Energy supply stability dominates the political and public discourse these days. Although there is a broad consensus that we have to complete the transformation to a carbon-free energy supply within the next few decades, there is still some debate about how to get there. Solar and wind are thought too erratic to serve as a foundation for 100% supply security. And because electrochemical power storage systems are far too expensive and will never be powerful enough anyway, many still dream of a future built on a hydrogen-based energy system or even a breakthrough in nuclear fusion. But these scenarios are not without their insurmountable hurdles.
Solar energy, especially photovoltaics, is already widely recognized as the cheapest way to generate energy. Wind is usually a close second - depending on which study you read. But it is still far ahead of all other fossil and nuclear energy sources. But both generation methods on their own have a major drawback in that energy supplied is weather-dependent and therefore difficult to plan, let alone control. If these technologies are combined with energy storage, the disadvantage can be mitigated somewhat, but generation costs increase disproportionately as the period of time to be bridged goes up and battery capacity increases. Thus, one of these technologies alone cannot solve our supply problem.
If we map both forms of generation against time and weather patterns, what we see is that solar and wind energy often complement each other, at least at inland locations in Western Europe. To put it simply, during the day there is sun and wind, and at night, there is only wind; in the summer, solar energy predominates, and in the winter, wind energy picks up the slack. So, what could be more obvious than combining photovoltaics and wind turbines to form hybrid power plants?
In utility-scale power plants, this combination of both technologies is almost old hat, and there is ample evidence that it works well. Even without integrated energy storage, a significant reduction in the load on the grid is evident at the site of the plant compared to a power plant with the same capacity using only one technology, since the hybrid system can feed electricity into the grid at a much more constant rate. A battery system further enhances this positive effect by temporarily storing excess energy the plant generates to bridge periods of low feed-in. In addition, the plant operator can use battery storage to supply balancing power, another important contribution to grid stability.
Transferring this method to smaller scale, distributed systems is technically possible, but requires a few considerations: Here we’ll focus on plants smaller than 500 kW to keep approval and construction costs to a manageable level. Only turbines with a total height less than 50 meters are considered small wind turbines. Although these are classified in Germany as so-called structural installations according to state building codes (Landesbauordnungen, or LBO) and generally require a building permit, this can usually be granted at any suitable location outside a residential area. They are not restricted to wind priority areas or wind power concentration zones, nor are they subject to often lengthy nature conservation and emissions-control procedures. Nevertheless, novices should not embark on a wind power project without professional support.
Small and medium-sized wind turbines are usually gearless with a synchronous generator, and of course pitch-control technology for power limitation is a must. The current cost is 2,200 to 2,500 euros per kilowatt of installed capacity. But these costs are not comparable with the costs of a PV plant, because wind turbines usually have a much higher number of annual full load hours and a correspondingly higher energy yield - by a factor of 1.5 to 2. To determine electricity production costs, consider two turbine sizes: a 20 kW turbine and a 100 kW model. These are sizes likely to be interesting for small business or agriculture. A 20-kilowatt wind turbine can generate power at a rate of 0.07 to 0.14 euros per kilowatt hour at an inland location, and at about 0.05 to 0.09 euros at a coastal location. If we increase the capacity to 100 kilowatts, generation costs drop by as much as 20%.
Price trends for small to medium-sized wind turbines is something that needs to be looked at in more detail in view of the high dependence on Chinese manufacturers. Unfortunately, there are only a few European suppliers in this sector. In any case, prices for solar panels have remained nearly unchanged compared to last month. Although the curves for mainstream and low-cost modules show a slight upward trend, prices for high-efficiency modules remain stable. This is mainly down to the fact that supplies of lower-power PV panels are getting scarcer, while the availability of products with efficiencies of 21% and higher is improving - the lines between these products are blurred anyway.
Larger bargain lots of low-power or used modules have all but vanished from the open market, which makes price data increasingly hard to come by. Towards the end of the year, however, the situation is likely to swing the other way somewhat, as suppliers and manufacturers seek to dispose of inventories and sell off lower output modules. Many manufacturers are starting the new year with new product lines. Higher outputs and, in some cases, new module dimensions await us in the first quarter of 2023.
The co-author of this article, Volkmar Tetzlaff, is the owner of TEV Consulting and has been working with wind turbines for 20 years. An electrical engineer with degrees in information technology and telecommunications, he works as an independent consultant and project manager and draws on more than 45 years of professional experience with a focus on project development in innovative engineering; measurement technology, microchips, wind turbines and the automotive sector.
Overview of price points broken down by technology in October 2022 including changes over the previous month (as of 21 October 2022):