Delay in "Assessment of PV software" Series

Due to some legal problems we can not start "assessment of various PV software" series for now. But we will sort out those problems and come up as early as possible.
Thanks!!!

Complete Assessment of Various Solar Photovoltaic Software

  Since the announcement of Jawahar lal Nehru National Solar Mission (JNNSM) India has been facing various difficulties in technical, industry trade and policy frameworks. But despite of all those hurdles we have reached cumulative installed capacity of  2.108 GW milestone last month. 

  This journey would not be possible without intervention of various PV software. As a result of dedicated work and collaboration of universities, government technical institutes and laboratories, companies and individual professionals we have highly advanced monitoring, analysis, planning and economical evaluation software. 

  Considering the importance of PV software we are starting this new series on "assessment of various PV software". In which we are going to compare different software on the basis of features, capabilities, performances, database collection, accuracy and compatibility. 

So get Ready for the first and the most well known software PVsyst !!!

SMA Inverter___ (Not an advertisement but I think they really deserve Endorsement!!!)

Anti dumping duty _ next burning issue in indian solar industry_ part 2

Anti dumping duty

    Definition- “Dumping is supposed to occur when the ‘export price’ of the goods is less than the ‘normal value’ of the articles sold in the domestic market of the exporter”

Indian solar (PV) manufacturer perspective

·         Indian solar PV manufacturers industry is largely smashed by cheap, large scale imported PV modules and cells from the countries like china, U.S, Malaysia and Taiwan. In phase 1 Domestic Content Ratio DCR was mandatory only on crystalline technology, so that project developers were choose thin film technology which was mostly imported from U.S at low cost with the support of us EXIM bank. though Under the draft policy for phase 2 MNRE has considering several options to implement DCR it is hard to predict what kind of decision MNRE will take (by considering project developers perspective).

·         In countries like U.S, china governments are providing lands at low cost, loan at 1-2% interest rates and subsidies financing model to the manufacturing companies due to all this they are capable to spend hefty amount on R&D and vertical integration which is reducing the cost of product. This is unfair for domestic players as they charged by 13% interest rates, low class technology, restricted capacity scaling. Many experts agree with the fact that thin film technology is not suitable for Indian environment but due to the low cost and attractive interest rates many developers were choose it.

·         From ISMA point of view anti dumping should be in charge along with strict instruction on DCR.

Project developer’s perspective

·          Solar Independent Power Producer Association (SIPPA) has come up to oppose anti dumping duty. Accordingly to them instead of applying anti dumping duty government should have to take some long term measures to protect domestic solar industry.

·         A recent research report by the Center for Energy Environment and Water (CEEW) has pointed out that very few Indian developers have adopted Crystalline Technology due to the import restrictions under the Solar Mission 2020 initiative. “Though there is numerous advanced Crystalline Silicon Technologies available the world over, the developers’ choice is restricted to domestically manufacture solar PV panels in this category.

·         Indian manufactures of crystalline silicon based modules import all major raw materials like poly silicon waters and cells and the prices of such raw materials have also crashed due to the heightened demand-supply gap. “In such a situation imposition of anti-dumping duty on solar photovoltaic modules would be counterproductive to the country’s solar aspirations.

·         Also If anti-dumping is imposed on solar imports, cost of solar power in India is bound to go up which will be borne by distribution companies and commercial consumers (as most of the DISCOMS are already poor in state).

   After assessing both the perspectives MNRE should have to take unbiased decision to protect Indian solar industry. Only imposing anti-dumping duties might work for the short-term, but it might de-incentivize innovation and investment in R&D. If India wants to improve its manufacturing, then it is imperative that a competitive advantage is maintained through investment is R&D and efficiency improvements.

    Whether to impose duty or not is not the big question, as industry is going to face little bit hard situation by either decision, the question is what measures MNRE will take to sustain domestic industry in long term basis.

Concerns regarding to selection of PV module

   Photovoltaic module occupies highest cost sharing in the overall cost of the project. Return on investment for investors are largely depends on performance of solar module after certain years. It is the only asset that generates real money for the investor. Obviously it has been getting highest attention on procurement of PV panels.

