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posted by Blackmoore on Thursday December 04 2014, @10:30PM   Printer-friendly [Skip to comment(s)]
from the just-short-of-obvious dept.

In the US, a new solar project is installed every 3.2 minutes and the number of cumulative installations now stands at more than 500,000. For years, homeowners who bought solar panels were advised to mount them on the roof facing south to capture the most solar energy over the course of the day. Now Matthew L. Wald writes in the NYT that panels should be pointed south so that peak power comes in the afternoon when the electricity is more valuable. In late afternoon, homeowners are more likely to watch TV, turn on the lights or run the dishwasher. Electricity prices are also higher at that period of peak demand. “The predominance of south-facing panels may reflect a severe misalignment in energy supply and demand,” say the authors of the study, Barry Fischer and Ben Harack. Pointing panels to the west means that in the hour beginning at 5 p.m., they produce 55 percent of their peak output. But point them to the south to maximize total output, and when the electric grid needs it most, they are producing only 15 percent of peak.

While some solar panel owners are paid time-of-use rates and are compensated by the utility in proportion to prices on the wholesale electric grid, many panel owners cannot take advantage of the higher value of electricity at peak hours because they are paid a flat rate, so the payment system creates an incentive for the homeowner to do the wrong thing. The California Energy Commission recently announced a bonus of up to $500 for new installations that point west. "We are hoping to squeeze more energy out of the afternoon daylight hours when electricity demand is highest," says David Hochschild, lead commissioner for the agency’s renewable energy division, which will be administering the program. "By encouraging west-facing solar systems, we can better match our renewable supply with energy demand."

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  • (Score: 0) by Anonymous Coward on Thursday December 04 2014, @10:41PM

    by Anonymous Coward on Thursday December 04 2014, @10:41PM (#122748)

    can you feel it

    • (Score: 0) by Anonymous Coward on Thursday December 04 2014, @11:32PM

      by Anonymous Coward on Thursday December 04 2014, @11:32PM (#122775)

      Wald writes in the NYT that panels should be pointed WWEEESSSTTTT so that peak power comes in the afternoon when the electricity is more valuable.

      WEST NOT SOUTH WEST NOT SOUTH
      WEST NOT SOUTH WEST NOT SOUTH
      WEST NOT SOUTH WEST NOT SOUTH

      https://www.youtube.com/watch?v=xW1fXL3s7bk [youtube.com]

  • (Score: 4, Interesting) by FakeBeldin on Thursday December 04 2014, @10:43PM

    by FakeBeldin (3360) on Thursday December 04 2014, @10:43PM (#122749) Journal

    They are basically suggesting that folks install new solar panels such that they receive less than the maximum possible energy from it. Doing that might solve an economic problem now, but comes across as rather short-term thinking.
    How about instead we work on the other associated technical issues to store the energy till needed?

    • (Score: 5, Informative) by zocalo on Thursday December 04 2014, @10:51PM

      by zocalo (302) on Thursday December 04 2014, @10:51PM (#122756)
      They've basically taken the position of trying to maximise the RoI over maximising efficiency, making a couple of quite major assumptions that are quite probably incorrect along the way. Firstly they assume that you can feed your spare capacity back onto the grid for credits in the first place, which is not always the case, and secondly that you don't have any local means of storing spare capacity until it's needed, like a bank of batteries. Thinking about it they've actually missed a trick as well - if you want to maximise your RoI, what you'd actually do is point your panels South to collect as much energy as possible into your array of batteries, but only feed your spare capacity in your batteries back onto the grid when the demand is highest.
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      • (Score: 1, Informative) by Anonymous Coward on Thursday December 04 2014, @11:03PM

        by Anonymous Coward on Thursday December 04 2014, @11:03PM (#122758)

        > Firstly they assume that you can feed your spare capacity back onto the grid for credits in the first place, which is not always the case,

        It is in about 95% of residential solar installations. Net-metering is BIG TIME nowadays, practically every solar installation now is grid connected.

        > secondly that you don't have any local means of storing spare capacity until it's needed, like a bank of batteries

        See the point about grid-connected solar, only the people who are literally off the grid have batteries now.

