Save Copper with Medium Voltage in PV Power Plants

Resource Requirements Save Copper with Medium Voltage in PV Power Plants

2026-02-02 From Michael Richter | Translated by AI 4 min Reading Time

Copper is becoming scarce, aluminum is energy-intensive and PV power plants are getting bigger and bigger. The classic low-voltage architecture is reaching its limits. A new system concept therefore relies on medium voltage.

Increasing the voltage reduces the cable cross-sections and therefore the copper requirement considerably.(Image: Fraunhofer ISE) — Increasing the voltage reduces the cable cross-sections and therefore the copper requirement considerably.
(Image: Fraunhofer ISE)

Photovoltaics is no longer thought of in gigawatts, but increasingly in terawatts. Over the coming decades, a massive expansion is expected worldwide that will exceed today's installed capacity many times over. This scaling will change the relevant issues. Whereas in the past the focus was on increasing efficiency at module level, today the focus is shifting to system aspects: material availability, infrastructure costs and the physical limits of traditional system concepts.

A key driver of this development is the increasing demand for electrical cables. Large photovoltaic power plants require enormous quantities of cables to collect and bundle the energy generated by the modules and feed it into the grid. This demand is growing faster than the production capacities for conductive metals. According to the International Energy Agency's Global Critical Minerals Outlook 2024, global demand for copper has exceeded the announced supply since 2025. This situation not only leads to rising prices, but also increases the risk of supply bottlenecks.

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The medium-voltage PV inverter used, which is based on high-barrier silicon carbide semiconductors, was developed by Fraunhofer ISE as part of the MS-Leikra project.(Image: Fraunhofer ISE)

Copper demand has exceeded global copper production since 2025 (source: Global Critical Minerals Outlook 2024).(Image: Fraunhofer ISE)

Increasing the voltage significantly reduces the cable cross-sections and thus the demand for copper. (Source: Fraunhofer ISE)

Cables Instead of Modules: Where Material Is Really Consumed

In a modern large-scale photovoltaic power plant with an output of several tens of megawatts, a significant proportion of the material used is not for the modules themselves, but for the electrical infrastructure. The total length of the DC and AC cables laid can reach several hundred kilometers. In addition, there are collection stations, transformers and transformer stations that bring the electricity to grid voltage.

Although the use of aluminum cables has partially reduced the need for copper, it only shifts the problem. Aluminum is energy-intensive to produce, causes high CO₂ emissions and is also considered a critical raw material in Europe. This makes it clear that the solution cannot lie in a change of material alone, but in a fundamental overhaul of the electrical architecture.

The Physical Logic of Higher Voltages

This is precisely where the PVgoesMV approach comes in. The underlying idea is simple but effective: electrical power is the product of voltage and current. If the voltage is increased for the same power, the current decreases. Lower currents enable smaller conductor cross-sections and therefore significantly reduced material usage.

In practice, this means that even a moderate increase in the voltage level has a significant effect. If the voltage is doubled, the required conductor cross-section can be reduced to around a quarter. This not only reduces the need for copper or aluminum, but also simplifies the transport, laying and installation of the cables. At the same time, cable losses are reduced, as they depend on the square of the current. Only the insulation requirements increase.

Effects on the Entire System Architecture

The advantages of higher voltages are not limited to the cabling. The grid-side components also benefit. Transformers can transmit higher power with the same installation space, which means that the number of transformer stations required in large systems can be reduced. Fewer stations mean less concrete, less steel, less space required and a simpler system structure.

For very large PV power plants in particular, this effect has a significant impact on investment costs. The voltage increase not only changes individual components, but also the entire system architecture of a power plant.

Why the Move to Medium Voltage Makes Sense

PVgoesMV is deliberately not pursuing a direct leap to high voltage, but is instead focusing on the lower medium-voltage level. The reason for this lies in the balance between benefits and technical complexity. Even in this voltage range, large parts of the material and cost savings can be realized without disproportionately increasing the complexity of the systems.

The necessary adjustments to insulation concepts, protection technology and components are technically manageable. Many existing technologies can be further developed instead of being completely redesigned. This assessment is also shared by numerous industrial partners who are actively supporting the project.

Pilot Plants as a Technical Reality Check

In order to test the theoretical advantages in practice, two pilot systems are being set up in Germany as part of PVgoesMV. The systems each have a connected load of around 135 kW. A voltage of 3 kV is used on the DC side, while the AC side is operated at 1.2 kV.

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The string inverter used is based on silicon carbide semiconductors with a high reverse voltage and was developed at the Fraunhofer Institute for Solar Energy Systems (ISE). The system will be further adapted for use under real conditions and tested in field operation over several months.

Different string concepts are being tested in parallel. On the one hand, established 1500 V modules with corresponding earthing are used, and on the other hand, specially developed module prototypes for real 3 kV strings. This approach makes it possible to evaluate solutions that can be implemented in the short term as well as future system generations.

From Demonstration to Scaling

A central aim of the project is to derive reliable findings for the planning, construction, operation and safety of medium-voltage PV systems from the pilot operation. These are to be incorporated into testing and quality concepts and form the basis for future standards. At the same time, the participating manufacturers will receive valuable feedback for the further development of their products.

PVgoesMV is therefore more than just a technical experiment. The project addresses one of the central questions of future PV expansion: How can solar energy not only be realized in a renewable way, but also in a material- and cost-efficient way on a terawatt scale? Raising the voltage level to medium-voltage level proves to be a logical and physically obvious step. (mr)