    Since solar market is still emerging worldwide, ideas about its development are untested; every year comes with new issues it may be regarding to overcapacity or the securitization of domestic market. Especially in India it is immature in nature. Many developers are never exposed to such situations, they are lagging in planning and commissioning of the project, procuring and testing of the equipment. In that background selection of PV panels becomes hard task.

    Conventionally developers’ buys solar panel based on warranty, Insurance and company’s balance sheet or past records. But recently those criteria seem to be falling down as many plants are raising issues with their PV panels. A warranty associated with PV panels does not cover most of the field failures, insurance can backup warranties but suitable insurance are highly expensive for the projects. Another important concern is that to claim for warranty after 10-15 years, manufacturing company should be exist on land to provide you money as day by day manufacturing unites are shutting down.

    Many buyers start their quality assessment when the modules arrive on plant which arises few problems, primarily Due to that when result revels any default in the modules at that time most of the panels were installed already.

       Increasing demand and failing manufacturing companies are triggering this concern about the selection criteria of PV module at the time of procuring. We are expecting more caution in this area in near future

Performance standards for PV technology part_4

Thermal test:-

1) Bypass diode:-

This test is a critical component determining the thermal behavior of the module under hot- spot conditions and therefore also directly affecting reliability in the field. The test method requires attaching a thermocouple to the diode (s) body, heating the module up to 75°C ± 5 °C and applying a current equal to the short circuit current Isc measured at STC for 1h.

Failures of bypass diode test still occur either by overrating of the diode manufacturer, or incorrect electrical configuration with respect to the module’s Isc by the module manufacturer.

2) Hot spot endurance:-

(This part was covered in diagnostic tests)

Irradiance check:-

1) Outdoor exposure:-

The purpose is a preliminary assessment of the module’s ability to withstand exposure to outdoor conditions. However, it only involves exposure for a total of 60 kWh/m2, which is a rather short period of time to make any judgments about module’s lifetime. IEC 61215 requires degradation of maximum power Pmax not to exceed 5% of the initial value. While for IEC 61646 Pmax not to be lower than the marked “Pmax – t%“.

2) UV preconditioning:-

This test is carried out to identify materials that are susceptible to ultra- violet (UV) degradation before the thermal cycle and humidity freeze tests are performed. IEC 61215 requires to subject the module to a total UV irradiation of 15 kWh/m2 in the (UVA UVB) regions (280 nm – 400 nm), with at least 5 kWh /m2.

But in the laboratory test condition very low UV irradiation is apply to the module than real exposures during the life time of the module.

Environmental test:-

1) Thermal cycling TC200:-

IEC 61215 requires the injection of a current within ±2% of the current measured at peak power (Imp) when the module temperature is above 25°C.this test is carried out to simulate thermal stresses on materials as a result of changes of extreme temperatures. The module is subjected to the cycling temperature limits of –40°C ± 2°C and 85°C ± 2°C with the below profile.

Failure rates for T C200 can be as high as 30- 40%. It is lower for thin-film.

2) Humidity freeze:-

 In this test module is subjected to 10 complete cycles as per harmonized profile below (IEC 61646) to determine the module’s ability to withstand the effects of high temperatures combined with humidity, followed by extremely low temperatures. Failure rates of this test remain in the range 10- 20%.

3) Damp heat DH1000:-

This test is carried out to determine the ability of the module to withstand long-term exposure to penetration of humidity by applying 85°C ± 2°C with a relative humidity of 85% ± 5% for 1000 hours. This test is known for highest failure rate test which is 40-50% for both technologies.

Mechanical test:-

1) Robustness of terminations:-

This test is carried out to determine the robustness of the module’s terminations, which can be wires, flying leads, screws, or as for the majority of the cases: PV connectors. The terminations undergo a stress test that simulates normal assembly and handling through various cycles and levels of tensile strength, bending and torque tests as referenced in another standard, IEC 60068-2-21.