        Corner cases really aren't the issue here, anyone who has gone to the effort (and more importantly the expense) of battery installation is going to be know to think for themselves.

        • (Score: 2) by pe1rxq on Thursday December 04 2014, @11:09PM

          by pe1rxq (844) on Thursday December 04 2014, @11:09PM (#122761) Homepage

          Net-metering is big indeed, I am doing it myself. But the price does not go up at the end of the day which would be needed for this theory to work.
            As long as that is the case. It makes most sense to maximize output and thus leave my panels facing south.

          • (Score: 0) by Anonymous Coward on Thursday December 04 2014, @11:16PM

            by Anonymous Coward on Thursday December 04 2014, @11:16PM (#122764)

            > But the price does not go up at the end of the day which would be needed for this theory to work.

            Yep. But places like california already have time-of-day pricing based on large intervals, they could refine it a little to encourage people to do installs that better match demand.

        • (Score: 2) by zocalo on Friday December 05 2014, @12:12AM

          by zocalo (302) on Friday December 05 2014, @12:12AM (#122787)
          Yeah, it's certainly headed that way, but it does vary quite a bit depending on where in the world you are, what incentives are available and how cooperative the local utilities are, which is the point I was trying to get across. Past stories on the other site led me to believe that at least some of the US utilities are extremely obstructive in this regard (I'm in the EU and we have a similar patchwork here, albeit generally favourable to back feeding onto the grid), but if that's changing for the better over the pond than that's excellent news for solar.
          --
          UNIX? They're not even circumcised! Savages!
        • (Score: 2) by WillR on Friday December 05 2014, @12:46AM

          by WillR (2012) on Friday December 05 2014, @12:46AM (#122798)
          "It is in about 95% of residential solar installations. Net-metering is BIG TIME nowadays"

          Or as a realist might put it: "95% of solar installations happen where the political/market conditions favor it. Solar is BIG TIME nowadays in places with net metrering"

          Or if you're a pessimist: "95% of US solar panel supply is wasted on ridiculous places like Vermont and Washington, because the hillbillies in the south where all the goddamn sunshine is won't vote for net metering."
      • (Score: 2) by Blackmoore on Thursday December 04 2014, @11:04PM

        by Blackmoore (57) on Thursday December 04 2014, @11:04PM (#122759) Journal

        or you mount your panels on a pivot and have them move with the sun to receive maximum solar input - tracking the sun as it arcs through the sky.

        but yeah. mounting them solid is cheaper. so that's what most installations are. So; you could mount it facing any direction BUT north depending on when you want the most going into you local storage.

        but I don't seem to recall Iron/acid deep sink batteries being available any more.

        • (Score: 4, Interesting) by Arik on Thursday December 04 2014, @11:37PM

          by Arik (4543) on Thursday December 04 2014, @11:37PM (#122777) Journal
          You can get installations that swivel and track the sun, and they can give a noticeable boost to your total output, depending on your latitude, but they also increase cost. You have to do the math yourself, but in many cases it's more cost effective to add an extra panel at roughly the same cost as the tracker mechanism.

          Increased complexity imposes a cost of its own on top of the ticket price; I'll give you a computer analogy, it's kind of like systemd - all these extra parts mean more places for things to break. So you can expect your fancy tracker system to not only cost more upfront, but also to break and require maintenance more often. ;)

          Again, do the math yourself, but it's rarely the best option.

          This is all in relation to active tracking - passive tracking is an idea that fascinates me, but it is probably a dead end. There was a guy in Qld. AU that used to make some of these back in the 70s or possibly the 80s, I have seen one working although not up close, and I cant seem to find anything on the web about them. As I understand it, the panel is mounted on a free swivel, then held in place from opposite sides with heavy black rubber straps that partially wrap around the swivel, so the one on the east actually pulls the panel towards the west, and the one on the west actually pulls to the east. In the morning, the band on the east side warms up faster than the one on the west, causing the panel to rotate towards the east.  As the sun progresses, the bands even out, then later in the day, the western band is warmer than the eastern, causing the panel to continue rotating to the west for the evening.

