Dec 21st, hows your energy production?

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jeffkruse
jeffkruse Solar Expert Posts: 205 ✭✭✭
This is the shortest day of the year. A first for my system. My pannels are on a fixed angle equal to my Lattitude (18deg). I noticed I have some shadding in the AM due to a 80 foot tall Breadfruit tree (just the top 8' of it). I don't start any real production untill 8:30AM.

I also noticed my PM production is better than I expected. Some shaddows in the PM gave me the motivation to do some heavy chainsaw pruning on a big Maria tree in the front yard. Ive been meaning to prune that tree even before I got the solar panels. I just needed the right motivation. ;)

My average production is only slightly less than what I saw in the summer. We have fewer PM clouds now.

Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
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    Re: Dec 21st, hows your energy production?

    18 latitude, eh?
    Try it at 52! :cry:
    Can't get near the cabin, but I suspect today's grand total of 6 hours maximum potential sunlight will produce barely enough to stay ahead of self-discharge. Providing it isn't too cloudy, that is.

    See what a difference location makes?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,502 admin
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    Re: Dec 21st, hows your energy production?

    In all honesty, I have spent more money on tree trimming than I have saved in GT solar electricity over the years...

    But, a lot of that trimming I have/would have done because too many large trees next to buildings/fence lines just is asking for trouble when the next storm hits.

    I know lots of people and cities really like large trees on residential lots--but they (the trees) generally out grow their physical location and the cities around here have the right to charge you to cut down your own tree... So, needless to say, when one comes down, none go up in my yard again. Down to one last tree on our property.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
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    Re: Dec 21st, hows your energy production?

    Sun hits the front panels about 9 am, getting on the roof by 10, off the front by 2, and the roof not much later. Nice cold mornings, (-30) and we get very high current for most of the day, ~18-20 amps out of 325 watts of PV (12vdc) leaving me a net of ~70 ah into the batteries, easily staying ahead of our use, which this time of year is ~40-60ah deficit by dawn. We have had little snow so far, and lots of sun. I haven't had to run the genny in a couple of weeks.

    Our worst harvest in typically in late October through early Dec. There are still enough leafs to cause a bit of shading, but mostly it is often grey, drizzling/snowing.

    Tony

    Merry Christmas to everyone, I'm going to be moving around a bit for the early part of the winter.
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
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    Re: Dec 21st, hows your energy production?

    Jeff, you might consider keeping track of your production over the next week. Even though this is the 'shortest day' the sun continues to fall a bit lower in the sky, at least up here @ 52* lat, and stay a bit longer in the PM. Has something to do with the wearths wobble rate...

    Just interested in if you see any difference due to the sun elevation in the PM. it may be a better deal to improve the PM insolation vs AM for winter at least

    Cheers
    Eric
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Dec 21st, hows your energy production?

    add to the short days the amount of snow that was on the pvs.:grr yes, it melted off, but it still takes more of the available light away while it's there. once gone there's more light available through reflection though.:D
    18 degrees?:confused: hardly a problem i would think as the bigger problem is the sun going east to west from nearly overhead for you.

    i don't know why my ip lookup says phoenix, but my original content holds true as you are about 18 degrees latitude.
  • jeffkruse
    jeffkruse Solar Expert Posts: 205 ✭✭✭
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    Re: Dec 21st, hows your energy production?

    No problem, I was just wondering how others were doing.

    I live in San German, Puerto Rico and not Phoenix.

    I am seeing a small improvement in production for the PM.

    I am still producing more than the batteries can take in during daylight hours :roll:

    I wish the absorb times didnt need to be so long. I hate to see so much power not used, 1000+W available but only 400 used in the PM.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,502 admin
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    Re: Dec 21st, hows your energy production?

    If you have optional loads that you can use during this time (pumping, washing clothes, etc.).

    Also, set the absorb voltage higher, especially during winter when there is less time for sun (although, you are much closer to the equator--so probably not as large an issue for you). High absorb voltage/currents will be somewhat less efficient, but if you have a bit of power to burn--it should not be a big problem (assuming you don't start boiling the batteries hard/using too much water).

    The batteries will just get a bit warmer because of the higher current flows (less efficient charging goes into making heat and hydrogen gas (gas when battery is fully charged).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • RandomJoe
    RandomJoe Solar Expert Posts: 472 ✭✭✭
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    Re: Dec 21st, hows your energy production?

    I designed my system based on winter insolation, and still haven't gotten around to all those ideas I have for automatically taking advantage of extra power... So, today it's done about the same as every other day! 1.24kWh / 94AH into the battery bank, and already floating.

