When the wind is asleep and the sun is not shining

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.

Hybridise existing assets or re-plan?

In practice, subsequent hybridisation is currently dominant: An existing wind turbine is supplemented by photovoltaics or vice versa. This is because grid capacity is scarce and wind projects take much longer than solar plants. Anyone who hybridises an existing wind turbine with photovoltaics achieves initial capital returns much earlier.

A practical example: The energy provider EDP hybridised three existing wind farms in central Spain with photovoltaics and increased electricity production by up to 40 percent.² Whether an additional battery storage system makes economic sense depends on the actual production overlaps and battery prices. As storage costs continue to fall, this option is becoming increasingly attractive.

In the future, however, hybridisation will also be considered from the outset when planning new systems. Benefits include: Wind and solar plants go through a joint approval process instead of two separate ones. This saves time and resources. 

Battery storage as an additional factor

Hybridisation does not necessarily mean combining different types of production. Instead, a storage technology is often added - in practice, usually a battery storage system, often in combination with photovoltaics. This is particularly useful if plants have to be regulated temporarily or if a high proportion of renewable energies in the grid leads to falling revenues due to cannibalisation effects.

The electricity produced can then be stored and fed in at a later point in time when the plant produces little or no electricity at all. This load shifting optimises the utilisation of the grid connection and allows electricity to be sold at higher prices during the day.

Compared to wind-photovoltaic hybrid systems, PV battery combinations offer clear benefits: lower approval hurdles, less space required and less potential for residential conflict.

Battery storage systems can also be usefully added to existing wind-photovoltaic hybrid plants if simultaneous production peaks regularly lead to bottlenecks.
 

Opportunities for investors

Hybrid plants can be a more stable source of revenue than single technologies. Combining different types of generation or battery storage compensates for fluctuations in yield. This makes investments in renewable energies particularly attractive for long-term investors who rely on reliable cash flows and at the same time improves the negotiating position for power purchase agreements (PPAs).

There are also economies of scale due to the common grid connection: The costs are spread over more kilowatt hours. The electricity is getting cheaper. And Hybridisation enables diversification, both in terms of generation types and technology and yield risks.

After all, in some regions of Europe, hybridisation is the only viable way to build new renewable energy capacity in the foreseeable future. Those who invest here early will benefit from a market segment that is still less occupied.

Nevertheless, challenges remain: The development of hybrid plants requires complex planning and coordination. Regulatory frameworks vary considerably from country to country. And economic success depends heavily on the specific design.

What this means for klimaVest investors

Hybridization optimises what is available. But the energy transition also needs more of this: more network. This is precisely why klimaVest expanded its portfolio by 2025 with a third component - in addition to wind and solar power plants, it now also includes grid infrastructure. With an indirect stake in Amprion, klimaVest is investing in one of the four German transmission system operators. Its high-voltage lines bring renewable electricity to where it is needed.

Wind + Solar + Grids: This is the completeness that the energy transition needs.

Summary and outlook

In recent years, the hybridisation of wind and photovoltaic systems has evolved from a niche approach to a central instrument of the energy transition. Two developments are further accelerating this trend: The cost of battery storage continues to decline, and the growing share of renewables in the grid increases pressure to smooth generation profiles.

For renewable energy investors, understanding hybridization is now a basic requirement. Where traditional individual systems meet grid boundaries, the combination of technologies opens up new opportunities - for more stable yields, more efficient use of capital and an accelerated contribution to the energy transition.

There is much to suggest that music will be playing here in the coming years.