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Power boostingSpanish PV operators add modules to increase system yield – and profi ts

Tuning cell effi cienciesUpdate on selective emitters now on off er from leading technology companies

The top trade showsOverview on the world‘s most important fairs for the PV sector in 2011

Super grid-connectionTh ree inverters tested by PHOTON Lab all awarded A+ grades

12-2010

Drenching PV to catch more sunSurvey on wet etching equipment for texturing wafers and thin-fi lm panels

OFFPRINT:

PHOTON LAB'S TEST R

EPORT ON

REFU 017KSOL

2 International December 2010

Metzingen, Germany-based RefuSol GmbH has another winner on its hands: the RE-

FUSOL 017K has risen to the top of PHOTON Laboratory’s test, just beating out a new contend-er from SMA Solar Technology AG (see article, p. 128). Based on medium irradiation, SMA’s Trip-ower tied with a second device, a smaller member of the RefuSol series, the REFUSOL 013K (see ar-ticle, p. 146). The manufacturer sent us both Refu-Sol devices in early August as part of the usual test agreement. The units are kitted out with above-av-erage equipment and have a circuit topology that is more suitable for use with thin-film modules than most other transformerless inverters.

Construction

The RefuSol series includes products with AC nominal powers between 10,000 and 19,200 W. All of the models in this range are transfor-merless. The REFUSOL 017K is very compact and appears to be simple to manufacture. The device makes a good, high-quality impression

Challenger to the crown

and is very small and light for a three-phase in-verter in this power class.

The internal set-up has several layers: on the upper layer is the control circuit board and the DC filter circuit board with the switched-mode power supply for auxiliary voltage. A large power element circuit board is located on the lower level. Three sinusoidal filter chokes and four storage chokes in the boost converter are cast into a separate section of the housing. The power element circuit board holds all of the input-side DC converter’s components, as well as the intermediate voltage circuit with the electrolytic capacitors, and the output bridges. The power semiconductors are located in three separate modules and are soldered to the bot-tom of the circuit board. For cooling, a large cooling element, without forced ventilation, is mounted to the back of the housing.

The electrolytic capacitors in the power ele-ment and the control electronics have a tem-perature class of 105 °C, and are therefore well-suited to handle ambient temperatures.

RefuSol’s REFUSOL inverter has once again beat out SMA to take the top spot in PHOTON Lab’s inverter test

Highlights

RefuSol GmbH’s REFU• SOL 017K is a three-phase transformerless inverter with a DC nominal power of 16.8 kWThe MPP range stretches from 460 to •850 V; the maximum MPP voltage is too close to the maximum input volt-age of 1,000 VThe unit’s maximum conversion effi-•ciency comes in at 98 percent, while the European efficiency is 97.7 per-cent and the Californian efficiency is 97.9 percentThe PHOTON efficiency at medium •irradiation was recorded as 97.4 per-cent, while it came in at 97.6 percent at high irradiationThe device is suited for installation in-•doors and outdoors, and offers many options for expansion

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97.4 % at medium irradiation

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REFU 017KSOL

97.6 % at high irradiation

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None of the visible components in the REFUSOL 017K showed critical temperatures during thermo-graphic imaging, although its multi-layer construc-tion means that the power element cannot be seen clearly.

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A large, internal fan operates under the circuit board to prevent heat pockets from forming. Its lifespan is listed as 80,000 hours at 40 °C – that corresponds to an operating period of around 9 years, which should suffice for a typical in-verter lifespan under normal circumstances. If, however, the fan malfunctions, it can be easily removed. The housing has an IP 65 protection type and is made of three pieces: the frame, the cover and a cooling element on the back.

To ensure safe operation, the device uses an automatic grid-monitoring unit, which checks the grid for proper voltage and frequency. Moreover, the unit performs a test to check the insulation resistance between the solar genera-tor’s connections and the ground, as well as in-specting the grid-side leakage current.

