Is it okay to cite the same source in two consecutive sentences?
Is it ok from an academic point of view? Absolutely. It is never wrong to cite a source that you use. However, it might be "wrong" from an flow-of-the-text point of view. I would sidestep the issue by just reformulating the two sentences. Something along the following lines would perhaps resolve your problem:

"As noted in [SOURCE1], wind and PV contributed about 12% of Europe's electricity supply in 2016. That study, carried out by the Joint Research Centre of the European Commission, concludes that a tripling of this contribution is needed in order to reach the 2030 target."

or even

"As noted by the Joint Research Centre of the European Commission, wind and PV contributed about 12% of Europe's electricity supply in 2016 [SOURCE1]. There, it is concluded that a tripling of this contribution is needed in order to reach the 2030 target."