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derKestrel t1_j1d0x4n wrote

If you concentrate sunlight and shine it directly into the water or on items absorbing sunlight which are inside the water, apart from refraction, reflection, and lens heating losses, all energy from sunlight should be transferred into the water. You lose some more from radiation of heat from the water vessel and the pipes.

In this case I think your efficiency is mainly ruled by your turbine efficiency: around 65 to 90 %, bigger turbines and hotter steam tend to be more efficient.

For the solar panels on the other hand, we look at 17 to 25ish %.

I guess steam power is still good.

I do have no idea about cost efficiency. The steam solution will have much higher maintenance costs and probably also setup costs.

You might also want to look at molten salt solar solutions.

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cuicocha t1_j1dhe6r wrote

All thermal power plants (solar and fossil fuel) have significant inefficiency related to the difficulty of converting heat into work. So the turbine contributes to the inefficiency but isn't the biggest factor. Solar thermal power generation looks less good considering this.

For things where you really need heat, like cooking or heating water, you can avoid that inefficiency of converting light or heat to power; for example, lots of people heat their hot water by collecting heat directly from collectors on their roof. However, despite the increased efficiency, this isn't necessarily cost-effective compared to other means of reducing fossil fuel energy use--electricity is just a really practical way to move energy around.

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