The solar generator is hooked up using MC4 connectors from Multi-Contact AG, four pairs of which are included. The grid connection uses a large five-pole connector from Phoenix Con-tact GmbH & Co. KG. After assembly, this con-nector can be attached to the inverter’s housing with two screws. The REFUSOL 017K has a DC circuit-breaker situated underneath the hous-ing’s frame, next to the DC connectors.

The display circuit board is mounted on the housing’s cover and covered with a transparent film. The device’s status is also shown via four LEDs. The inverter offers an array of connec-tion possibilities for external devices, includ-ing irradiation and temperature sensors, relays (230 V, 2 A AC), RS485 (input and output), USB and Ethernet.

Using the USB port or Ethernet connec-tions, the device can communicate and update its firmware. Moreover, the device contains an internal datalogger, which can record up to 40 measurements. These have to be added individ-ually, and the parameters set accordingly.

The following configuration options are avail-able: larger mains supply plugs, various PV con-nectors, remote monitoring with the help of differ-ent external monitoring devices, and a fan module to build inverter towers (called Powercap).

Operation

The device arrives at the customer’s home well packaged and protected by thick cardboard. The unit is hung on the wall with a bracket. At 40 kg, the unit is relatively lightweight.

As long as the solar generator is properly de-signed and the DC disconnect is switched on, the inverter is ready for operation, and requires about 126 seconds to run a number of tests be-fore it starts working.

The white backlit display, flush with the front cover, is easy to read and offers the following languages: Czech, English, French, German, Italian and Spanish. Using eight buttons, op-erators can set parameters. A »default« display provides an overview of AC power, AC voltage, DC voltage and daily energy yield. There is also another menu stating DC power, DC voltage, DC current, AC power, AC voltage, AC cur-

rent and AC frequency. Users can also see the cooler and internal device temperature as well as irradiation and module temperature, if the proper sensors are connected. The display can also show absolute and standardized yield data (daily, monthly, annual and total values). The daily amount of fed-in current can be shown in a bar graph. Thus, the device offers users a very wide range of values in a clear display.

Instruction manual

The device comes with a short version of the operating instructions in printed form and an extensive instruction manual as a PDF file on a CD-Rom in Czech, Dutch, English, French, Ger-man, Italian and Spanish. Recently, Korean has also been added to the list. The short version is designed for quick connection of the inverter. It includes technical data and general explana-tions, as well as tips for installation, connection and operation. Overview graphics explain how to navigate the menu. Moreover, the use of the display, grid connection and DC connection are also explained. The extensive instruction manual on the CD-Rom contains a lot of diagrams and a comprehensive presentation about the unit’s menu structure. Both versions of the manual, as well as the technical data, can also be down-loaded from the manufacturer’s website.

Circuit design

In principle, the REFUSOL 017K has a two-stage circuit design, but doesn’t have a classic topology. First, energy from the PV generator reaches the power stage via an EMI filter. The device has a split intermediate circuit capacitor, the center of which is connected with the grid’s neutral wire. It possesses two three-phase output bridges, which are connected in parallel on the output side. The first output bridge is directly connected to the DC input. The second bridge is supplied by two boost converters that are located in DC input’s positive and negative conductors, and which feed the second split intermediate cir-cuit capacitor. The sinusoidal wave modulation is distributed between these two output bridges, so that both of them only transmit a portion of the voltage boost to the output chokes to produce the sinusoidal current. This reduces the losses in the power transistors and output chokes.

Furthermore, every output in each phase has a free-wheeling path, which prevents energy stored in the output choke from flowing back into the intermediate circuit capacitor, which would cause greater losses. A successive filter smoothes the voltage blocks into sinusoidal voltage with a grid frequency of 50 Hz. An ENS disconnect unit separates the inverter from the grid as soon as grid voltage or grid frequency deviate from the designated limits, as well as if it detects residual current on the grid side. In-sulation resistance is measured on the DC side. An output filter, installed directly in front of the grid clamp, eliminates any radio interference.

