Outline of project:
1. Case Study 1
i. Background of solar power systems
ii. A putative solar power system for the farm- Design and Construction
iii Design an area for cooling the animals by using fans powered by solar energy.
2. Case Study 2
1. Issues facing designing places with no electricity
2. Design of a village with no electricity
a. Requirements
b. Planning
1. Case study 1:
a. What are the advantages of having a solar power system for the farm?
Solar powered farms provide a lot of advantages and can perform many useful functions, A farm involves running and maintaining many utilities. Solar powered farms are useful in this as they provide the additional capacity to supplement the existing base power generator sources such as coal, during peak time usage. Secondly, solar power generators are more portable and compact as compared to base power generators. If one goes down, it won’t have that much of an effect on the functioning of the whole solar panel, whereas in case of the base power generators, the collapse of one will lead to the collapse of the whole grid. What makes a solar power system viable is that you don’t need as much labour as you would need to run and maintain a traditionally powered plant, no water, sudden breakdowns etc and you can also monitor the power production online. You can let the sun do all the energy production while working on other things. What is best is you only need to dedicate a small amount of area for building your solar power system.
b. Designing and building a solar power system
You can design a solar power system according to your requirements, depending on whether you are setting a power system for a large-scale farm or a small one. A small-scale farmer, can use standalone systems for solar power generation, which include a couple of Photovoltaic panels, battery and charge controller, which can be built from scratch or purchased as kits. For large farming, you need to add on a separate land with a solar power grid as an extension to your farm.
The most important consideration to go into when designing a solar farm is to calculate your power production and what you can expect from the system you installed on a daily, weekly or monthly basis. How much does the production balance the usage. As solar energy amount may fluctuate on a daily basis, it is imperative to monitor the daily peak solar production on a daily basis so that your production/usage ration does not go awry. The amount of energy generated depends on the kind of Solar power system installed. As mentioned, there are different kinds tailored to different specifications. One needs to do a load profile analysis ( if you are using that energy for your own purposes) before selecting a suitable design to evaluate your load requirements and what times you need maximum solar energy supply. And then to balance this demand by appropriate system which provides the necessary amount of energy and not an excess as un utilised or surplus energy produced by the system is wasted.
How you go into designing and building such a solar power system is as follows:
1. You need to evaluate the site for its solar potential. The site should have sufficient exposure to the sun which will generate horizontal irradiation of at least 1000kWh/m2. You need to check whether there are any things which interfere with the sunlight falling on the PV plates such as buildings, trees, other structures. The efficiency of photovoltaic cells can be reduced if the area is shaded. PV panels perform best when there is no blockage which interferes with the reception of the sunlight and it falls uninterruptedly between 900 am and 300 pm.
You also need to test out various orientations of the PV plates and decide which would be the optimum orientation. Orientation towards south, east and west may be optimum. The plates perform when they are oriented at an angle of twenty degrees to the sun. PV plates can be mounted on the ground or on the roofs. You have to check whether there is sufficient area on the ground to allow for the placement of a solar array (or number of arrays, as per your requirement)or whether it can be installed on the roofs? If so, you need to identify the kind of roof and decide on the PV panel accordingly.
2. You need to evaluate the area needed for installation of the solar panels.- The area needed for installing the pV panels may vary from as small as 50 sq metre to 1000 sq metre, according to requirements. The ratio is that 1ooo watt of PV modules would require at least 100 square feet of ground for high quality PV modules. For cheaper and less efficient PV panels, the area required for collection of sunlight have to be doubled.
3. Review of current energy charges and peak demand pricing.
4. Photovoltaic Panel system:
You need to identify the PV system configurations and components, which are required for common grid systems. PV panels – These are the core of the system and they convert light to electricity. Installation of these PV panels is especially useful when your farm does not need to consume a lot of electricity. They can be used as panels or tiles and they can be inserted into the construction of the structure or mounted on the roofs or on the ground on platforms. They can be roof or ground mounted. The PV panels consist of many solar modules which are connected together to create a continuous panel. Based on the material they are composed of, they are of different kinds
There are three kinds of PV panels which can be used:
a. Microcrystalline – most priciest, most efficient. These are composed of single crystals.
b, polycrystalline- moderate cost and efficiency
c. thin film- cheapest and least efficient but they can be easily attached to other materials
The panels may be composed of silicon, cadmium or a combination of these.
Some more decisions regarding the PV panel are critical. These are as follows:
1. It has to be decided whether the output from the PV panel is going to be used directly to serve the electricity needs for the farm or house or whether it is going to be transmitted and distributed via a grid to far off places.