          Beautiful scheme in theory, far fewer things to break (and no draining your electric output to move the panel) but even so he was apparently never able to make it cheap and reliable enough to take off.
          --
          If laughter is the best medicine, who are the best doctors?
      • (Score: 3, Interesting) by frojack on Thursday December 04 2014, @11:19PM

        by frojack (1554) Subscriber Badge on Thursday December 04 2014, @11:19PM (#122766) Journal

        Firstly they assume that you can feed your spare capacity back onto the grid for credits in the first place, which is not always the case, and secondly that you don't have any local means of storing spare capacity until it's needed, like a bank of batteries.

        Not exactly, and here's way....

        The first assumption is in fact true in many places, especially in places where there is a LOT of roof top solar. (Hawaii)
        When you have excess, the grid in such places also have an excess, and you might have the interconnect, but still not be contributing anything.

        The second is true in all too many cases, where people install roof-top solar, but count on feeding the grid, and they forego the battery bank, to save money and complexity, and hence assumption one kicks in.

        Still, I think this is a pretty silly article, and a stupid recommendation. Either the Grid or the household will sooner or later, have to build storage.

        There is no way to run Solar without storage, other than having a worldwide virtually loss-less grid, which the geography of Earth works against.

        --
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      • (Score: 2) by c0lo on Friday December 05 2014, @07:00AM

        by c0lo (156) Subscriber Badge on Friday December 05 2014, @07:00AM (#122857) Journal

        what you'd actually do is point your panels South to collect as much energy as possible into your array of batteries

        What??? I'm living in the Southern hemisphere, you insensitive clod.

        --
        https://www.youtube.com/watch?v=aoFiw2jMy-0
        • (Score: 3, Funny) by zocalo on Friday December 05 2014, @10:02AM

          by zocalo (302) on Friday December 05 2014, @10:02AM (#122877)
          Apologies. You'd still mount your solar panel facing south, but also upside down. :)
          --
          UNIX? They're not even circumcised! Savages!
      • (Score: 2) by morgauxo on Tuesday December 09 2014, @04:23PM

        by morgauxo (2082) on Tuesday December 09 2014, @04:23PM (#124228)

        You seem to be under the mistaken impression that storing energy in and retrieving it from batteries or sending it long distances via wire are efficient processes. Account for all the losses and producing the power you need at the actual time when you need it for yourself becomes far more profitable than either storing it for later or selling it back to the grid. Those things are more methods of retrieving some value from the crumbs then they are useful as a main end goal.

    • (Score: 2) by morgauxo on Friday December 05 2014, @04:22AM

      by morgauxo (2082) on Friday December 05 2014, @04:22AM (#122841)

      Well, when you go through the trouble of replacing all of your attic full of expensive current-technology batteries with the unobtanium ones we all hope are available in the coming years that would be a great time and reason to re-orient your west-facing panels towards the south. In the mean-time it makes more sense to generate the power when you actually want to use it.

      • (Score: 1) by mr_mischief on Friday December 05 2014, @04:10PM

        by mr_mischief (4884) on Friday December 05 2014, @04:10PM (#122949)

        So we should generate it with both east and west-facing panels with a few panels facing south for the middle of the day when we're at work?
        You know, because the household is using power all day.

        • (Score: 2) by morgauxo on Tuesday December 09 2014, @04:18PM

          by morgauxo (2082) on Tuesday December 09 2014, @04:18PM (#124225)

          Did you mean to reply to my comment or was that supposed to be directed at another? I really can't see any way to twist the English language and get what you are implying from what I wrote. Feel free though to point your panels in any direction you please. Maybe if you point them all straight down you can detect some neutrinos or something like that.

    • (Score: 2) by FatPhil on Friday December 05 2014, @08:56AM

      by FatPhil (863) <reversethis-{if.fdsa} {ta} {tnelyos-cp}> on Friday December 05 2014, @08:56AM (#122871) Homepage
      They are looking for their lost keys near the lamp-post, as it's lighter there.

      This is no more illogical than pumped hydro-electric power. Pumping water to a high reservoir at night when the prices are cheap, and then generating electricity from it when there's higher demand and higher prices are paid. Who cares about the laws of thermodynamics - they don't include "price" in the equation.
      --
      I know I'm God, because every time I pray to him, I find I'm talking to myself.
  • (Score: 2) by richtopia on Thursday December 04 2014, @11:03PM

    by richtopia (3160) Subscriber Badge on Thursday December 04 2014, @11:03PM (#122757) Homepage Journal

    Work nights, watch your TV at noon.

