Solar PV System Design and Installation at Roof Top ...

Proceedings of 11th Global Engineering, Science and Technology Conference 18 - 19 December, 2015, BIAM Foundation, Dhaka, Bangladesh, ISBN: 978-1-922069-92-4

Solar PV System Design and Installation at Roof Top to Partial Fulfillment of Elevator and Common Load Mohammed Rafiqul Islam$, Md. NurAlam* and Rezaul Karim# Bangladesh is a developing country where energy crisis seems to be the major problem in spite of being blessed with rich solar irradiation (~4.5Wh/m2 -Day). To deal with the crisis, the government starts to take initiatives introducing building integrated renewable energy technologies in the urban area. Particularly solar energy is abundant in Bangladesh and can fruitfully be harnessed. But the large number of buildings rooftop of Dhaka cities is not used or installed solar system. Some building rooftop has already installed solar system, but most of the solar panels installed at rooftop areas are not being efficiently used. The objective of this paper is to highlight the benefit and scope of introducing solar PV system at Roof top on urban residential areas to meet some partial demand of energy especially elevator &common load like security light, guard room load, water pump of the building. This will reduce the pressure on the existing grid network.

I. Introduction Energy is one of the main concerns for the rising future of any nation. Energy certainly plays a vital role in development and welfare of human being. There exists a direct correlation between the development of a country and its consumption of energy. Bangladesh aspires to be a middle-income country by 2021. This will require increasing GDP growth to 7.5 to 8 percent per year based on accelerated export and remittance growth [1]. Only 62% percent of the entire population has access to power supply and the per capita power consumption is only 321 KWh [2]. Government has set up the goal of providing electricity to all by 2020 and to ensure reliable and quality supply of electricity at a reasonable and affordable price. Sustainable social and economic development depends on adequate power generation capacity of a country. There is no other way for accelerating development except to increase the power generation by fuel diversification The total power generation in Bangladesh is almost entirely dependent on natural gas, which accounts for about 62.59% of the electricity generation of the total installed capacity as on September, 2015 is 11877 MW [3].Generation of electricity using different fuel as shown below:

_____________________________________________________________________________________________ Shift Engineer$, Unique Cement Power Plant Ltd. $, [email protected] $, Research Engineer*, Centre for Energy Research*, [email protected]*,Shift Engineer#, Everest Power Generation Co. Ltd.#, [email protected]#,

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Figure 1.1: Different fuel consumption for energy generation

Development of Renewable Energy is one of the important strategies adopted as part of Fuel Diversification Program. In line with the Renewable Energy policy 2009, the Government is committed to facilitate both public and private sector investment in Renewable Energy projects to substitute indigenous non- renewable energy supplies and scale up contributions of existing Renewable Energy based electricity productions. The Renewable Energy Policy envisions that 5% of total energy production will have to be achieved by 2015 and 10% by 2020. To achieve this target, GOB is looking for various options preferably Renewable Energy resources. Under the existing generation scenario of Bangladesh, Renewable Energy has a very small share to the total generation. The share of Renewable Energy exceeds more than 1% till now. The present Government is placing priority on developing Renewable Energy resources to improve energy security and to establish a sustainable energy regime alongside of conventional energy sources [4]. In urban area like Dhaka city, the demand of power is increasing gradually. The government starts to take initiatives through installing solar panel at building roof top. Like as all government buildings are to be recommended to use solar energy in Dhaka by 2013 through the Ministry directive [5]. The government also has declared that any multi-stored building (to be built in Dhaka and other big cities in future) will have to plan for solar based power supplement before the building design gets approved by the city authority [6]. To get maximum benefit from the solar energy, suitable building location is needed and to introduce high-performing solar installation. In this paper we have focused about the installation of solar PV at roof top to reduce pressure on existing grid network and to mitigate partial demand of energy especially elevator & common load like security light, guard room load, water pump of the building.

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Proceedings of 11th Global Engineering, Science and Technology Conference 18 - 19 December, 2015, BIAM Foundation, Dhaka, Bangladesh, ISBN: 978-1-922069-92-4 II.

Motivation and background

Everyone knows renewable energy is the energy for tomorrow. Still it is not affordable to use renewable energy to full fill all our needs. All have to be smart with using renewable energy for different requirements. Common loads of apartment are one of the biggest sources where renewable energy can have a significant role. Weather condition in Bangladesh is also suitable for this project.

