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But what is the conversion efficiency of the new solar panels they're describing? I.e., if 100 watts of light hits it, how many watts of electricity comes out?

But what is the conversion efficiency of the new solar panels they're describing? I.e., if 100 watts of light hits it, how many watts of electricity comes out? I guess, though, if you can manufacture it cheaply enough to spam it over every man-made surface in a city, you could overcome some inefficiency... But the article still left me confused as to whether the described technology is more efficient, less, or the same, as what we have now.

Alex3917 19y ago
The absolute efficiency isn't very important. To quote Earth: The Sequel again, "At just 10% efficiency-- that is, if only 10 percent of that solar energy were converted to electricity-- no more than a square of land 100 miles on a side would be needed to produce enough electricity to power the entire United States." (The thin-film CIGS type tech described in this article is typically a little less than 10% efficient, so pretty good.) The key statistic is being able to calculate when solar is cost competitive with coal, because once you hit that point it will start showing up everywhere. Of course this depends on where you live, because different regions of the country A) receive differing amounts of sunlight B) pay differing rates for the amount of electricity generated. If you're talking about an area like LA where there is a lot of sunlight and electricity costs a lot, solar is already probably cheaper than coal. In Fairbanks, AK on the other hand it will take a bit longer. Another key to getting solar to be cheaper than coal is implementing real-time pricing. To quote again, "Though solar power is generally judged on the basis of whether it can beat the retail price of coal-generated electricity, the comparison is in some ways misleading. The true value of solar power lies in the fact that it is most productive when the weather is sunny and hot-- precisely when consumer demand forces a utility to operate at full throttle. According to PG&E, peak demand is growing 25 percent faster than overall electricity needs, but the last quarter of capacity is needed less than ten percent of the time. 'Peak shaving' with electricity produced by rooftop solar panels relieves that pressure on utilities, damping the prime driver to build new gas-fired plants. It also reduces costs. Utilities "turn on" power plants in order of their variable cost, often called "dispatch cost," starting with the least expensive plant to operate and moving to the most expensive as demand rises. Solar installations produce electricity at virtually no extra cost at just the same time when units with very high variable costs are called upon to run. By displacing these high-variable-cost units, solar units can provide tremendous savings for the utility and the consumer-- and the atmosphere." "To date, however, most owners of solar photovoltaic systems owners do not get the discount they deserve on their electric bills. Typically, utilities charge customers using a weighted average of the cost of generating electricity over the course of a day. Some jurisdictions are now experimenting with a different rate structure-- 'real time pricing'-- charging customers hour by hour for the true cost of the electricity they use, and thus allowing them to reap the full value of avoiding the cost of peak power on the grid." "Given all that, almost everyone in the industry agrees that when the price per peak watt falls to $1 and the storage problem is solved, solar-generated electricity will compete with coal-fired electricity virtually everywhere." (p. 19)
- anamax 19y ago
  Efficiency is important - it's what lets you put the panels some place other than a giant solar farm in the middle of no where. Consider house-top installations. If each only produces 100 watts, the cost of the inverter and utility hookup will make it untenable even if the panels are free. (Inverter cost/watt goes down pretty fast with capacity and most of the hookup cost is independent of the capacity.) There's also a huge psychological boost in being able to be energy neutral.
  - maximilian 19y ago
    Of course efficiency is important. 10% is horrible by today's standards. They are up to 20%, which would save you half of the panels cutting your costs in half. The cost (or revenue) of an installation is directly connected to the efficiency of your solar-technology. If you only have a fixed space to build it in, and your panels are twice as efficient, you make twice as much power and twice as much energy.
    - Alex3917 19y ago
      Price isn't proportional to efficiency. Making a solar panel that's 10% efficient instead of 20% efficient might require only 1/20th as much silicon. Also, the current limiting factor is the cost of manufacturing, not the cost of land. That's why companies are racing to build a new generation of low-efficiency low-cost photovoltaics.
      - anamax 19y ago
        When did doubling the size of my roof become cheaper than a solar system? Silicon isn't the only cost. As I wrote, inefficient technology makes small systems uneconomic. FWIW, the systems with the highest efficiency right now actually have less silicon than typical rooftop systems. Note also that there is no one "cost of silicon" - silicon prices vary widely. Many of the low-silicon cost/efficiency systems actually use more silicon than some of the high-cost/high-efficiency systems.

