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www.photon-international.comThe Photovoltaic MagazineInternational2-2009DIEHL AKOOFFPRINTWashers for glass and foilsMarket survey on cleaners for crystallineand thin-film module production'!3J48EF-abhjaa!:K;mSolar modulesupdate 2009Technical specs for over2,700 different modelsStrong US marketgrowthInstalled PV capacity increasesby 70 percent in 2008Solar loansMany German banks stillfinancing PV systemsPHOTON PhotovoltaicTechnology ShowLatest production equipmenton display in Munich in MarchInternational February 2009 107

science & technology | inverters | testThe Photovoltaic MagazineInternationalA +96.9 % for high irradiation2/2009www.photon-international.comShooting for the starsTesting Diehl AKO’s Platinum 6300 TLThe Photovoltaic Magazine96.8 % for medium irradiationHighlightsInternationalA +www.photon-international.com2/2009• Diehl AKO’s Platinum 6300 TL achieveda PHOTON efficiency of 96.8 percentfor medium irradiation and 96.9 percentfor high irradiation• It ranks third among all the devicesPHOTON Laboratory has tested so far• The device has a DC nominal powerof 5,700 W, an MPP voltage range of350 to 710 V – comfortably below themaximum input voltage of 880 V – aswell as a European efficiency of 97.3percent and an almost identical Californianefficiency• Overall maximum efficiency came inat 97.7 percent• Operators can make use of nearlythe entire MPP range, a 112-percentoverload capacity and a wide temperaturerangenew member has joined the exclusive clubA of inverters that perform so well that evenan A grade isn’t good enough. Following in thefootsteps of the Refusol 11 K and SMA’s SMC8000TL, Diehl’s Platinum 6300 TL is the latesttest candidate to achieve an A+ in PHOTONLaboratory’s test.The Platinum 6300 TL is the second devicePHOTON Lab has tested from German manufacturerDiehl Controls, which belongs to theDiehl Group located in Wangen, Germany. Thefirst Diehl test candidate (see PI 4/2008, p. 96),a Platinum 4600S device with a grid disconnectiontransformer, showed a rather averageC grade performance, which may explain whyPHOTON Lab’s staff was so anxious to get itshands on the Platinum 4600’s transformerlesscolleague, with its 5,500 W AC nominal power,5,700 W DC nominal power and 6,300 W maximumDC power.ConstructionThe test candidate has a very straightforwardconstruction, with just a few connecting cables.A large circuit board accommodates the powerelement and the control circuit board is mountedvertically onto it. The power supply terminalcovers a portion of the power element circuitboard, the upper edge of which is attached tothe power transistors on the back side. Theseare affixed to the cooling element with a steelspring-clamp terminal block. The filter chokesare located above the cooling element in themolded aluminum casing.The electrolytic capacitors in the power elementand the control electronics have a 105 °Ctemperature class, so they’re well-designed forhandling ambient temperatures. The coolingelement, which acts as a mounting platform, isactively cooled by a DC fan with an estimatedlifespan of 80,000 hours (around 9 years) at anambient temperature of 40 °C. That would normallysuffice for the operating life of a typicalinverter, although the usual restrictions applyto this type of cooling method: that is, the fancan clog and malfunction if operated in a particularlydirty environment, and repairs cannotbe carried out easily.The communications and display circuitboard is located outside the power element boxin a separate transparent plastic box attached tothe cover. A protective molded foam element isclipped onto the cover and serves as the device’sfront enclosure. Thus, the housing consists offour parts: the cooling element, the side walls,108 International February 2009

