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The future of solar power

  1. May 19, 2017 #81
    Yes, yes, yes, I understand how the numbers 'work'. But you are looking at the micro-level, and I'm looking at the macro-level. At the macro level, physics and economics and common sense say residential rooftop solar makes no sense, compared to large industrial scale installations. At the micro-level, Congress (with few if any physicists or engineers) has warped the market.

    Please read the excellent post above from mfb. I'd summarize that by saying - the utility is currently paying residential solar generators retail cost for something they normally buy at wholesale, and everyone else on the grid is going to pay extra for that. That is not reasonable and it is not sustainable.

    Anyone who really wants to promote solar for environmental reasons (or any other reasons I guess) should be against residential installations and in favor of large scale installations. If someone just wants what they can get from the government and their fellow taxpayers, well, I think that's outside the realm of a physics forum.
  2. May 20, 2017 #82
    a lot of panels, inverter(s), step up xfmer. as the efficiency of panels get better the number of panels needed will go down. i dont know what the quantum limit is, thats the real stickler.
  3. May 20, 2017 #83
    Residential solar is less economically efficient - well known "economies of scale" reasons apply here. The cost of installation, for example. The same worker can install maybe 20-50 times more panels in the same time span when he is installing them at the solar farm, not on a smallish roof.

    This will be somewhat alleviated when integrated solar roofing becomes mainstream. If you need to build a roof anyway, then ordering a solar roof only costs more than ordinary roof, but the same workers do about the same amount of work and it takes about the same amount of time.
  4. May 20, 2017 #84
    Getting back to your earlier post, here are my thoughts... Using the large roof of schools, big-box stores, etc does not require any additional transmission lines, storage facilities (no more than residential), or significant power disruption either. Here's some numbers:

    I mentioned the large school install near us. 440 KW, 1760 panels. So lets put that in perspective. When converted to 120 V, that would be 3667 Amps. A typical NA home has 200 Amp capacity wiring, so we could think about one of these buildings as needing the same wiring capacity as about 18 homes (or 9 homes if that is 200 Amps capacity per each branch of two phases, I'm not sure on that). Off hand, I would think any big building would have that much wiring capacity (large A/C systems). Since the panels offset usage first, we never exceed the panel power amperage, it is always subtractive. We would have full panel amperage on the wiring only if the building was shut down to zero. As long as the panel peak power does not exceed the wiring capacity of the building, no upgrades to any of the distribution system is required. In fact, the panels reduce loading on the distribution system, on average.

    You might be picturing solar farms that are the size of present thermal power plants, ~ 1 GW. But there is no need for that. We don't need to have solar distant from homes, as there is no smoke or other need for separation. Better to distribute 2000 large roofs of 1/2 MW each distributed throughout the area consuming it.

    There is talk of large solar farms in the desert, and those would need large transmission lines. I haven't seen the numbers, but offhand, I wouldn't think that added % of sunshine would offset the cost of transmission lines, when smaller, distributed local installations would need little/no infrastructure changes.
  5. May 20, 2017 #85
    This whole thread has pointed out the higher cost of solar to traditional. http://energyrates.ca/ontario/green-energy-ontario/

    Another point is personally owning the electricity / installation. A very attractive feature that makes economic sense...sometimes (smelting, pulp) making your own coal / hydro plant makes economic sense. "Soon" it will "make sense" even for jane doe consumer.

    Who on earth thinks that paying to get electricity from here to there, a profit margin, supporting billions in infrastructure, at the mercy of market pricing is better economically than simply owning your own power generation equipment and having it on your own property?
    Last edited: May 20, 2017
  6. May 20, 2017 #86
    This would vary greatly from jurisdiction, Some places the homeowner could install and hook up the panels, others may require the permission of neighbors to even have them in the first place. Some may ban (Texas?) their use all together.
  7. May 20, 2017 #87
    I suspect large installations are significantly cheaper per kW. When you plan and install 1 km^2 of PV, there are significant economies of scale.
  8. May 20, 2017 #88

    This has to do with homeowners associations (in Texas) who you agree to abide by their rules which can vary anywhere from forcing you to garage your car every night to regulating your landscape and color of your house. We lived in one that required approval of the architecture of the house before building it. The advantage I guess is that you have the same taste as your neighbor.

    And as far as the unsightliness? is concerned Tesla is manufacturing roof tiles with the solar electric capabilities.
  9. May 20, 2017 #89
    With Texas I was leaning on their ban of Tesla dealerships...not sure of any details. For all I know Texas is big on solar for electricity (fine with there being a solar industry there.
  10. May 20, 2017 #90


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  11. May 20, 2017 #91


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    You have not made the case from running entirely off "your own power equipment", but rather for using your own installation part time, and then when it doesnt work, and often it won't, receiving the benefit of a trillion dollars worth of reliable electric grid almost for free.
  12. May 20, 2017 #92


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    Many things begin with a single step, like getting lost the forest.
  13. May 20, 2017 #93
    Hello - from your fellow Earthling!

