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It's difficult to say. Solar thermal is not dropping in cost the way that solar PV is. For now, at low penetrations, solar PV is a far better bet. But solar th

It's difficult to say. Solar thermal is not dropping in cost the way that solar PV is. For now, at low penetrations, solar PV is a far better bet. But solar thermal has the advantage of integrated storage. When solar overall is at some reasonably high penetration (say, 10-15%) storage will become important. At that point, it depends on the cost curve of storage technologies. If batteries or other energy storage technologies have gotten cheap enough, PV + storage will be cheaper than solar thermal. If batteries haven't dropped in price enough, solar thermal may see a resurgence. My bet is on PV + storage, though there is no certainty here.

Jedd 11y ago
Great, thank you Ramez. I know they're different technologies, but I wonder on the cross-over effects of the two. If people see a solar thermal plant going up near their town, will it encourage or discourage them from installing PVCs? Are nation states that encourage / subsidise large-scale solar thermal deployments more likely to encourage end-user scale (PVC-based) systems? Entirely agree managing storage is increasingly the pain point - in both scales of systems (thermal just rides out cloudy / dark periods more smoothly, I believe). Is it still true that the most $-effective large-scale power-storage mechanism is to pump water up a hill?
- pjc50 11y ago
  If people see a solar thermal plant going up near their town, will it encourage or discourage them from installing PV? I don't think this will make much difference - individual PV installation is an investment decision (just like other big home improvements) based on cost of energy and subsidies. It makes some difference to how "green" people feel, but the cost matters more. It may have an effect in planning battles. Here in the UK (esp Scotland) it's all about the wind farms. European solar thermal is currently struggling against low natural gas prices: http://www.estif.org/statistics/st_markets_in_europe_2014/ http://www.estif.org/statistics/st_markets_in_europe_2014/ Pumped storage requires naturally occuring suitable locations (not too many available) and incurs environmental damage of damming a river. (Calling it "PVC" is really confusing me with the flexible polymer)
  - Jedd 11y ago
    Understood, but I find solar too ambiguous. Like when people talk about nuclear. I like the idea of fusion reactors, but steadfastly oppose fission. Solar tech has two big branches, and conflating them is something we should stop doing any time now. As to influence - I think HN types are more informed than the GP, so in our bubble it may be hard to speculate accurately on any such influence. By which I mean, if you're not informed about the technology or the trends, then any intrusion of these technologies into your life will be more significant. Perhaps I am wrong. For Scotland I would think we're some way off a sufficiently efficient cell, given hours and angles of incidence of sunlight. Disclaimer - I'm in Australia, about 35 degrees south, and to be candid don't really understand how even places like Germany have so much love for PVCs ;) How do you think the fact that natural gas is guaranteed to decrease in availability / increase in cost (over the long term) compared to the guarantee solar will decrease in cost, will influence users? And how do you think the idea of users being able, or being primed, to think of themselves as producers as well as consumers will influence their decisions on power?
    - pjc50 11y ago
      I have a 3.8kW rated system (cost about £5k) at about 56N, and it actually produces that much on clear summer days. Currently it's grey outside and outputting about 2kW (I can ssh into the computer looking at the meter). The high latitude does mean extended summer days. Admittedly it probably wouldn't be viable without subsidy today. I don't think individuals are very good at adapting to the long term market. If I know gas will be more expensive in 5 years, I can't do very much with that today. There's also the old "the market can stay irrational longer than you stay solvent": if I invest too early I can just as easily lose money. In the UK, I think the general public are ahead of the media and politicians on the issue. There's a noisy anti-environmentalist and anti-windfarm contingent, but most people recognise the tradeoffs. I don't think people want to be their own producer en masse, any more than grow their own food or be their own bank, but if they can make a capital investment that saves money and produces income then you're speaking the right language to the middle class. People might start to get vocal when gas prices go up in the UK; complaints about fuel poverty and demands for more fracking. It'll require a long period of gas being more expensive than electricity for fuel and heating for people to switch their homes over.
brrt 11y ago
There's also, at least on a global-energy-system scale, the issue of efficiency. Solar thermal (I'm thinking of solar towers and the like) can heat a medium to about 300, maybe 400 C, and if I'm not mistaken using a conventional steam turbine that can give you a Carnot efficiency of ~25%, maybe 30%. Real generators engineered today are on the level of 90% efficiency, meaning that a solar thermal plant can - practically - convert ~20% of incident solar energy to electricity. Commercial PV will likely not reach that level of efficiency for years, and there are - probably - good ways to improve thermal efficiency beyond this 20%. Of course, thermal generators required direct incidence (don't work well on diffuse light), but the long and short of it is that with thermal we (may) need about half the total area we would need for PV. (On the other hand, PV can practically uses space - rooftops - which is inaccessible for thermal.) Nice blog, by the way :-)
ridgeguy 11y ago
Somewhat OT, but I'd be interested in your thoughts. How serious are grid stability issues presented by solar PV (without storage) at high penetration rates (say > ~ 20%)? Important? Not? Thanks.

