Solar Powered Auto Irrigation System - Assignment Example

1 Sizing methodology Sizing is very necessary in this project because oversizing would result to unnecessary costs and undersizing 1 PV SIZING Various solar power panel modules produce different amounts of power. To size the solar power panel that peak wattage for the module needs to be found. The amount of the peak watt is directly proportional to the size of the PV module, location of the module and the climatic conditions of the area. To accurately determine the load, the sizing is done as follows; STEP 1: Total load connected Typically the total hydraulic energy required, Where; E- The required hydraulic energy (kWh/day) - The density of water (1000 kg/m3) g- The force of gravity (9.81 m/sec2) H- The hydraulic head (m) V- Volume of the total water needed ( m3/day) Replacing all the values into the equation, E= 0.002725 (kWh/day) STEP 2: Total power produced by the PV solar panels STEP 3: Peak Watt (WP) capacity required STEP 4: The number of solar PV panels needed for the installation 2 SIZING OF THE BATTERY The sizing of the battery is done in terms of ampere hours (Ah). STEP 1: Total load connected STEP 2: Battery calculations 3 SIZING THE STORAGE TANK The storage tank will be sized according to the method below; The sizing is based on volume of water that is pumped out of the normal operating hours. 4 WATER REQUIREMENT FOR THE PLANTS Assumption: 500 plants The water requirements for the plants depend upon the stage at which the plants are and also changes with time. A lot of water is required during the flowering and the maturing stages. Another key factor is the soil type and the prevailing climatic conditions of the area in question. To ensure that all the stages of growth are catered for, maximum water requirements are considered and parameters replaced in the equation below. Whereby; -Crop coefficient -Is the pan coefficient (0.7 to 0.8) -Evaporation rate of the pan (mm/day) -The percentage wetted area -Uniformity of emission (0.9) The table below illustrates the various constants for the growing of bananas. Table 1: Crop constants for bananas Perth Weather data Table 2: Perth rainfall records in the past year (Bom.gov.au, 2015) Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Rainfall (mm) 0.2 0.0 7.4 24.6 152.6 93.6 151.2 107.0 77.0 37.0 23.8 0.0 2 Daily Insolation The energy output of the solar PV panels requires sufficient insolation of the sun per given day. The insolation is dependent on the climatic conditions. When design for water requirements of a given farm, calculations are based on the minimum records of rainfall in that particular year. Therefore, calculations are done according to the ratio between the water required and the available insolation (Ijesi.org, 2015). Optimum PV design will be found in the month with the highest ratio. 3 Orientation of the PV array This is vital parameter of site assessment. The PV array is put in such a way that the maximum energy from the sun can be tapped on a particular day. The ideal direction is in the true south direction (Ijesi.org, 2015). This means that the PV array will be directed to the sun for most of the time available during the day. There are however seasons when the direction of the sun changes. In such situations the PV array is rearranged considerably (Ijesi.org, 2015). 4 The tilt angle of the PV array The tilt angle of the PV array depends on the location of the site where the PV array is going to be installed. The panels are usually positioned using a clinometer (Ijesi.org, 2015). The latitude for Perth, Australia is 31.92 Degrees south while the longitude is 115.87 Degrees East at an elevation of 24 m (Bom.gov.au, 2015). 5 Life cycle cost Analysis (LCCA) of the automated solar powered irrigation plant This can be explained as the actual sum of the cost of ownership of a given facility. The total costs that have been used to set up the facility are all put into consideration. This includes the capital costs in acquiring the facility and the costs incurred when the facility is disposed. The equation below shall be used in calculating the LCC. In this case, CC-Capital cost MC-Maintenance cost EC-Energy cost SC-Salvage cost 2 Results and Calculations 1 Water requirements Using the maximum water required by the banana plant, the water requirement for the banana was calculated and tabulated as follows. Table 3: Water requirements per given month 2 Daily insolation The average solar insolation is obtained using weather data provided by the Bureau of Meteorology in the Australian government. Table 4: Mean daily solar exposure for Perth Metro Month Mean daily solar exposure (MJ/(m2)) January 29.4 February 26 March 21.1 April 15.2 May 11.3 June 9.3 July 10 August 13 September 16.7 October 22.7 November 26.6 December 30 Water requirement to solar insolation ratio Table 5: Water requirement to solar insolation ratio Month Water requirement(litres per day per plant) Mean daily solar exposure (MJ/(m2)) Mean daily solar exposure (W/(m2)) Ratio January 6.78 29.4 340.277778 0.0199249 February 8.3 26 300.925926 0.02758154 March 9.26 21.1 244.212963 0.03791773 April 13.175 15.2 175.925926 0.07488947 May 17.22 11.3 130.787037 0.13166442 June 5.814 9.3 107.638889 0.05401394 July 4.62 10 115.740741 0.0399168 August 5.02 13 150.462963 0.03336369 September 7.234 16.7 193.287037 0.0374262 October 8.651 22.7 262.731481 0.03292715 November 7.867 26.6 307.87037 0.02555296 December 7.451 30 347.222222 0.02145888 From the calculations, the month of May has the highest water requirement to the level of solar insolation. This means that a solar irradiation of 130 W/m2 and a water requirement of 17.22 litres per plant were used to optimize the design of the solar PV array. 3 Sizing of the PV module The number of plant = 500 plants Peak water requirements= 17.22 litres per day per plant18 litres per day per plant The head is taken as; 26 m Total volume of water required: Therefore; Using the actual number of hours of sunshine on a given day: 8 hours Total power in watts for the solar PV panel Taking into account the losses in the system; The total number of solar panels required; This means that 4 solar panels each rated at 74 W would suit this design. For such a PV module, the technical specifications are as shown in the table 6 below. The parameters is done at 25 degrees Celsius and a solar intensity of about 1000 W/m2. Table 6: A photovoltaic module specifications 4 Sizing of the Solar Pump The hydraulic energy needed (kWh/day) = volume needed for the plants (m³/day) x head (m) x water density x gravitational pull / (3.6 x 106) = 0.002725 x volume (m³/day) x Hydraulic head (m) Solar power array power required (kWp) = Hydraulic energy required (kWh/day) Average daily solar irradiation (kWh/m²/day x F x E) Where F -array mismatch factor = 0.80 E = daily subsystem efficiency which is between 0.25 - 0.40 This means that a solar pump that will serve the purpose of irrigating the farm will have a sizing of 313W. 1. Project schedule and budget Figure 20: Project schedule Mar Apr May Jun Aug Sep Oct Nov Develop design problem Conceptual Design Design approval Acquiring materials Implementation Figure 11: Project budget Materials and Equipment Solar panels $1800 Water tank $600 Water pump $800 Micro controllers $400 Piping $300 Implementation $500 Miscellaneous $260 Total $4,660 2. Conclusion From this project, it was concluded that the solar panels must be sized in accordance to the maximum water requirement of the farm. A total of 4 PV arrays were found to be enough to substantially cover the area that had been used in the design. The total amount of energy produced by the solar panels was 312.5735294 W. This amount of power was enough to be able to sustain a water head of 26 m from the ground to an above ground tank. The sizing of the tank was done in accordance to maximum water requirements by the plants. It was found through calculations that a maximum capacity of 9,000 litres was sufficient to water the plants in month of maximum water requirements. Therefore a 9,000 litre tank was chosen for the automated solar powered irrigation. Sensors in the soil were used to initiate the irrigation process in such a way that when the soil got dry, the system automatically allowed water into the soil. On the other hand, when the water level in the tank went low, sensors were able to detect and the pump switched on accordingly. Read More