8344.47651.56853.3605259.265.144photon-pictures.com (2)3628The design of the inverter’s housing, with its molded foam protector, is unusual, but the components inside are neatly arranged and apparentlyfunction well: Thermographic images show temperatures never rise above 65 °C.the sheet metal cover and the protective foam.The housing has an IP 66 protection type, whichmeans it’s suited for installation outdoors.To ensure safe operation, the device uses anautomatic grid-monitoring unit, which monitorsthe three-phase grid for proper voltageand frequency. Moreover, an insulation test isperformed between the solar generator’s connectionand ground. The device’s status canbe monitored using the display and two LEDs.According to the manufacturer, the device canbe used with Multi-Contact connectors (3 or 4mm cable diameters), as well as Tyco connectors.The grid wires are inserted through a cablegland in the housing and then connected to atop-hat rail terminal block.The Platinum 6300 TL can be networkedwith other inverters using an RS485 interface,used with optical and acoustic warning devices,and offers the possibility of remote monitoringand analysis of system data.OperationThe device arrives at the customer’s homewell-packaged and protected. It can be installedon a wall using a wall bracket, but at 29 kg it’snot exactly a lightweight device. As long as thesolar generator is properly designed and the internalDC disconnect is switched on, the inverteris ready for operation. During various tests,the device required about 35 seconds beforeconnecting to the grid and starting to work.The backlit display is able to show graphics(resolution: 170 × 76 pixels) and is easy to read.Regarding language options, users can choosebetween Dutch, English, French, German, Italianand Spanish. Parameters can be set and avariety of current values selected with the helpof six buttons. The standard screen shows thecurrent power, the yield – as well as its value ineuros – the amount of reduced CO 2emissionsand a graph displaying the system’s feed-ingradient over time. In addition to various statusand error messages, the display is able toshow the following values: DC voltage, DC current,DC power, AC voltage, AC current and ACpower. All the values are stored in a dataloggerand can be tracked back to the day when theinverter began operation.Instruction manualAccording to Diehl AKO, the installation andinstruction manuals are now available in thesame six languages as the display preferenceoptions. The manual explains installation andconnection, provides descriptions of operationalbehavior, display and error messages, andcontains a few block diagrams. The manual isnot yet available on the company’s website.Circuit designThe Platinum 6300 TL’s circuit design has asingle-stage topology. First, energy from the solargenerator reaches the power stage via an EMI filter.The power stage consists of two simple transistorhalf bridges, followed by two sinusoidal filterchokes at the power element’s output. The energystored in these chokes is led into the inverter outputthrough two antiparallel free-wheeling paths,similar to the HERIC circuitry developed by theFraunhofer Institute for Solar Energy Systems(ISE) and Sunways AG. This, as well as the use ofpower diodes as silicon carbide semiconductors,ensures the power element has a high conversionefficiency. The sinusoidal filter smoothes themodulated voltage blocks into sinusoidal curveswith a mains frequency of 50 Hz.An ENS disconnect unit separates the inverterfrom the grid as soon as grid voltage or gridfrequency deviate from the designated limits,text continues on p. 115International February 2009 109

science & technology | inverters | testMPPT adjustment efficiencyThe MPPT adjustment efficiency is highover the entire operating range – above anMPP voltage of 369 V and powers of morethan 5 percent, it is consistently higherthan 99 percent. Only when voltages below350 V come into play is the adjustment efficiencydependent on the grid voltage level.If the grid voltage is higher than around 230V, the device limits output power.s jmm=áå=sTNMSVNSTOSRPSPQSNRRVSRTTRRURPVRONRMOQUPQSQQQRQOSQMTPUUPSVPRMVVNM OM PM QM RM SM TM UM VM NMM NNM NOMB=kçãáå~ä=éçïÉê=Em jmmFBNMMVUVSVQVOVMUUUSUQUOUMTUTSTQTOTMM× Conversion efficiencyThe Platinum 6300 TL can operate at 110percent of nominal power in an MPP voltagerange of between 350 to 710 V. Themaximum efficiency of 97.7 percent lies at25 percent of nominal power and 388 V MPPvoltage (at the intersection of the two bluelines). The area of maximum efficiencystretches over the power range between20 and 75 percent. At high MPP voltages,maximum conversion efficiency drops bybetween 0.5 and 1 percentage points. DCnominal power is 5,700 W.s