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Area of PV needed per capita?

Discussion in 'Energy, Environment, and Policy' started by 9837264723849, Oct 5, 2015.

  1. 9837264723849

    9837264723849 Member

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    How many solar panels would be necessary to provide electricity for France?

    Worst day

    I tried to work out the surface of PV needed for the worst day this year so far - with a daily maximum of 2,025 GWh consumed in February (according to RTE).
    With a population of 66 million, this translates into a consumption of 30.67 kwh per capita in a day. That's over 4x the daily average, according to the World Bank (7.300 kwh in France)

    According to ADENFI, France gets 53,3 kwh/m2 of horizontal solar irradiance in a day, in February (average over 2012-14).
    I don't know how to take the panel inclination into account, so I'll translate this directly into 0,41876 kwh/m2 for an entire day, with a 22%-efficient panel (cf. Solarcity latest module).

    From there, one could say France needs at 73.24 m2 of PV to provide enough energy on the peak day.

    Is it big?

    I couldn't find the total area of roof in France.

    The average housing area was 40 m2 in 2006, according to INSEE, but I don't know how to convert that into roofing (depends on the number of floors). I also don't know the area of offices, parking, industrial and commercial spaces. That might double the total area of roof.

    Some very-ballpark estimations: 1 m2 of space for every m2 of housing and all buildings have 2 floors on average. This makes 40 m2 of roof per inhabitant. If 100% of the roof area could get a 22% efficient solar panel, we would need 33 m2 of ground-level PV per capita... or a full 13.82 kwh backup battery (but how to charge them the day before with so little solar energy?).

    How reliable and insightful is this estimation?

    Any advice to correct/improve this calculation, especially to estime

    • the impact of panel angle on the PV efficiency %
    • the total area of roof that could get solar panels
    • the energy available per capita from a backup powerwall battery.

    What does it say about a 100% "solar+panels" future? And how could house-mounted wind turbines compensate for the lack of solar power in a peak day? How to tackle the electrification of cars? Fortunately, we already have the TGV!
     
  2. Larry93428

    Larry93428 Member

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    30 kWh per person per day seems way too high.
    Solar panels are not limited to roof tops.
    ~Larry
     
  3. Drucifer

    Drucifer Active Member

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    Agree, seems way too high. In our house we consume about 40 kWh per day (including the 15 kWh +/- the Tesla uses), so the house is about 25 kWh with 3 residents. 8 kWh per capita. And this is a fairly large house with substantial HVAC and Refridgerator/Freezer, garage freezer, wine cooler, beer fridge and other fairly heavy uses.

    Our solar production is about 20 kWh per day using 25 panels @ standard approx 2 meter square size.
     
  4. 9837264723849

    9837264723849 Member

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    I chose the worst day ever: 30 kwh is for the peak day in last February, when the consumption in the whole country (including non-residential) was at its daily maximum. If a country like France switched entirely to solar + battery, it would need to satisfy the need for electricity every day - including the worst day of the year.

    It's an extreme case for this exercise, but it's interesting none the less. The benefits of solar are pretty clear (at least to me) so I'm trying to understand the limits and their consequences. My guesstimates of 75 m2 per person in winter doesn't seem impossible (and impossible n'est pas français, even when powered by the atom).
     
  5. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    I think the calculations are probably correct. Those who question the 30kWh/d most likely are considering only residential consumption, which is about 1/3 to 1/4 of a nation's total.
     
  6. Electric700

    Electric700 Member

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  7. RDoc

    RDoc S85D

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    It seems to me that the real issue with using solar and/or wind is storage to deal with long periods of very low sun and/or wind. During the winter, Paris and all of northern Europe can go for many days with very little sun.
     
  8. ohmman

    ohmman Maximum Plaid Member

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    Correct, it seems you have to find the solution for your highest load in conjunction with the longest potential duration of low generation. Only then would you have the capacity necessary to meet demand. The downside is that you'll end up with vast excesses most other times.

    This is similar to how Amazon Web Services was started, in that they need a very high server capacity in order to serve peak shoppers on a couple of days in the year. Most of the year they are massively underutilized, so they began to slice off computing time slices and sell them. In the France problem, this would have to amount to finding a market and transport mechanism for the excess most of the year.
     
