Best solar panel angle for east/west to maximize Sunrise to Sunset

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bryhan67
bryhan67 Registered Users Posts: 37 ✭✭
in Off Grid Solar & Battery Systems #1

Looking for some advice on best angle for putting some extra solar panles on my off grid home. I already have a surplus amount of panles. I have 60 panles of 315w  each so by 9am my batteries are full. and thats only using 40 panles. I want to take about 12 panles, 6 facing east and 6 facing west. This way I can use less of my battery bank.  I am in south west usa zip code 92231. Its very hot and run the Air Conditioner 24/7 so anything to use less battery is great long term. Mostly only concerned for summer time. 


My roof is already east / west pitch. I was think on the pint of my roof put the 12 panles back to back. I wonder if 45deg is enough. 45deg A frame is easy to do. Trying to stand them vertical at 90deg would be tough but doable.


Also and idea the power the panles produce with the sun hitting at 45deg?  


Again not looking for a daily max power out of the panel. Just get that extra hour or two each day not dipping into my batteries. 


45deg vs 90deg what is the difference to extend charging later in day and early in morning. Maybe I will do some test to. Really all about the time of day and still charging vs on battery power. 


Every day I watch the clock and crank all the air conditioner to get the house cold usually 8am to 5pm I can run it all. would be nice 7am to 6pm crank it all.


As cheap as solar is im surprised there is not more discussion. I guess this would mostly apply for off grid homes.  

19k Watt system, 60 Jinko 315w panles. 5 Midnite Solar Classics, 2 Aims 6,000w 48v Inverter, Battery bank 1,600 AH. EnerSys PowerSafe DDm100-33 UPS batteries 24 Batteries. Additional 12 Batteries as backup'
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,044 ✭✭✭✭✭
    edited July 2022 #2
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     Funny, I live in San Felipe but my mailing address is in the 92231. Yep, I'd say it gets warm there.
     90 degrees would not give very good results as the sun while on the horizon is coming through a lot of the haze, smoke, dust etc. in the atmosphere and  as the sun rises it will be losing  its optimum angle to the panels. I would try 45 degrees and something slightly south of East and West for best year round output.
     You haven't mentioned your controller and wiring scheme but typically you want to wire the added panels in matching voltage strings to the existing array.
    .

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    edited July 2022 #3
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    Setting the panels at East West or more appropriately southeast and southwest is often called virtual tracking.

    You don't have to guess much! Use the site PVwatts linked below to enter trial data to see what return you will get by mounting panels at various angles both in degrees east vs west and pitch.

    PVWatts Calculator (nrel.gov)


    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.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #4
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    As the guys above say... Virtual track is nice. And while it is a bit less efficient than using a real mechanical tracker--Panels are so cheap, that you can add a few more for less than a real tracker.

    Closer to the equator, pure East/West facing arrays with some tilt is probably "best". Using PVWatts, you can figure out your optimum tilt fo the location (and winter vs summer harvest... Optimize for summer for A/C and summer place. If there in winter, lots of loads, less sun, optimize for winter. (array tilted to latitude, South East and South West?).

    With virtual tracking, you are getting more time on charge. For Lead Acid Batteries, they need time on charge (2-6 hours just for absorb + time at full current) to charge (upwards of 8-10 hours per day of "charging").

    With lithium ion batteries--I don't think you really need a virtual tracking array. Just setup for optimum direction and tilt, and dump as much current as the array can into your battery bank (following battery max charging specifications). Another Li Ion advantage.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • 706jim
    706jim Solar Expert Posts: 514 ✭✭✭✭
    #5
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    I'm at latitude 48 north. My panels are tilted 60 degrees to the ground.

    They just look good at that angle.
    Island cottage solar system with 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter, Outback Flexmax 80 MPPT charge controller 8 Trojan L16's. Insignia 11.5 cubic foot electric fridge. My 30th year.
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  • bryhan67
    bryhan67 Registered Users Posts: 37 ✭✭
    #6
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    #1 goal is extend power at sunrise and sunset from July to September. Im not worried about watts over the complete day. I have plenty for power 9am to 5 pm. Im in full float mode. Actually the optimal would be North west and North east. This time of the year its more north than south. 

    Used the PVWATTS and did by hour. I pulled only for one day 7-1-22. Yellow is easy in both 45 and 90 deg and green is west the same. I put in one KW for size. I guess thats 1000 wats of solar panles? East is for the sunrise and west for sunset. Not sure if I agree. Just tilting one panel seemed to show different data. base on that program 45 to 90 is not that much different. I will play with actual panles. I can measure amps but maybe volts are dropping too. Once I put some to a controller I will know actual watts.


    19k Watt system, 60 Jinko 315w panles. 5 Midnite Solar Classics, 2 Aims 6,000w 48v Inverter, Battery bank 1,600 AH. EnerSys PowerSafe DDm100-33 UPS batteries 24 Batteries. Additional 12 Batteries as backup'
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