jmm=áå=sáå=BsNMMNIMMMVRUMMVMSMMURQMMUMTROMMTMNM OM PM QM RM SM TM UM VM NMM NNM NOMMM O Q S U NM NOâtTNMSVNSTOSRPSPQSNRRVSRTTRRURPVRONRMOQUPQSQQQRQOSQMTPUUPSVPRMVS VTNM OM PM QM RM SM TM UM VM NMM NNM NOMB=kçãáå~ä=éçïÉê=Em jmmFTNMSVNSTOSRPSPQSNRRVSRTTRRURPVRONRMOQUPQSQQQRQOSQMTPUUPSVPRMTM TR UM UR VM VR NMMáå=BBNMMVUVSVQVOVMUUUSUQUOUMTUTSTQTOTMM= Overall efficiencyThe 6300 TL’s maximum DC voltage is at 880V far above the specified MPP voltage upperlimit of 710 V, which is why just a small(hatched) area is shown in the diagramwhere limitations take effect when usedwith thin-film modules. Otherwise, the diagramshows a highly consistent overallefficiency.s jmm=áå=s pìã=áå=BsNMMNIMMMVRUMMVMSMMURQMMUMTROMMTMNM OM PM QM RM SM TM UM VM NMM NNM NOMMM O Q S U NM NOâtTNMSVNSTOSRPSPQSNRRVSRTTRRURPVRONRMOQUPQSQQQRQOSQMTPUUPSVPRMVSVTNM OM PM QM RM SM TM UM VM NMM NNM NOMB=kçãáå~ä=éçïÉê=Em jmmFTNMSVNSTOSRPSPQSNRRVSRTTRRURPVRONRMOQUPQSQQQRQOSQMTPUUPSVPRMTM TR UM UR VM VR NMM pìã=áå=BBNMMVUVSVQVOVMUUUSUQUOUMTUTSTQTOTMM110 International February 2009

science & technology | inverters | testWeighted conversion efficiencytÉáÖÜíÉÇ=ÅçåîÉêëáçå=ÉÑÑáÅáÉåÅó= bìêçI=`b`=áå=BNMMVU bìêç=ã~åìÑ~ÅíìêÉê=ëéÉÅáÑáÉÇ=Z=VTKO=BVSVQVOVMUUUSUQUOUMTUTSTQTO=bìêçéÉ~å=ïÉáÖÜíÉÇ=`~äáÑçêåá~å=ïÉáÖÜíÉÇ bìêçj~ñ=Z=VTKP=B`b`j~ñ==Z=VTKP=BTMPRM PSV PUU QMT QOS QQR QSQ QUP RMO RON RPV RRU RTT RVS SNR SPQ SRP STO SVN TNMs jmm=áå=sEfficiencies at different VMPP voltageslîÉê~ää=ÉÑÑáÅáÉåÅó= pìã=áå=BNMMVU pìãj~ñ==s jmm=Z=PRMKM=s=Es jmmãáåFIVSVQVOVMUUUSUQUOUMTUTSTQTO pìãj~ñ=Z=VTKPS=B==s jmm=Z=PUTKV=s=Es jmmpìãj~ñjáåF pìãj~ñ=Z=VTKQQ=B==s jmm=Z=TNMKM=s=Es jmmã~ñFI pìãj~ñ=Z=VTKMT=B==^îÉê~ÖÉ=çîÉê~ää=ÉÑÑáÅáÉåÅó =^îÖpìãj~ñZ=VTKON mãÉÇZ=VSKU=BI= mÜáÖÜZ=VSKV=BTMR NM NR OM OR PM PR QM QR RM RR SM SR TM TR UM UR VM VR NMM NMR NNM NNR NOMB=kçãáå~ä=éçïÉê=Em jmmFAccurancy of inverter displayaÉîá~íáçå=áå=BPMOUOSOQOOOMNUNSNQNONMUSQOMJOJQJSJUJNMJNOJNQJNSJNUJOMJOOJOQJOSJOUJPMR NM NR OM OR PM PR QM QR RM RR SM SR TM TR UM UR VM VR NMM NMR NNM NNR NOMB=kçãáå~ä=éçïÉê=Em jmmFThe courses of the weighted conversion effi ciencywith European and Californian weighting (according tothe definition from the California Energy Commission)are practically identical. Both values decrease by just0.5 percentage points over the entire voltage range.The European efficiency is highest at low MPP voltagesand at 97.3 percent, even slightly higher than themanufacturer’s specification of 97.2 percent.Efficiency increases steeply and remains constant. Itonly decreases at a minimal MPP voltage of 350 V withrising powers. At 388 V, the inverter reaches its maximumefficiency. Still, the overall course at this MPPvoltage remains stable even when the device reachesits maximum of 710 V. As one would expect, the averageoverall efficiency course is equally first-rate.The output power measured and displayed by theinverter deviates from the measurements of a poweranalyzer at lower powers by around 4 percent. Thisdecreases to less than -1 percent at 15 percent ofnominal power.112 International February 2009

science & technology | inverters | testInverter test resultsInverterObserved voltage rangeMedium irradiationHigh irradiationeta PmedGrade Position eta PhighGrade PositionPI issueRefusol's 11 K 380 – 800 V 96.9 % A+ 1 97.2 % A+ 1 9/2008SMA's SMC 8000 TL 335 – 487 V 96.9 % A+ 1 97.0 % A+ 2 10/2007Diehl AKO Platinum 6300 TL 350 – 710 V 96.8% A+ 3 96.9% A+ 3 2/2009Aros Sirio 4000 250 – 450 V 95.1 % A 4 95.7 % A 4 12/2008Sunways' AT 4500 250 – 600 V 94.6 % B 5 94.8 % B 7 7/2008Fronius' IG Plus 50 230 – 500 V 94.5 % B 6 94.8 % B 7 8/2008Phoenixtec's PVG 2800 (updated model) 250 – 450 V 94.4 % B 7 95.1 % A 5 5/2008Xantrex's GT5.0SP 240 – 550 V 94.1 % B 8 94.7 % B 9 1/2009Conergy's IPG 5000 vision 301 – 706 V 94.0 % B 9 94.7 % B 9 7/2007Delta Energy Systems' SI 3300 150 – 435 V 93.9 % B 10 94.7 % B 9 5/2008Mitsubishi's PV-PNS06ATL-GER 260 – 650 V 93.9 % B 10 94.6 % B 12 6/2008Sputnik's SolarMax 2000C *1 165 – 515 V 93.8 % B 12 93.1 % C 20 4/2007Sunways' NT 2600 (lower range) 350 – 623 V 93.8 % B 12 95.1 % A 5 11/2007Ingeteam's Ingecon Sun 3.3 TL 159 – 414 V 93.4 % C 14 94.3 % B 13 8/2007SMA's SB 3800 208 – 395 V 93.2 % C 15 93.6 % B 16 2/2007Diehl Ako's Platinum 4600S 320 – 628 V 92.9 % C 16 93.3 % C 19 4/2008Kaco's Powador 3501xi 350 – 597 