Have a look at my reply to 

https://www.researchgate.net/post/Multilevel_data_or_panel_data_analysis

Yes, you can use time series independent variable in panel regression.

Dear Mr ozili 

As you are saying that this can be done, could you please tell how data would be arranged for analysis?  Should I repeat the independent variables cross section? If I do so,  won't it affect my results as the observations for independent variable will be repeated 300 times for the sample of 300 companies.? 

Have a look at the reply I suggested it explains the issues.