Large, dark blue panels atop rooftops supplying solar powered electricity is still not a familiar sight in India. Though relatively few homes have them, commercial use of solar power is picking up slowly but steadily. Although it is regarded as ‘the wave of the future’, usage of solar power will still take some time to be a household name in India, as industry analysts put it. However, once the initial investment in hardware is made, one can have free electricity for years to come, hence worth considering its usage.
By Srabani Sen
Thursday, February 18, 2010: Some of the common advantages of using solar panels may see its usage going up faster. Solar panels are basically clean—while generating electricity from sunlight, they produce virtually no pollution, whereas burning fossil fuels releases large amounts of toxic gases into the atmosphere. The portability factor of solar panels is another major advantage as they can be used for powering calculators, laptops and even small motorised vehicles. No doubt their applications are limitless but solar panels are still very expensive. “We must consider the cost of production of electricity by harnessing solar power vis-a-vis the cost of using conventional means of producing electricity like hydel and thermal, in terms of money cost, environmental cost and the time period taken in setting up power plants,”says Baldev Aggarwal, managing director, Ashi Green, which represents a Chinese channel based company Jinko Solar Ltd. Jinko Solar is one of the few companies in the world in vertical integration. It processes polysilicon raw material and manufactures silicon ingots, wafers, cells and panels. Ashi Green not only distributes solar panels, it also offers solar integrated solutions.
Applications of solar panels
Recent years have seen rapid growth in the number of solar panels installations connected to electricity grid. This growth has been stimulated in part by government subsidy programmes.
The use of solar panels to generate commercial electricity is becoming popular. Solar panels can be placed on the roof of homes, businesses or remote research stations and can be used independent of or in conjunction with the local power grid. In fact, there are many small scale applications that can be easily implemented at relatively low cost. Probably the most widely applicable usage of solar power is charging electronic devices such as cellphone, MP3 player, etc. “But in India, solar panel applications are still limited. Government has so far promoted solar lanterns and solar street lights. Now with the Solar Mission Policy being implemented, we may expect their usage to increase considerably,” says Aggarwal of Ashi.
“Nowadays most applications require a low voltage DC source or AC grid to supply the requisite power. Hence, battery charging, lighting, communication equipment, inverters, water pumps, onsite electricity generation, village electrification, are some of the primary applications of solar photovoltaic (SPV) panels,” informs Sunil Goel, vice president, Maharishi Solar Technology Pvt Ltd. Maharishi Solar is the first in the country to manufacture multi-crystalline silicon wafers for solar cells, solar modules with multi-crystalline solar cells and also the first to introduce AR coating on solar cells which increases the efficiency of cells by 2-3 per cent. It is also one of the leading companies in the country manufacturing silicon wafers, solar cells and panels in a completely vertically integrated facility in Andhra Pradesh.
According to K Srinivas Kumar, CEO, Kotak Urja Pvt Ltd, photovoltaic modules can be used for generating required voltage ranges. “For small home applications, they can generate voltage levels of 12V or 24V and for power plant applications, they can be coupled to generate 100V-600V of power. This high voltage DC power can be converted to AC and fed to the grid power,” he adds.
Solar panels can also be used to pump water in remote areas. Largescale desalination plants can also be PV powered. Cost effective solar panel applications are also available. For example, solar lanterns which use different sizes of solar panels. They can be placed anywhere as they do not require any wire.
What’s latest in solar panels?
Solar panels are of various kinds. “The differentiation depends upon the efficiency of the cells. Higher the efficiency of cells, lower will be the size of the panels. Solar panels need good open space to be installed, especially when setting up grid-connect and off-grid solar power plants. If bigger panels are used, bigger space is required. But by using panels with better efficiency cells, the project cost of setting up solar power plants comes down. We offer panels with highly efficient cells—the cells used in Jinko solar panels are 17.5 per cent efficient. That’s our unique selling point,” says Aggarwal of Ashi.
Lighting devices such as portable lanterns, home lighting systems, street lighting systems and water pumps are some of the stand alone products powered with solar panels. “These products now have an established market, especially in areas where grid supply is non-existent or is very erratic. These products have been around for several years now but we have added an entire new range of the same products using white LEDs as the lighting source. This range is extremely wide, covering both solar powered DC lighting, as well as high powered AC lighting which replaces energy guzzling mercury, halogen and sodium lamps. We have also introduced new solar powered products like the smallest solar mobile charger, solar rooftop based power plant and megawatt size grid tied power plants,” says Goel.