2) Mechanical load test:-

This test comes after Damp Heat and therefore done on a sample that has undergone a severe environmental stress. This test is carried out to investigate the ability of the module to withstand wind, snow, static or ice loads. If the module is to be qualified to withstand heavy accumulations of snow and ice, the load applied to the front of the module during the last cycle of this test is increased from 2400 Pa to 5400 Pa.

An issue remains with this test is that if module failed then it may due to structural problems, or because of an inappropriate mounting technique.

If the module is to be qualified to withstand heavy accumulations of snow and ice, the load applied to the front of the module during the last cycle of this test is increased from 2400 Pa to 5400 Pa.

 Successful completions of IEC61215/61646 tests means

• The product has met a specific set of requirements
• Those modules that have passed the qualification test are much more likely to survive in the field and not have design flaws that lead to infant mortality.
• They suffer almost no degradation in power output from the test sequence.

Limitations of IEC61215/61646

• It does not identify and quantify wear-out mechanisms.
• It doesn’t differentiate between products that may have long and short lifetimes
• Not to address all failure mechanisms in all module designs
• Not to address failure mechanisms for all climates and system configuration

Performance standards for PV technology part_3

Diagnostic tests:-

1) Visual inspection:-

The purpose is to detect any of the “major visual defects” defined above by checking the module in a well illuminated area (1000 lux).

It is frequently occur throughout the procedure.

2) Hot spot endurance:-

Technically hot spot occur due to the operating current of the module exceeds the reduced short –circuit current of a faulty cells. This will force the cell(s) into a reverse bias condition when it becomes a load dissipating heat. Serious hot spot phenomena can be as dramatic as outright burns of all the layers, cracking, or even breakage of the glass. This test is carried out to determine the module’s ability to withstand localized heating caused by cracked, mismatched cells, interconnection failures, partial shadowing or soiling.

Electrical test:-

1) Insulation resistance:-

This test is carried out to determine whether a module has a sufficient electrical insulation between its current-carrying parts and the frame. A dielectric strength tester is used to apply a DC Voltage source of up to 1000 V plus twice the maxim um system voltage. After the test, there shall be no breakdown, nor any surface tracking. F or modules with an area larger than 0.1 m2, the resistance shall not be less than 40 MΩ   for every square meter.

2) Wet leakage current test:-

In this test the module is submersed in a shallow tank to a depth covering all surfaces except cable entries of junction boxes not designed for immersion. A test voltage is applied between the shorted output connectors and the water bath solution up to the maximum system voltage of the module for 2 minutes.

To pass this test the insulation resistance shall be not less than 40 MΩ   for every square meter for modules with an area larger than 0.1 m2. There is not any IEC standard for PV connectors, but there is a harmonized European standard (EN 50521) for it.

The wet leakage current test is ranked as one of the most reoccurring failures during PV qualification at the testing laboratories

 Performance parameters tests:

1) Maximum power Pmax:-

It is common practice among PV laboratories to perform it at 1000W/m2, 25°C cell temperature, with a reference solar spectral irradiance called Air Mass 1.5 (AM1.5), as defined in IEC 60904-3. A correct and traceable Pmax measurement to the World PV Scale is of critical importance. Not only is it one of the pass/fail criteria, but the measured values can also be used by the end users as a performance indicator for power yield evaluations.

Due to its importance it is perform frequently in the process.

2) Temperature coefficients:-

This test is carried out to determine the temperature coefficients of short- circuit current Isc (α), open-circuit voltage Voc (β) and maximum power Pmax (δ) from module measurements. over an interval of 30°C (for instance, 25°C-55°C), and at every 5°C intervals, the sun simulator takes an I - V measurement (Isc, Voc, Pmax are not reflected, but measured during the I-V sweep) including Isc, Voc and Pmax. The values of Isc, Voc and Pmax are plotted as functions of temperature for each set of data. The coefficients α, β and δ are calculated from the slopes of the least squares fit straight lines for the three plotted function.

