JLanka-Solar-System-vs-Conventional-Systems

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J Lanka - SolarEdge provides next generation solar power harvesting and monitoring solutions that effectively remove all known system constraints across the photovoltaic energy space. Our Smart DC …

J Lanka - SolarEdge provides next generation solar power harvesting and monitoring solutions that effectively remove all known system constraints across the photovoltaic energy space. Our Smart DC ASIC technology and active electronics enable increased production of clean, grid-ready energy at a lower cost.

Traditional photovoltaic installations suffer from a broad range of limitations that prevent them from reaching their full potential. Module mismatch and partial shading prevent systems from achieving their optimum. System design is made complex due to numerous constraints, such as the inability to leverage full roof real estate, to combine strings of different lengths, or to easily address differing roof facets. Traditional systems lack monitoring and analysis capabilities, as well as critical safety features. The systems can pose risks to workers installing or maintaining the system, as well as to firefighters dealing with fires in the vicinity of a PV installation.

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  • 1. The difference between The SolarEdge distributed power harvesting system And Conventional Systemswww.JLankaTech.com
  • 2. The typical specifications of a solar panelOutput Current (A) Isc – the output current of the panel when output terminals are short circuited Maximum power point Voc – The voltage at the output terminals Isc without any load connected to the panel Impp Maximum power point is the point which gives the maximum value for the V x I To harvest power from the solar panel requires to monitor where this point is. This process is called Maximum Power Point Tracking or MPPT Voc The values of V and I at the maximum Vmpp power point is referred to as Vmpp and Output Voltage (V) Impp respectively.
  • 3. The variation of maximum power point of a solar panel according to solar irradiation Solar irradiation level Maximum power point at Pout = 150W corresponding solar irradiation level Pout = 128W 1000Wm-2 is the sun light Pout = 96W level at noon under clear sky or bright day light Pout = 66W The panel output voltage is Pout = 35W almost constant, but the output current significantly varies with solar irradiationwww.JLankaTech.com
  • 4. The variation of maximum power point between similar brand and power rated solar panels for the same level of solar irradiation All the three panels are manufactured by the same manufacturer, in the same production line. But the power output is not similar and unmatched. Also the maximum power point is not same, and exists a considerable variation among each other. That is at the same voltage, the output current is differentwww.JLankaTech.com
  • 5. The panel layout of a typical solar power generation system String of PV panels + - + - + - + - + - + - + - + - Inverter Typical string may have up to 20 panels per string and two or three such strings DC are connected in parallel to form the DC 230 Vac supply to the inverter. ACwww.JLankaTech.com
  • 6. The problems and disadvantages of a typical solar power generation system 1.The panel mismatch Averaged String current ( ) When several modules are connected in series, each one has a slightly different MPP current. The series connection does not allow the optimal MPP current to be drawn from each module. The Output Current (A) inverter will select the current which gives the average peak power point of the string or array. This peak power is always less than the theoretical sum of the individual peak power points of every module. This is referred to as mismatch loss. In standard residential and commercial PV installations, it can be as high as 5% ! Output Voltage (V)www.JLankaTech.com
  • 7. The problems and disadvantages of a typical solar power generation system 2. Partial shading Shading on any part of the array will reduce its output, but this reduction will vary in magnitude depending on the electrical configuration of the array. Clearly, the output of any shaded cell or module will be lowered according to the reduction of light intensity falling on it. However, since this shaded cell or panel is electrically connected to other unshaded cells and modules, their performance may also be lessened since this is essentially a mismatch situation. Partial shading of crystalline solar modules will result in dramatic reduction of solar module output. One completely shaded cell can reduce a solar module’s output by 40% to 95%. In residential systems, partial shading losses are estimated to contribute between 5% to 25% annual power losseswww.JLankaTech.com
  • 8. The problems and disadvantages of a typical solar power generation system 3. Inefficient MPPT algorithms The MPPT algorithms must be able to efficiently track the power point variation as the solar irradiation changes time to time. If it is not, there will be tremendous amount of loss in the harvestable power. 4. System feedback and trouble shooting A solar installation will cost a considerable amount of money. But the problem is, There is no way to find out individual panel performance except entire systems performance. This becomes tragic since a malfunctioned panel can be hidden inside the system, while the clouds being the guilty party! 5. Retrofit and long term fault tolerance For conventional solar installations, it requires all the solar panels to be in same ratings. That is no way to connect a different panel. The solar panels comes with a 20 years or more warranty period and the technology behind the panels keeps developing each day like mobile phones. So after 10 years how can some one can find a panel that is exactly similar to the ones that was installed 10 years ago! The conventional systems becomes a dead end in this case.www.JLankaTech.com