According to Kumud Tyagi, vice president, Bergen Associates Pvt Ltd, high efficiency crystalline silicon based solar modules are the latest in the market. “Cells and modules made on our machines are tested and certified with highest quality standards. They are available in various capacities.”
Though the use of basic crystalline silicon solar cell is still on, significant improvements are now taking place. “The industry is using thin film technology which is referred as the second generation PV. However, a lot of research is still needed as the technology is still confined to the developed countries like USA. While the world has progressed substantially in production of basic silicon monocrystalline PV cells, India has fallen short to achieve the worldwide momentum,” says Shashidhara BV, business head-renewable energy (PV solutions), Delta Energy Systems (I) Pvt Ltd.
“We offer solar panels for both off-grid and on-grid applications, along with advanced crystalline solar cells and modules that are ideal for all types of applications. We are among a few companies in the world to offer a wide range of modules, inverters and system integration services. We also offer turnkey solutions for PV application for building integrated photovoltaics (BIPV), telecom and power plants along with key components supply for the PV projects like solar modules, inverters and monitoring system,” informs Shashidhara. “Our solar panels have positive power tolerance of 0 to +3 per cent and provides a stable, high energy system output. The PV cells in the panel shunt resistance and increase power output under low light conditions. Moreover, the state-of-the-art manufacturing technology leads to high per kWh output at low cost.,” he adds.
Solar panels constructed using amorphous silicon technology are more durable, efficient and thinner than their crystalline counterparts. Very high efficiency solar cells are constructed from gallium arsenide by a process called molecular beam epitaxy. Solar panels made of these cells are much more efficient than the conventional types but the process and materials involved make them far too expensive for everyday applications.
The latest solar panels function on the molecular or quantum level. These panels are created by implanting carbon nanotubes or quantum dots into a treated plastic. Unlike silicon based solar panels, these panels do not have to be constructed in a clean room, and therefore, production cost is lower.
Kotak Urja produces 300Wp modules with less than 2 sq m of area with module efficiency of over 15 per cent. “These modules are independent and silent power producers with 25 years’ of life,” explains Girish. Recently, Kyocera has also introduced K D series solar panels of capacity 135 Wp and 210 Wp. “These are high efficiency multi-crystal PV modules. The conversion efficiency of the Kyocera cell is over 16 per cent and is protected from the severest environmental conditions,” says Sanjay Aggarwal, marketing manager, Kyocera. “Our solar panels are framed with anodised aluminum to provide structural strength and ease of installation,” he adds.
Innovation that’s taking place
Solar panels today are made using either thin film technology or crystalline silicon technology. Both have their merits and demerits as thin film solar panels are lower in efficiency, and hence, less expensive. Whereas solar panels made with crystalline silicon cells are comparatively costly but are more efficient. Girish feels that the technological upgradation that is happening is for increasing efficiency of solar modules. Agrees Goel, “No doubt innovation is taking place. Industry is attempting to achieve higher efficiencies at lower cost/watt through R&D in technology, materials, processes, etc. Solar cells which were 350-400 micron thick a few years ago have reduced to 160 micron, leading to higher efficiencies—up to 21 per cent efficient cells are available commercially.” Mechanisation and automation in manufacturing processes have led to production of bigger and higher wattage solar panels in both technologies which were not possible with manual practices. However, Tyagi is concerned over scientists researching with various materials. “These alternate methods are difficult to get commercialised,” he says.
A new solar panel has been unveiled by the Georgia Tech Research Institute which differs in design. Traditional solar panels are often flat and bulky. The new design features an array of nanotowers like microscopic blades of grass that increase surface area to trap more sunlight. But to generate electricity, a cell has to churn out voltage as well, and this is where the new designed solar panel has fallen short. However, there is still enough resistance within the cell to produce electricity.
Cost of solar panels
Cost of solar panels varies depending upon the type, wattage and brand of panel. Solar panels of the same size may produce variable amounts of electricity—this discrepancy arises from variations in the functioning age of the solar cells, their quality and the technology used to produce them. Therefore, with a trusted solar panel manufacturer, quality improves as the technology involved becomes more advanced and precise. The best way to compare the value of two solar panels is to measure the value/watt ratio. “At one time, solar cells used to sell at $16 per watt. But with advancement in technology, the cost has come down to $2.2 per watt. New technology has made the wafers thinner and the cost of the cells has come down, reducing the cost of the panels,” points out Aggarwal of Ashi.
