Reliable electric power supply in any country as a result of industrialization is a prime factor /agent for sustaining infrastructure development and Economic Transformation of that state. This paper will be limited to how this could contribute to sustaining infrastructure development and economic transformation of Eket Local Government of Akwa Ibom State. The electricity requirements of the world including Nigeria are increasing at an alarming rate and the power demand has been running ahead of supply. It is also now widely recognized that the fossil fuels (i.e. coal, petroleum and natural gas) and other conventional resources, at present being used for generation of electrical energy, may not be either sufficient or suitable to keep pace with the world’s ever increasing electrical energy demands. Also, generation of electrical power by coal-based steam power plants or nuclear power plants causes pollution, which is likely to be more acute in future due to the larger generating capacity on the one hand and greater awareness of the people to this issue on the other hand. The recent severe energy crisis has forced the world to develop new and alternative methods of power generation, which could not be adopted so far due to various reasons. The non-conventional methods of power generation such as solar cells, fuel cells, thermo-electric generators, thermionic converters, solar power generation, wind power generation, geo-thermal energy generation and tidal power generation are now recommended. This paper highlights the method of sizing the capacity of battery banks and solar panel design for 8-hour runtime for a total power demand of 1000 watts. Recommendation for the type of renewable energy source is emphasized. Calculations are performed to illustrate the design and benefits derived from this source of energy.
Sizing of battery banks and Solar panels for use in the Renewable energy system
Battery bank sizing is the important aspect when designing a UPS equipment. Calculations are required to obtain optimum parameters for a sustainable power bank. If the battery bank is oversized you risk not being able to keep it fully charged; if the battery bank is sized too small you won’t be able to run your intended loads for as planned. Many renewable energy (RE) systems incorporate batteries. Batteries can be used in all types of systems including: photovoltaic (preferred).wind power, Hydro electric generators, Hybrid renewable energy systems, other DC power sources.
Factors to consider for the design
The first thing to note is the amount of energy you will be consuming per day. It is desirable to do a careful evaluation of exactly what loads (appliances, electronics) you plan to use and for what lengths of time. Keep track of this information on a load lists;you will refer to this list often for sizing other components as well, Your final tally should be expressed in watt-hours per day If you know the kilowatt-hour(Kwh) per day just multiply that number by 1000 to determine the watt-hours per day.(Example:1Kwh =1000Wh)
Days of Autonomy
Next, you must determine the days of battery backup that you want to have on hand. In other words, if you are unable to charge your batteries by any means, and you still need to draw power, you must provide this additional storage by increasing the size your battery bank, if your primary electricity source is solar panels (solar energy), you must determine the average number of hours of sunlight. This information can be found in the data you have collected using your data-logging anemometer.
In Eket local Government Area the average sunlight is estimated at 6 hours per day (10AM to 4PM). This information is based on my study during this period of rainy season (worst case condition for the design).I f you are sizing a battery bank to be used in conjunction with an on-demand fuel powered generator, the number of days of backup will represent the number of days you wish to go without using your generator.
Depth of Discharge (DoD)
In this design, it is a requirement to consider the planned Depth of Discharge (DoD) of your chosen battery bank.Lead Acid batteries, sealed AGM Batteries sealed gel batteries are all rated in terms of charge cycles. A single cycle takes a battery from its fully charged state, through discharge (use) then back to full charge via recharging. The depth of discharge is the limit of energy withdrawal to which you will subject the battery (or battery bank). Depth of Discharge is expressed as a percent of total capacity. The further you discharge a battery, the fewer cycles that battery will be capable of completing. Simply stated, deeper discharge shortens battery life. Never discharge a deep –cycle Batter below 50% of its capacity; however many battery manufacturers recommend even shallower depth of Discharge (DoD).If you are only using the batteries occasionally as a backup system, you can factor in a DoD of 50% or perhaps more.
Temperature affects battery life and also its capacity; always keep batteries in a ventilated area to maintain its efficiency.
Identify your system voltage say 12 volts.
Assume that our total load is 1000 watt-hours per day.
Three days of autonomy
Planned depth Discharge of 40%
Battery bank ambient temperature average of say
60 degree F
Step 2: Multiply days of autonomy by total power demand in watt-hour/day
1000Wh/day i.e. 1000x3=3000Wh
Step 3: Identify Depth of Discharge (DoD) and convert to a decimal value divide the result step 2 by this value. 40% DoD we have
Step 4: derate battery bank for ambient temperature effect. Select the multiplier corresponding to to the lowest average temperature your batteries will be able to be exposed to. Multiply result from step3 by this factor. Result is minimum Watt-hour capacity of battery bank. From tables, 60degrees correspond to 1.11, hence 7500x1.11=8325Wh.
Step 5: Divide result from step 4 by system voltage. The result obtained is the minimum amp-hour (Ah) capacity of the required battery bank...
Approximate this to 700Amp-Hour battery bank. This will be required to supply power to a power inverter that will in turn power your home appliances.
Power inverter provides uninterrupted power to run household electrical devices and offices. Power inverters are alternatives to electric power generators when it comes to supplying backup or standby power during power failure for hours. The power inverters convert Direct Current (DC) voltage from batteries to Alternative Current (AC) voltage used by appliances in our homes and offices
.Inverters work with stored energy in the battery to
power homes and offices for hours depending on usage. The total power required to charge this battery bank assuming 6 hours of sunlight from solar panel could be determined as follows:
Power from solar panels = Battery bank capacity x system voltage divide by average time for sunlight per day
Power=Voltage (V) x Current (A) (700Ah*12V)/6 h
Benefits of the Renewable Energy Source (The Battery-Inverter System) Charged by Solar cells
1) Extended power backup: you will gain several hours of backup to meet your power needs every day. Inverter supplies you with over 10, 12, and 24 hours of power.
2) Zero Running Cost: The system requires no consumables like diesel, petrol or oil, saving you lots of money spent on power generators, Minimize frequent breakdowns that are common with petrol and diesel alternators.
3) Noise free: Your renewable energy power source is noiseless. Now you can spare yourself that generator noise that is associated with the engine.
4) No oil spills on ground: The inverter uses no oil, causes no oil spill or dirt and is a clean appliance like other tools in your room.
5) No fumes: The inverter produces no fumes or smoke, saving your environment all that air pollution.
Finally, commercial establishments will find this system useful to enhance economic development. Banks find this useful to keep ATM machines functional. Other possible areas of application include hospitals, schools, hotels, supermarkets, filling stations and small scale businesses.
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