is 15.2 hr (Actual operating time – operation time of the street light) Maximum time required to charge these batteries upto 100 % is 11.65 hr. and given by the ratio of battery energy to PV panel array wattage.

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120 W Atiode LED Lights, 6 m height pole with concerte base including panel mounting structure plus battery box, 2 of each 12 V/ 230 Ah deep cycle rechargeble Batteries, 2 of each 175 Wp PV panels, 40 Amperes automatic on & off charge controller.

15.2 hr.

12 hr.

Time required to charge batteries up to 100 % (hr.)

Operation time of the solar street light (hr.)

ATIODE LED SOALR STREET LIGHT SPECIFICATIONS

Actusl back up time (hr.)

Case study: Igbelaba village has around 665 m central street. After analysing the site in details, conclusions were made to install 22 units of 120 W Atiode LED solar street light each and the spacing between each pole is 30 m apart with a pole height of 6 m from the concrete base level. Each LED Street light of 120 W [10], and plus considering the system losses as 25 % of the load, then the new load becomes 150 W need to be powered using solar PV panels. A standalone street light is considered here and hence keeping into consideration of the worst case scenario, operation time of the street light is set as 16 hr. (One night is actual required time plus 4 hr. as back up time). Total electrical energy required to operate a load of 150 W for 16 hr. is 2,400 W.hr, considering the system voltage as 12 V, required charge capacity for battery is calculated as 200 Ah. If we consider 12 V/200 Ah deep cycle discharge batteries we need 2 batteries (actual needed is 1.25 but is rounded off to 2) for supplying required energy to the LED solar street light. Connect these two batteries in parallel. Our required charge capacity is 200 Ah, from the solar radiation data considering the least sun

TABLE I.

Solar street light spscification

The design and the feasibility of solar street lighting system [7,8] involves knowing the number of hours (this includes time of operation & back up time), street light needs to be operated which gives the energy required. Based on the energy required for operation number of batteries needed are to be decided. Once this is done the amount of charge capacity supplied by PV panels to charge batteries in one day or with in the specified time is estimated. Solar utilization involved some losses due efficiency factor of the components used, this includes around 25% losses (Losses due to batteries, controllers and PV panels are together considered as 25 %). A generalized flow chart that describes the design of a solar PV system is shown in Fig. 2. To understand this clearly a case study of Igbelaba Village in Nigeria has been described below.

11.65 hr.

International Conference on Modelling, Simulation and Control (ICMSC - 2015)



Calculation of helpful hydropower

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Available solar energy

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The month with the minimum solar radiation



Sizing of solar PV generator or PV array

The amount of water required per person depends mainly on daily lifestyle of an individual and also on the climatic conditions of each region. We mainly needs water for drinking, cooking, washing and bathing. In addition to this water is consumed by animals for their survival and also for agricultural activities. [15] This means solar water pumping system is applicable for above mentioned activities. Once if we are clear with water audit as per the requirements of clients, then evaluate the flow rate (Q) by considering location peak sunshine hours, then evaluate the total dynamic height (TDH). Now select a pump based on this two parameters (Q & TDH) curves given by the pump manufacturers. Calculate the power required and this can be looked up from the Q & TDH curves, then determine the sizing of inverter, batteries, controllers and PV panels. Case study: A client from Jigawa, Nigeria wanted to supply water for its community using 5 boreholes which are powered by solar. These 5 boreholes has similar design because community papulations are almost similar. Each tank capacity is 37.85 m3 and the daily water requirement from one of the tank is 17 m3/day. Considering this, a solar water pumping systems shown in Fig. 4. is designed as follows:

No. of batteries = Charge capacity/ (DOD*Battery Ah)

(3)