  • 9. The problems and disadvantages of a typical solar power generation system 6. System safety When solar panels are installing it is very difficult to cover from the sun. There for the series connected solar panel string is always live. Even a series connected three panels (36V) produce enough power to electrocute a person if accidently touched. Also in case of a fire, there is no way to shut down the strings. In such a cases these Dc power lines can be short circuited and become another fire causing factor.www.JLankaTech.com
  • 10. Conclusion We described the structure of PV systems and several drawbacks and disadvantages in the way these systems are designed and built. Though previous works focused on improving different aspects of photovoltaic systems, no single holistic approach was presented that could solve many of the current problems present in PV installations. Solar Edge Technologies distributed power harvesting system is the only power harvesting system and architecture that offers a full, robust solution that harvests up to 25% more energy and resolves the issues described in this paper. The next sections describe how the SolarEdge distributed power harvesting system handle all these issues.www.JLankaTech.com
  • 11. Back to some basics…. Power = Voltage x Current That is a 100W can be expressed as, Power (W) Voltage (V) Current(I) 100 10 10 100 20 5 100 25 4 100 50 2 The idea here is Power Conversion. To do this a special device known as DC- DC converter has to be used. It does the same thing above. That is we can input it a 100W (20V x 5A) and take a 100W of power at 50V x 2A. This also can be done in the opposite way.www.JLankaTech.com
  • 12. The SolarEdge Systemwww.JLankaTech.com
  • 13. The SolarEdge System…How this works The method of connection 1. Each panel must be connected to a power optimizer 2. These power optimizers are then connected in series to form the strings 3. There must be at least 8 such power optimizers per string The method of functionality 1. As the sun rises the panels start power production and wakes the power optimizers 2. The power optimizers check how much POWER can be take from the panel they connected 3. Then all the power optimizers send these details to the inverter 4. The inverter process these data and commands all of them to start power production. The output voltage of the power optimizers will be changed so as to maintain a constant current and also to response shading conditions. This will be explained in detail in coming sections.www.JLankaTech.com
  • 14. The SolarEdge System VS All known Mismatches As we said earlier, solar panels are not matched even they are power rating is similar and from same brand The problems and losses due to the series connected such panels are were also discussed in greater detail. Since in SolarEdge system, the actual string is made of series connected power optimizers and the panels are connected to the power optimizers. That is the panels are buffered by the power optimizers from the DC bus. The power optimizer harvest energy from the panel and supply it to the DC bus. There for not only mismatched panels, but even different panels can be used for the installation.www.JLankaTech.com
  • 15. The SolarEdge System VS Shadingswww.JLankaTech.com
  • 16. The SolarEdge System VS Mixed panels 1. The solar panels are connected to the power optimizers 2. There for the panels and the string are independent from each other. 3. So as the input of the power optimizer any panel can be connected. The power optimizer converts what ever the available power from the panels to the required level by the inverter as explained earlier. 4. This is the only system that can be used with mixed panel types.www.JLankaTech.com
  • 17. The SolarEdge System VS Monitoring and Safety 1. This is the only system that comes with a WEB based monitoring facility as a standard feature. 2. It monitors entire system performance to each panels performance in every 30 minutes and updates the web portal provided by the manufacturer. 3. So isolating a fault is just a few minutes job and locating it in the installation is even simpler and can be done even from the office. There for only the required panel can be removed without shutting down the system. 4. Also until inverter commands the power optimizers does not output power and it will output only 1V. This very much helpful since the number of panels installed is equal to the output voltage. For example 15 series connected panels means 15V. Any loosely connected panel or polarity changed panel can be identified easily.www.JLankaTech.com
  • 18. The SolarEdge System VS Power Point Tracking 1. A conventional system can have maximum of 2 maximum power point trackings. This too is not the optimum and it is a averaged one as explained earlier. 2. But in solaredge system. The power point tracking is implemented in each power optimizer. There for every panel has a dedicated maximum power point tracking implemented for its own. 3. The end result is solaredge system has minimum of 8 maximum power point tracking and increases with addition of every power optimizer to the system.www.JLankaTech.com