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In Germany all panels have warranties starting at 30 years. Regardless of manufacturer.
Your degrading numbers are way way off.

After 25 - 30 years basically all known solar panel (PV) technologies are at a capacity around or above 80% : http://energyinformative.org/l...

There was a study recently from an dismantled small solar plant in either Sweden or Norway, don't remember. While a few cells failed mechanically, the whole installation was still above 80% capacity: after being out in the field in harsh weather for about 25 years.

Solar PV Cells degrade over time expected life 20 years

No, Solar panels have a derating over 25 years.

They continue functioning just fine, but with a reduced power output.

A typical solar installation will cost about $25 per kwH per month. at $0.10 per kwH, that is the equivalent of about 20 years repayment time assuming two things: 1st, the cost of electricity does not go up over that 20 years, and 2nd, there is no subsidy on the cost of the panels.

The panels themselves will still produce 70% of their rated power after 30 years, so at some point around the 30 years mark it becomes financially beneficial to replace old solar cells, but make no mistake, over the actual life of a home, it will be cheaper to put new panels on the roof every 30 years, than it will be to pay for electricity for those 30 years, and that is assuming no government subsidies for solar power at all.

At the rate that panels are reducing in cost, and the cost of energy is rising, the subsidies for solar will be completely unnecessary in less than 10 years, maybe even as short as 5 years.

Also, solar panels are frequently used well past 25 years. They decline in production but produce useful levels of electricity for long past their warranty periods.

http://energyinformative.org/l...

        A 33W solar panel (Arco Solar 16-2000) actually outperformed itâ(TM)s original factory specifications 30 years after it was manufactured.[2]
        World`s first modern solar panel still works after 60 years.[3]
        Kyocera has reported several solar power installations that continue to operate reliably and generate electricity even though they are nearly 30 years old.[4]

Yeah, or I can use Google.

"The total installation time for a standard 3-kilowatt solar system of about 20 solar panels is usually somewhere between 1 and 3 days. Average labor time is 75 man-hours, which can be further broken down into electrician installation labor (49 man-hours) and non-electrician installation labor (26 man-hours)." - source

You can do the next one: go ahead and find the numerous references to SolarCity getting installs done in a few hours, or YouTube timelapse videos of the whole thing being done before lunchtime.

If the solar industry themselves are saying 1 to 3 days, and yet one company is able to get it done in less than half a work day, I'd say they are far above the average when it comes to install time. Do you think that massively reducing install labor by having better mounting hardware might have some effect on installed cost per watt?

Good call. I'm in Seattle, and after five years, my panels no longer put out enough power to even charge my batteries.

Then you have defective panels or possibly defective batteries. There is nothing specific to the climate in Seattle that would cause solar panels to degrade that fast.

I've spent more in Windex and paper towels than I've gotten back in power.

You don't clean solar panels with Windex and paper towels. If you are on the roof with Windex and paper towels then you are Doing It Wrong.

Solar might work in Arizona, but it certainly doesn't around here.

Strange. Solarcity could not make a penny if solar power didn't work in Washington and yet they do business there all the same... Thanks but I'm going to trust the profit motive of Elon Musk over they unsubstantiated ravings of an Anonymous Coward.

http://energyinformative.org/l...

80% output after 25 years.

Decline is essentially linear at 10% per decade. So 70% output after 35 years.

I.e. put on 25% more panels and you are fine. Or use more efficient devices that use 30% less electricity in 35 years and you are fine.

BTW, I never see any reports on the relatively short lifespan of PV cell panels. They lose their effectiveness largely after 5 years of exposure.

According to this one, most manufacturers warrant that their panels will still produce at least 80% of their rated power after 25 years. Your statement about largely losing effectiveness in 5 years is misinformed at best.

Re batteries, The purpose of the video is to show the potential of battery storage. Anti-renewables people like to claim there is no viable solution to the variability of wind and solar, clearly that isn't true.

Re solar price, Yes there are subsidies for renewables, but those subsidies aren't even needed now, the payback for a roof solar system is about 6 years with subsidy and 12 years without. I can understand the initial reasoning for the generation subsidy but even I think that should be phased out with that information being clearly given.

To reiterate, solar will still pay for itself without subsidy, solar panels are still 80 to 87% efficient after 25 years. ( http://energyinformative.org/l... )

Tesla batteries work out to about $240 per Kwh. The implication there is that you could store a days worth of electricity for an average UK household in just $1608 (962gbp) worth of batteries. And battery technology is advancing rapidly, the cost is falling by 10-15% per year.

but the panels need to be replaced after about a decade.

You're using very old information. Current generation solar panels are guaranteed to produce 80% of original power after 25 years. The original 'modern' panel is still working 60 years later, and there are lots of evidence they last at least 30.

Though I agree on the nuclear power. I'd be building at least 300 new reactors if I could. It's just that in my original post I was saying that using solar electricity to pull CO2 out of the atmosphere is stupid, especially at those efficiencies. Note that I said 'Even in'; I didn't mean to say that it was the most efficient option.

And yes, synthetic hydrocarbons produced from nuclear power would be a welcome alternative, though I still hold hope for algae based biodiesel/fuel*.

*You can get oil and diesel out of the fats, ethanol or gasoline equivalent out of the carbohydrates.

Modded you up as everything you say is true. Here's some further facts illustrating that without tax breaks/subsidies, Solar is at most a "wash" at best for consumers:

SOLAR FACTS:
- Most Efficient Solar Panel - 44.7% efficient Fraunhofer Q-Cell (1), AVERAGE efficiency between American's top 5 retailers: 17% (Kyocera KD+SunPower+SunPower+SolarWorld+Canadian Solar), which is crap compared to corporate use panels that average 21%.
- Photovoltaic (PV) Degradation Rate - Every Solar panel loses between 0.5% and 4% of its efficiency per year (depending on a-Si, CdTe and CIGS films) further resulting in a constant decline in ones ROI (2)
- Solar pricing is a monopoly: Green Building Programs that offer incentives (http://www.dsireusa.org/) are in decline year-over-year due to reduced cost of panels. (3)

REFERENCES:
1) http://cleantechnica.com/2014/...
2) http://www.nrel.gov/docs/fy12o...
2) http://energyinformative.org/l...
3) http://www.energymanagertoday....