The solution, which is becoming increasingly popular in practice, is conceptually elegant: You simply combine several producers on a single grid connection. Solar power flows throughout the day. Wind delivers at night and in winter. Together, they use the existing infrastructure much more efficiently than any technology alone.

This is called hybridization. One of the most important trends in the energy transition.

Hybridization - a growing trend

Renewable energies now generate significantly more electricity than they did a few years ago. However, we encounter bottlenecks in the transmission networks. This applies not only to the large high-voltage connections over long distances, but also to the local grid connections through which photovoltaic or wind turbines feed in.

Some of the capacity of these connections is often left unused due to weather and time of day. This is where hybridization comes into play: By combining different types of generation - and storage technologies where appropriate - an existing grid connection can be used better and more efficiently. Hybridising existing systems can even create new capacities. Without the need to remove the net.

What are the benefits for energy policy and operators?

1. Optimisation of energy production

Wind turbines and photovoltaic systems have different generation profiles. Wind produces regardless of the time of day and often weakens exactly when solar reaches its daily peak. This complementarity is not a random addition, but has a physical reason: Thermal effects slow down the wind during the day, while solar radiation reaches its maximum. The combination partially compensates for daily and seasonal production fluctuations. The result is more continuous power generation. 

2. Efficient use of grid connections

Each mains connection has a maximum active power. In Germany, the full load time for photovoltaics is up to 1,000 hours per year, depending on the location, and up to 2,500 hours for onshore wind turbines at suitable locations. Combined, this results in an average capacity of around 3,200 full-load hours per year, i.e. a significantly more even utilisation of the existing connection.

3. Grid stability and capacity expansion

When wind and solar balance each other, the grid becomes more stable. And because the feed flows more evenly, additional capacities are created. 

4. Increased revenue

The electricity price fluctuates depending on the time of day and weather conditions. Those who produce a lot when everyone else produces a lot also achieve poorer prices. Hybrid systems have a structural benefit here: Their combined generation profile of wind and solar is less likely to coincide with low-price periods than each technology alone. This translates into better capture prices, the actual average revenue achieved per kilowatt hour fed in.

Added to this is the more uniform production profile. It reduces the volume risk for the buyer and thus strengthens the negotiating position for PPAs. PPAs are long-term direct contracts between producers and buyers at pre-agreed prices.

Hybridising wind and solar is a promising strategy. However, it alone is not sufficient to guarantee a stable base load. There are always periods when neither the sun is shining nor the wind blowing, the so-called dark whisper. A full baseload supply from renewables requires strong pan-European grid infrastructure and storage capacity. Nevertheless, hybridisation helps to make better use of the existing infrastructure and enable a more even local feed-in.

Regional differences and choice of location

In principle, all locations are suitable for hybrid plants, provided there are no structural or technical obstacles. How well this works depends on how much wind and sun a site actually offers.

Ideally, the generation profiles of the technologies should overlap as little as possible. This requires careful planning, as a 50:50 split or systems of the same size are rarely the best solution. A study using three comparative sites in Portugal shows: The relationships between wind and solar energy can vary greatly from place to place, but the correlations on a day-to-year basis are very low or even negative. The greater the complementarity, the greater the hybridization potential.¹

Both generation types do not have to be directly next to each other. It is only important to have a certain spatial proximity to the common grid connection. A practical example: A photovoltaic power plant northeast of Berlin with 130 megawatt peak had a cable route of more than 20 kilometres that was hardly used at night. Thanks to the addition of a wind farm with five turbines and a rated output of 30 megawatts nearby, the connection is now being used much more efficiently. It only required just under a kilometre of additional cable.