The VC and investment world in energy technology is quite different then the A16z and traditional VC world or financial heavyweights.
Having had GS invest in companies in the energy tech space in the past and having not particularly great success - I wouldn't think this is a strong signal. More that the financial heavyweights think there is action and they want to get in.
Goldman has army of analysts that are covering the field. Many many more than Even VCs that specialize in it. I would definitely write them off when it comes to smart investing.
Put another way it sounds like a corporate investor or VC into an industry they know a little about but have heard good things. Goldman Sachs is not known to be a good energy investor. Who knows maybe now they are.
Having had GS invest in companies in the energy tech space in the past and having not particularly great success - I wouldn't think this is a strong signal. More that the financial heavyweights think there is action and they want to get in.