Table 1: Crop constants for bananas Perth Weather data Table 2: Perth rainfall records in the past year (Bom.gov.au, 2015) Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Rainfall (mm) 0.2 0.0 7.4 24.6 152.6 93.6 151.2 107.0 77.0 37.0 23.8 0.0 2 Daily Insolation The energy output of the solar PV panels requires sufficient insolation of the sun per given day. The insolation is dependent on the climatic conditions. When design for water requirements of a given farm, calculations are based on the minimum records of rainfall in that particular year.

Therefore, calculations are done according to the ratio between the water required and the available insolation (Ijesi.org, 2015). Optimum PV design will be found in the month with the highest ratio. 3 Orientation of the PV array This is vital parameter of site assessment. The PV array is put in such a way that the maximum energy from the sun can be tapped on a particular day. The ideal direction is in the true south direction (Ijesi.org, 2015). This means that the PV array will be directed to the sun for most of the time available during the day.

There are however seasons when the direction of the sun changes. In such situations the PV array is rearranged considerably (Ijesi.org, 2015). 4 The tilt angle of the PV array The tilt angle of the PV array depends on the location of the site where the PV array is going to be installed. The panels are usually positioned using a clinometer (Ijesi.org, 2015). The latitude for Perth, Australia is 31.92 Degrees south while the longitude is 115.87 Degrees East at an elevation of 24 m (Bom.gov.au, 2015).

5 Life cycle cost Analysis (LCCA) of the automated solar powered irrigation plant This can be explained as the actual sum of the cost of ownership of a given facility. The total costs that have been used to set up the facility are all put into consideration. This includes the capital costs in acquiring the facility and the costs incurred when the facility is disposed. The equation below shall be used in calculating the LCC. In this case, CC-Capital cost MC-Maintenance cost EC-Energy cost SC-Salvage cost 2 Results and Calculations 1 Water requirements Using the maximum water required by the banana plant, the water requirement for the banana was calculated and tabulated as follows.

Table 3: Water requirements per given month 2 Daily insolation The average solar insolation is obtained using weather data provided by the Bureau of Meteorology in the Australian government. Table 4: Mean daily solar exposure for Perth Metro Month Mean daily solar exposure (MJ/(m2)) January 29.4 February 26 March 21.1 April 15.2 May 11.3 June 9.3 July 10 August 13 September 16.7 October 22.7 November 26.6 December 30 Water requirement to solar insolation ratio Table 5: Water requirement to solar insolation ratio Month Water requirement(litres per day per plant) Mean daily solar exposure (MJ/(m2)) Mean daily solar exposure (W/(m2)) Ratio January 6.78 29.4 340.277778 0.0199249 February 8.3 26 300.925926 0.

02758154 March 9.26 21.1 244.212963 0.03791773 April 13.175 15.2 175.925926 0.07488947 May 17.22 11.3 130.787037 0.13166442 June 5.814 9.3 107.638889 0.05401394 July 4.62 10 115.740741 0.0399168 August 5.02 13 150.462963 0.03336369 September 7.234 16.7 193.287037 0.0374262 October 8.651 22.7 262.731481 0.03292715 November 7.867 26.6 307.87037 0.02555296 December 7.451 30 347.222222 0.02145888 From the calculations, the month of May has the highest water requirement to the level of solar insolation.

This means that a solar irradiation of 130 W/m2 and a water requirement of 17.22 litres per plant were used to optimize the design of the solar PV array. 3 Sizing of the PV module The number of plant = 500 plants Peak water requirements= 17.22 litres per day per plant18 litres per day per plant The head is taken as; 26 m Total volume of water required: Therefore; Using the actual number of hours of sunshine on a given day: 8 hours Total power in watts for the solar PV panel Taking into account the losses in the system; The total number of solar panels required; This means that 4 solar panels each rated at 74 W would suit this design.

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