2016-04 / SteadyEye / Hybrid System

April 21st, 2016

GHI forecasts in Australia – PV Diesel hybrid system management


In Australia, numerous sites are not connected to the electricity network.

They are fed by fuel generating sets or hybrid power plants. The management of the latter can be largely improved by using of a very short-term forecasting solution

(cf. http://steady-sun.com/wp-content/uploads/2016APR-Study_SkyImager_for_Hybrid.pdf ).


In the example shown here-below, we produce GHI forecasts (Global Horizontal Irradiance).

It is a well brightened up day with light cloudy spells at noon and in the afternoon. The use of the P20-P80 confidence interval (in orange) allows to anticipate these irradiation drops (and thus of production) 5 minutes in advance (see. figure 1).


Figure 2 shows the forecasts provided 20 minutes before. Logically, one can notice that the uncertainty is more important (the interval P20-P80 is on average wider). The short-term drop which occurs at noon is not as well anticipated in amplitude, but given the time horizon (20 minutes) and the duration of the event (1 minute) this outcome is not so surprising.

Solar forecasting GHI SteadyEye 5 min with P20-P80

Figure 1: Actual (in blue) vs Forecast (in red/orange for the percentiles P20-P80) – 5 minutes ahead

Solar forecasting GHI SteadyEye 20 min with P20-P80

Figure 2: Actual (in blue) vs Forecast (in red/orange for the percentiles P20-P80) – 20 minutes ahead