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Technology / Re: Are solar panels worthwhile?
« on: 25/04/2022 21:29:54 »
Conspiracy theories can be fun
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No.Solar panels aren't scrapped after 25 years, they have about 0.5% loss of output per year, so they're still outputting nearly 90% of their original output after that. That's just the suggested lifespan, but they're clearly going to go a lot longer.Whilst this is somewhat true of current panels, many older panels are significantly worse, plus there is the lifespan of associated equipment/faults/ servicing.
https://news.energysage.com/how-long-do-solar-panels-last/#:~:text=The%20industry%20standard%20for%20a,below%20what%20the%20manufacturer%20projected.
But given this degradation that is reported widely at 1% a year and the lack of cloudy sky generation, I have to think this is being rushed into. When cloudy sky generation is improved most solar in the uk will be replaced.
Problem with solar is that all the sources go off line at the same time, and windmills may not work at all for several days at a time - the primary sources are not independent.But you know it's doing that before it happens, because of something called a 'weather forecast'.
This wouldn't be a problem if renewable generators were backed up with adequate storage, but that would not be profitable, so grid integrity relies on fossil fuels to maintain the profitability of renewables.Thing is, backup generators are relatively cheap, and the grid already has them anyway. It costs fuel, but hydrogen and perhaps other things like ammonia is looking promising for that.
The retail cost of electricity is the renewables subsidy. The retailer gets a profitable 27p per unit whether the wind is blowing or not, so there is no incentive for the wholesaler to build the storage system needed for a fully renewable supply.If the retailer is getting 27p/kWh then it's still in their interest to get the electricity for the lowest possible average cost. Note that wind power is usually sold on Contract For Difference, which is essentially a fixed price of 7p/kWh or whatever.
coe
hi again. other people on different fora have been debating the question. member "uatu" on the german allmystery.de forum has provided what I consider the definitive solution with a graph illustrating the key parameters. my primitive derivation indicated an initial parabolic rise in ke, followed by an asymptote at around 3/4 fuel consumption. the rigorous expression provided by "uatu" does the same followed by a sharp downturn. this derivation seems to be rock-solid, in my limited mathematical abilities. bottom line: the coe is safe and emmy noether can rest peacefully.FWIW this is somewhat subtle stuff. There was actually some disagreement about the relationships between rockets and energy but it was laid to rest by Hermann Oberth.
The retail cost of electricity has very little to do with physics and a great deal to do with profits, taxes and subsidies.There are not really any solar subsidies anymore in the UK. They pay you what is basically cost (or more accurately, they pay the electricity supplier, most of them just pocket this, but Bulb gives you the money.)
Having lived through many, I understand a good deal about UK summers. Yes, the sun is above the horizon for over 16 hours in June, but the solar angle never exceeds 62 degrees in London, 59 in Inverness, which is why it is generally colder in Scotland than in England and the north pole (24 hour sunlight) stays frozen.Gee, if only someone could work out a magic way to deal with that issue, such as tilting the panels at ~30 degrees. But apparently you can't think of any way. Must be impossible.
And we do have a lot of cloud over these Atlantic islands.Yeah, except not so much in summer. Solar is quite predictable in summer, and isn't permanently hidden by clouds in the UK.
The value of mains electricity and gas is 24/7/365 availability at any level from zero to the supply rating. Until the cost of renewables includes that of maintaining an adequate overnight and strategic (say 10 day) reserve, you are not comparing apples with apples.Wrong. Dispatchable electricity is certainly useful to have, but you want to use it as little as possible because: it's always £££ and high CO2 emissions. But a lot of our electricity is predictable and highly correlated with the daytime.
Note that solar panels work better in the UK than Australia during their respective summers, because the UK is such a long way north. We get over 14 hours of sunshine.Not according to the folk who sell solar power systems - see the attached chart of annual equivalent sun hours. The polar regions get 24 hours of sunshine in the summer but remain covered with ice! And of course demand is maximised in winter, not summer.
The more I learn about renewable sources of electricity, the more I am convinced that their commercial success so far depends almost entirely on the flexibility of fossil fuels. If it wasn't possible to fire up a gas-powered generator quicker than coal, wind and solar would never have featured in the energy market.
No, but wind does..
The fact that the panels are only producing about 10% of the time doesn't matter, because they DO produce during the day, when people are using more energy
And they do produce during the winter when people need energy by far the most.?
Hi.Blue line is the instantaneous energy efficiency (force times vehicle speed/half the exhaust velocity squared) of the rocket engine expressed as a percentage of the internal engine efficiency at turning available chemical heat energy into fast moving exhaust.
Nice diagram @wolfekeeper . Out of interest, what was the blue line?