7894.74 W.hr is the energy supplied to battery and it is given as the ratio of energy supplied by battery to inverter to the efficiency of battery i.e. 85%. In this design we used maximum power point tracking (MPPT) charge controllers and whose efficiency is almost 99%. Energy supplied by the charge controller to batteries is 7974.48 W.hr. Charge required to supply 7974.48 W.hr from the PV panel array is calculated as 7974.48 W.hr/ 12 V which is equals to 664.54 Ah. By considering the sunshine hours of the location as 8.5 hr. total current from the PV panel array is calculated as 78.18 Amperes. For supplying this current 8 PV panels of each 150 W are connected in parallel which supplies almost 81.63 Amperes (each panel supplies 10.2 Amperes). Charge controller is sized in a way that current rating of the controllers is higher than the PV panel array current. Two 12 V/ 45 Amperes MPPT charge controllers are connected in parallel at the panel output side. SOALR WATER PUMPING SYSTEM SPECIFICATIONS

Solar water pumping system spscification

TABLE II.

Fig. 3. Solar water pumping systems for borehole at Jigawa, Nigeria. [10]

Equation (1 & 2) are used to calculate Flow rate (Q) and Total dynamic head (TDH) [16]. Flow Rate (Q) = Daily water requirement in m3/ (Sunshine hours of the location* 60 min per hour.) (1)

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1 HP , SQ 2-55 Grund fos submersible pump 6 of each 12 V/ 150 Ah deep cycle rechargeble Batteries, 8 of each 150 Wp PV panels with mounting structures, 2 of each 45 Amperes MPPT charge controller, Battery box, cables & others.

3.74 hr.

8.5 hr.

Time required to charge batteries up to 100 % (hr.)

Quantity of water requited on a daily basis

After the site analysis, TDH was determined as 55 m and this includes frictional losses and elevation of the tank and its height. A pump model of AC, 50 Hz, 1 HP, SQ 2-55 from Grundfos Submersible Pumps is selected for the flow rate (Q), 17 m3/day and total dynamic head (TDH), 55 m as per the sunshine hours of the location, 8.5 hr. [9] (This 8.5 hr. is considered for worst case scenario). Energy required by 1 HP pump to delivery 17 m3 of water in 8.5 hours is 6375 W.hr. and this is the energy supplied by inverter to pump. 6710.53 W.hr is the energy supplied by batteries to inverter by considering the efficiency factor of inverter (Efficiency of inverter is 95 %). An inverter system of 1.5 KVA is selected by considering 30 % of extra load and for future adjustments in load. System voltage is considered as 12 V. Battery sizing is done by calculating the charge capacity, i.e. 6710.53 W.hr/12 V which is equals to 559.21. While sizing batteries depth of discharge (DOD) of the batteries is considered. In this case 150 Ah/12 V which has DOD of 0.7 is considered. Equation (3) [17] is used to calculate the number of batteries required, in this design 6 batteries of each 150 Ah, 12 V is considered.

Operation time of the system for delivering 17 m3/day (hr.)



Total dynamic Head (TDH) = Draw down + Standing water level + Elevation + Frictional losses (2)

Actual back up time (hr.)

B. Solar Water Pumping System Design of a solar PV water pumping system needs to follow the consideration given below: [11,14]

7.65 hr.

International Conference on Modelling, Simulation and Control (ICMSC - 2015) III.

INSTALLATION AND MAINTENANCE

Prior to installation of a PV system proper assessment of the site is to be made in order to select the most potential site with adequate solar radiation. It is also worthwhile to mention that the duration of solar radiation availability must be maximum only then should the sight be selected. The various stages involved in the installation and maintenance of a PV system is mentioned below. A. Installation Procedure  After selecting a potential site civil works should be carried out and then mechanical structure must be made ready as per the location constraints.  Provide a strong foundation for the mechanical structure.  Mount the PV panels such that it receives maximum radiation during the day. In order to achieve this the PV modules are placed at an angle equal to the latitude angle of the location. In order to improve the efficiency further the PV panels can be provided with sun tracking systems.  Connect the batteries to the PV panel through the controller as specified on it and proceed with rest of the connections. If it’s a solar street light place the batteries and the controller in a box which is protected from unauthorized personal and varying weather conditions. B. Maintenance Procedure Photovoltaic systems generally have very less maintenance work to be done. The major maintenance work involves checking the health of the batteries and any malfunction that may have occurred due to extreme weather conditions, power electronic device failure or failure in the load itself. The battery health must be checked by checking battery water level and also carbon formation at the terminals at regular intervals in order to keep the battery performance at its best. IV.