3) Nominal Operating Cell Temperature (NOCT):-

NOCT can be used by the system designer as a guide to the temperature at which a module will operate in the field and it is therefore a useful parameter when comparing the performance of different module designs. The test setup requires data logging and selection for irradiance (pyronameter), ambient temperature (temperature sensors), cell temperature (thermocouples attached on the back side of the module corresponding to the two central cells), wind speed (speed sensor) and wind direction (direction sensor).All these quantities shall be within certain intervals in order to be acceptable for the calculation of NOCT.

                                                                                                    ,,,,,,,,,,,, TO BE COUNTINUED

Performance standards for PV technology part_2

1)  Major visual defects (IEC 61215/61646):-

• A crack in a cell the propagation of which could remove more than 10% of that cell's area from the electrical circuit of the module

• Broken, cracked, or torn external surfaces, including superstrates, substrates, frames and junction boxes

• Bent or misaligned external surfaces, including superstrates, substrates, frames and junction boxes to the extent that the installation and/or operation of the module would be impaired

• Bubbles or delaminating forming a continuous path between any part of the electrical circuit and the edge of the module

• Loss of mechanical integrity, to the extent that the installation and/or operation of the module would be impaired

            Separately for IEC 61646

• Visible corrosion of any of the thin film layers of the active circuitry of the module, extending over more than 10% of any cell

• Module markings (label) are no longer attached, or the information is unreadable

2) ’Pass/fail’ criteria:-

• the degradation of maximum output power does not exceed the prescribed limit after each test nor 8% after each test sequence

• no sample has exhibited any open circuit during the tests

• the insulation test requirements are met after the tests

• there is no visual evidence of a major defects

• specific requirements of the individual tests are met

• the wet leakage current test requirements are met at the beginning and the end of each sequence and after the damp heat test

Conclusion from “pass/fail” tests

	CONDITION	RESULT
1)	Two or more samples failed in test criteria	Fail
2)	One sample failed If one or both of these new samples also fail  If both samples pass the test sequence	Remaining  2 Start from beginning Result  “Fail” Result  “Pass”

                                                                                                    ,,,,,,,,,,,, TO BE CONTINUED

Performance standards for PV technology

Under the JNNSM, MNRE has mentioned certain technical requirements for selection of PV module for grid connected power plant

Crystalline Silicon Solar Cell Modules     IEC 61215

Thin Film Modules                                      IEC 61646    

Concentric PV modules                              IEC 62108

In addition for safety qualification test    IEC 61730

         For Highly corrosive atmosphere    IEC 61701

But what exactly IEC stand for?

What kinds of tests are carried out for what purpose?

Do those standards also define ‘reliability’ of the module?

 Are IEC standards sufficient for comparison of module ‘quality’?

As a part of emerging market many similar questions are unclear in the industry, though due to the custom or branding it is followed by manufacturer and developers. But on the long term scenario those questions should be clear.  

The design qualification is responsible to represent the ‘performance’ capability of the module under standard climate condition. So despite of having defined climate condition if someone is considering its module performance future under the basis of IEC standards results then it may prove wrong. 

There is another concern about modules ‘reliability’ which is ambiguously related to the ‘quality’. But in reality both are quite different term, in fact there isn’t any standard introduced to claim modules reliability. Reliability is neither defined, nor covered by the existing IEC standards. Experts from manufacturers, testing institutes and standardization bodies are coming together in an effort to elaborate the basis for a PV reliability standard.

IEC 61215 has been designed based on crystalline silicon (c-si) technology, while IEC 61646 is on amorphous silicon (a-si) technology such as CIGS, CdTe etc. Both standards require that samples for testing be taken at random from a production batch (accordingly IEC 60410)

In the following articles we will explain important tests and its requirements Along with few insights about other accelerated stress tests, qualification tests like JPL block buys tests and limitations of IEC 61215/61646

  

  Tests carried out under the Performance standards IEC 61215/61646

·       Diagnostic: Visual inspection, Hot spot.

·       Electrical: Insulation resistance, Wet leakage current

·       Performance: Pmax at STC, Temperature coefficients,  NOCT, Pmax at low irradiance.

