German research institute Fraunhofer ISE has launched a project to explore how medium-voltage technology can make material-intensive solar components more efficient and cost-effective.
The ‘SeVen’ project will test the efficacy and affordability of medium-voltage combiner boxes and “other system components”, which Fraunhofer ISE defined as voltage up to 1,000V. This compares to AC system voltages of 400-800V currently in operation in the PV industry, and could deliver two benefits: cable cross-sections could be reduced, leading to savings in both material and installation costs for cabling; and the performance of substations can be improved, meaning projects deliver the same amount of power with a lower requirement for transformers and switchgear.
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Fraunhofer ISE will test this theory by assessing the impact of different voltages at a power plant, then develop a demonstrator inverter and string combiner, to assess how these changes perform in a pilot study. This pilot project will aim to deliver material savings of 75% in cables, 30% in copper and ferrite in winding materials and 20% in heat sinks.
The target voltage of 1,000V is somewhat lower than the 1,500-2,000V milestone that parts of the PV industry are moving towards, but when asked about this, Andreas Hensels group manager Power Electronics and System Technology at Fraunhofer ISE, drew a distinction between PV voltage and component voltage, the latter of which is measured in AC.
“The minimum PV voltage will be 2kV,” Hensels told PV Tech. “The exact specifications for the AC voltage are still being determined. The target range is a minimum of 1,000V AC, with up to 1,500V AC being within the target corridor.”
Partners in the SeVen project include inverter manufacturer KACO New Energy and module and component manufacturer SUMIDA Components & Modules, both of which are based in Germany. Associated partners include German software company Streamergy and clean energy developer BayWa r.e., and Fraunhofer ISE expects to complete the project in 2028.
Cost and material savings
In addition to delivering higher voltages for the benefit of project performance, the shift towards larger voltages has significant potential for cutting project costs. Fraunhofer notes that, while the price of PV modules has fallen by about 80% in the last decade, balance of system costs—including inverters, cabling and distribution boxes—are an “increasingly important” part of solar projects, accounting for a greater proportion of project costs as module costs continue to fall.
Fraunhofer ISE also names aluminium, steel and copper as vital resources that will see increased demand, and increased pressure on supply chains, in order to meet the appetite for new solar deployments. Copper, in particular, is expected to see a 24% demand surge in the next decade, according to Wood Mackenzie, and making efficient use of materials such as these will be an important factor in reducing strain on supply chains.
“This is exactly where the project comes in,” added Hensels. “Our objective is to develop a holistic and sustainable concept for large PV power plants that optimises electricity production costs and increases resource efficiency. We consider the entire system, from the PV module string to the grid connection, including all key components.”