V 92.6 % C 17 92.9 % C 21 6/2007Kaco's Powador 2500xi 350 – 597 V 92.5 % C 18 93.4 % C 18 12/2007Sunways' NT 2600 (upper range) 476 – 749 V 92.3 % C 19 93.9 % B 14 11/2007Solon Satis 40/750 IT *2 375 – 575 V 92.3 % C 19 93.5 % B 17 11/2008Mastervolt's QS 2000 *1 212 – 366 V 92.3 % C 19 92.7 % C 22 1/2008Riello's HP 4065REL-D 255 – 435 V 91.7 % D 22 93.9 % B 14 9/2007Fronius' IG 30 150 – 397 V 91.4 % D 23 92.2 % C 23 1/2007Siemens' Sitop solar 1100 Master *1 200 – 552 V 90.2 % D 24 91.7 % D 24 5/2007Phoenixtec's PVG 2800 (original model) *1 255 – 435 V 78.4 % E 25 85.8 % E 25 2/2008*1device no longer being produced, only leftover stock available *² prototypeEfficiency: Explanations of measurements and diagramsConversion efficiency is the relationshipbetween the AC power (P AC) supplied bythe inverter and the power absorbed onthe inverter’s DC side (P DC). To demonstratethe dependence of efficiency oninput voltage V MPPand input power P DC, theMPP voltage range is divided into 20 stepsand the DC power range into 24 steps.The result is 480 different solar generatorcurves and a measurement cycle consistingof 480 individual measurements. Everycurve has a fill factor of 75 percent.From this series of measurements, wegather 480 efficiency values, which formthe basis of the three-dimensional diagrams.The third dimension in this diagramis color, which shows all conversion efficienciesachieved. The color spectrumand its correlation to measurements arepictured next to the diagram.While the input voltage (in the rangespecified by the manufacturer) is providedin absolute numbers on the y-axis, thespecified power P MPPis shown on the x-axis in relative values. This is standardizedaccording to the inverter’s nominal inputpower P DCNom, and given in percent of P MPPnominal power. Just how far this rangestretches beyond the 100 percent markdepends on manufacturer specifications.If the maximum MPP voltage specifiedby the manufacturer is close to the maximumDC voltage, there are hatched areasin the diagrams representing MPP adjustmentefficiency, conversion efficiency andoverall efficiency. These hatched areasshow limitations on the inverter when it’sused with crystalline modules, and belowthat another area with hatching in the oppositedirection that shows limitationswhen used with thin-film modules.Both above and to the right of the diagramare cross-sections that are picturedin the three-dimensional color diagram.These show the dependency of efficiencyon standardized power, and efficiency onvoltage V MPP. At the top right, the inverter’soperating range is shown in relation to theMPP voltage range and the MPP power.MPPT adjustment efficiency is calculatedcomparing the available DC power(P MPP) with the DC power absorbed bythe inverter. It provides insight into the inverter’sstatic MPP tracking, so how wellthe solar generator absorbs the inverter’spredefined P MPPpower.The overall efficiency is calculated as aproduct of the conversion efficiency andthe MPPT adjustment efficiency for all 480measurements. The diagram is arrangedin a manner similar to that of conversionefficiency: above and to the right of thediagram are cross-sections through thethree-dimensional color diagram. Theseshow the dependencies of overall efficiencyon standardized power, as well ason voltage V MPP. On the top right is again alisting of the inverter’s operating range inrelation to the MPP voltage range and theMPP power.The diagram showing the overall efficiencygradient displays the minimum andthe maximum MPP voltage with each ofthe maximum values. The average overallefficiency gradient is attained by averagingall overall efficiency results. That’s followedby averaging all overall efficiencyresults across all voltage levels at a particularpower level. This produces a twodimensionalcurve. The analysis coversthe entire V MPPrange given by the manufacturer– including the hatched areasmentioned above. The average is formedfor power levels between 5 and 100 percent.The PHOTON efficiency is then determinedusing the values calculated fromthe average overall efficiency.114 International February 2009