4 International December 2010

percentage points; toward lower voltages, it dropped by only 0.2 percentage points. Below 15 percent of nominal power, there is a more drastic decrease of 3 to 4 percentage points. The power factor cos φ at nominal power was about one.

MPPT adjustment efficiency: The MPPT adjustment efficiency is consistently high (more than 99 percent) across the entire operating range. Only at lower powers and higher voltages does the MPP tracking show any weaknesses.

Overall efficiency: The area of maximum overall efficiency is located in the medium volt-age range at more than 50 percent of nominal power. The vertical line at 55 percent of nominal power and the horizontal line at an MPP volt-age of 583 V meet at the maximum overall ef-ficiency of 98 percent.

Weighted conversion efficiency: The Euro-pean efficiency reaches its peak in the medium voltage range. At 97.7 percent, it deviates from the manufacturer’s specifications (97.8 percent) slightly. The difference between the maximum conversion efficiency and the maximum Eu-ropean efficiency is just 0.3 percentage points. The Californian efficiency is 97.9 percent, so 0.2 percentage points higher.

Course of overall efficiencies, average overall efficiency and PHOTON efficiency: The PHOTON efficiency for medium irradia-tion is 97.4 percent, while the PHOTON effi-ciency for high irradiation is 97.6 percent.

Feed-in at nominal power: The inverter feeds in 100 percent of nominal power over an input voltage range of 460 to 850 V at an ambi-ent temperature of 25 °C.

Displayed output power: The inverter was fed with different powers between 5 and 100 percent of nominal power at a constant MPP voltage of 645 V, so in the medium range. The device’s displayed power values were then com-pared with those from a power analyzer. At lower powers, the inverter’s displayed power showed a deviation of up to +7 percent. Beyond 20 percent of nominal power, this deviation dropped to +1.3 percent. Thus, the display’s ac-curacy is equivalent to that of a class B meter (previously known as precision class 1), but in-terestingly enough is much less accurate than the REFUSOL 013K (see article, p. 146).

Operation at high temperatures: The RE-FUSOL 017K feeds 100 percent of its nominal power into the grid up to an ambient tempera-ture of around 58 °C, after which it reduces its power. The selected operating point was 16,800 W and an MPP voltage of 645 V. After that, ef-ficiency decreases by just 0.2 percentage points. Once again, in this case, the 013K performed better than its bigger brother. Considering the very wide temperature range of -25 to 55 °C, and the housing’s IP 65 protection type, the REFU-SOL 017K can be installed in warm areas or even outdoors.

Overload behavior: If the REFUSOL 017K is offered an overload of 1.3 times its nominal input power, so 21,840 W, at an MPP voltage of 645 V and an ambient temperature of 24 °C, the device

limits power to 17,107 W. This corresponds to an overload of 1.8 percent. Thus, the device has a very small overload range, at which point power limitations push the operating point on the IV curve toward higher input voltages. The DC volt-age adjusts itself to a value of around 720 V.

Own consumption and night consump-tion: In its tested construction, the inverter’s own consumption is around 0.4 W on the AC side and up to 27 W on the DC side. The manu-facturer provides no specifications. At night, the inverter consumes around 0.48 W of real power from the grid. That matches the manu-facturer’s specification of »less than 0.5 W.«

Thermography: Thermographic images show the inverter from above while it is operat-ing at nominal power at an ambient tempera-ture of 24 °C. Due to the multi-layer design, the power element is largely hidden under a metal plate. Any temperature increases detected were within the normal range; the maximum tem-perature recorded was 60.4 °C.

Summary

The REFUSOL 017K is compact and appears easy to manufacture. The workmanship is im-pressive: it is small and light for a three-phase device in this power class. A very informative display, a number of integrated communica-tions possibilities, and internal dataloggers round out the picture.

The power element’s topology makes it possi-ble to distribute the potential of the DC connec-tion symmetrically to the grounding conductor, and results in a very high efficiency.

