Solar Seasonal Tilt

Studies done in certain solar PV plants in the Central India revealed that shadow effects were resulting in generation losses. Losses were more at the 35 degrees tilt angle whereas after moving to the 5 degrees tilt angle, at the onset of spring season, the shadow effects were negligible. To tide over the problem, either the shadow causing objects had to be removed or the tilt angle altered during the winter season. A limited exercise to move panels to 18 degrees of certain Solar arrays during January (this tilt angle is usually scheduled for July) was done but shadow effects were still seen.

One can do a cost benefit analysis with respect to losing generation at an unintended angle for that season and loss due to shadow effects. In this case, the exercise was futile to move the panels to 18 degrees to counter shadow effects. Following on the generation closely for all the 6 months at the 35 degrees tilt, it was noticed that in January the panels which were not affected by shadows were performing lesser than the forecasted generation itself. Probably another tilt angle could be tried for January month alone. However, it is not feasible once Module mounting structure (MMS) design considerations are frozen for 3 specific tilt angles.

Two equal sized and co-located Solar plants were compared on different aspects basing it against the forecasts – i) the generation differences at different tilt angles ii) Effect of shadows across both plants. Following were the findings.

1. The generation differences for the 2 plants at the 18 degrees tilt angle was higher for one plant against the forecasts.

2. The benefits of generation in the 35-degree tilt angle was the least in both the plants as compared to the 18 degrees and 5 degrees tilt.

The effect of shadows at both the plants had a major impact on generation at the 35 degrees tilt, and it was more in one of the plants. It was evident that the terrain and its compounded impact on shadow effects resulted in generation loss at the 18 & 35 degrees angle and thereby the gains of seasonal tilt were limited.