similarly 43,200 W.hr per month. On considering unit cost per one unit of energy in Nigeria is NGN 29.46, [18] the total cost of energy is NGN 1272.67 per month. On an average it would cost NGN 15,272.06 per annum on powering one 120 W LED street light. Cost for installing LED solar street light is around NGN 442,000.00 per one. For this simple payback period may take around 28.94 years, which is not financially or economically viable in the places where they have grid connection. But in the places like some rural areas of Nigeria, where they don’t have any transmission lines, this solar works better. B. Payback Periods for Solar Water Pumping Systems In order to operate a 1 HP submersible pump for pumping the water to a community for 12.24 hr. on grid consumes approximately 9,180 W.hr per day and similarly 275,400 W.hr per month. On considering unit cost per one unit of energy in Nigeria is NGN 29.46, the total cost of energy is NGN 8,113.28 per month. On an average it would cost NGN 97,359.41 per annum on powering 1 HP submersible pump. Cost for installing 1 HP solar water pumping system is around NGN 991,000.00 per one. For this if we take simple payback periods, it is around 10.17 years, which is financially or economically viable. V.

CONCLUSION

This paper has clearly shown the design procedure, installation, maintenance and economical viability with the case studies in Nigeria on solar energy utilization. It can be concluded that solar energy became one of the best solution for many African countries, especially Nigeria for powering their dark streets and for water pumping etc. This paper also showed the payback periods of solar energy utilization, in which using solar is much more economical for water pumping than street lights. But however it is more economical to use solar in the places where they don’t have any means of power supply. In long run solar saves a lot of money and it is free source of energy without any environmental effects.

Acknowledgment Authors, thank the Atiode Solar Systems Ltd. and others for providing their excellent support for this work.

ECONOMIC VIABILITY

Cost in utilizing solar energy is more than any other conventional source of energy this is mainly due to the manufacturing of PV panels, batteries and the power electronic devices. Even though it is costly it has less environmental effects when compared to fossil fuels. The time required for installation is less and also the man power required for installation is less. In the long run the cost of operation of a LED solar street light and solar water pumping are much cheaper when compared to operating the same by connecting to the grid. A simple pay back periods [17] were calculated and its shows that utilization of solar energy in long run is economically viable. A. Payback Periods for LED Street Light In order to operate a 120W LED street light for 12 hr. on grid consumes approximately 1,440 W.hr per day and

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[2]

[3]

[4]

[5]

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International Conference on Modelling, Simulation and Control (ICMSC - 2015) Energy.gov, “How energy efficient light bulbs compare with traditional incandescents,” http://energy.gov/energysaver/articles/how-energyefficient-light-bulbs-compare-traditional-incandescents, November 2014 [7] Gang Liu, “Sustainable feasibility of solar photovoltaic powered street lighting systems,” International Journal of Electrical Power and Energy Systems, vol. 56, pp. 168-174, March 2014. [8] How to design and size a solar lghting systems. http://www.solarlighting.com/blog/how-to-design-size-solar-lightingsystem [9] Abdul Salam D., Mbamali I., Mamman M. and Saleh Y. M., “An assessment of solar radiation patterns for sustainable implementation of solar home systems in Nigeria,” American International Journal of Contemporary Research, vol. 2(6), pp. 238-243, June 2012. [10] Atiode Solar Systems Ltd. www.atiodesolar.com [11] Christopher W. Sinton, Roy Butter and Richard Winnett, “Guide to solar powered water pumping systems in New York State,” New York State Energy Research and Development Authority, pp. 1-29. www.nyserda.org [12] M. Abu-Aligah, “Design of photovoltaic water pumping system and compare it with diesel powered pump,” Jordan Journal of Mechanical and Industrial Engineering, vol. 5(3), pp. 273-280, June 2011. [6]

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