2. The type of output produced by it has to be chosen. Whether it will produce direct current or alternating current. Or whether the direct current produced by it will be converted later into alternating current.
3. It can be connected to a battery which will store the electric energy and which can subsequently can be used to power devices. So it needs to be determined whether a battery backup is required.
4. To allow for possible interferences in the harvesting of solar energy, which would otherwise interfere with the generation and transmission of electric power for various purposes, it may be necessary to have a standby generator. This is for emergency purposes.
Therefore you can have the pV panel connected to a grid system which may or may not have battery back up. Very basic PV solar systems would not have a battery back up. More expensive set ups will have either battery backups or generator back- ups.
5. An Inverter is needed for converting the electricity output from the PV panels from DC to AC which can then be put to various uses. The power can be used immediately, exported and to charge batteries.
4. Battery packs- These are of different kinds. AGM batteries and Lithium ion units are two commonly used.
5. Charge Controller – is required to manage the voltage. Also, the system needs to be grounded so that lightning does not damage the system through electrical surges. Hence surge protectors may also be needed to protect the mechanism from the surges of electricity.
6. Metres- need to be installed to measure the consumption of energy
5. installation and labour costs required for building and installing PV and safety considerations need to be also taken into consideration.
6. Analyses showing potential energy production as compared to the existing load profile and how much difference it would make as well as consumption during peak demand time
c. Energy requirements: Energy demands and energy provided by the solar power system
- Load profile analysis needs to be done as to how much energy it needs, and how much watt does it need, and how much we get from solar panels."
- farm is 50 * 50 m2
- in general solar power system of 1kW installed capacity power requires at least 7 m2 area.
-2500 m2 area would require a solar PV of at least 350 kW installed capacity . This can be achieved by placing together solar panels which would provide the required capacity, either as ground based or on the roof as shown below.
The formula below is used to estimate the actual electricity generated in the output of a photovoltaic system
Energy= A * r* H * PR where A =Total solar panel in square meter
r= solar panel yield (percentage)
H= Annual average of solar radiation falling on the tilted solar panels
PR= performance ratio/coefficient losses
Accordingly one can get a photovoltaic system which provides 350 kWh between the ranges of 4.7 kw to 2.2 kw, depending upon the total number of sun exposure hours available.
c. Design an area for cooling the animals by using fans powered by solar energy.
Farms in hot countries like Qatar need well ventilated farm houses so that the animals are provided with fresh air. There is also the need for the hot air to be released out. If there are no such provisions, the resultant heat buildup and lack of cooling will make animals die in the extremely hot temperatures of Qatar.
Solar energy can be used to create a cooling system which can be used to cool the farms. The power generated by the Solar Panels installed on the farm as previously described can be used to drive a vent, the opening and closing of which can be used to allow fresh air to enter and the hot exhaust to be released. It can also be used to run an exhaust fan or a ceiling fan or solar gable fans for as long as the sunlight is available or the power source can be connected to a temperature regulator which can be used to control the duration for which the fan operates. The whole system can be controlled via a remote control.
The solar fans can be attached to the solar power system or installed separately but connected to the PV plates. An example is solar gable fan which can be attached to grills through which ventilation is provided. Vents are arranged in such a way that it provides adequate cooling by sucking up the hot air and these fans are usually high up. When there is plenty of sunlight, there would be plenty of airflow and hence more cooling.
Three kinds of fans can be used in barns and housing sheds for animals.
A. Circulating Fans
- used only on hot days in barns which are otherwise naturally ventilated
-Dimensions of exhaust fan: 36 to 48 or 50”
- Recommended CFM/watt: 14-21 @o.5 SP
Rough number of fans per group of animals would be: one to two rows of high speed fans /group therefore three to six rows of fans for three groups of animals.
The fans would be arranged in such a way, one row along the feeding path blowing over the backs of the animals and other row over the beds
B. High Volume Low Speed Fans
Large fans to be used in big buildings with high ceilings and have diameters upto 24 feet. They are powered by 1 or 2 horsepower motors and They can push air at almost three or four times the amount of air as that pushed by high speed circulating fans that are powered by a single motor. These fans can be installed at every 60 feet along the middle of the barn and over the feeding tray. An advantage of these fans are that they have adjustable speed regulators, through which their speed and hence usage of power can be reduced according to needs. Each such fan would consume 1650 Watts as compared to 940 Watts per 50 “ high speed fan. The only disadvantage with such fans is that it does not really cool the animals as compared to the high speed circulating fans
C. High Speed Circulating Fans
These can be used to increase the speed of air circulation and aerate the buildings more and lessen the staleness. It increases the influx of fresh air and efflux of exhausted air. These fans are more useful in regulating the body temperatures of the animals. The larger fans are usually more effective at utilizing the energy but usage of protecting devices as well as fan belts will reduce the efficiency as well as improper maintenance, hence it is very important to ensure that these fans are maintained very well.
