They've yet to turn a profit and so it's nothing more than a low risk ($1/share) speculative play in the hopes of a buyout rumor, an actual buyout, or actual profitable growth over time. Institutional investors (who are responsible for seriously bidding up the price of stocks) generally won't touch stocks under $10.
This, and if their cost of producing panels was reduced, and passing that reduced cost onto the consumer. Ie... If solar companies can reduce the panel price down to a reasonable level, create contracts with a home builder to have them installed, then the homeowner can pay off that panel cost over 20 years in a mortgage while actually having a significant reduction in energy bills (Reduction in bill > Cost)...then I'd be interested.
There is a good chance that solar stocks could make a strong comeback if and when carbon capping and credit certification becomes a little more formalized. Solar is a front runner in many parts of the world for carbon offsetting.
I am out of my long SPWRA as of this morning. It's had a nice 15% pop over the past week courtesy of upgrades coupled with high short interest. I don't particularly feel good about making money in situations like this, since it's just dumb luck and not verification that I was right about the stock.
All trades carry some risk but I think solar energy is pretty much a certainty if not now then in the long run.
My personal opinion on solar panels and if they are ever going to come back is YES they are. In the long term that is, in maybe 2-3 years it will be hot like flap jacks on a griddle Look for a strong company over $5-$10 with a high volume and is widely recognized and pump in the cash andddd wait..