·       Thermal: Bypass diode test, Hot spot.

·       Irradiance: Outdoor exposure, UV exposure, Light soaking.

·       Environmental: Temperature cycles, Humidity freeze, Damp heat.

·       Mechanical: Mechanical load, Robustness of terminations, Hail impact.

       

                                                   ,,,,,,,,,,,, TO BE COUNTINUED

Solar energy / Solar photovoltaics / Photovoltaic effect (3D animation)

Solar start ups

What a tremendous force of start ups are lifting solar energy worldwide!!! This is ranging from technological development in manufacturing of photo-voltaic panels to the triple coating vacuum tubes in water heating system. Advance technological development and socio-economical aspects should go hand by hand. New generation is taking this convoluted opportunity by standing confront of conventional odds by creating frugal way to tap solar energy in their arms. They are not only making social impact but also generating handsome profit in marginal sections. This new era of companionship with sun is the only solution to the brighter future.

solar vs wind

As the world continues to search for the best renewable energy resources, two sources continually come to the forefront: solar and wind. Although both of these sources are considered to be environmentally friendly, there are pros and cons to be aware of.

Wind Energy

In many parts of the world, wind power is available in abundant amounts. Along with this, it is 100 percent free. Areas that are clear of obstructions (such as the United States plains), close to the shoreline, or at a higher altitude make a better fit for wind energy.

Pros

1. Wind energy does not release any pollution into the air: Along with this, it does not contribute in any way, shape, or form to global warming – except in their manufacture. When you add the fact that wind turbines do not consume any water, it is easy to see why this is at the top of the list in terms of alternative energy sources.
2. Wind power does not cost a dime: In short, it is clearly one of the best renewable sources of energy as it is considered inexhaustible. In other words, there will always be wind. There is only so much oil and coal in the world. Along with this, it must be extracted from the earth which costs a lot of money. On the other hand, wind turbines can continuously harness the endless supply of kinetic energy derived from wind.
3. A great source for local jobs: From construction of wind turbines to daily maintenance, as the use of wind energy increases more and more local jobs will be created. With the unemployment rate rising and no end in sight, any jobs created by this form of energy should be considered a huge benefit. Additionally, wind resources are often located in remote areas that are already at an extreme economical disadvantage. Bringing wind power to these areas can provide steady revenue to local communities including land owners and farmers.

Cons

1. Not a reliable source in all parts of the world: In short, this form of energy is only efficient when there is enough wind to power the turbines. As you can imagine, there are many parts of the country that lack the necessary wind force.
2. Wind farms are unappealing to the eye: Do you enjoy driving down the highway, looking off into the distance to admire the view? Well, this could come to an end, to a certain extent, as more and more wind farms are built throughout the world. Although beauty is in the end of the beholder, some feel that wind farms are nothing more than an eyesore.
3. Land is expensive: One of the biggest costs associated with wind energy is the land on which the turbines will be constructed. Not only will this land need to be purchased or leased, it is often times more expensive in the areas (such as coastal communities) in which wind power is most effective.

Solar Energy

Over the past five years, solar energy has become more and more popular. This holds true both among commercial and residential properties. Although there are many benefits of solar energy and this appears to be the wave of the future, there are disadvantages holding back mass production and installation.

Pros

1. No pollution: For some, this is the clearly the number one benefit of solar power. Solar panels give off no pollution. The only pollution produced is the direct result of the manufacturing process.
2. The sun is an endless, clean supply of renewable energy: As long as the sun continues to shine this form of energy will do its job. On the contrary, finite fossil fuels, such as oil and coal, are not going to be around forever.
3. Saves money in the long run: There is no denying the fact that solar panels can be an expensive upfront investment (more on this below). That being said, this source of alternative energy can save you money in the future. Since you are using less energy, your utility bills will be much less. In some cases, you may not owe any money at all.