  9. 9837264723849

    9837264723849 Member

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    Thank you for the AWS comparison. I couldn't find the solar irradiance on the day of peak consumption but the 53,3 kwh/m2 is the national average for the month of February (so it shouldn't be that far off). As you said, we'd need to know the day when there's the biggest gap between generation and consumption. But this should also apply not to the country in its entirety but to a small area (where a microgrid would operate independently).

    Even though I really want to know the requirements for a 100% solar + battery system, I'm not discarding the need for the grid. This thought started from @jhm idea that roof solar could become baseload power, battery could generate peak load and backup power would come from the grid.
     
  10. Robert.Boston

    Robert.Boston Model S VIN P01536

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    And then there's the issue of what to do with all the excess power on sunny days. Throwing away electricity isn't as simple as it may sound, and the absolute rule is that power generation must equal power consumption + losses (within a very small margin).
     
  11. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    If you go to the smallest and least populated of the Canary Islands, El Hierro, you will find they now are powering almost all their electricity by a wind-water combo. Any excess wind power goes to pump water uphill to a holding lake; when the winds fail the water passes through hydroplants to a downstream holding lake. It works, more or less, pretty well, and the entire system easily could be altered by having PV power substitute for wind power. This would alleviate Rob't B's concerns about excess PV power.

    5 October 2015 BBC link to El Hierro: The greenest island in the world? - BBC News
     
  12. brianman

    brianman Burrito Founder

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    Bitcoin miners and climate control for them.
     
  13. mwulff

    mwulff Member

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    Couldn't you just technically unplug a solar array? Or would that damage the panels in some way? Maybe remote controlled covers to lower production
     
  14. RDoc

    RDoc S85D

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    For some places, like California, running desalination plants might be a good use for the excess power. There are several proven technologies for water storage.
     
  15. ohmman

    ohmman Maximum Plaid Member

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    I don't believe it damages the array. When panels are installed, they are typically left offline for a period of time until they're eventually hooked up to the inverter and eventually (if a grid tied system), tied to the grid. Some places in Hawaii have had panels mounted on their roofs for up to 3 years without being on because the utility told them the grid couldn't handle their production. (That's another story).

    I think it would be easy to create a relay system that would take them offline if absolutely necessary, but I think some storage or excess use scenario is a better way to go about things.
     
  16. AntronX

    AntronX Member

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    Interesting exercise.

    According to my napkin calcs, to match cumulative electricity generated in February 2014 in France with solar panels would require 710GW of installed PV capacity costing 852 Billion Euro and would occupy 5920 square kilometers of land or a square 76 kilometers on each side. That's not including any electric storage. Here is what it looks like:

    france_solar_needed.JPG
     
  17. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Active Member

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    Hmm, transport mechanism, I think I have an idea ... :p

    - - - Updated - - -

    How about putting some in the clearance area of the TGV and nukes? :p
     
  18. AntronX

    AntronX Member

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    But then you wouldn't see them from space! :biggrin:
     
  19. 9837264723849

    9837264723849 Member

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    #19 9837264723849, Oct 8, 2015
    Last edited: Oct 8, 2015
    So you get 90 m2 per inhabitant for the whole month (vs. 73.24 m2 for my peak day). What roofing area do you think is already available for each person?

    EDF owns 400 km2 of land (incl. 4.4 km2 of premises), so we get 83.60 m2/pers from AntronX estimation.
    RFF (railway network) owns 1030 km2 of land (incl. 930 km2 of railways) while SNCF (railway company) owns 69 km2 of land (including 9 km2 of premises) (source), so we get 67 m2 per capita. Funky.

    In Metropolitan France, 5.6% of the land is artificialized. That's 37,800 km2 and Antronx's area of PV represents 15,66% of it.
    On this page (no source), it says the area of buildings, roads and parking is 28,974 km2.
     
  20. Robert.Boston

    Robert.Boston Model S VIN P01536

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    Interesting cost estimate -- over $1 billion to replace existing assets that are working reasonably well? That's not a story that sells well with voters. The immediate goal should be to stop building NEW fossil and nuclear plants (except in very particular circumstances). The economics of NEW renewables vs. NEW conventional power is reasonably close, but the economics of NEW renewables vs. operating EXISTING fossil/nuclear is much harder, particularly in the absence of a meaningful carbon charge.
     

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