As previously observed, electricity markets can be strange at times.
Especially when there are two (or more) separate markets dealing with virtually the same article.
Usually such situation leads to arbitrage opportunities.
In case of electricity, we often have the separation of the Day Ahead Market (DAM) - when one declares amount of electricity he will provide or consume - and balancing market - when differences between DAM declarations are settled.
When you are a Renewable Energy Producer (RES), and forecasting your energy generation is not perfect, you face two possible scenarios:
- production excess - you have produced more than you declared (sold on the DAM)
- production deficit - you have produced less than you declared (sold on the DAM)
Let's focus on the later - production deficit.
Regulations differ, but usually when you are short (in deficit), you must buy the amount of the "missing" energy (forecasted amount declared/sold on the DAM minus the actual production). Unless you are able to do it on the Intraday Market (IDM), you must settled on the balancing market.
Normally the deficit prices are higher than the DAM prices, meaning that you pay for the errors in your production forecast.
For example, in Romania, the average difference between DAM and deficit prices was minus 98 RON / MWh (approx. minus 23 EUR / MWh) over the October 2013 - May 2014 period (some preliminary data used).
However, on rare occasions (<5% of the cases), deficit prices were lower than DAM prices.
Fig. Distribution of the differences between DAM and deficit prices in Romania, 2013-10 - 2014-05
Hence, selling as much energy as possible (for example your whole installed capacity) on the DAM, for the moments when DAM price is expected to be higher than deficit price would bring you a profit (on average 21 RON / MWh).
A "tiny" problem remains though. How to predict when DAM>deficit? :)
Fig. Differences between DAM and deficit prices by the hour
Fig. Average differences between DAM and deficit by months and hours
Note: all values negative, best -39 RON