Medium voltage string inverter for photovoltaics

The Fraunhofer Institute for Sun Power Methods ISE has advanced and operates the sector’s first medium-voltage string inverter for large-scale energy crops. By way of feeding energy to the medium voltage grid, the MS-LeiKra venture group demonstrated that PV inverters are technically able to dealing with upper voltage ranges.

The advantages of photovoltaics come with massive price and useful resource financial savings on passive elements and cables. The software lays the root for a brand new machine thought for the following era of large-scale photovoltaic energy crops, which will also be implemented to wind generators, electrical mobility and business programs.

Trendy PV string inverters have an output voltage between 400 VAC and 800 VAC. Even supposing the manufacturing of energy crops is rising often, the voltage has no longer but higher. There are two causes for this: First, development a extremely environment friendly, compact inverter in keeping with silicon semiconductors is difficult. Secondly, there are these days no PV requirements that handiest duvet the low voltage vary (most 1500V DC / 1000V AC).

In a venture of the German Federal Ministry for Financial Affairs and Local weather Motion (BMWK), Fraunhofer ISE, in cooperation with Siemens and Sumida, has advanced an inverter that permits the output voltage to be higher to the medium voltage vary (1500 V). At 250 kVA. The important thing to that is using silicon carbide semiconductors, that have a better blockading voltage.

The analysis group additionally applied a extra environment friendly cooling thought the usage of warmth pipes, which reduces the volume of aluminum required.

Skinny cables be offering massive financial savings attainable

The typical PV energy station calls for tens of kilometers of copper cable. Expanding the voltage creates nice attainable: with these days’s attainable output voltage of 800 VAC, a 250 kVA string transformer calls for cables with a cross-section of a minimum of 120 mm². By way of expanding the voltage to 1500 VAC, the cable cross-section may also be diminished to 35 mm². This in flip reduces copper intake through about 700 kilograms consistent with kilometer of cable.

“Our useful resource analyzes display that within the medium time period, the electrification of the ability machine will result in copper shortage. Expanding the voltage permits us to avoid wasting precious assets,” says Prof. Dr. Andreas Piet, Director of the Fraunhofer Sun Institute. ISE Power Methods.

With the “MS LeiKra” venture, they’re going past the low voltage requirements (<1000 VAC / <1500 VDC). There are these days no PV requirements for this vary. That is why the venture group additionally works on parameters that can outcome from higher effort.

Having effectively fed energy into the medium voltage grid, the analysis group is now on the lookout for sun farm builders and grid operators to check the ability plant thought within the box.

But even so photovoltaics, low-voltage bypass could also be vital for different programs, equivalent to wind generators, the place rising machine capacities additionally require cables with vast cross-sections. The similar applies to charging infrastructure for big electrical cars and automobile fleets, and business networks, the place medium-voltage transformers may save numerous subject matter if cable cross-sections might be diminished.

Equipped through the Fraunhofer Institute for Sun Power Methods (ISE).