An acquaintance wrote,

      sometimes "dollars/savings" aren't the only consideration regarding the ultimate "well-being" of an investment or asset purchase...I really get a good feeling in my stomach when I pull into my garage and see the solar cells on my roof top...
      I paid $39,000 for the system in 2005...I've generated approximately 66,000 KWH...therefore I believe I've saved approximately  $19,800 (66,000 x $.3/KWH)..which isn't even half way to breakeven...but the "good feeling" I get makes up for the crappy return...(by the way I'm adding another bank of solar panels to get me to around 5,000 net KWH usage for the year.

 In Palo Alto, the retail rate is $0.09524 for the first 300kWh/month, 0.13020 for the next 300, and then 0.17399 for the rest.  I personally run 350-500 kWh/month so my marginal rate is $0.13020/kWh.  Palo Alto pays $0.05841/kWh for "surplus" electricity.

If your system has generated 66,000 kWh since 2005 then (let's be generous and call that 7 years) that means that back in 2005 you laid out $39,000 for for a stream of 9429 kWh/year for approximately 25 years.

In Palo Alto, the actual cash savings (assuming, incorrectly, all the kWh offset my higher marginal rate) would be 0.1302*9429 = $1228/year.  This might be my out-of-pocket savings, but in a larger sense it's not the right rate to use to analyze this, since I still have to pay my fair share of the fixed cost of electrical infrastructure. Thus the buyback rate of $0.05841 ($551/year) is the correct rate to use for economic analysis. But at that rate, the project is a total loser: $551/year for 25 years is only $13,769 for an undiscounted loss of $8,309.

Even at $0.13020, the project doesn't pay: 25 years of $1227.66/year savings is only $30,691 - again, an undiscounted loss of  $8,309 or $332/year.

Straight-line depreciation over 25 years means an annual expense of $1,560 worth $624/year at a 40% total tax rate for a net twenty-five year annual after-tax undiscounted loss of $1008.

But the discount rate is important for this project, where the total outlay is at the start of the project and the returns come in equal annual installments.  At a 2% discount rate, the loss is $9,331.  At a 5% rate (which would reflect some of the risk of maintenance issues and lower future electricity prices), the loss is $17,582.

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You are correct I probably haven’t recouped these costs, yet.  But without taking the leap in a new technology that is absolutely the future for our species, then we can not make the mistakes / improvements / refinements and efficiencies that will/should happen. Some of these improvements are unimaginable today. 

It's silly to say that any particular new technology "is absolutely the future for our species" - that's the kind of thinking that led to dire predictions of firewood shortages back in the nineteenth century.  We have no idea of what technologies will be available in even fifty years.  But what is clear is that government is distorting our allocation of capital from the most promising technologies to the most politically favored. Toyota and Solyndra and venture capitalist Vinod Khosla are beneficiaries of huge and stupendously wasteful government subsidies, while capital and attention are diverted from other possibilities.

It's well-established that residential solar panels in temperate suburbs are a waste of resources.  We should invest in something better.

Unless one believes there is absolutely unlimited carbon/fossil fuel. 

Of course it isn't "absolutely unlimited."  Sunshine isn't "unlimited" either. But there is plenty of oil and coal and natural gas for humankind - and as it gets more expensive to extract, refine, and transport, Adam Smith's "invisible hand" will ensure we have good substitutes.  For political reasons, our oil supply is subject to price discontinuities - but our financial markets, the diversity of our energy sources, and the lessons learned from previous oil shocks already shield us from the worst effects of that (except when government screws things up or blames "speculators" for doing their job in sending pricing signals).

Anyway, your Prius is a gasoline-powered car.  A fully-charged Prius battery has the energy equivalent of less than one ounce of gasoline!

I just figure I can be one of many who helps in this process by being a pioneer and assisting through the “mistake process” ... and it will be a long one.

How does buying a Prius or putting up rooftop solar at 38N "assist"?  You're reinforcing technologies that are proven to be uneconomic and encouraging the misallocation of capital.  Better to read lots of business plans and bet your cash on a new venture, or just invest in an energy fund.  Or, better still, buy up oil and gas partnership shares.  We don't need marginal improvements in failed technologies - we need whole new ways of doing things.