as well as if it detects residual current on the grid side. An outputfilter, installed in front of the grid clamp, eliminates any radiointerference.MeasurementsAll of the following measurements are based on a grid voltageof 230 V.Locating the MPP: At a predetermined IV curve with anominal power and an MPP voltage of 521 V (the middle of thespecified MPP range), the inverter needs around 35 seconds toconnect to the grid. After about 6 seconds, it reached its MPP.When switching from 521 V to 501 V, the device needed around10 seconds to locate the MPP again and around 9 seconds whenswitching to the next lower MPP range.MPP range: The MPP range stretches from 350 to 710 V,which gives this inverter a wide range. The maximum MPP voltageof 710 V lies comfortably below the maximum input voltageof 880 V.Conversion efficiency: The inverter can operate at 110 percentof nominal power in its MPP voltage range – therefore, efficiencycould be recorded for this area. In the three-dimensionalcolor diagram, the area of maximum efficiency is pictured as alarge area at a high level, which stretches across the entire voltagerange as well as over the power range between about 20 to75 percent.At a maximum DC voltage of 880 V, there’s a small area ofhatching inside the demarcated MPP range. This represents thelimitations that occur when the device is used with thin-filmmodules, due to the narrow distance between the maximumMPP voltage and the maximum DC voltage.The device achieves its maximum efficiency of 97.7 percent– slightly higher than the manufacturer’s specification of 97.6percent – at 25 percent of nominal power and an MPP voltage of388 V (this is represented in the diagram by the intersection ofthe two blue lines). At higher MPP voltages, the maximum conversionefficiency dips by just 0.5 to 1 percentage points. At lowerpowers below 15 percent of the DC nominal power of 5,700W, the efficiency drops by just 4.5 percentage points. The powerfactor cos ϕ at nominal power was about 1.Weighted conversion efficiency: Weighted conversion efficiencyis given together with European and Californian weighting– so for medium and high irradiation levels. The Platinum6300 TL’s European efficiency is highest at lower MPP voltagesand reached 97.3 percent in our test, which is even slightlyhigher than the 97.2 percent specified by the manufacturer. TheCalifornian efficiency is almost identical. Both values decreaseby just 0.5 percentage points over the entire voltage range. Thedifference between maximum conversion efficiency and maximumEuropean efficiency is only 0.4 percentage points.MPPT adjustment efficiency: The MPPT adjustment efficiencyis very high and consistent over the entire operatingrange. Above an MPP voltage of 369 V and 5 percent of DC nominalpower, adjustment efficiency is consistently higher than 99percent. At the lower end of the operating range – so at 350 V– adjustment efficiency depends on the mains voltage. If this ishigher than about 230 V, output power is limited.Overall efficiency: The area of maximum overall efficiencyis located at lower voltages and about one-third of the nominalpower. In the diagram, the intersection of the vertical blue lineat 25 percent of nominal power and the horizontal line at 388V MPP voltage marks the maximum overall efficiency at 97.4percent.Course of overall efficiencies, average overall efficiencyand PHOTON efficiency: On account of poorer adjustment atlower MPP voltages, the overall efficiency for 350 V decreaseswith rising power. However, at a maximum MPP voltage of 710International February 2009 115

Manufacturer’s responseThe measurements of the MPPT adjustmentefficiency and conversion efficiencyare slightly lower than oursand those performed by the Arsenal Researchtest institute in Vienna, Austria.These deviations are minimal and canbe explained by the tolerances of themeasuring devices and the inverter’scomponent tolerances. We understandand acknowledge the curve values.V, the course is steady. The same is true for 388V – the value at which the device achieves itsmaximum efficiency. The device has a PHOTONefficiency for medium irradiation of 96.8 percentand a PHOTON efficiency for high irradiationof 96.9 percent – resulting in an A+ grade.In fact, it’s the third best inverter test result thusfar in PHOTON Lab (see table, p. 114).Feed-in at nominal power: The Platinum6300 TL feeds in 100 percent of nominal powerover an input voltage range of between 350 