What do you mean by "predict"? Which predictors do you have, and what timescales are you interested in?
If you are interested in forecasting future output given knowledge of past output, on the scale of minutes to hours, there are a number of papers comparing different forecasting methods for solar power output. Over short time horizons (e.g., less than 1 hour), persistence is difficult to beat. Time series methods (e.g., ARIMA) may have a slight advantage over persistence but not always, and it is hard to argue against the simplicity of a persistence forecast. Also, time series methods require some special treatment to handle sunrise correctly. Over longer time horizons, it is likely that you need a numerical weather simulation, because nature is not always a smoothly changing system.
however i studied in the past years neural networks structures to predict the output of a PV plant up to 24 hours ahead, with data gathered from weather forecasts free websites...
i used a one stage method with a self learning structure, described in:
Online tuned neural networks for PV plant production forecasting, PVSC 2012
solarelectricpower.orgPage on solarelectricpower.org
Inman, R. H., Pedro, H. T., & Coimbra, C. F. (2013). Solar forecasting methods for renewable energy integration. Progress in energy and combustion science, 39(6), 535-576.