    Due to the way the shadow from a neighbor's tree tracks across my roof in the afternoon, I am actually getting more sun now than a few weeks ago (and of course will in a few weeks). Right now the sun is south of / below the main part of the tree!

    Edit: Sun is now down. Total for the day was 1.34kWh, 101AH.

    Really need to come up with a way to usefully put that extra capacity to work!
  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
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    Re: Dec 21st, hows your energy production?
    RandomJoe wrote: »
    and still haven't gotten around to all those ideas I have for automatically taking advantage of extra power...

    Well I did. Set another C60 controller up as a diversion controller.

    Here are the results: Left is from 2008 and right is from 2009:
  • RandomJoe
    RandomJoe Solar Expert Posts: 472 ✭✭✭
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    Re: Dec 21st, hows your energy production?
    n3qik wrote: »
    Well I did. Set another C60 controller up as a diversion controller.

    Just read through your site again - it's been a while, and didn't remember what you were doing with the extra power. Those are some nice numbers! :cool:

    You are doing much what I had in mind, how do you handle the switchover between grid and inverter? My primary concern is the fridge, if it just happens to be running at the time I switch, and the compressor stops, it won't restart. So I need to either make sure it isn't running at the time or have a 5 minute or so delay between off-to-on. Or make sure the switchover is fast enough that the compressor doesn't notice - I do hate to rely on that though...

    I also have a couple servers I've thought about using, as they are a constant load while the fridge spends much of its time off. But they definitely don't like power glitches. I suppose just leave them on the UPS and switch THAT back and forth... Need to be sure they don't get switched when the grid goes down - they aren't a "necessary" load!

    I always get hung up (as you mention yourself) on having "too much load / not enough panel" and it sure would be nice to have an inverter that could "mix" grid and solar as it is available. Not grid-tie, but to a subpanel. Seems like Xantrex could do this, since they can grid-tie anyway all the "logic" is there, not sure if they do though...
  • Photowhit
    Photowhit Solar Expert Posts: 6,004 ✭✭✭✭✭
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    Re: Dec 21st, hows your energy production?

    Sunny day back in Misery (Missouri) so I suspect I'm topped off and ready for the snow and small numbers coming later in the week. Just checked they changed Saturday for 13H 8L to 30H 22L (a pretty nice day) I'd like to see lows above 20 as I shut everything down except a pilot light.

    On the other hand I'm in Florida doing some bird photography and enjoying Christmas with my family.

    Merry Christmas all!
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • Ralph Day
    Ralph Day Solar Expert Posts: 1,019 ✭✭✭✭
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    Re: Dec 21st, hows your energy production?

    Yesterday, Dec 21st 8.8kwhrs on 2.1kw pv. This surpasses some summer days with longer insolation times. Sunny, snow on the ground, works grand.

    Ralph

    Lattitude 44deg, Prince Edward County, the blob that sticks out into Lake Ontario
  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
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    Re: Dec 21st, hows your energy production?
    RandomJoe wrote: »
    Just read through your site again - it's been a while, and didn't remember what you were doing with the extra power. Those are some nice numbers! :cool:

    I have not updated it. Need to start over as I backed up wrong data during a hard drive switch over. Thanks for the comments.
    RandomJoe wrote: »
    You are doing much what I had in mind, how do you handle the switchover between grid and inverter? My primary concern is the fridge, if it just happens to be running at the time I switch, and the compressor stops, it won't restart. So I need to either make sure it isn't running at the time or have a 5 minute or so delay between off-to-on. Or make sure the switchover is fast enough that the compressor doesn't notice - I do hate to rely on that though...

    Using the PLC to set switchover times and the transfer switch for the inverter to do the switchover.
    RandomJoe wrote: »
    I also have a couple servers I've thought about using, as they are a constant load while the fridge spends much of its time off. But they definitely don't like power glitches. I suppose just leave them on the UPS and switch THAT back and forth... Need to be sure they don't get switched when the grid goes down - they aren't a "necessary" load!

    This will not work, the UPS's do not like most outputs from inverters.
    RandomJoe wrote: »
    I always get hung up (as you mention yourself) on having "too much load / not enough panel" and it sure would be nice to have an inverter that could "mix" grid and solar as it is available. Not grid-tie, but to a subpanel. Seems like Xantrex could do this, since they can grid-tie anyway all the "logic" is there, not sure if they do though...

    Xantrex XW series of inverters will do this. Was looking at them, but have too many items that run at 12V.