III.

Climate Study

Apart from the solar radiation availability the climatic (ambient temperature, humidity etc.) and microclimatic parameters (wind speed, dust level etc.) make significant impact on the performance of solar PV system. A. Average Temperature Maximum and minimum temperature significantly impact on voltage production in solar panel therefore it is important to consider in design. Figure 1.2 shows the average maximum and minimum temperature of the project site where minimum temperature is 7 degree Celsius in January and maximum temperature is 41.6 during month of Mar. Figure Error! No text of specified style in document..2: Monthly Average Temperature of the Site (NASA Surface Meteorology) 35 Minimum

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Proceedings of 11th Global Engineering, Science and Technology Conference 18 - 19 December, 2015, BIAM Foundation, Dhaka, Bangladesh, ISBN: 978-1-922069-92-4 B. Average Precipitation Figure Error! No text of specified style in document..3: Average Precipitation (NASA Surface Meteorology) Average Precipitation

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C. Humidity There is an adverse effect of too much humidity in the atmosphere on the PV module performance too. It becomes worse when humidity starts condensing on the panel in night and dust got deposited on the panel, and reduces the amount of solar radiation reaching on the solar cells. This will reduce the power output from the plant. Hence special consideration should be given for the cleaning of the solar panels. Here in the power output calculation from the PV plant is considered by taking in to account the effect of the humidity as well. Figure Error! No text of specified style in document..4: Average Humidity of the plant location (NASA Surface Meteorology)

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100 90 80 70 60 50 40 30 20 10 0 Jan Feb Mar Apr May Jun

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IV.

Potential of Solar Energy in Dhaka

Dhaka city lies between 23 046΄ north and 90 0 23΄ east latitude and the climate is tropical; this very location makes Dhaka good recipient of solar energy. The monthly average sunshine hour varies 4.1 to 7.8 hrs, an average daily solar radiation from 4.02 to 5.76 KWh/m2, which is a very favorable range of solar extraction [7]. Center for Energy Studies (CES), BUET, recorded average solar radiation in Dhaka 4.7 KWh/m2/day in a year, which is significantly higher than Europe to use solar energy. Daily average of bright sunshine hours and daily average of solar radiation at Dhaka city is given in table 1. Table 1: Solar Radiation and Sunshine Hour In Dhaka Month January February March April May June July August September October November December

Solar Radiation 4.36 4.92 5.59 5.76 5.30 4.53 4.23 4.29 4.02 4.32 4.28 4.21

Sunshine Hour 5.3 6.6 7.2 7.8 7.2 4.2 4.1 5.1 4.2 5.4 6.6 4.9

(Source: Bangladesh Meteorological Department and NASA, SSE Database) The area of Dhaka mega city is 4.31 × 108 m2 of which DCC Wards occupies a total area of 1.32 × 108 m2 and average 4.2 KWh/m2 solar intensity falls on this land over 300 days per annum. Even if one percent of this land is used to harness solar energy for power generation at efficiency of 10%, theoretically, a total of 555 MW of electricity can be generated annually (assumption).

V.

Basic Block diagram

The installation of solar PV system at roof top needs different elements such as solar panel, battery, inverter and control circuit which is completely lucid and easy to install. The generated electricity from the solar energy will be supplied to elevator, battery charging and common load like security light, guard room load, water pump of the building. Let us see each block in detail.

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Figure 1.5: Block Diagram of the system

A. Solar Panel In general, a solar cell or photovoltaic cell (PV) is a solid state electrical device that converts light into electric current using the photoelectric effect. Each panel is rated in accordance with its DC output power under standard conditions, and typical specification ranges from 100 to 320 watts. We espouse a collection of 200 watt panels to form 1000 watts. The conjectured efficiency of these panels is 80% and thus we could postulate that a figure of 1870 watts may be collected from this section. A photovoltaic system conventionally comprehends an array of solar panels, an inverter, and an optional battery. B. Battery A rechargeable battery, storage battery is a type of electrical battery which can be charged, discharged into a load, and recharged many times, while a non-rechargeable or primary battery is supplied fully charged, and discarded once discharged. It is composed of one or more electrochemical cells. It is known as a secondary cell since its electrochemical reactions are electrically rescindable. Rechargeable batteries are used by grid energy storage applications for load-leveling, where they accumulate electric energy. For sustainable energy uses, the energy stored during day time can be used during peak load hours at night. We use a couple of batteries, each of 2V and 1040Ah capacity forming 48V and 1040Ah capacity. C. Inverter A solar inverter, or PV inverter, or Solar converter, converts the variable direct current (DC) output of a photovoltaic (PV) solar panel into a utility frequencyalternating current (AC) that can be fed into a commercial electrical grid or used by a local, off-grid electrical network. It is a critical BOS– component in a photovoltaic system, allowing the use of ordinary AC-powered equipment. We use a 1.5kVA inverter with standard output specifications of 230V, 50Hz to suit our requirements.

