HELP ... array orientation

walang_problemawalang_problema Posts: 9Registered Users
:confused: We currently have a project where the roof has a 5 degree pitch and is oriented 36 degrees south east. would it be better of we face our modules at true south or we could just follow the roof's orientation and just make it at a 15 degree pitch? Would there be a big difference in power produced if we face it in a different way? :confused: thanks.

Comments

  • crewzercrewzer Posts: 1,832Registered Users, Solar Expert ✭✭✭✭
    Re: HELP ... array orientation

    You can use the tool below to model variations in array alignment.

    See: http://rredc.nrel.gov/solar/codes_algs/PVWATTS/version1/

    HTH.
    Jim / crewzer
  • mike95490mike95490 Posts: 7,901Solar Expert ✭✭✭✭
    Re: HELP ... array orientation
    :confused: We currently have a project where the roof has a 5 degree pitch and is oriented 36 degrees south east. would it be better of we face our modules at true south or we could just follow the roof's orientation and just make it at a 15 degree pitch? Would there be a big difference in power produced if we face it in a different way? :confused: thanks.

    If North is 0 / 360 deg, and east is 90 deg, south is 180 deg, 36 falls in as NE.

    Since I didn't bother to look up where your IP is from, and you didn't give us a CLUE of where you might possibly be, NE may or many not be a problem.
    -- edit:

    Makati, Philippines ?? Thats north of the equator, then 36deg is not a good angle. due east would be better, but the otherside of the roof, SW would be OK. Mounting brackets that are sturdy, are expensive, if you try to "tilt" an array on a roof. You might be better off with a pole mount in the ground.
    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 ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BB.BB. Posts: 27,883Super Moderators, Administrators admin
    Re: HELP ... array orientation

    Manila, Philippines?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • walang_problemawalang_problema Posts: 9Registered Users
    Re: HELP ... array orientation

    sir/maam thank you for your replies much appreciated
    sir it's located in quezon city Philippines, the south facing roof is 144 degrees from north azimuth. is it possible to tilt it 15 degrees only and just follow where the roof is facing, or orient it facing true south
    thanks
  • BB.BB. Posts: 27,883Super Moderators, Administrators admin
    Re: HELP ... array orientation

    WP,

    Normally, I would directly you to this site:

    http://rredc.nrel.gov/solar/codes_algs/PVWATTS/version1/

    Because you can input different panel orientations and get "your answer"... However, Philippines does not have any listings...

    So, looking around 14 degrees north, island setting, for something that is in the data base... Hawaii is around 20 degrees north. Bangkok is near 14 degrees, San Juan Puerto Rico at 18 would be another one to try...

    So, using the above links, lets make some assumptions...

    15 degrees of tilt is just about the minimum you will want because it is self cleaning... The closer you get to zero degrees, the more you will have to clean the panels... This may, or may not, be an issue for your installation... We will try 15 and 0 degrees and see what we get.

    Also, I will assume that this is an off grid application and use 0.52 as the derating factor. Assumes lead acid flooded cell batteries, a good MPPT charge controller, and an inverter for DC to AC conversion to run your 120/240 VAC appliances. You can use 0.77 as a derating factor for Grid Tie inverter systems (solar panel to inverter to your utility mains--used where power is reliable but expensive--and utility lets you connect Grid Tied (Utility Interactive) Inverters to reduce your costs (and spin your meter backwards)...

    Also, we will try 180 degrees and 144 degree panel orientation--Note that local weather conditions will affect you... In my area, we have morning fog and afternoon sun on the coast--so pointing more towards the west is better. In parts of Florida, they have afternoon thunderstorms and hot afternoons--panels pointing a bit more East do better there.

    OK... For now, I will use 1 kWatt of solar panels (smallest this website allows)... If your panels are only 100 watts, divide the answers by 10. If your panels are 2,000 watts, multiply the answers by 2, etc...

    And the answer will be kWhrs per year--you can get answers in kWhrs per month/day/hour--but we are looking at overall efficiency for now.

    1kW, 180 south, 15 degrees, 0.52 off-grid derating, fixed mounting:

    Hilo Hawaii; 800 kWhrs per year
    Bangkok; 819 kWhrs per year
    San Juan PR; 921 kWhrs per year

    As above, but facing 144 degrees (east of south):

    Hilo Hawaii; 793 kWhrs per year
    Bangkok; 812 kWhrs per year
    San Juan PR; 914 kWhrs per year

    Surprisingly close answers... Just for the heck of it, what if you installed a one axis tracker (rest the same):

    Hilo Hawaii; 997 kWhrs per year
    Bangkok; 940 kWhrs per year
    San Juan PR; 1,173 kWhrs per year

    And two axis tracker:

    Hilo Hawaii; 1,030 kWhrs per year
    Bangkok; 969 kWhrs per year
    San Juan PR; 1,212 kWhrs per year

    I am guessing that weather is showing an effect between the three sites (larger island with inland city for San Juan PR--more sun less fog/rain/clouds?)

    In any case, your initial answer shows that the difference between 144 and 180 degree orientation is:

    Hilo Hawaii; 793/800= 99%
    Bangkok; 812/819= 99%
    San Juan PR; 914/921= 99%

    1% loss would be impossible for you to measure in the field.

    So, I don't have an exact answer for Quezon City Philippines, but I believe we have a reasonable answer for your question.

    Take care,
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzercrewzer Posts: 1,832Registered Users, Solar Expert ✭✭✭✭
    Re: HELP ... array orientation

    Data available from this site may help: http://www.gaisma.com/en/dir/ph-country.html
    Check data for Manila (QC is a part of metro Manila).

    HTH,
    Jim / crewzer
  • walang_problemawalang_problema Posts: 9Registered Users
    Re: HELP ... array orientation

    BILL/CREWZER

    thank you sir bill and sir jim for the information, its been a great help for us, since we are just starting in renewable energies and we are currently studying about it, thanks again sir

    -walang_problema
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