and710 V at an ambient temperature of 25 °C.Displayed output power: To test the inverter’sdisplay accuracy, the device was fed withdifferent powers between 5 and 110 percent ofnominal power while maintaining a constantMPP voltage of 521 V (so in the middle of theMPP range). When comparing the values displayedby the inverter and the power analyzer,there was a deviation from the analyzer’s measurementsat lower powers of around 4 percent.Beyond 15 percent of nominal power, the deviationwas less than -1 percent. Thus, the display’saccuracy is equivalent to that of a class B meter(formerly known as precision class 1).Operation at high temperatures: Due tothis inverter’s very wide temperature rangeof -20 to 60 °C and its IP 66 protection class,it can be installed without restriction bothunder a roof or even outdoors. Still, the 6300TL’s efficiency decreased slightly – namely 0.25percentage points – when measurements weretaken at 5,700 W, so at DC nominal power, andan MPP voltage of 521 V when operated at ambienttemperatures of around 55 °C.Overload behavior: If the Platinum 6300 TLis offered an overload of 1.3 times its nominalinput power of 5,700 W, so 7,410 W, at an MPPvoltage of 521 V and an ambient temperatureof 29 °C, the device limits DC power to 6,374W. Thus, at 112 percent, this device has an extensiveoverload range. When the power limitstake effect, the device moves the operatingpoint on the IV curve towards a higher inputvoltage. The DC voltage adjusts itself to a valueof around 570 V.Own consumption and night consumption:The inverter’s own consumption in its testedconstruction is 4.4 W on the AC side and 1 to5 W on the DC side. The manufacturer doesn’tprovide any specifications here. At night, theinverter consumes around 1 W of real powerfrom the grid. The manufacturer lists this valueas »less than 2 W.«Thermography: Thermographic imagesshow the inverter from above while it is operatingat nominal power and at an ambient temperatureof 27 °C. It shows component temperatureson the circuit board of up to 65.1 °C. Still,not all of the components are visible due to thedevice’s construction. The highest temperatureswere produced by the common-mode chokes inthe AC and DC EMI filters.SummaryDiehl AKO’s Platinum 6300 TL inverter has aclean construction, simple operation and comeswith a very informative display. The display isalso impressively accurate concerning inverteroutput power. The housing with its moldedfoam protector takes a little getting used to, butlooks fine nonetheless.The conversion efficiency’s voltage and powerdependencies are low enough. The device’s consistentand high MPPT adjustment efficiencyproduces an overall efficiency course that differsonly slightly from the conversion efficiencygradient. When using crystalline modules, theentire MPP voltage range specified by the manufacturercan be exploited, due to the large distancebetween the maximum MPP voltage andthe maximum DC voltage, but users still needto take into account the MPP’s temperaturerelatedlimitations. Thin-film modules, on theother hand, put limits on the MPP range due totheir high open-circuit voltages.Because the conversion efficiency remainsconsistently high over the entire MPP voltagerange as well as the power range, the device’sPHOTON efficiency is very high. At 96.8 percentfor medium irradiation and 96.9 percentfor high irradiation, the inverter will operatewell in all locations. The difference of less than1 percentage point between the conversion efficiencyand the PHOTON efficiency is a gaugeof the device’s very low voltage and power dependencies.When designing the MPP for a PV system,operators can select from nearly the entire MPPrange. Moreover, PV system design is also facilitatedby the inverter’s large overload range of112 percent and the cooling system’s high thermal-timeconstant. The inverter’s temperaturerange is very wide and the limitations that dooccur due to temperatures above 55 °C result injust a small reduction (0.25 percentage points)in conversion efficiency.The Platinum 6300 TL’s A+ PHOTON efficiency– and its many other positive characteristics– clearly place it among the front runnersof all the inverters we’ve tested thus far.Text Heinz NeuensteinFurther informationContacts page 233116 International February 2009