The manufacturer only approves the power element for open-circuit voltages of less than 960 V, which is why the simulator’s open-circuit voltage was limited to this range during the mea-surements. The MPP voltage range is very wide, but shows limitations in the upper range due to the insufficient distance between the maximum DC voltage and maximum MPP voltage.

Conversion efficiency is consistent over the voltage and power ranges, and reaches a maxi-mum of 98 percent. The unit also has a good Eu-ropean and Californian efficiency: the European efficiency is just 0.3 percentage points and the Californian efficiency just 0.1 percentage points lower than the maximum conversion efficiency. The very consistent and high MPPT adjustment efficiency allows for an overall efficiency course that only deviates slightly from the conversion efficiency. The MPP tracking only showed weak-nesses at low powers and very high voltages. De-spite the wide voltage range, the results show a very high PHOTON efficiency of 97.4 percent for medium irradiation and 97.6 percent for high ir-radiation: the best results seen in PHOTON Lab’s inverter tests so far.

When selecting the MPP of a PV system, operators should choose voltages up to 740 V. The inverter has a very low overload range, but a very wide temperature range with minimal power limitations. The conversion efficiency’s

Manufacturer’s response

The measurements taken by PHOTON Lab match our results, taking measure-ment accuracy issues into account.

In response to the critical appraisal of the MPP range's upper limit of 850 V, the most important factor for system de-sign is the open-circuit voltage, which should not exceed the approved maxi-mum DC voltage of 1,000 V. We haven't chosen to unnecessarily limit the MPP range of our device in order to allow the MPP to function optimally in the event of cloud cover and a cold genera-tor. Furthermore, this equips us well to handle the next generation of modules with even better fill factors.

Although this variety of circuitry compo-nents makes the device’s construction very elaborate, it has a high efficiency, good elec-tromagnetic compatibility (EMC) and a DC potential at the DC connection terminal that is balanced with the ground.

Measurements

All of the following measurements are based on a grid voltage of 230 V. The REFUSOL 017K’s maximum DC voltage is 1,000 V; the DC nomi-nal power is 16,800 W.

During the measurements, the simulator’s open-circuit voltage was limited at MPP voltage ranges above 788 V, since a fill factor of 75 per-cent would result in voltages higher than 960 V, which is the upper limit specified by the manu-facturer for the power element.

Locating the MPP: At a predetermined IV curve with nominal power and an MPP voltage of 645 V, the inverter needs around 126 seconds to connect to the grid and another approximately 33 seconds to locate the MPP. When switching from 645 V to 624 V, the unit required 11 sec-onds, while a switch from 645 V to 665 V took around 13 seconds.

MPP range: The MPP range stretches from 460 to 850 V, which is a wide range. Considering today’s fill factors, the maximum MPP voltage of 850 V is too close to the maximum input voltage of 1,000 V. In the efficiency diagrams (covering conversion efficiency, MPPT adjustment and overall efficiency), there is a hatched area that represents limitations on the use of crystalline modules above about 805 V, and for thin-film modules above around 740 V.

Conversion efficiency: In the diagram, the area of maximum efficiency is located in the middle of the MPP voltage range, reaching a very high level of 98 percent. The maximum level is achieved at 55 percent of nominal power and an MPP voltage of 583 V. The manufacturer specifies 98.1 percent. At higher MPP voltages, the conversion efficiency decreased by just 0.5

science & technology | inverters | test

International December 2010 5

Conversion efficiency

× MPPT adjustment efficiency

= Overall efficiency

Way up high: Conversion efficiency with this level of consistency across the entire MPP voltage and power ranges is rare.

Tiny weaknesses: The MPP tracking shows a small drop at lower powers and higher voltages – otherwise, the REFUSOL 017K‘s overall result would have been a tenth of a percentage point higher.

The diagram for overall efficiency is a pleasing picture and is an indication of the unit‘s excellent PHOTON efficiency.

