The launch of the Jawaharlal Nehru National Solar Mission and other policy initiatives taken by several state governments have set the stage for large scale production of grid connected solar power in India. To achieve this, solar farms to be set up in the country need to look into several technical as well as infrastructural aspects before going ahead with the production of solar energy full throttle.
Saturday, April 17, 2010: Government policy in India provides for a power purchase agreement (PPA) to be signed between the solar power project developer and the government for 25 years. Such a long duration of the PPA means the quality and performance of the solar modules will be the single most important factor driving the success of the solar projects. Therefore, the importance of getting 25 year warranty on solar modules will be one of the most crucial aspects in getting the projects off the ground.
Individual parts like solar panels, wires and cables, transformers, etc, must be of the required specifications and standards, and the systems integration must be of the highest standards.
For the success of the mission, equipment suppliers, engineering, procurement and construction (EPC) contractors and project developers must work in coordination. Operations and maintenance should be handled by qualified personnel. And at all stages, the highest levels of safety standards must be maintained to avoid accidents, especially during installation and commissioning.
Thus, in the light of the above mentioned aspects and the fact that huge initial investments are involved in setting up and maintaining solar farms, it becomes imperative to select the key components with utmost care.
Investment in suitable land is one of the most important components for a startup in solar space. “It is advisable to build the solar PV farm closer to a substation and grid to save costs of laying a new power line. In India, practically all places receive adequate insolation (sunshine) for photovoltaic (PV) systems to work well. In fact, what is gained in high insolation in some places may be lost in high temperatures since PV systems deteriorate incrementally in performance with the rise in temperature above a certain degree. In addition to nearness to substation, it would be better if the selected land is close to a paved road. Availability of water for cleaning the panels is essential. Ensuring safety and security of the installation throughout the life of the project would also be important,”explains K Subramanya, CEO, Tata BP Solar India Ltd.
“We recommend to go by a thumb rule of choosing 4.5-5 acres of land to produce 1MW of power from solar PV power farms using crystalline silicon technology, and 12-15 sqm of land to produce 1kw of solar power from an off grid farm,” adds Subramanya.
Raghu Nandan, associate vice president, PV & Engineering, Kotak Urja Pvt Ltd, says that four acres of land is suitable to build a farm using crystalline technology to produce 1MW of solar power, while 8 acres of land is required for thin film farms producing 1MW of power. “The life span of a solar farm is driven by the right kind of land, which, in turn, plays a critical role in producing grid mode solar power. The land must get solar radiation throughout the year with no threat of flooding, and the location needs to be dust free. This will make the cleaning of panels easy. A grid of 33 KV or above must exist near the solar farm so that the power could be supplied to the grid,” he adds.
Cells and modules
The main component of any solar project is the solar cell which makes up the PV modules, covering roughly 60-65 per cent of the cost of the farm. Therefore, it is of utmost importance that the project developer selects cells and modules with the performance guarantee of 25 years.
Another important consideration should be the ‘derating’ factor. The derating in the case of crystalline silicon is 0.5-1.5 per cent per annum varying from manufacturer to manufacturer of solar module.
“The buyer must look at the guaranteed output at the end of say 10 years, and certainly at the end of 25 years. For example, Tata BP Solar offers a guaranteed output of 93 per cent over 12 years and 85 per cent over 25 years. This may compare better than another company which is offers say guaranteed output of 80 per cent over 25 years. The buyer must compare the offers not only on the basis of the initial cost, but also on long term cost and delivered value. A company that offers cheaper modules which may underperform in the long run should be avoided. Another factor is the enforceability of the guarantees, warranties and performance contracts. It is recommended to go for an Indian company that is expected to last for the next 25 years,” informs Subramanya.
“However, long term warranty and efficiency are the major considerations apart from the installation base of the supplier,” says Hitesh Doshi, chairman and managing director, Waaree Energies Pvt Ltd.
Selection of power conditioners
Setting up a solar farm requires investment of Rs 17-18 crore per megawatt. Hence, to get a high return on investment, it is necessary to select the right equipment. Besides investing in the key components, it is also important to invest in inverters, wires and cables, the structure to hold the panels, transformers, etc.
Besides, there will be other critical issues such as the robustness of electricity infrastructure including substations and the connectivity to the grid–it should be at 33 KV or above, that will play a significant role in achieving the mission targets. The performance quality of the inverters, crystalline silicon cell technology, which could be mono or multi crystalline, will also play a significant role in optimum system performance. The structures that hold the panels must be designed and engineered to stand the weathering caused by natural forces of sun, wind, rain, hailstorms, dust, etc, for 25 years. Moreover, the inverter efficiency and essential for the project. Solar inverters are good choice for solar farms.
“In India, there is a dearth of solar inverter solutions, so this area is still to be penetrated by the Indian inverter manufactures,” says Sanjay Aggarwal, marketing manager, Kyocera Asia Pacific India Pvt Ltd.
Investment on manpower is a very small portion of the capital cost. Moreover, the number of people required in a solar power farm depends on the system size. “Manual work is required only during day time, that too only for monitoring the operations. In addition, panel cleaning is to be scheduled regularly. Security of the equipment also requires to be taken care of,” says Nandan.
Manpower required is mainly for project execution. Apart from security personnel, only three to five people are generally required for maintenance and supervision of the farm. “However, you may require more manpower for government liaison and getting reimbursement for your grid feed,” says Doshi.
“The employees must have a good understanding of energy, economics and the local geography. They must be trained for the job from a recognised institute. Knowledge of local site conditions, electrical codes and safety behaviour are very important criteria for selecting the manpower,” concludes Subramanya.
It is also essential that prospective solar power project developers work with globally competitive suppliers who have the technical experience and expertise, strong balancesheet, trained manpower for post sales support and believe in working in partnership. It is, therefore, essential to select manpower with good experience.
Electronics Bazaar, South Asia’s No.1 Electronics B2B magazine