Influence of electricity tariffs on optimal solar collectors orientation in Negev region

In case of fixed electricity tariffs, fixed-orientation solar collectors in grid-connected systems are typically positioned to the south, tilted approximately at location latitude. Such orientation maximizes annual energy and hence the total income. On the other hand, in case of time-varying feed-in tariffs the maximum annual energy yield does not necessarily correlate with the maximum income. Therefore, in order to shorten the rate of return, both the tilt and azimuth of solar collectors should be varied accordingly. The paper demonstrates a case study for Negev region of Southern Israel, based on clear sky irradiation model and current feed-in tariffs. In order to estimate a typical annual energy yield, 1-hour-resolution irradiation data are used in order to obtain the power output of a typical solar panel with similar resolution. A typical losses model is employed to improve the prediction accuracy. Correspondent temperature and wind speed data are also utilized to account for temperature-induced de-rating. The results may also be used to indicate the feasibility of the feed-in tariffs to avoid economical imbalance. It is shown that unlike in previously described cases, a similar rate of return for both maximum energy and maximum income orientation are obtained in Israel, demonstrating excellent choice of feed-in tariffs for solar energy in Israel.