Looking at these aspects, it seems desirable to install high speed circulating fans with a diameter of around 50” for the farm in Qatar as this farm would need a continuous supply of fresh air and the hot air needs to be removed as fast as possible In addition, while selecting the fans for a animal barn, such as this one, some factors which needs to be kept in mind are:
1. Air delivery at static pressure of 0.10 inches
2. Ventilation rates under different climatic conditions. These should be determined before purchasing the fans.
3. It should have a suitable airflow ration.
4. Energy efficiency of the fan will be affected by the kind of climatic conditions. Extreme summer conditions would mean higher energy usage and costs, which is likely in Qatar.
Design of a cooling area powered by solar powered fans
The energy requirements for this are as follows:
1 horsepower= 746 Watts
Assuming that One exhaust fan may require: 1/10t of a horse power ~ 75 Watts
A row of such fans may have at least 5- 10 units depending on the diameter of the fans. You can choose lesser number of fans but of greater diameter if the cost is affordable. Six rows of fans may be needed in a large sized barn house, catering to three groups of animals. The fans may be placed in such a way that they cover the areas where the animals are assembled to feed and to sleep. (These are rough estimates, the usage of a fan can go up depending on its kind, its size etc)
Therefore, total energy consumed by these fans would be:
1 row of fans would require = 10 fans = 750 W
6 rows of fans would require = 750 * 6= 4500 Watts of energy
Assuming that the number of hours they would be running: 12 hours (as Qatar is an extremely hot country and would require longer operating hours as compared to other places. The night time should be cool so may not require the fans to be operated)
Therefore, the total energy requirement: 4500 * 12 = 54 Kwh
Since the fans are going to be used every day, it will have a Duty cycle: 100 %
Number of sunlight hours available – assuming a well lit area it would be around 6- eight hours and assuming a poor lit area – 4hours. For countries such as Qatar, with extremely sunny and hot climate conditions, on a n average the number of hours can go from six to eight.
Cost of fans to be installed: average 39 USD per fan for the animal house
Therefore total cost= 60 * 39= 2340 USD
Throughghout the world, many areas are still living without electricity. Electricity is vital for development. And as long as there is no progress for ensuring that every place, every house in the developing countries receive electricity, all other aspects dependent on electricity would be affected including development, education, industry etc. Statistics show that almost 2 billion people over the world live without electricity.
So, what can be done for those places which cannot afford to have the expensive power grids which supply power in many developed countries? The challenges include that fact that grid power technology is physically inaccessible and will take time to develop and reach them. Trying to connect such places to far off power grid sources using lengthy power cables would be non viable.
Many kinds of alternative energy sources are being researched into, which could provide sustainable solutions to the needs of the people in such areas. These technologies include photovoltaic cell technology, wind powered turbines and hydro based power generation systems. Amongst this, Solar energy has come up as a very important source of energy.
Solar energy, the energy provided by the sun, is free and easily available throughout the world and all that is needed is to harness it effectively. Establishing Solar based power systems in villages which lack conventional electrical supply, would revolutionise their life and improve their quality of life in a way which was not possible before. Many developing countries are investing in alternative energy resources such as solar energy to bring power and development to these deprived people.
There are three kind of ways in which solar energy can be used to supply energy purposes, without the usage of a conventional power grid. This is called off grid applications. These differ according to the amount of energy required for usage and the way the system is designed. The three kinds are:
1. Individual homes or dwellings- small amount of energy usage, light load, small lighting and home appliances
2. rural community levels- for community services
3. General electrification of the community
The solar power energy systems which are tailored for these purposes are of two kinds:
1. Individual units which serve specific purposes at each site
2. Centralised systems which distribute the power into different loads to different places through a mini-grid
The mini-grid system would serve the purposes of a community of people ranging in hundreds and provides energy to fulfill a variety of purposes.
In this case study, an attempt has been made to design a solar based power system for a village ABC which does not have electricity. The traditional livelihood is agriculture based. The village has 2500 households, a maximum number of 12500 people, and has a school and a park. The size of the village is 1000000 square metre. The power supplied will have to adequately supply this. The dimensions of the house is 21 m * 14 m ( with three bedrooms, one living room, kitchen, bathroom, store and multiuse room) and 24 light bulbs to be used in the whole house. The kind of bulbs to be used are LEDs or Light Emitting diodes. These are very energy efficient short bulbs. They can be used singly or in a cluster with a diffuser arrangement which will increase their effectiveness. You may even have upto 180 bulbs in a cluster. The LED bulb emits light in a particular direction and this is good in places with limited lighting facilities or where light is just needed in sufficient amounts.. Some of the advantages of using LEDs as compared to other lamps:
1. they last much longer
2. they do not have a filament and hence are not susceptible to damage due to falls and breaks
3. they generate much less heat as compared to an incandescent lamp, hence are more cooler and contribute to less power consumption.
