The sale of electricity is the most important source of income for a wind turbine. Accordingly, it is imperative how much electricity the wind turbine can produce. When preparing a budget for a wind turbine investment, there are a number of ways to calculate how much electricity the wind turbine can produce over the coming 20-25 years.

In case of new turbines that have not yet been commissioned, one would normally order wind assessments reports (Windgutachten) from German wind assessment companies. Unfortunately, experience has shown that these wind reports from the German assessment companies are more than often too optimistic about the wind. When making a wind report you use reference numbers from wind turbines in the same region as well as a so called wind index for that region. The index expresses how much wind can statistically (and based on years of historic data) be expected on the current site. The German wind reports are often too optimistic because the underlying indexes that they use are too optimistic.

In our opinion Denmark has one of the best wind assessment companies in EMD International A/S in Aalborg. Based on a thorough recalibration of the German indexes, EMD has prepared their own wind indexes, which have a more conservative (and realistic) view on the wind to be expected in the various German wind regions. Over the years, we have had impeccable experience with all assessments and control calculations from EMD, who have been extremely precise in their production forecasts in more or less all projects sold by us.

Therefore, when we sell new turbines that have not yet been commissioned and therefore have no historic production, we always have EMD carry out control calculations of the German wind assessments. Such control calculations also include an on-site visit in Germany. It is our practical experience that this calculation is very precise.

As investor it is very important to know that most brokers or sellers of new turbines only use the German wind assessments as basis for their budgets and do not have EMD make control calculations.

The consequence is that you as an investor pay too much for the turbine, which means that the actual yield from the investment will most likely be much lower than expected in the budget prepared by the broker or seller. Our best advice is to be critical towards the broker and get competent assistance.

If you want to know more about the use of wind index, then click here to read our article published in the Danish Wind Turbine Owners Association’s monthly magazine, Naturlig Energi.