In California, this is true. It is also the reason that your electric rates are 3-4 times mine.

ICE evolution isn't at the steep part of the curve anymore, but everything about them has come a LONG way since the 1930's. Metallurgy, environmental impacts of production, smoothness, longevity, peak power AND overall power (over entire operating range). Computers have given the biggest push, both in physical engineering (FE, fluid, computational, etc.) and running the systems. There are still a few big ones left, and you'll see a couple in the coming decade.

Transmissions have also come a long way. And again, computers are mostly to thank. But 6 speeds are becoming the norm, and 8 speeds will be normal pretty soon. CVTs have come a long way. Computer shifted manuals are coming along.

Just look at the peak power outputs of the early 1980's for any given displacement, then measure today. Double the power.

Yet better fuel economy (many thanks to things you mentioned as well) despite increasing weight and greater rolling resistance from ever wider tires (as tastes change).

Not really. 44 states have buyback programs, including Texas (some utilities, not all). California average is $0.14/kwh, Texas is 0.10.

California is infested with idiots that refuse to acknowledge that California is one of the largest industrial economies on the planet and won't let us build any more power plants unless they are crappy and hugely overpriced "green" powerplants, which they won't build either because no one wants it in their back yard.

Listen, with the cost of real estate here in California, the power plant you build in my little backyard wouldn't be enough to power even my neighborhood block.

Interesting. Here are some scenarios:

Scenario #1

Take the system cost James gave above (the one with total cost $14.2K with $1.50/watt panels and generates mid-point 24kwh/day.). The net present value (cost) of that system is simply -$14.3K since all of the cost is incurred in year 1. Assume the system lasts for 20 years.

Then take current grid rate for electricity of, say, $0.11/kwh (picked because happens to be my grid rate). Suppose you pay grid rate for 24kwh/day for 20 years, assuming grid rate rises 5%/yr and discount rate (time value of money) of 3%/yr. The net present value (cost) is -$24.7K.

To recap this scenario: NPV of PV system = -$14.2K. NPV of paying grid = -$24.7K. Payback in 12 years. Then PV system saves you $10.5K (today's dollars) over next 8 years.

Lesson: at $0.11/kwh, the PV system makes financial sense under a discounted cash flow analysis.

Now try out some different scenarios.

Scenario #2 - you're in California
- Change the current grid rate to $0.30. NPV of PV system = -$14.2K. NPV of paying grid = -$67.3K. Payback in 5 years. Then PV system saves you $53.1K (today's dollars) over next 15 years.
- Lesson: the PV system is financially almost a no-brainer in California, under that feed-in tariff. Well, do have to adjust for higher installation cost.

Scenario #3 - panel cost falls more
- Change the panel cost to $1.00/watt, leave other system costs the same. NPV of PV system = -$12.2K. NPV of paying grid = -$24.7K. Payback in 11 years. Then PV system saves you $12.5K (today's dollars) over next 9 years.
- Lesson: a 33% decline in panel prices, alone, is helpful but doesn't radically change the financial analysis.

Scenario #4 - interest rates go up
- Increase discount rate to 5%. NPV of PV system = -$14.3K. NPV of paying grid = -$20.2K. Payback in 14 years. Then PV system saves you $6.0K (today's dollars) over next 6 years.
- Lesson: if interest rates go up, the PV system becomes less financially attractive (as does any long-duration investment).

These scenarios ignore any tax incentives, etc.

Much increase in power output has come from VVT and four valves per cylinder, which was covered in the 1930's text book. These are also more expensive than just making a bigger engine.

But power output isn't fuel efficiency. And yes, out taste is not like the late 1970's/early 1980's, cheap, efficent, light econoboxes (my Datsun B210!).

As has ben pointed out, Solar cells have been around a long time. They have been improved and made cheaper. But they are still not cheap enough.

If TOU metering becomes the norm, PV will come on line faster. PV puts out full power right when it is needed. And with TOU, people will shift everything they can to nighttime (dishwashers, clothes washers, etc).

Again, the problem isn't just the PV panels. The grid-tied inverters are not cheap enough.

John,

Thanks for the financial analysis. It is getting closer. The problem is, I pay 8 cents per kWh.

Let's not conflate things used in race cars from Alfa, or 1930's text books with common everyday use in a sufficient part of the nat'l vehicle fleet to make a big difference in economy or emissions.

Did anyone mention direct injection yet?


How is Housetown's power generated?

Yes, the Boeing 777 isn't all that special. I saw a drawing of Leonardo daVinci's from the 1480's of a similar flying contraption. Well, except for execution. But the mechanical concept was the same. Not much progress for 500 years.

The only place that would make sense for PV for me is on top of one of the hills behind my house (I'm at the end of a box canyon, at the bottom. I'd have about a 300 foot electrical run or more to my electrical panel. My biggest electrical expense is A/C, I think I''d get better return reinsulating my walls and attic first.

