SOLAR PV SYSTEM – Focus On Scenario Of Uttar Pradesh

Solar energy is the best option amongst all other renewable energy sources in India as it has uniform availability of solar radiation throughout the year in most parts of the country... - Dr Rajesh Gupta, Alok Kumar Singh, Vivek Kumar, Rahul Sharma, Shweta Sharma

Development of any country is determined by various factors. Among these factors, the amount of electrical power consumption is the major factor. India is a developing country, so its corresponding power requirement is also increasing with its development. This demand of electrical power cannot be fulfilled solely by conventional sources, so we need to look for some alternative means to fulfil this surplus amount of power requirement. Due to high depletion rate and increasing cost of conventional fossil fuels, we cannot rely on it completely. Import of fuels is not a best alternative for long run. The country must focus on the sources that are available in abundance and renewable in nature. Solar energy is the best option amongst all other renewable energy sources in India as it has uniform availability of solar radiation throughout the year in most parts of the country. The reason for rich availability of solar energy is due to the fact that India is located in the equatorial belt of the earth. About 1600 to 2200 kWh/sq-m/year of solar radiation is received by our country, equivalent to 6000 million GWh of energy / year, which is higher than energy received by the country’s conventional energy reserves. But, we are incapable of utilising this energy due to its higher harvesting cost. Till now, we have been capable of harvesting only 0.23% of the total energy received from the sun. Various initiatives have been taken at individual level as well as by the Indian government [1]. The government took the first major step in the field of solar in year 2006 in the form of Rural Electrification Program, which focuses on implementation of off-grid solar photovoltaic (PV) applications [2]. This primarily included solar home systems, solar pumps, solar lanterns, street lighting systems and home lighting systems. Under this policy, at the very early stage, 33.8 MW capacity of solar PV system was installed till Feb. 2012. A lot of technical advancement is still needed in the field of solar PV system in order to optimise its size, setting cost and losses etc. One of the major disadvantages is large area requirement for setting up of the plant. Still it can be overcome by using waste lands.

Micro grid is a newer concept for meeting the local energy demands. It is very helpful at the time of extremity. Nowadays, micro grid can act alone as a complete system for meeting the local demands. Grid connected and stand alone modes are the two different modes of operation of the micro grid. Frequent variation in the solar radiation due to fluctuating weather varies the power generation capacity of the solar PV system. Generation depends upon solar radiation reaching the panel’s surface. Maximum power point tracking technique can be used to exploit maximum power generated from the solar panels. To enhance the reliability on power generated by solar panels, we need to have an energy storage system that can store the surplus amount and supply it back whenever required. Among all the technologies of electrical energy storage present today, battery is the most economical option. Block diagram of a solar PV system is shown in Fig.1. About 5,000 trillion kWh per year energy is incident over India’s land area with most parts receiving 3-5 kWh/sq.m/day. Based upon the availability of land and solar radiation, the potential of solar power in the country has been assessed to be 750GW. Out of this, the Uttar Pradesh (UP) has potential of 22.83 GW (3.04%, shown in Fig. 2 [3]. Status of Grid Connected Solar Power Projects under various schemes in India is 3883.507 MW till 29-05-15. Out of which total commissioned capacity of Grid connected Solar Power Projects in UP is 71.26 MW till May 29, 2015 [4]. The Ministry has so far sanctioned 361 MW aggregate capacity of grid connected rooftop solar systems in the country, of which 42 MW has been commissioned. Of this, 12MW has been installed in UP under ‘Rooftop PV and Small Solar Power Generation Programme’ (RPSSGP) Scheme [5].

Fig.1: Generalised block diagram of Solar PV system…

Fig.2: Solar potential available in India [3]..

Ministry of New and Renewable Energy (MNRE) has launched a program on ‘Development of Solar Cities.’ The program aims at minimum 10% reduction in projected demand of conventional energy at the end of 5 years, which can be achieved through a combination of energy efficiency measures and enhancing supply from renewable energy sources. The cities of UP chosen under this program are Allahabad, Moradabad and Agra [6]. The program assists Urban Local governments in:

  • Preparation of a master plan for increasing energy efficiency and renewable energy supply in the city
  • Setting-up institutional arrangements for the implementation of the master plan
  • Awareness generation and capacity building activities

Govt of India has proposed 1,00,000 MW of Grid Connected Rooftop Solar Project, which is to be installed till 2022 across the country. The state of Uttar Pradesh has a major chunk of this project to be installed in different parts of the state.