Price of Maharishi Solar panels is dependent on quantity, off-take ratings and other commercial terms. Generally, 2Wp solar panels are offered at Rs 220-225 per Wp, whereas 74-120Wp are offered at
Rs 110-125 per Wp, Kotak Urja panel prices are around $2 per Wp. Kyocera panels cost $2-2.6 per watt, depending on the quality, cell origin and ordered quantity.
Shashidhara feels that solar power is currently prohibitive due to high initial cost of deployment. “To spawn a thriving solar market, the technology needs to be competitively cheaper,” he says.
Using scrap solar cells can save a considerable amount on solar panel investment. Scrap solar cells are those cells which are broken during manufacturing and solar cell producers often sell these at very cheap prices.
Generally, buyers may look for a standard application such as solar lantern, water pump, home lighting or street lighting, wherein the design and performance is comparatively well defined and standardised. For other requirements, a buyer generally specifies his solar panel needs by its name plate capacity or rating. Others may define their application and need or fill out a questionnaire provided by the solar panel supplier/manufacturer who will recommend the best type, quantity and rating suited for the application. “The above is generally true of customisable applications such as rooftop power generators, office or industry power backup systems, etc, where one standard package does not work. The SPV generator has to be designed keeping in mind the average energy consumption daily by the user,” explains Goel.
While Tyagi says that buyers look for short delivery time, low cost and flexibility in usage, Girish believes that buyers’ needs depend on the application areas. There are two kinds of market segments—off grid (like lantern, small home, street light, battery chargers, etc) and grid (for generation of power and feeding it to the grid).
Says Baldev Aggarwal, “Buyers look for a combination of high quality and low price. We are, therefore, offering good quality panels at a very competitive price. However, the Indian market is still very immature. Buyers should give more importance to quality than low price.”
Challenges faced by buyers
Cost is the biggest barrier for purchasing a solar panel or a complete system based on solar power. Quality of the solar panel and its rated capacity is another challenge which an uninformed buyer faces. “The true rating cannot be measured outside the laboratory or testing facility. Hence, some small manufacturers, system integrators and dealers pass off low power panels at the cost of standard rating. Warranties are not honoured as the solar panel or the complete system performs differently in varying climatic conditions and the user is left guessing whether the lower performance is due to an inferior quality of the solar module or due to the weather,” explains Goel.
Solar panel being a component which can generate electricity is by itself of not much use unless integrated into a system. Qualified and experienced personnel are required to calculate and specify the choice of solar panel as the range is quite wide—less than 1Wp to 300Wp. “Series and parallel connection of panels to form arrays, size and rating of arrays, number of arrays, selection of the appropriate power conditioning unit or the charge controller, battery bank, inverter, light, fan, computer, electronic equipment, electrical motor, etc, are some of the issues faced by a designer or consultant while integrating a solar power generating system,” informs Goel, adding, “Not just the solar panel but also the balance of system (BOS) is equally important and its right selection determines the life and performance of the overall system. A typical storage type of solar power generating system consist of 50 per cent by value of solar panels, 25 per cent by value of battery bank and balance 25 per cent by value of electronics, mechanical fixtures, cables, junction boxes, plus miscellaneous commercial expenses and margin.”
PV modules are available in bulk. “It is essential for a buyer to select PV modules from IEC certified companies as they guarantee life up to 25 years,” points out Girish. Sanjay Aggarwal also feels that a buyer mostly faces problems related to issues like quality, lower output, safety, lower capacity supply than ordered, lower efficiency cells in module and obsolete technology used by some suppliers. Since solar based solutions are still highly subsidised by the government, another problem buyers may face, points out Baldev Aggarwal, is that they may not know from where to buy subsidised products.
The credibility of the company, efficiency of cells and price are what a buyer should look for,” sums up Baldev Aggarwal.
What a buyer should consider
The amount of power solar panels produce is influenced by the quality of the panels, materials and technology used in making and the amount of time the solar panel has been in use. When purchasing solar panels, it is, therefore, wise to look beyond size and look at the value/watt ratio.