6 International December 2010

Weighted conversion efficiency

Overall efficiency at different VMPP voltages

Accuracy of inverter display

The European and Californian efficiencies remain almost unchanged across the entire MPP voltage range and run unusually close to the maximum overall efficiency.

End result: Averaging the different efficien-cy courses results in the best PHOTON ef-ficiency achieved so far.

In the lower range, power measurements are fairly inaccurate, but at higher levels they improve considerably.

science & technology | inverters | test

International December 2010 7

dependence on temperature is very low at -0.2 percentage points. The display of output power is not as precise as the smaller REFUSOL 013K, but is still equivalent to that of a class B meter.

All in all, the REFUSOL 017K is a top device, not only due to its exceptional PHOTON effi-ciency, but also thanks to its excellent equip-

A tiny challenger to the crown While the REFUSOL 017K is the latest efficiency king in our inverter tests, the device’s little brother, the REFUSOL 013K, is nipping at its heels; the REFUSOL 013K shares second place with SMA’s STP 17000TL-10

Highlights

The REFU• SOL 013K is a three-phase transformerless inverter with a DC nominal power of 12.7 kWThe device’s MPP range stretches •from 420 to 850 VIts maximum conversion efficiency •is 98 percent, while its European ef-ficiency is 97.6 percent and its Califor-nian efficiency is 97.9The inverter’s PHOTON efficiency for •medium irradiation is 97.3 percent; its PHOTON efficiency for high irradia-tion is 97.6 percent

The REFUSOL 013K is a very compact and production-friendly inverter. It makes an

excellent, high-quality impression and is very small and light for a three-phase device in its power class. It offers a large number of inte-grated communication possibilities and en-ables easy statistical analysis with its internal datalogger and graphics-capable display.

The power element’s topology makes it possi-ble to distribute the potential of the DC connec-tion symmetrically to the grounding conductor, resulting in a very high efficiency. During initial testing, the inverter was only able to reach 98.4 percent of its nominal power, but a firmware update addressed this error. The changes to the software have been integrated into the serially produced device, according to Refu.

The manufacturer approves the unit’s power element for maximum open-circuit voltages of up to 960 V. It should be noted that although the inverter’s MPP voltage range is very wide, there are limitations in the upper range: the dis-tance between the maximum DC voltage and the maximum MPP voltage is too small.

The REFUSOL 013K’s maximum conversion efficiency is 98 percent, and this efficiency is very consistent over the entire voltage range and power range. The same applies to its weighted ef-ficiency: the European efficiency is just 0.4 per-centage points below the maximum conversion efficiency at 97.6 percent, while the Californian efficiency is just 0.1 percentage points below the maximum conversion efficiency at 97.9 percent. The device’s very consistently high MPPT adjust-

ment and flexible usability – it can even be used with thin-film modules, albeit with some limi-tations. According to Refu, the company has no problem issuing individual approvals for use with First Solar modules; GS Solar has issued a general approval for the use of its products with the RefuSol series (REFUSOL 010K to 020K),

and approvals from additional manufacturers (such as Abound Solar) are to follow.

Text Heinz Neuenstein, Jochen Siemer Further information Contacts page 233

ment efficiency allows for overall efficiencies that are just slightly lower than conversion efficien-cies. Only minor weaknesses emerge in the lower power range and at higher voltages. This results in a very stable overall efficiency path. Therefore, the test candidate received a grade of A+ for its PHOTON efficiency of 97.3 percent at medium irradiation and 97.6 percent at high irradiation – despite its wide voltage range.

When setting the MPP for a PV system, a range of up to 740 V should be selected. The inverter’s overload capacity is small, but its temperature range is very wide, so there are no limitations on power. The dependence of the unit’s conversion efficiency on temperature is very low at -0.1 percentage points. Another ex-cellent feature is the display’s ability to measure output power very accurately.