Fig.3: State wise rooftop installed solar capacity [5]…

Fig.4: Projected cumulative solar capacity to be installed in Uttar Pradesh till 2022 [7]…

Fig.5: Different types of solar cell technologies [9]…

Fig. 4 shows the year wise growth of installed Rooftop Solar Projects in U.P. Solar PV Projects Commissioned in Uttar Pradesh under Rooftop PV and Small Solar Power Generation Programme (RPSSGP) Schemes established under MNRE projects are shown in table 1 and under state policy in table 2, respectively.

Besides this, under State Solar Power policy, Uttar Pradesh state government has planned to set up a total of 200 MW power plants across different parts of the state. The list of successful bidders of 200 MW power from Grid Connect Solar PV Power Projects is given in table 3. Another 105 MW Solar PV project planned to be set up in UP. List of successful bidders are shown in table 4. There is a provision to install Solar Park and to be implemented by state under solar energy policy 2013.

Installation of total 600 MW solar parks is to be done in Jalaun, Etah, Mirzapur, Allahabad and Jhansi districts of the UP. Development and management of solar parks is designated to state agency Uttar Pradesh New and Renewable Energy Development Agency (UPNEDA) and is to be made by the joint venture with Solar Energy Corporation of India (SECI) of the Government of India.

Solar PV Modules

The source of electrical power in the solar PV system is a solar cell. The solar cells when connected in series form a solar PV module. Generally a group of PV modules connected in series and parallel forms a solar array in a solar PV plant.

Solar Cell Technologies

Different types of solar cells are shown in fig 5 and its comparison is listed in table 5.

Crystalline silicon also known as solar grade silicon is the most accepted choice of material for solar cells. It is categorised into ribbon or wafer depending upon crystal size. Polycrystalline silicon cells are made from large blocks of molten silicon carefully cooled and solidified. They consist of small crystals giving the material metal flake effect. Poly-silicon cells are economical but less efficient, than mono-crystalline silicon. Thin film technologies reduce the amount of active material in a cell. In most of the designs the active material is sandwiched between two panes of glass. They have double weight and lesser conversion efficiency than that of crystalline silicon panel.

Solar PV System Design

Solar PV system design is done for both commercial as well as domestic loads, which estimates the number of panels, batteries and ratings of electrical equipments required for a solar plant. All those loads whose requirement is less than 10 kW is considered to be domestic load and greater than 10 kW is considered as commercial load. System voltage is decided depending on the load conditions. If demand is more than 10 kW, then system voltage is 48 V. For demand less than 10 kW and greater than 1 kW, system voltage is 24 V. For lesser demand it is 12 V. Following analytical study is required for solar PV plant installation purposes:

  • Expected energy demand
  • Average generation
  • Number of PV modules
  • Size and number of battery bank
  • Losses in system
  • Insolation of the geographical area.

Expected Energy Demand

While setting up the solar plant, the calculation for average energy demand is necessary. It is required to first calculate total load connected to the system and its duration of operation. This study is necessary for estimating the number of PV panels required in a PV array. Table 6 shows the power consumption for a residential unit taken as an example. A detailed analysis has been carried out for setting up a solar power plant in Allahabad, India, for a small residential/commercial unit that needs to be operated as a standalone system under all weather condition.

Total load connected to the system = 3.99 kW Total unit consumption/day = 26.52 Unit/day (1 Unit = 1000 Watt-hour)

Average Generation

After deciding the connected load and its demand throughout the day, average energy generation from the solar panels is calculated, considering the losses occurring in different

parts of the system. Calculate the power which needs to be generated from solar panels using the following formula [12],

Where, Q = Unit of solar electricity in Watt/m2 in day (varies during different months), D = Solar intensity (1000 W/m2 at STC), A= Batteries efficiency factor (~ 0.9), B = Heat and other loss factor (~0.9), C = Efficiency of Inverter (~0.93).

Table 7 shows month wise observation of load requirement and available solar electricity for Allahabad city. From table 7,

Qavg = 5006.67 watt/m2/day.
Power of the cell
= 7031.64 watt

No. of 250 W Modules/Panels required

= 7031.64/250 = 28
System voltage chosen = 48 V.
Solar panel output voltage
= 30.7 V
No of panels in series connections
= 48/30.7 = 1.56 = 2
No. of panels in parallel connections
= 28/2 = 14

Battery requirement

Battery Capacity: The true capacity of a battery is dependent on the rate of discharge. Faster the rate of discharge, lesser the total Ah capacity can be delivered. This phenomenon was described mathematically back in 1897 by a researcher named Peukert. He formulated the equation [14]

Where, T= duration of discharge, I = Discharge current, n = constant, related to the battery construction (1.05<n<2), C= Capacity due to discharge

For above example, to run the complete load (4 kW) from the battery (for 8 hrs. minimum), ampere hours (Ah) required =

Current drawn from battery at full load
Actual Ah of battery required is = 8×83.331.1
= 1037.5 Ah
No. of batteries required =
No. of batteries, each rated for 12 V, 150Ah required = 40 (for 8 hrs. full load back up condition).