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Proceedings of 11th Global Engineering, Science and Technology Conference 18 - 19 December, 2015, BIAM Foundation, Dhaka, Bangladesh, ISBN: 978-1-922069-92-4 D. Control Circuit In the system there must be a scheme to detect when a cell reaches full charge (change in terminal voltage, temperature, etc.) and to stop charging before harmful overcharging or overheating occurs [5]. We can incorporate cooling fans if needed to keep the cells from heating. Here we use a control circuit with voltage level sensors to obviate a detonation. E. Load In this system our main purpose to supply electricity from solar panel to elevator & common load like security light, guard room load, water pump of the building. F. National Grid Supply of electricity from the solar panel totally depends on whether condition of the atmosphere. If sunshine is not available or battery storage isn’t sufficient at night, then electricity will be supplied from the national grid.

VI.

Design Calculation

For our design calculation, we consider maximum possible time use by common load. A. Load Calculation Let consider 5 storied building. The common load of that building are lift, water pump, and ground floor load such as security light, guard room load etc. Load calculation of Lift, We choose 500lb lift, specifications of that lift are travel up to 50 ft, CAR size – 12 sq. ft, speed 30 ft per minute and most important it requires 2 hp instant reversing single speed motor for operating. We consider lift will operate maximum 12 hours (after 12 am most of the lift will off). Total Wh required for lift is 2 X 746 X 12 = 17904 Wh ≈ 18000 Wh. Load calculation of water pump, We choose 2 hp motor, which can operate 10 times in a single day and that motor can pump 1000 liters of water by 15 minutes. Total Wh required for water pump is 2 X 746 X (15/60) X 10 = 3730 Wh ≈ 3800 Wh. Load calculation of other common load, Security light at different floor, guard room light, fan, and ground floor light etc. Let consider maximum 300 w powers required for that loads and which can operate average 10 hours. Total Wh required for other common loads is 300 X 10 = 3000 Wh Total Load = 18000 + 3800 + 3000 = 24800 Wh.

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Proceedings of 11th Global Engineering, Science and Technology Conference 18 - 19 December, 2015, BIAM Foundation, Dhaka, Bangladesh, ISBN: 978-1-922069-92-4 B. Battery Calculation Total Wh = 24800 Wh. Total battery capacity required = 24800/48 = 516.66 Ah ≈ 520 Ah. Total battery capacity required = 520 X 2 = 1040 Ah (Consider 50% loss due to DOD 70% & battery life cycle 80%). No. of battery required (48 V, 1040 Ah) = 1040 / 10401. We Know, size of (48 V, 1040 Ah) battery is very large. So we use (2 V, 1040 Ah) battery [24 (2 V, 1040 Ah) battery will connect series]. Thus, required no. of battery (2 V, 1040 Ah) =1 X 24 = 24. C. Panel Calculation Each an everyday each cluster we need 520Ah charge by solar panels. So, each cluster we need = 520 / 6h (sun light) = 86.67 A ≈ 100 A charging current (consider 6 hours sunlight for each day). Let consider 110 W panel, Impp of 110 W panel is 6.4 A (Solar land PV model SLP110-12U 110watt). Each cluster we need = 100 / 6 = 16.67 or 17 panels. So total no. of panels required = 17 X 1 = 17 panels. Total capacity of Solar PV system are = 17 X 110 = 1870 W or 1.87kWp. Total area required for 1.87kWp panels are = 17 X 7.878 ft2 = 133.926 ft2. Here we use solar panels only for battery charging. D. Inverter Calculation Total capacity of solar pv system will be 1.87 kWp. So we will use 1.5 kW bi directional inverter, which will convert DC to AC as well as AC to DC.