Alex3917 19y ago

The absolute efficiency isn't very important. To quote Earth: The Sequel again, "At just 10% efficiency-- that is, if only 10 percent of that solar energy were converted to electricity-- no more than a square of land 100 miles on a side would be needed to produce enough electricity to power the entire United States." (The thin-film CIGS type tech described in this article is typically a little less than 10% efficient, so pretty good.) The key statistic is being able to calculate when solar is cost competitive with coal, because once you hit that point it will start showing up everywhere. Of course this depends on where you live, because different regions of the country A) receive differing amounts of sunlight B) pay differing rates for the amount of electricity generated. If you're talking about an area like LA where there is a lot of sunlight and electricity costs a lot, solar is already probably cheaper than coal. In Fairbanks, AK on the other hand it will take a bit longer. Another key to getting solar to be cheaper than coal is implementing real-time pricing. To quote again, "Though solar power is generally judged on the basis of whether it can beat the retail price of coal-generated electricity, the comparison is in some ways misleading. The true value of solar power lies in the fact that it is most productive when the weather is sunny and hot-- precisely when consumer demand forces a utility to operate at full throttle. According to PG&E, peak demand is growing 25 percent faster than overall electricity needs, but the last quarter of capacity is needed less than ten percent of the time. 'Peak shaving' with electricity produced by rooftop solar panels relieves that pressure on utilities, damping the prime driver to build new gas-fired plants. It also reduces costs. Utilities "turn on" power plants in order of their variable cost, often called "dispatch cost," starting with the least expensive plant to operate and moving to the most expensive as demand rises. Solar installations produce electricity at virtually no extra cost at just the same time when units with very high variable costs are called upon to run. By displacing these high-variable-cost units, solar units can provide tremendous savings for the utility and the consumer-- and the atmosphere." "To date, however, most owners of solar photovoltaic systems owners do not get the discount they deserve on their electric bills. Typically, utilities charge customers using a weighted average of the cost of generating electricity over the course of a day. Some jurisdictions are now experimenting with a different rate structure-- 'real time pricing'-- charging customers hour by hour for the true cost of the electricity they use, and thus allowing them to reap the full value of avoiding the cost of peak power on the grid." "Given all that, almost everyone in the industry agrees that when the price per peak watt falls to $1 and the storage problem is solved, solar-generated electricity will compete with coal-fired electricity virtually everywhere." (p. 19)

anamax 19y ago
Efficiency is important - it's what lets you put the panels some place other than a giant solar farm in the middle of no where. Consider house-top installations. If each only produces 100 watts, the cost of the inverter and utility hookup will make it untenable even if the panels are free. (Inverter cost/watt goes down pretty fast with capacity and most of the hookup cost is independent of the capacity.) There's also a huge psychological boost in being able to be energy neutral.
- maximilian 19y ago
  Of course efficiency is important. 10% is horrible by today's standards. They are up to 20%, which would save you half of the panels cutting your costs in half. The cost (or revenue) of an installation is directly connected to the efficiency of your solar-technology. If you only have a fixed space to build it in, and your panels are twice as efficient, you make twice as much power and twice as much energy.
  - Alex3917 19y ago
    Price isn't proportional to efficiency. Making a solar panel that's 10% efficient instead of 20% efficient might require only 1/20th as much silicon. Also, the current limiting factor is the cost of manufacturing, not the cost of land. That's why companies are racing to build a new generation of low-efficiency low-cost photovoltaics.
    - anamax 19y ago
      When did doubling the size of my roof become cheaper than a solar system? Silicon isn't the only cost. As I wrote, inefficient technology makes small systems uneconomic. FWIW, the systems with the highest efficiency right now actually have less silicon than typical rooftop systems. Note also that there is no one "cost of silicon" - silicon prices vary widely. Many of the low-silicon cost/efficiency systems actually use more silicon than some of the high-cost/high-efficiency systems.