It didn't make sense all along. 10 years ago this would have been crazy because PV hardware was so much more expensive then.
A lot of people do fail to do the math. Many people are not quantitatively analytical, even in situations where such analysis is in their material self-interest.
A few years ago I encountered an engineer who was really angry about lightbulb minimum efficiency standards. "I already switched to LED bulbs where it made economic sense. Anyone with a brain did! Now the government is forcing me to buy these expensive bulbs for places where they run for less than 10 hours a year, like my attic. It's worse for the environment too when you consider the additional embodied energy in LED manufacturing."
His technical analysis was perfectly sound. His social analysis wasn't. A huge number of people won't do the smart thing as soon as it becomes the smart thing. (Or maybe ever. My mom stockpiled incandescent bulbs in anticipation of efficiency standard upgrades. She also complains about how high her electric bill is, after running 8 incandescent bulbs for several hours a day in the kitchen ceiling lighting...)
Much to the annoyance of people who are perfectly able and willing to do their own analysis, it can take too much effort to judge who's rationally avoiding higher up-front costs because they won't pay off in the long run and who's just being myopic. A one-size-fits-all rule forces smarties to do something worse as the price of forcing fools to do something better. There's an aggregate benefit because the fools outnumber the smarties several times over.
What I mean is, "or it would make sense to do it, but homeowners will be too stupid to do the math." My hypothetical is about people who 1) would not install panels but 2) installing panels would be in their individual interest.
I agree that PV technology has improved in price/efficiency.
>Many people are not quantitatively analytical, even in situations where such analysis is in their material self-interest.
That's a fair point. You're entirely right - some people will not think about it. Some people will think about it but be wrong.
My intuition is that people are still better at making the the decision themselves than if the decision is made legislatively. Let me explain why.
Firstly, I'm skeptical of residential solar. Why? Installation costs (on average) 59 cents/watt. [1] This would be cheaper if it were on the ground rather than on a roof. There is lots of cheap land (assuming that you don't care that it's out in the boonies.) You could put solar panels there instead. However, there is an incentive to put solar panels on a roof: net metering. The utility must buy the residential solar, even if it's useless to them. I think that this is a misaligned incentive, and it might be more efficient to have huge fields of solar panels than to have solar panels on each house.
Second, this seems like something with limited political accountability. It seems like they could have created an alternate way of complying: pay the government enough money to build an equivalent amount of solar somewhere else. Then, you can remove the exception for shaded houses/tall buildings, because they have a non-stupid way of complying. This seems like it's better for everyone involved. However, it would then be clear how much money the policy costs, rather than "homes have gotten more expensive, but it's hard to pin down how much of that is caused by the policy and how much is other factors."
Good points. I'm ambivalent about this requirement myself. From a technical perspective, I wonder what they're going to do in new subdivisions where every house is overproducing at certain times of the day/year. From a financial perspective I wonder how net metering rates are going to be pushed down when a lot more houses are participating. And I also agree that large-scale solar farms are going to be more cost-effective.
But I'm not totally against this change for a couple of reasons. One is that one of my ecologist friends is really alarmed at California's use of heretofore undeveloped desert land for solar farms when rooftop capacity is so underutilized. "Just because it's not full of trees doesn't mean it's a disposable ecosystem." Now personally I think the tradeoffs are worth it to get more solar built faster and cheaper, but it's not a universal perspective. A second related reason is that I've seen large solar farms in other regions prompt community pushback from people who dislike their appearance -- similar to, if less severe than, people objecting to visible wind farms. Those objections don't come up with distributed rooftop systems.
Right now the annual energy production per dollar of upfront cost is much lower from rooftop PV systems than from large-scale utility PV systems. If California installation costs can get down to German or Australian level, the cost effectiveness will be closer to (though still less than) large solar farms. There are reasons to believe that making rooftop systems mandatory will drive American costs down closer to German/Australian costs. For example, according to the presentation you linked, German rooftop PV installers spend $0.07/watt on customer acquisition. American installers spend $0.69/watt. If every new house is required to have PV, I expect acquisition costs to go down significantly; installers can court builders instead of trying to persuade one homeowner at a time. And investment into producing a design and a bid won't ultimately be rejected with "we decided not to add solar after all." (Though it could be rejected with "the other installer made a better offer.") Having every rooftop designed to support solar from the outset also makes installation less complicated, which should lower labor costs over retrofit-installs on 20th century housing stock.
Government also pushed the CFL (fluoret) disaster (economic and environmental mercury) on us for 10 years. There's a reason centrally planned economies tend to collapse
A lot of people do fail to do the math. Many people are not quantitatively analytical, even in situations where such analysis is in their material self-interest.
A few years ago I encountered an engineer who was really angry about lightbulb minimum efficiency standards. "I already switched to LED bulbs where it made economic sense. Anyone with a brain did! Now the government is forcing me to buy these expensive bulbs for places where they run for less than 10 hours a year, like my attic. It's worse for the environment too when you consider the additional embodied energy in LED manufacturing."
His technical analysis was perfectly sound. His social analysis wasn't. A huge number of people won't do the smart thing as soon as it becomes the smart thing. (Or maybe ever. My mom stockpiled incandescent bulbs in anticipation of efficiency standard upgrades. She also complains about how high her electric bill is, after running 8 incandescent bulbs for several hours a day in the kitchen ceiling lighting...)
Much to the annoyance of people who are perfectly able and willing to do their own analysis, it can take too much effort to judge who's rationally avoiding higher up-front costs because they won't pay off in the long run and who's just being myopic. A one-size-fits-all rule forces smarties to do something worse as the price of forcing fools to do something better. There's an aggregate benefit because the fools outnumber the smarties several times over.