According to Goel, the best practices include selection of a high efficiency solar panel against an over-sized solar panel which may appear to be of a higher rating but in reality it is of lower power. “Every solar panel is accompanied with an electrical data known as ‘IV CURVE’ which is a computerised printout of its test data. ‘IV CURVE’ contains the true power of the solar panel besides other relevant information. As the warranty of a solar panel may be 5-15 years depending on its rating, solar panels manufactured by Maharishi Solar come with a permanent self adhesive sticker pasted on the reverse of each panel. A buyer pays for the power as per the name plate capacity,” says Goel. “The buyer should also carefully see the year of manufacture printed on the sticker laminated within the solar panel. The serial number, year of manufacture and model number help in tracing and availing warranty claims in the event of a solar panel degrading or developing manufacturing defects within the warranty period,” he adds.
Tyagi strongly feels that a buyer should check value for his investment. “There are suppliers who would try to push inferior products. Also, a buyer should be careful during installation of the panel and designing of the system installation, as these play extremely important roles. Wrong installation can result in lower power generation,” he adds. A buyer should invariably ask for a bill against purchase of the solar panel. “Unscrupulous vendors may pass off recycled panels as genuine and new units. Recycled panels should be avoided as they could be stolen property and of doubtful quality and life,” says Goel. “The credibility of the company, efficiency of cells and price are what a buyer should look for,” sums up Baldev Aggarwal.
• Power generation plant (grid-tie and standby)
• Street lighting
• Drinking water/water pumping
• Irrigation pumping
• Telecommunication towers
• Traffic light system
• Railway signals
• Aviation lights
• Environmental data monitoring
• Medical facilities in rural areas
• Emergency communication
Types of solar panels
Single crystalline (also called monocrystalline): This is the oldest technology, the most tried and trusted and the most expensive to make, but they have the highest efficiency. They are made up of single silicon crystals, sliced up into wafers. Each circular wafer has its sides cut square and the solar panel is made up of a matrix of these wafers laid flat. They have very slow degradation—losing 0.25- 0.5 per cent per year.
Polycrystalline (also called multi-crystalline): These panels are also sliced from long cylinders of silicon, but the silicon used is multi-crystalline which is easier to make. These are very similar to single crystalline in performance and degradation, except they are slightly less efficient.
String ribbon: This is a relatively new technique that uses less energy than the above two. They drag a pair of metal strings through a thin film of molten silicon and it creates a ribbon of silicon that does not need to be sliced or diced any further. However, it has lower efficiency.
Thin film or amorphous: This new technique sprays the silicon onto a base as a thin film. It is claimed to be less in degradation than the above three. The production process is more energy efficient than any of the other panel types, so the cells are typically cheaper for the same rated power.
Solar panel efficiency
Solar panel efficiency is the percentage of solar energy that is captured and converted into electricity. It is the ratio (as a percentage) of energy in the sunlight hitting the panel area to electrical energy in the wires coming out of the panel.
It is difficult to give an exact number, so the numbers below are an average percentage of efficiency that the different types of solar panels output. Thin film solar panels will generally degrade approximately 1 per cent each year, whereas crystalline panels degrade at approximately 0.5 per cent. Below are the approximate percentages for each type of solar panel:
Monocrystalline: 18 per cent
Polycrystalline: 15 per cent
Amorphous (thin film): 10 per cent
Solar panel care
The most wonderful thing about solar panels is that there is no moving part therefore, almost no maintenance is required. It only needs to be occasionally wiped or brushed which helps prevent buildup of dust and grime that can impact the effectiveness. Usually the rain takes care of this. Other than that, just a visual inspection of the frame seals and wiring from the junction box is all that is needed.
Source: Kotak Urja
For an owner of a solar power plant, income depends upon the power generation by modules and its feeding to the grid. If some breakdown happens in future or output of modules diminishes more than rated, it will be a huge loss to the owner. A customer should, therefore, check the following before making purchasing decision:
• Efficiency of the modules should be checked. The higher the efficiency, the more watts of electricity the consumer will get per volume of material used in the solar panel. The advantage of higher efficiency panels is that generally the higher the efficiency, the smaller the panel a buyer will need
• A buyer should check the history of the supplier to check his reliability as the warranty period on the output is quite long—20-25 years—and initial investment is high
• A customer should check the financial stability of the supplier because of the long warranty period. This is to make sure that if something goes wrong with the modules in future, the customer should not be in loss
• The modules should have international safety standards
• Checking the records of output diminishing curve over life period of the modules is must
• Technology used in production matters a lot
• Technical parameters especially for grid-tie power generation projects should be checked
• Capability of the supplier to deliver timely needs to be checked
Electronics Bazaar, South Asia’s No.1 Electronics B2B magazine