Enter Zipcode

Results 1 to 10 of 10

Thread: output from solar panels winter vrs summer

  1. #1
    Junior Member
    Join Date
    Oct 2011
    Posts
    5

    Default output from solar panels winter vrs summer

    Hello,

    I'm fairly new to the solar scene. And my experience with the amount of power genereated from my solar panels is limited to the winter (in CT). My question is whether or not I can expect the amperage (and wattage) of my panels to increase during the summer months? I know the days will get longer, and the hours of sunlight will be more, but will the different angle of the sun amount to an increased level of generation? For example, if I'm reading an average of 5 amps between my 3 panels in the winter, can I expect to see an increase in amerage in the summer? Thanks in advance.

  2. #2
    Administrator
    Join Date
    Feb 2011
    Location
    Annapolis Md
    Posts
    6,182

    Default

    Total output will be more amperage may or may not increase. It will depend on the angle of the sun to the panels and how hot it is outside. Highest amperage is generally spring and fall when the temps are cool but the sun is fairly high in the sky.
    Rich
    WWW.solarsaves.net

    NABCEP certified Technical Sales Professional

    http://www.solarpaneltalk.com/showth...Battery-Design

    http://www.calculator.net/voltage-drop-calculator.html (Voltage drop Calculator among others)

    www.gaisma.com

  3. #3
    Member
    Join Date
    Jan 2012
    Location
    Louisiana
    Posts
    36

    Default

    Do you know what the tilt of your array is? Amperage is related to irradiance. You get maximum solar exposure if the plane of your array is perpendicular to the sun's rays. So if your array is closer to 56 degrees, then it will have better winter production, and if its closer to 26 degrees then it will have better summer production (since CT is around 41 degree latitude, and the rule of thumb is -15 in summer, +15 in winter).

  4. #4
    Junior Member
    Join Date
    Oct 2011
    Posts
    5

    Default

    Quote Originally Posted by andrewc View Post
    Do you know what the tilt of your array is? Amperage is related to irradiance. You get maximum solar exposure if the plane of your array is perpendicular to the sun's rays. So if your array is closer to 56 degrees, then it will have better winter production, and if its closer to 26 degrees then it will have better summer production (since CT is around 41 degree latitude, and the rule of thumb is -15 in summer, +15 in winter).
    My array's at around 40 degrees. I'm going to jack that up to 65, and see the difference. And I'll keep your advice long term, as the summer draws closer. At that time I'll bring it to around 25. I'll keep you posted. Thanks.

  5. #5
    Solar Fanatic
    Join Date
    Jun 2010
    Posts
    393

    Default

    Your panels put out their maximum voltage in winter when its cold out. They also will put out the maximum wattage during cold weather with snow on the ground.Unfortunately there are a lot more hours of daylight in the summer than in the winter. In most areas there are more dyas of clear weather than int he winter but thats highly variable on the location.

    Of course some "rocket scientists" dont plan on shade from trees in the summer so their actual hours of daylight are less than what is availlable . I drive by a high profile DIY system near me that is in the shade in the afternoon during pasrts of the fall due to trees on a neighbors property.

  6. #6
    Junior Member
    Join Date
    Jan 2012
    Posts
    21

    Default

    irradiance/conversion/AR coatings/resistance effect amperage
    Hot/Cold weather effects voltage

    The happy medium is to get a fixed tilt to latitude/azimuth of fall and spring for best results. Or maximize fix tilt for latitude/azimuth of summer solstice. Never do you want a fixed tilt for winter solstice as it lacks the most sun hours within the season even if its colder to increase voltage, if PTC exceeds STC even in short sun hour duration's fuses will just become costly to replace IF by chance exceeding the medium voltage of 600V.
    I personally like fixed tilt for spring/fall conditions although sun hours are 1/3 less than that of summer solstice, there are double the amount of sun hours combined to summer sun hours. everyone has their own preference however.

  7. #7
    Moderator
    Join Date
    Jul 2009
    Posts
    8,436

    Default

    Quote Originally Posted by solarpowered View Post
    irradiance/conversion/AR coatings/resistance effect amperage
    Hot/Cold weather effects voltage - - - - - - there are double the amount of sun hours combined to summer sun hours. everyone has their own preference however.
    To avoid confusion for any newby reading - when people use the term sun hours they really mean taking the daily insolation and dividing it by 1000. Insolation being the amount of watts received per square meter per day. It is a funny usage apparently dumbing the insolation number down for solar salesmen.

    An insolation of 4,500 watts per m2 = 4.5 sun hours.

    Approximate insolation for your location can be learned from PV Watts http://mapserve3.nrel.gov/PVWatts_Viewer/index.html
    Last edited by russ; 02-24-2012 at 02:48 PM. Reason: spelling

  8. #8
    Administrator
    Join Date
    Feb 2011
    Location
    Annapolis Md
    Posts
    6,182

    Default

    Changing tilt on collectors is IMHO probably not worth it. The increased output is only about 3 or 4%
    If you tell me your zip and azumuth (true direction) I can run a tilt optimizer to tell you what fixed tilt is best.
    Rich
    WWW.solarsaves.net

    NABCEP certified Technical Sales Professional

    http://www.solarpaneltalk.com/showth...Battery-Design

    http://www.calculator.net/voltage-drop-calculator.html (Voltage drop Calculator among others)

    www.gaisma.com

  9. #9
    Moderator
    Join Date
    May 2009
    Location
    off grid retirement in Northern Calif
    Posts
    7,175

    Default

    re tilt optimizing.

    I'm off-grid, and have my tilt set for winter (nov-feb) because I need every bit of sun in the short days. Summer, with the longer sun days, it's not much of a loss.

    Also, the steeper tilt, allows for a bit more "self cleaning" of the panels. I've got no snow, so I can't gain from any reflections.

    Looking through my charge controller logs, on several really cloudy days, my 3KW array put out about 150 watts peak ! Clouds are bad for harvest.
    Since the dawn of time it has been mankind's dream to blot out the sun.
    Montgomery Burns

    "Always listen to experts. They'll tell you what can't be done and why. Then do it."

    spreadsheet based voltage drop calculator:
    http://www.solar-guppy.com/download/...calculator.zip
    http://www.solarpaneltalk.com/showth...oss-calculator

    http://www.mike-burgess.org/PVinfo_2.html

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,
    battery lugs http://tinyurl.com/LMR-BigLug
    Setting up batteries http://tinyurl.com/LMR-NiFe

    gear :
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV || || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

  10. #10
    Member
    Join Date
    Aug 2011
    Location
    Eastern Pennsylvania
    Posts
    71

    Default

    PV Watts mentioned above will tell you the story.

    I'm amazed at how fast production increases in the spring.
    I will go from a best day in December of ~32 Kwhr to hitting almost 70 in mid-march which is pretty much the peak because the heat kicks in and makes the panels less efficient.

    I think I'm about 29 degree pitch
    10Kw solar PV
    GSHP (6-2011)
    Solar hot water 2x SPP-30
    Meter has been going backwards since May 20th
    Anyone wanna buy some SREC credits? (cheap!)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •