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Solar thermal is more efficient than photovoltaics in terms of energy captured per unit of surface/land area. However, photovoltaics are significantly cheaper p

Solar thermal is more efficient than photovoltaics in terms of energy captured per unit of surface/land area. However, photovoltaics are significantly cheaper per unit of energy generated. So, solar thermal makes more sense in space-constrained environments rather than vast deserts. Solar thermal also makes more sense where you're directly utilising the heat generated, eg: for industrial processes. If you're just using that heat to spin turbines to make electricity, you're adding a layer of inefficiency.

Diggsey 6y ago
AIUI, photovoltaics also lose a lot of efficiency when they heat up, so the ideal place to use them is somewhere cool but with a lot of sun. In contrast, solar thermal runs at extremely high temperatures to begin with, so even in a hot climate, there's a huge temperature difference from which to extract power. It seems to me that mirrors would be cheaper than photovoltaics, and the power-plant itself is a fixed cost, so most of the cost must come from the motors and electronics needed to angle the mirrors, and the maintenance of that. I wonder: could you have a system where the mirrors are all fixed in place, and you simply move the target as the sun moves. (Or at least move a smaller set of mirrors/lenses that refocus the light onto a fixed target)
- Reason077 6y ago
  Yes, the ongoing maintenance costs associated with turbines are significant. Lots of moving parts, high temperatures, high pressures, etc. Photovoltaics, on the other hand, are very low maintenance. There's also a nice scalability aspect to PV: if you want to expand your plant's output, it's really just a matter of adding more panels as you need them. Where as once you hit the limits of your collector/turbine/etc, you pretty much need to build a whole new plant to expand it further. One of the world's largest solar farms is in Dubai, obviously an extremely hot region. It contains a mix of PV and thermal technologies, though it sounds like they are leaning towards more PV for future phases: https://en.wikipedia.org/wiki/Mohammed_bin_Rashid_Al_Maktoum_Solar_Park https://en.wikipedia.org/wiki/Mohammed_bin_Rashid_Al_Maktoum...
  - JoeAltmaier 6y ago
    Their O&M is higher than the 'capacity' figures make it seem. They run under 25% capacity on average. This site https://www.scottmadden.com/insight/solar-photovoltaic-plant-operating-and-maintenance-costs/ https://www.scottmadden.com/insight/solar-photovoltaic-plant... estimates $60 per kW-year for maintenance. Half cleaning; most of the rest in inverter replacement. How does that compare with turbine I wonder.
    - Reason077 6y ago
      This is from 2010 so I'd imagine the figures have likely changed significantly since then, along with all the economics of photovoltaics. Today's inverters are almost certainly more reliable than pre-2010 models. Cleaning is certainly a cost in dry areas where dust can coat the panels. But generally not in temperate climates where you can rely on self-cleaning via regular rainfall.

Diggsey 6y ago

AIUI, photovoltaics also lose a lot of efficiency when they heat up, so the ideal place to use them is somewhere cool but with a lot of sun. In contrast, solar thermal runs at extremely high temperatures to begin with, so even in a hot climate, there's a huge temperature difference from which to extract power. It seems to me that mirrors would be cheaper than photovoltaics, and the power-plant itself is a fixed cost, so most of the cost must come from the motors and electronics needed to angle the mirrors, and the maintenance of that. I wonder: could you have a system where the mirrors are all fixed in place, and you simply move the target as the sun moves. (Or at least move a smaller set of mirrors/lenses that refocus the light onto a fixed target)

Reason077 6y ago
Yes, the ongoing maintenance costs associated with turbines are significant. Lots of moving parts, high temperatures, high pressures, etc. Photovoltaics, on the other hand, are very low maintenance. There's also a nice scalability aspect to PV: if you want to expand your plant's output, it's really just a matter of adding more panels as you need them. Where as once you hit the limits of your collector/turbine/etc, you pretty much need to build a whole new plant to expand it further. One of the world's largest solar farms is in Dubai, obviously an extremely hot region. It contains a mix of PV and thermal technologies, though it sounds like they are leaning towards more PV for future phases: https://en.wikipedia.org/wiki/Mohammed_bin_Rashid_Al_Maktoum_Solar_Park https://en.wikipedia.org/wiki/Mohammed_bin_Rashid_Al_Maktoum...
- JoeAltmaier 6y ago
  Their O&M is higher than the 'capacity' figures make it seem. They run under 25% capacity on average. This site https://www.scottmadden.com/insight/solar-photovoltaic-plant-operating-and-maintenance-costs/ https://www.scottmadden.com/insight/solar-photovoltaic-plant... estimates $60 per kW-year for maintenance. Half cleaning; most of the rest in inverter replacement. How does that compare with turbine I wonder.
  - Reason077 6y ago
    This is from 2010 so I'd imagine the figures have likely changed significantly since then, along with all the economics of photovoltaics. Today's inverters are almost certainly more reliable than pre-2010 models. Cleaning is certainly a cost in dry areas where dust can coat the panels. But generally not in temperate climates where you can rely on self-cleaning via regular rainfall.