Research is going on a project in USA on

solar panel with in-built batteries. They have created a battery that is 20% more efficient and 25% cheaper than others. Scientists

have conjoined the battery and solar panel into one system.

A company named Novatec Solar, has developed a PV system using molten salt storage technology, which uses inorganic salts to transfer the energy generated by solar PV systems into solar thermal using heat transfer fluid rather than oils. These plants operate at over 500 0C which results in much higher output. Hence, cost of the plant is also very low [15].

Losses In The System

Significant factors that affect power generation from the solar PV system are discussed below:

Tolerance

This is the range within which a panel manufacturer promises that module can differ from its specified Standard Test Condition (STC) power.

For example: for ±2% tolerance on a 250 W panel, the panel power will vary between 255 W and 245 W. Nowadays 0% negative tolerance panels are available.

Temperature

The output power delivered by the panel decreases with increase in temperature. Effect of temperature can be minimised by putting the solar panel above the rod endings at a height from the roof top.

Dirt and dust

It covers the glass covering of the panel and reduces its output. Hence, these need to be cleaned regularly. It also causes an increase in leakage capacitance.

Shading

It mostly affects the generation during morning and evening hours due to elongated shadows of tree leaves, roofs or any such other objects. This reduces the solar output power.

There is a danger of hotspot effect in the PV panels due to shading. In order to eliminate this effect the solar panels are supplied with bypass diodes which saves the PV panels. However they reduce the power output during shading condition.

Mismatch and wire loss

There are mismatch and wiring losses which are minimised by using special type of DC cables used. Losses occur in inverter during power conversion, which is minimised by using modern inverters, which are efficient up to 98%.

Insolation of the geographical area

Position of the solar panels in a geographical location is one of the deciding factors for extracting maximum power from it. Changing the position of the solar panels every time in accordance with the earth’s position, with respect to sun is not practical.

In order to have optimum utilisation of the solar panels, it should be mounted at an appropriate angle so that it gives optimum output throughout the year.

Challenges And Opportunities

Land is a meagre resource in India and per capita accessibility is less. Large land requirement of 1 km2 for every 40-60 MW solar power plant may have to compete with the other necessities. Large setting up cost is also one of the major issues. State governments have taken initiative to counteract with this major issue by installing solar panels on rooftop of the houses, metro stations, etc.

Govt. of Gujarat launched Canal Solar Power Project for the estimated generation of 1 MW, which will save land, reduce overall setting cost and prevent evaporation of water. It is estimated that 2,200 MW of power can be harnessed from over 19,000 km length of canal in Gujarat.

The government is providing subsidies for the installation of PV power system, in which there will be reduction in the cost price and this can promote more usage of solar power in India. The Jawaharlal Nehru National Solar Mission was launched on the 11th January, 2010 by the Prime Minister for deploying 20,000 MW of grid connected solar power by 2022.

This mission aimed at reducing the cost of solar power generation in the country through (i) long term policy; (ii) large scale deployment goals; (iii) aggressive R&D; and (iv) domestic production of critical raw materials, components and products, as a result to achieve grid tariff parity by 2022.

Conclusion

This article presented the current scenario of solar energy in the country with a special focus on Uttar Pradesh. It also mentioned the upcoming solar projects in the state. A complete installation of medium sized off grid solar plant has also been covered.

At present, the main focus of the companies is on reducing the size of solar panel, thereby increasing energy density. With the further advancement in the field of solar energy trapping and utilisation, it is expected that solar energy harvesting would become more economical in near future.

Future Scope

Research is being carried out for making solar panel transparent, less costly, lightweight, flexible and ultra efficient. In the future, there will be solar panel roads which will be capable of supporting vehicle’s force.

Moreover, with the feature of heat radiation from solar road, the problem of snow or ice would be vanished. A 70-metre solar panels cycle path has been installed in Amsterdam, Netherland by an American company Solar Roadways, meant for all types of roads [15].

Since 70% of Earths’ surface is covered with water, land concerns associated with installation of solar plants can be solved by using the concept of Floating solar. Some research organisations, including French firm called Ciel et Terre, are experimenting with this technology.

The company has projects, set up in France, Japan, and England and other parts of the world including a project in India [15]. Space based solar technology is being tested by India, China and Japan in which space based satellite capture sunlight and convert it into microwave energy that is then beamed back to earth. The technology promises to capture nearly 90% percent of sunlight.


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