Your absolutely correct, alternative energy has been very cyclical in recent times. Sadly the market shows greater interest when the price of oil is rising. It's like the government not encouraging alternate energy when prices are down, that's part of the reason we are in this situation.
As you know the market is very fickle. I believe that long term there is no choice, we must seek solutions from all possible sources.
So long term I am bullish on this sector. There is a ton of R&D in the pipeline that will produce many investment opportunities.