4. they use only 2 to 17 watts of energy and hence are very energy saving
5. Because of all these features, they are very compatible with solar panel usage and helps males solar powered systems for feasible and economical for villages such as this which cannot afford to have big power grids or generators.
Each house has a maximum power usage of 10 kW . For 2500 houses: 25000 kW
Assuming the power of one light bulb is 8 Watt
Total number of light bulbs required for one house = 24
Total number of bulbs for village = 24 * 2500+ 100 (schools and park) = 60100
Power consumption per house: 24 * 8 =192 W
Total operating hours per day:
1. Morning power requirements per house = 7 hours
2. Evening power requirements per house= 3 hours
3. Total number of hours in a year= 10 hours * 365 days= 3650 hours
Total power usage for the whole village =60100 *3650*0.008 = 1754.92 KWh
Therefore, for this village’s purpose, the solar panels which need to be installed should provide atleast 2000 kWh of energy. The difference between the required and supplied power should be as less as possible as excess energy provided by the solar panel which is not used, will be wasted and cannot be reused. For this village, a one kW PV panel should provide the required amount of energy annually, which can be the basis of a grid, from where the power can be distributed to the rest of the houses. In case, if the grid arrangement is not possible then individual houses would have to be solar plated on the roof top. The roof area of each house can be calculated as 21 * 14 square metre = 294 square metre = 3164.59 sq feet. This would produce, if plated with solar panels, power roughly equal to 28 kW
Cost of a 1kw solar panel would be roughly 2700 US Dollars (based on estimates from here http://www.solarchoice.net.au/blog/solar-pv-system-prices-australia-march-2014-100314/)
Design of the village:
We needed to have a total energy requirement of ______________ for the village. For this, based on the energy requirements, we have decided to install a mini grid based solar power package which is modular in nature. We designed it in such a way that there would be a pair of solar panel array grids, one at set of arrays at each end of the village, from which two distribution lines would arise. Each distribution line would serve a set of houses. In this way there would be a balance of load distribution so that in case of any power failure, only a small section would be affected, which could be managed.
The solar arrays would be installed in sites which would be receiving plenty of sunshine through the year, so that at least 10 hrs of electric power per day can be generated. These sites were protected from weather elements such as dust storms which would interfere with its functioning and were enclosed in walled structure.
The solar power system for the village would contain the following components:
1. Photovoltaic Cells of 1kW solar energy system. These are the solar cells which capture the light energy of the sun and utilize it to create electricity. PV cells are based on the photoelectric effect wherein, light energy in the form of photons falling on one part of a set of negatively charged plates, excite electrons which get forced to other end of the plate, leading to a flow of electrons and hence electricity. The flowing electric current can be collected in DC form and subsequently converted into Alternating form, in which form it is supplied to various parts of the village supplied by the PV system. The advantage of using PV panels are that they can last for long time especially if they are used only for couple of hours a day. In such a village, where the requirements are basic, it can very easily be maintained. These systems are designed to withstand all weather conditions such as high temperatures, wind, rain etc. Excess energy produced by the system can be stored and used for later purposes. They can be easily manipulated, removed and reinstalled when there is a need to clean the housing place or there is reconstruction going on.
2 Solar charge controller – which regulates the current going from PV panel to the battery and protects the battery
3. Lead Acid Batteries- stores the electrical energy to be used for doing work such as providing light or for charging equipment
4. inverter- converts the DC output of PV panels into AC form of electricity which can then be used for doing work or transferred to grid to be distributed
5. Switch to control the operation of the system
References:
https://www.stthomas.edu/engineering/facultyresources/pdf/GSM_2011UgandaPower.pdf
http://www.leonics.com/support/article2_12j/articles2_12j_en.php
http://www.villageenergyuganda.com/
http://www.nrel.gov/docs/legosti/old/7227.pdf
"Design of High Volume Low Speed Fan Supplemental Cooling System in Dairy Free Stall Barns" D.W. Kammel, M.E. Raabe, J.J. Kappelman, University of Wisconsin-Madison.
Comparison of High Volume Low Speed (HVLS) vs. Conventional Fans in a Free Stall Dairy Barn in a Hot Humid Climate, J.W. Worley, J.K. Bernard, University of Georgia, 2006.
