10 to 20 years at most is the lifetime of a solar panel, and of course the older they become the less effective they are. Though I don't know if the metal can be recovered and recycled afterward.

I think the biggest problems with solar panels are:
- A relatively large area is needed to produce substantial amounts of energy
- Suitable areas for solar panels (deserts and such) are generally far away from the places where the energy is needed (urban areas), making energy distribution problematic
- Maintenance is somewhat impractical because huge solar farms would cover large, remote areas in countries with little infrastructure
- Solar panels lend themselves for decentralized energy networks, but virtually all current networks are tailor-made for large central power plants servicing a wide area; using this local approach however raises the issue that the production peaks in the summer, while usage peaks 6 months later.

We don't know when that will be, and we might even hit obstacles that make the whole thing completely impractical no matter how much science we throw at it. For now, it's a nice dream.

A better form of solar power is using reflectors to heat water which then drives turbines. Its starting to be used all over the place. And all you need is some shiny metal, and pipes.

Some Finn, who thought he was clever, invented a heating oven which you could load with wet and snowy wood. It was kind of a clever invention, the heat of the dry burning wood melted and dried the snowy wood before it got loaded in turn. I don't remember if it needed electricity for the conveying, or if the heat produced also the needed motion somehow. Anyway, you could go to the forest, get something to burn, chop it and load it, in the middle of the winter. But I bet most of the energy in the wood goes to the melting and drying. IIRC to melt 0° ice to 0° water needs as much energy as warming 0° water to 72°. And you need even more energy to vaporize it.

The clever thing to do is the usual way of storing the snowy wet wood and let the sun dry it during summer and burn it next winter. This is kind of solar power, used for centuries.

I have a uni work mate that is building a house (Melbourne, Australia), by law, he is required to install solar hot water heating, that uses gas or electricity back up. It will be gas, as Australia has access to large amounts of it, so its cheap. But the Australian government is putting things on the people, so that the industry doesn't have to cut back so much.

Look, all I was saying was solar power won't "run out" due to the limited supply in rare metals. I certainly didn't say anything about it being free, at all. Tax has absolutely nothing to do with what I was talking about.