    • (Score: 2) by bob_super on Thursday December 04 2014, @11:32PM

      by bob_super (1357) on Thursday December 04 2014, @11:32PM (#122774)

      Work out, power your LED TV with your exercise bike.

  • (Score: 2) by danmars on Thursday December 04 2014, @11:31PM

    by danmars (3662) on Thursday December 04 2014, @11:31PM (#122773)

    The first link text in the summary says he's saying to point them south instead of south, which is a bit confusing.

    • (Score: 1) by Buck Feta on Friday December 05 2014, @03:39AM

      by Buck Feta (958) on Friday December 05 2014, @03:39AM (#122833) Journal

      They turned them 360 degrees in the opposite direction.

      --
      - fractious political commentary goes here -
      • (Score: 0) by Anonymous Coward on Saturday December 06 2014, @08:30PM

        by Anonymous Coward on Saturday December 06 2014, @08:30PM (#123288)

        haha! +5 clever

  • (Score: 2) by bob_super on Thursday December 04 2014, @11:35PM

    by bob_super (1357) on Thursday December 04 2014, @11:35PM (#122776)

    So, when I pull the trigger an get my panels on the only appropriate section of my roof, facing south-west, do I get the extra $500 or not?
    And is the installer just going to charge me a new "orientation" fee and pocket it?

  • (Score: 3, Informative) by Immerman on Friday December 05 2014, @01:48AM

    by Immerman (3985) on Friday December 05 2014, @01:48AM (#122812)

    The only way this makes sense (from a physics perspective) is if total peak solar, plus non-adjustable baseload generation, is beginning to approach 100% of demand during peak solar hours. Or if existing generating capacity is unable to handle peak demand. Until that happens though, 100% of the solar-generated power is being put to good use, and tuning peak generation timing to match peak demand only serves to dramatically reduce the total amount of solar power generated, increasing fossil fuel usage and reducing the ROI of the solar panels.

    Of course, if you're having to fire up substantially less efficient generators to handle peak demand you *might* be better served by dramatically reducing total solar power generation in exchange for better alignment with demand. But that would be entirely dependent on the nature of the existing local generating infrastructure.

    It may also make good long-term sense to start shaping generating patterns now, in which case getting proper incentives in place (time-of-generating credits, rather than the flat rate usually offered) would help shape the buildout of new capacity. But I still have my doubts - after all west-facing panels will generate hardly any power at all during winter months, when the sun is at it's furthest south.

    My gut says that, at least for the immediate future, following this advice in the US does nothing more than give simultaneous handouts to both the fossil fuel and solar panel production industries. $500 is unlikely to even begin to cover the 20-year loss in generating capacity of a poorly aligned solar installation.

  • (Score: 1) by tftp on Friday December 05 2014, @02:28AM

    by tftp (806) on Friday December 05 2014, @02:28AM (#122818) Homepage

    In late afternoon, homeowners are more likely to watch TV, turn on the lights or run the dishwasher.

    In late afternoon homeowners are extremely likely to be at work. They won't get home until much later. The Sun will be lower above the horizon, and in many cases solar panels get no light onto them because of obstructions.

    Sending generated solar power into the grid during the day requires less energy to be produced at that time by coal and gas plants. Nothing good can come from the plan to reduce generation of solar power to meet a nonexistent peak in consumption around 4-5PM. Nobody runs a dishwasher at that time, nobody uses lights. If people happen to be at home while it's still daylight - which happens in summer - they tend to work outdoors.

  • (Score: 0) by Anonymous Coward on Friday December 05 2014, @05:06AM

    by Anonymous Coward on Friday December 05 2014, @05:06AM (#122849)

    if the electric company is paying for the panels and their installation (90-100%), they can install them anywhere they want on my home. if they are setting up their own 'solar farm', they probably should have at least half of them pointing west to help with peak demand. if i buy and install panels, they are going to face south and charge my battery bank during the day.