Jedd 11y ago

Great, thank you Ramez. I know they're different technologies, but I wonder on the cross-over effects of the two. If people see a solar thermal plant going up near their town, will it encourage or discourage them from installing PVCs? Are nation states that encourage / subsidise large-scale solar thermal deployments more likely to encourage end-user scale (PVC-based) systems? Entirely agree managing storage is increasingly the pain point - in both scales of systems (thermal just rides out cloudy / dark periods more smoothly, I believe). Is it still true that the most $-effective large-scale power-storage mechanism is to pump water up a hill?

pjc50 11y ago
If people see a solar thermal plant going up near their town, will it encourage or discourage them from installing PV? I don't think this will make much difference - individual PV installation is an investment decision (just like other big home improvements) based on cost of energy and subsidies. It makes some difference to how "green" people feel, but the cost matters more. It may have an effect in planning battles. Here in the UK (esp Scotland) it's all about the wind farms. European solar thermal is currently struggling against low natural gas prices: http://www.estif.org/statistics/st_markets_in_europe_2014/ http://www.estif.org/statistics/st_markets_in_europe_2014/ Pumped storage requires naturally occuring suitable locations (not too many available) and incurs environmental damage of damming a river. (Calling it "PVC" is really confusing me with the flexible polymer)
- Jedd 11y ago
  Understood, but I find solar too ambiguous. Like when people talk about nuclear. I like the idea of fusion reactors, but steadfastly oppose fission. Solar tech has two big branches, and conflating them is something we should stop doing any time now. As to influence - I think HN types are more informed than the GP, so in our bubble it may be hard to speculate accurately on any such influence. By which I mean, if you're not informed about the technology or the trends, then any intrusion of these technologies into your life will be more significant. Perhaps I am wrong. For Scotland I would think we're some way off a sufficiently efficient cell, given hours and angles of incidence of sunlight. Disclaimer - I'm in Australia, about 35 degrees south, and to be candid don't really understand how even places like Germany have so much love for PVCs ;) How do you think the fact that natural gas is guaranteed to decrease in availability / increase in cost (over the long term) compared to the guarantee solar will decrease in cost, will influence users? And how do you think the idea of users being able, or being primed, to think of themselves as producers as well as consumers will influence their decisions on power?
  - pjc50 11y ago
    I have a 3.8kW rated system (cost about £5k) at about 56N, and it actually produces that much on clear summer days. Currently it's grey outside and outputting about 2kW (I can ssh into the computer looking at the meter). The high latitude does mean extended summer days. Admittedly it probably wouldn't be viable without subsidy today. I don't think individuals are very good at adapting to the long term market. If I know gas will be more expensive in 5 years, I can't do very much with that today. There's also the old "the market can stay irrational longer than you stay solvent": if I invest too early I can just as easily lose money. In the UK, I think the general public are ahead of the media and politicians on the issue. There's a noisy anti-environmentalist and anti-windfarm contingent, but most people recognise the tradeoffs. I don't think people want to be their own producer en masse, any more than grow their own food or be their own bank, but if they can make a capital investment that saves money and produces income then you're speaking the right language to the middle class. People might start to get vocal when gas prices go up in the UK; complaints about fuel poverty and demands for more fracking. It'll require a long period of gas being more expensive than electricity for fuel and heating for people to switch their homes over.

brrt 11y ago

There's also, at least on a global-energy-system scale, the issue of efficiency. Solar thermal (I'm thinking of solar towers and the like) can heat a medium to about 300, maybe 400 C, and if I'm not mistaken using a conventional steam turbine that can give you a Carnot efficiency of ~25%, maybe 30%. Real generators engineered today are on the level of 90% efficiency, meaning that a solar thermal plant can - practically - convert ~20% of incident solar energy to electricity. Commercial PV will likely not reach that level of efficiency for years, and there are - probably - good ways to improve thermal efficiency beyond this 20%. Of course, thermal generators required direct incidence (don't work well on diffuse light), but the long and short of it is that with thermal we (may) need about half the total area we would need for PV. (On the other hand, PV can practically uses space - rooftops - which is inaccessible for thermal.) Nice blog, by the way :-)

ridgeguy 11y ago

Somewhat OT, but I'd be interested in your thoughts. How serious are grid stability issues presented by solar PV (without storage) at high penetration rates (say > ~ 20%)? Important? Not? Thanks.