More miles/charge requires larger batteries and lighter cars, a dangerous combination.

... I don’t agree with your assumption/presumption that there will be larger batteries.  Look at the first computers... vacuum tubes?!! 

We're talking about storing energy in a mechanical and chemical device, and energy stored per unit mass has been increasing very very slowly.  In fact, alkaline batteries are still the leader in watt-hours/liter, and they've been around since 1899, and in their modern form since 1957.  See e.g. http://www.allaboutbatteries.com/Battery-Energy.html and http://en.wikipedia.org/wiki/Alkaline_battery

Don’t agree.. electric plants could operate more efficiently if we used electricity at midnight to 6 am ... utility companies [could] "draw" on energy from the cars if needed to cool heat buildings… should require less power plants.

Power plants wouldn't work more efficiently in this scenario - just longer.  Again, the main problem for electric power plants is peak capacity.  If you discharge your car's battery at the end of the day, how do you get home?  You'd need a quick recharge at precisely the time of highest demand.  This isn't close to making economic sense.  The best value for energy storage now is pumping water to a higher elevation at night to drive turbines during the day - that's orders of magnitude cheaper than batteries.

Being “green” in my opinion, means being conscious of your use of resources and thinking about how you might make small changes in your life that could be meaningful if everyone made similar changes.  These changes typically don’t change one’s quality of life….like taking “navy showers” …

None of these things matter a whit.  The only big eco-decision we make is whether to have children.  But the really big eco-question is whether we rich Westerners demand that the rest of the world -- Indians and Chinese and Africans and Latin Americans -- live in horrific CO2-bounded poverty, or whether we allow them to enjoy wealth like ours - which may be measured with great precision in the freedom of flexible, individual transportation, and in abundant electricity to power communications and computing systems and labor-saving appliances.

driving a car that is more energy efficient.

See Jevons Paradox http://en.wikipedia.org/wiki/Jevons_paradox :  increased efficiency in the use of a resource inevitably leads to increased use of that resource!

I find my Prius much much less expensive when it comes to repairs and maintenance than my previous car; a BMW.

That has much more to do with the different business strategies of Toyota and BMW than the underlying car technologies.

... By now I would have thought if batteries were performing at a level “less than anticipated” there would be news…

The charging control circuit will probably light up only when the car's batteries get to 5% of initial capacity... A hybrid's battery is not like a laptop's battery where the clock shows how much charge it holds.  Most of the time you use only a little bit of the car's battery power.  You probably won't get any indication of failure until it's completely dead.

The underlying premise of this discussion is that oil is a disappearing resource and heroic individual measures are necessary to conserve it.  That is just not so.  In spite of a century of dire predictions about the imminent end of our oil supply - and in spite of cartels and government blundering - with the brief exception of a few months under Jimmy Carter's stupidity we've managed to deliver ample supplies at reasonable market-clearing prices.  Sure, prices will fluctuate, sometimes abruptly and unpredictably, but I have no doubt that gasoline as a transportation fuel will be the best value for centuries to come.

The paradox of having Americans reduce their standard of living to "conserve" fuel is that it tends to depress the world price of oil.  This means that other consumers (Chinese, Indians) will buy it and indeed use more oil and for lower economic purposes than ours.  If oil is the best solution for you, bid the price that maximizes your utility and enjoy it.  You're maximizing your profit and doing the right thing.

The biggest transportation problem in our area is congestion, and I think that could be solved quickly by removing the government monopoly on public transportation and also by removing the government limits on taxicabs and buses and limousines.  Uber, Zimride, Lyft, and others are pioneering a dynamically-routed and priced system which takes you from where you are to where you want to go, when you want to travel - and struggling with a government that seems determined to stop them.  They offer you a menu of pricing options for a luxury solo direct ride, or a shared car or jitney or bus with varying numbers of stops.  In my opinion, anyone with $5 million liability coverage should be allowed to offer rides - let insurance companies police the providers.  In under a year, services like this could solve our congestion problems - and make the air cleaner and make life better for all of us.  But government, protecting public employee unions and the taxicab cartel, will again and always do what it can to impoverish everyone for the benefit of a few favored cronies.