You can't build green ones either. The solar projects in the desert are all on hold. I know, I'm consulting on one.

Of course, it's all about the 787 now. :p

If you're going to derail the thread, at least use a comparable object, like the Concorde...

What is a realistic lifetime for a residential PV grid-tie system (w/o batteries)? 20 years? 30? What wears out?

Is there any maintenance required, or is cost literally zero after year 1? I would think you want to hose off dust and leaves now and again? My roof is three stories up and I'm not sure how I'd do that - have images of having to build a hatch in the center of the roof and plumb water to a rooftop hosebib - sounds weird.

Is is correct that, w/ current module design, a shadow on one part of the module (say, a leaf), reduces the output from the whole module?

How can one estimate how much sun a given location gets per year? I assume latitude, climate, panel direction/angle all factor into it. Assume no shadows from trees/other buildings. Is there a online calculator where I can plug in a location and get a reasonably decent estimate?

It looks like James, your scenario equates to 6 hours/day of full sun - but that's got to be specific to TX and similar South/SouthWest locations?

Solar output depends on where you are and your clearness ratio. In Houston, we can expect 5 times the nameplate rating in watt-hours, averaged over the year. In So Cal, the number is closer to 7. You only get "full power" when the panel is exactly lined up with the sun. But the sun shines for an average of 12 hours a day.

If you put the panels on a tracking system, you can increase the watt-hour ratio by quite a bit, but that is usually offset by the cost of the tracker. They look cool, though!

Maintenance: Yeap, you need to clean the panels periodically for maximum output.

Life: 30+ years. Most of the panels will degrade over time and they are generally guarenteed to produce 80% of the nameplate after 30 years.

Failed panel: It depends on how the system is wired. If the panels are in parallel, then you only lose the power from that panel. For larger arrays, the panels are in "Strings". The entire string is affected by a bad panel. The design of the system depends on the characteristics of the inverter.

The SMA Sunnyboy is designed to work best with your peak voltage from the panels at 480 volts. If the panels nominal best output is 30 volts, then strings would be best to be 16 panel units. The voltage range of the Sunnyboy is 250 to 480 volts. It will adjust the operating voltage on the panels until it gets the most power. With lower light levels, this is important. It is called MPPT (Maximum Power Point Tracking). If you use 10 panels, then the inverter will only work when the combined panel votlage is above 250, but they max out at 300!

Again, I might choose either a different inverter or play with which panels we pick.

If you go with microinverters, each panel has its own inverter and MMPT system. A dead panel only removes that panel. The panels are tied together on the A/C side instead fo the D/C side. And the better microinverters have IP over AC and will connect to a monitoring unit and you can see the power producition and the condition of each panel.

Are dead panels typically easy to identify? I've seen a life of 30 years mentioned a lot, but on a normal house with no severe weather taking the things out how many would normally expire per year (and is that something a warranty would cover)?

John - your utility can point you to insolation per month - you need to get your own particular site analyzed for trees, etc. - several places do that here for free (in the hopes you will get them to do the install) & there must be many such places in PDX

It can be done DIY fashion, but requires some equipment and labor.


also - within 30 years you may well want to upgrade to a future panel, tho the rest of the installation could remain

On the subject of heat loss:
Last year, we had about 8-9 inches of open-cell spray foam(~R7/in) put on top of the ceiling drywall in the attic which wrapped the joists. They also pulled the carpet, drilled small holes, did the second floor rim joist, as well as wrapping the underside of the cantilever.

In the basement, the rim joist was also sprayed and then painted with a fire-retardent paint(manditory because that stuff will burn easily). The previous owner had already put 3 inches of foam panels on the outside of the foundation. I have heard 25-30% of heat loss is through the sill plate/rim joist.

Some areas were first sprayed with an inch or so with blue DOW closed-cell, the stuff they use in airplanes and other structural/commercial applications, but that was an expensive mistake: too much money and the fumes made me sick as a dog.
There is also a cementous-based spray foam available on the market with about the same R-value and price which is supposed to be insect and flame retardant.

Air exchange with tightly sealed homes is a must. We replaced the ozone-emitting electronic air filter with a paper element with a UV-Aire to kill the microbacteria. On recommendation from the foam company, I bought a $400 Panasonic "WhisperComfort Spot ERV" which draws 17-23W with a 70% heat and moisture exchange for the wintertime. My girlfriend still opens the windows.:rolleyes:

Slow-rise spray foam can still be installled in existing homes with batt or no insulation by simply drilling small holes between the studs, then filling the cavity from within.

Pretty easy. You would check the Open Circuit voltage and the Short Circuit current with a volt meter and that will tell you for sure.

You'll notice power production is down and you will test the individual strings for voltage. Then you will test each panel in the string.

Most of the panels have a 20 year warranty. I wouldn't expect any to quit. They are pretty reliable. I expect they will suffer the most from lightning strikes, so most system incorporate a lighting arrestor.