VII.

PVsyst Simulation Result

After Hand calculation we also simulate our project by PVsyst software, which is one of the well know Solar PV system simulation software. A. Input Data The shadow effect should be considered in PV array design, which should be wakened or eliminated. The general requirement is that, at the time of the winter solstice, when the longest shadow in a year appears, the spacing between the two rows of PV arrays should be big enough that the shadow of the PV array in front would not block the array behind, especially from 8 a.m to 5 p.m. Local latitude angle has been considered for the inclination or tilt angle of the PV module facing towards the equator (south). Dhaka city is located at 23o latitude and in northern hemisphere. So, to get the maximum of the incident rays of the sunlight, the module should place at a tilt angle equal to local latitude and facing towards south.

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Figure 1.6: Inclination angle of PV panel

Figure 1.6: Input data of PVsyst software

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According to PVsyst software the system will produce 3045 kWh/year with Performance ratio 78.8% Figure 1.7: Simulation Result (Yearly power generation of the system)

VIII. Study The price of electricity and gas is increasing day by day. In this paper, we implement a solar based system and find out the feasibility of the idea and the monetary profits of using it rather than using electric supply for light load. The project if successfully implemented, operated and maintained will have significant environment benefits mainly derived from the switch of power generation from a fossil fuel (diesel) source to a renewable source (solar energy). The only type of physical work is installing solar power generation systems on top of existing buildings. Apart from this the project will also impact in social perspective as described below. A. Job Creation To operate the PV system therefore there will an employment opportunity for local people. In addition, during construction a considerable number of manpower will be required to construct the project maximum of the workforce could be avail locally. B. Use of unused rooftop The rooftop of building to be used for the proposed 850kWp grid connected solar power system is now mostly unused. Therefore, implementing the power plant the land can be used in an efficient way to produce power approximately 1417MWh annually.

C. Avoidance of Carbon dioxide emissions

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Proceedings of 11th Global Engineering, Science and Technology Conference 18 - 19 December, 2015, BIAM Foundation, Dhaka, Bangladesh, ISBN: 978-1-922069-92-4 Solar PV technology is an environmentally friendly technology. It does not emit carbon when generates power converting the sun light. The amount of carbon dioxide can be avoided throughout the period of the plant lifetime. Grid emission factor of Bangladesh is 0.67 ton per MWh. D. Increased Energy security Bangladesh is an energy striving country. There is a considerable gap between demand and generation of power. Building such power plant can improve the scenario and reduce dependency on imported fuel significantly.

IX.

Conclusion

World reserve of conventional energy sources are limited and will be used up once. Therefore, the whole world is looking for non-exhaustible energy sources for their future. Among the all nonconventional energies, solar energy is the best option if it can be used in a cost effective manner. Moreover the technology is environmentally sound. So now it is high time for the building owners to install solar PV at roof top to collect the solar energy as the alternative source of electricity for partial mitigate of their demand.

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References

[1]http://www.worldbank.org/en/country/bangladesh/overview [2]https://en.wikipedia.org/wiki/Electricity_sector_in_Bangladesh [3] Bangladesh Power development Board “Key statistics” as on September, 2015 [online]. Available:http://www.bpdb.gov.bd/bpdb/index.php?option=com_content&view=article&id=5&Itemid =6 [4]http://www.bpdb.gov.bd/bpdb/index.php?option=com_content&view=article&id=26&Itemid=24 [5] Rahman, M. M. &Rahman. I., “ Renewable Energy System for Residential Buildings in New Satelite Towns of Dhaka: Barriers and Probable Solutions”, Conference on Engineering Research, Innovation and Education, CERIE 2011, 11-13 January, Sylet, Bangladesh, 2011 [6] kabir, M. H., “Using Dhaka’s Bright Roof-tops For Solar Electricity Generation”, Star Campus, Science Feature, Vol. 2, no. 7, Dhaka 2010 [7] Rahman, M. M., “Renewable Energy Systems: an alternative source for urban residential buildings in Dhaka, Bangladesh”, unpublished MSc thesis, MSc Programme in Urban Management and Development, International institute of Urban Management of Erusmus University, Rotterdam, The Netherlands, 2010

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