The REFUSOL 013K is therefore truly a top-class inverter. And what’s more, it can also be used with thin-film modules despite its trans-formerless design – with limitations. Refu says it has no problem approving the device for First Solar modules in individual cases, and GS-Solar has approved its modules for general use with the RefuSol series (REFUSOL 010K to 020K). Approvals from other module manufacturers (for instance, Abound Solar) are in the works.

Text Heinz Neuenstein, Jochen Siemer Further information Contacts page 233

97.3 % at medium irradiation

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REFU 013KSOL

97.6 % at high irradiation

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REFU 013KSOL

Inverter test resultsInverter Observed voltage

range*3Medium irradiation High irradiation PI issue

etaPmed Grade Position etaPhigh Grade Position

RefuSol’s REFUSOL 017K 460 - 850 V 97.4% A+ 1 97.6% A+ 1 12/2010RefuSol’s REFUSOL 013K 420 - 850 V 97.3% A+ 2 97.6% A+ 1 12/2010SMA's STP 17000TL 400 - 800 V 97.3% A+ 2 97.5% A+ 3 12/2010RefuSol’s REFUSOL 011K 380 - 800 V 96.9% A+ 4 97.2% A+ 4 9/2008SMA's SMC 8000 TL 335 - 487 V 96.9% A+ 4 97.0% A+ 5 10/2007SMA's SMC 11000TL 333 - 500 V 96.9% A+ 4 96.8% A+ 11 7/2010Diehl AKO's Platinum 6300 TL 350 - 710 V 96.8% A+ 7 96.9% A+ 9 2/2009Danfoss' TLX 15 k 430 - 800 V 96.7% A+ 8 97.0% A+ 5 6/2010Sunways' NT 4200 340 - 750 V 96.7% A+ 8 96.8% A+ 11 3/2010Conergy's IPG 15T 450 - 800 V 96.6% A+ 10 97.0% A+ 5 8/2010SMA's SMC 700TL 333 - 500 V 96.6% A+ 10 96.8% A+ 11 5/2010Danfoss' TLX 10 k 430 - 800 V 96.5% A+ 12 97.0% A+ 5 8/2010Power-One's Aurora PVI-12.5-OUTD-FS 360 - 750 V 96.4% A 13 96.9% A+ 9 4/2010Kaco's Powador 4000 supreme DCS (9 kHz) 350 - 510 V 96.2% A 14 96.7% A+ 14 1/2010Fronius' IG TL 5 0 350 - 700 V 95.9% A 15 96.2% A 15 9/2010Kaco's Powador 4000 supreme DCS (18 kHz) 350 - 510 V 95.7% A 16 96.1% A 16 1/2010SMA's SB 5000TL-20 175 - 440 V 95.7% A 16 96.0% A 17 5/2009Power-One's Aurora PVI-6000-OUTD-S 180 - 530 V 95.4% A 18 95.9% A 18 3/2009Aros' Sirio 4000 250 - 450 V 95.1% A 19 95.7% A 20 12/2008Conergy's IPG 5 S 275 - 750 V 95.0% A 20 95.8% A 19 9/2009Fronius' IG Plus 100 230 - 500 V 94.8% B 21 95.0% A 23 11/2010Sunways' AT 4500 250 - 600 V 94.6% B 22 94.8% B 27 7/2008Fronius' IG Plus 50 230 - 500 V 94.5% B 23 94.8% B 27 8/2008Phoenixtec's PVG 2800 (updated model) 250 - 450 V 94.4% B 24 95.1% A 21 5/2008Kaco's Powador 8000xi (new software) 350 - 600 V 94.4% B 24 94.7% B 30 3/2010Kaco's Powador 2500xi