Cons

1. Cost of installation: As noted above, installing solar panels on a home or commercial property can be very expensive. This is a large upfront investment that is not affordable for everybody. However, if you can afford the initial cost you will more than make your money back in the long run thanks to smaller or non-existent utility bills. Generally speaking, the cost of a residential 5-kW system is approximately $35,000 depending on your location.
2. Aesthetics: Are you aware that solar panels can take up a lot of space on your roof? For this reason, they are often times eyesores that homeowners are not willing to deal with. This is one of the biggest drawbacks because there is no solution.
3. Not efficient for around the clock use: Solar panels only work when the sun is shining. When the sun goes down, you are forced to rely on stored energy from the panels or an alternative system. In turn, this could result in a small utility bill every month.

A grid connected pv system

Size of the PV generator

The economically optimal size of a grid-connected PV system  depends mostly on different financial incentives and legal parameters, since grid parity - meaning the costs of photovoltaic generated electricity are equal to or cheaper than the price of grid power - is achieved only in a very few regions today.Net metering concepts, as they are widely in use in the US and Canada, provide - like with stand-alone systems - no incentive to build systems that generate more electrical energy than consumed at the same estate during the year; the grid replaces only a local battery storage. Feed-in tariff systems on the other side render big systems with net excess profitable.
A PV system may cover the whole roof; the pictured solar roof (233 square meters) has a nominal power output of 24,2 kilowatt (kWp). Picture: Hieronimi regenerative Energien GmbH

- Required module space:

Within bigger systems mostly crystalline silicon modules are used today. To install a nominal capacity of 1 kWp (Kilowatt Peak) with such modules and area between about 7 m² (using monocrystalline cells) and 10 m² (using polycrystalline cells) is required. Otherwise unused pitched roofs are in many cases the most cost-efficient places to install a PV system, especially if they are oriented to south and inclined to a degree of about 30° to 37°.

- PV Orientation and Output

The efficiency of the photovoltaic process is at its highest if the sun rays hit the panel vertically. Therefore PV modules should be oriented to south (speaking of the northern hemisphere) and somewhat inclined; the optimal inclination angle depends on the location (including latitude, altitude and other factors). As a rule of thumb the inclination angle would be best between 3/4 and 4/5 of the latitude – resulting            in angles of 32° to 38° in Middle and Western Europe or 30° to 36° in most of the US. However: Small divergences from the optimal orientation and inclination result only in even smaller reductions of energy output per year.

In order to most effectively use Solar Radiation, a PV Module or Collector of a photovoltaic system and Solar Heating System, respectively, is aligned to absorb or collect as much of the radiation as possible. The radiation's angle of incidence, the tilt angle of the module or collector, and the azimuth angle all play roles in achieving the greatest possible power production.
The azimuth angle (β) in the picture at right) specifies how many degrees the surface of the module or collector diverges from the exact south-facing direction. The tilt angle (α) specifies the divergence from the horizontal.

Experiments show that photovoltaic systems operate most effectively with an azimuth angle of about 0° and a tilt angle of about 30°. Of course small variances in these values are not at all problematic: with the system oriented towards the south-east or south-west, about 95 % of the highest possible amount of light can still be absorbed. Large systems with arrays are fitted with electric motors which track the sun in order to optimize output.
Installation of power inverters of a 123 kWp PV system in Germany.

- Power inverter:

PV systems provide direct current (DC) voltage. To feed to the grid, this DC voltage has to be inverted to the grid alternating current (AC) voltage by a »mains-commutated« or grid-tied inverter, synchronizing automatically its AC output to the exact AC voltage and frequency of the grid.

This MPP fluctuates during operation in an interval depending on the radiation, the cell temperature and the cell type und has so to be tracked by the inverter controlling unit.

The second important job of the solar power inverter is to control the PV system to run near its Maximum Power Point (MPP), the operating point where the combined values of the current and voltage of the solar modules result in a maximum power output. This MPP fluctuates during operation in an interval depending on the radiation, the cell temperature and the cell type und has so to be tracked by the inverter controlling unit.

solar friend app by bosch solar energy AG

http://itunes.apple.com/us/app/solar-friend/id441719298?mt=8&ls=1#