    We have so many examples where it is worthwhile to purchase the end product rather than DIY. Electricity is a fantastic example of that.

    Even with the present situation where you get to use the grid for zero, or near zero cost, solar PV has a pretty long payback (and subsidies don't really count, that is still a cost, it is just someone else paying for it). With all the uncertainties, I'd rather get what I need at ~ $0.11/kWh.

    As @mheslep pointed out, it isn't as 'simple' as you say ("simply owning your own power generation equipment and having it on your own property"). You are still very reliant on that big, old, bad, profit seeking utility and their billions of infrastructure. If you really want to disconnect from the electrical grid, be my guest. But please let me know how much it will cost for batteries and inverters to store enough kWh to get you through a cloudy, snowy Canadian winter, or how people would do it with large A/C needs?

    The economy of solar PV you see is because we have a grid available for you to use at night, in bad weather, and to pull from anytime your instantaneous power demand exceeds your system capacity. The grid is your storage system, and you are getting it almost for free. You deride it, but I bet you won't give it up!
  14. May 20, 2017 #94
    lol the grid is free,

    Who's still reliant on "still very reliant on that big, old, bad, profit seeking utility"? What's more in my province ultimately the populace owns the infrastructure, well apparently just a controlling share at this point...they sold 60% to those big bad stakeholders. teeheee hee the infrustrure was failing apart, repair greatly increasing the cost...of electricity, hmmm...
  15. May 20, 2017 #95

    You didn't answer the question. What would it cost you to disconnect from the grid?
  16. May 20, 2017 #96
    It sound like people with solar panels should feel guilty for not paying their fair share of the transmission cost. How is that different from a person who has a second home which is used for 4-5 months and turns off the power when not in use. In the US 15 million residences are occupied part time.

    I don't get it. One user putting power on the grid is the same as one user reducing his pull from the grid by the same amount. The fluctuations of demand from the grid from solar at least currently is small the great fluctuations occur in the morning as household and commerce awake and at night when they wind down.

    Except as new solar installations come on line the solar effect on fluctuations should be predicable but new solar usually comes on line in very small negligible capacities. As new solar comes on line so do new houses without solar which increase the demand on the grid which must be accommodated. I can't see where solar is particularly bad for the power companies.
  17. May 20, 2017 #97
    That's a good question, I'll try and measure-calculate it. It'll take me some research and stuff but will do it as I'm interested to know myself.

    I have played with measurements from a single solar panel, I can't remember exactly but think it farmed maybe 0.10$ over a day (not straight /kwh cost, our billing includes fixed recurring costs). So maybe 30 panels , lets add a 1/3 for bad weather, so 40 panels for 90$ (assumed cost of current elec use - $3*30days) of electricity. $5000 just for the panels (40*$100+$tuff).

    then there's the batts...

    super rough guess is $10k per person per 15yrs. looking for to getting it from a measurement perspective.

    1kwh for 0.08 - 0.16$ is SO CHEAP, it'll be bad lol
    Last edited: May 20, 2017
  18. May 20, 2017 #98
    No, it is very different.

    Take the simple case where a solar home nets to zero, they have a very low bill (connection fees vary), but they used the grid for most of the day. If they are able to net to zero, they had an excess around noon (so used the grid to absorb the excess), and then they used the grid to pull what they need for ~ 18 hours/day. Yet they pay almost nothing. Their solar system would not function w/o the grid, they ought to pay for it's use, the same as anyone.

    If I reduce my consumption through efficiency, I'm using the grid less, and it's reasonable for me to pay a lower share of its support.
  19. May 20, 2017 #99


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    I don't say people should feel guilty, but keeping it in mind is certainly not a bad idea.
    As long as it replaces coal or oil, I think it is a great thing, and I happily pay for it.
    That house won't suddenly need power if it is cloudy, and the owners use electricity and pay elsewhere for the grid infrastructure.
    The daily cycles are highly predictable, and changes occur over a timescale of about an hour. The overall fluctuations from solar power can be faster and they are less predictable. They are small today, sure, but the fraction of solar power is small as well.
  20. May 21, 2017 #100


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    You added a 1/3 (10 panels ) for bad weather on your initial 30 panels... did that estimate include bad weather for the 10 added panels ?
    Last edited: May 21, 2017
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