DCS 350 - 600 V 94.3% B 26 95.0% A 23 1/2010Sunways' AT 2700 181 - 600 V 94.3% B 26 94.8% B 27 8/2009Sputnik's SolarMax 6000S 220 - 550 V 94.3% B 26 94.7% B 30 11/2009Carlo Gavazzi's ISMG150DE 200 - 450 V 94.1% B 29 95.0% A 23 5/2010Xantrex's GT5.0SP 240 - 550 V 94.1% B 29 94.7% B 30 1/2009Conergy's IPG 5000 vision 301 - 706 V 94.0% B 31 94.7% B 30 7/2007Kaco's Powador 8000xi (old software) 350 - 600 V 94.0% B 31 94.7% B 30 3/2010Kostal's Piko 10.1 400 - 850 V 94.0% B 31 94.4% B 41 7/2009Delta Energy Systems' SI 3300 150 - 435 V 93.9% B 34 94.7% B 30 5/2008Mitsubishi's PV-PNS06ATL-GER 260 - 650 V 93.9% B 34 94.6% B 36 6/2008SMA's SMC 7000HV 335 - 560V 93.9% B 34 94.2% B 43 9/2009Sunways' NT 2600 (lower range)*1 350 - 623 V 93.8% B 37 95.1% A 21 11/2007Steca’s Stecagrid 9000 3ph 350 - 680 V 93.8% B 37 95.0% A 23 7/2010Sputnik's SolarMax 2000C*1 165 - 515 V 93.8% B 37 93.1% C 55 4/2007Kaco's Powador 4202 200 - 510 V 93.7% B 40 94.6% B 36 10/2010SMA's SB 2100TL 200 - 480 V 93.7% B 40 94.6% B 36 6/2009Oelmaier's PAC 4 330 - 600 V 93.6% B 42 94.6% B 36 12/2009Mastervolt's Sunmaster XS6500 180 - 480 V 93.6% B 42 94.1% B 44 2/2010Ingeteam's Ingecon Sun 3.3 TL 159 - 414 V 93.4% C 44 94.3% B 42 8/2007SMA's SB 3800 208 - 395 V 93.2% C 45 93.6% B 48 2/2007Dasstech´s DSP-123KH 350 - 600 V 93.0% C 46 94.6% B 36 10/2010Diehl AKO's Platinum 4600S 320 - 628 V 92.9% C 47 93.3% C 52 4/2008Power-One's Aurora PVI-2000-OUTD-DE 210 - 530 V 92.8% C 48 94.0% B 45 2/2010Diehl AKO's Platinum 2100S 206 - 390 V 92.8% C 48 93.3% C 52 10/2009Kaco's Powador 3501xi*1 125 - 391 V 92.6% C 50 92.9% C 56 6/2007Kaco's Powador 2500xi 350 - 597 V 92.5% C 51 93.4% C 50 12/2007Sunways' NT 2600 (upper range)*1 476 - 749 V 92.3% C 52 93.9% B 46 11/2007Solon's Satis 40/750 IT*² 375 - 575 V 92.3% C 52 93.5% B 49 11/2008Mastervolt's QS 2000*1 212 - 366 V 92.3% C 52 92.7% C 57 1/2008Powercom’s SLK-4000 205 - 408 V 92.0% C 55 93.4% C 50 11/2010Phoenixtec's PVG 10000 320 - 720 V 91.8% D 56 93.3% C 52 6/2010Riello's HP 4065REL-D 255 - 435 V 91.7% D 57 93.9% B 46 9/2007Fronius' IG 30 150 - 397 V 91.4% D 58 92.2% C 58 1/2007Siemens' Sitop solar 1100 Master*1 200 - 552 V 90.2% D 59 91.7% D 59 5/2007Danfoss' ULX 1800 HV IN 260 - 500 V 89.2% E 60 91.3% D 60 4/2010SMA's SB1100 139 - 320 V 89.1% E 61 90.5% D 61 10/2009Phoenixtec's PVG 2800 (original model)*1 255 - 435 V 78.4% E 62 85.8% E 62 2/2008

*1 device no longer being produced, *2 prototype, *3 range at which the model was tested and to which the grade applies