Need Info On A Small Solar System

MIDGAPATRIOTMIDGAPATRIOT Registered Users Posts: 5
I'm wanting to put together a small solar system. I need to power a well pump, the well is 110' deep. The water would go into a storage tank. I also want to power a refrigerator/freezer, just a normal one like you have in your kitchen. What do I need? How many panels, inverter, batteries, and so forth. I know NOTHING about any of this so any info is GREATLY appreciated. Thanks in advance!!!!

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,736 admin
    Re: Need Info On A Small Solar System

    In general, solar off-grid power is very expensive... So to limit the costs of over design (and undersign failures)--You really first need to know your daily power needs (by season).

    Basically, if your power system can run on ~3.3 kWH per day (100 kWH per month) or less... That is a pretty reasonable amount of solar power for an off-grid home/cabin.

    But that is not a cheap system... You are looking at ~1,600 watts of solar panels, an ~800-1,650 AH battery bank (at 12 volts), solar charge controller, inverter, mounts, wiring, fuses, etc... Plus a backup genset and AC battery charger if you need power during poor weather conditions/backup power.

    It would not be out of the realm of possibilities to say that this would be a $10,000-$20,000 or more off-grid solar system to install... Plus you would need to replace the batteries every ~4-15 years, and replace electronic hardware every 10-15 years or so...

    We can go into the details--but I wanted to understand your power requirements and what you expected from the system (I am not in solar equipment sales, I do not do this for a living--Just trying to help).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 8,471 ✭✭✭✭✭
    Re: Need Info On A Small Solar System
    I'm wanting to put together a small solar system. I need to power a well pump, the well is 110' deep. The water would go into a storage tank. I also want to power a refrigerator/freezer, just a normal one like you have in your kitchen. What do I need? How many panels, inverter, batteries, and so forth. I know NOTHING about any of this so any info is GREATLY appreciated. Thanks in advance!!!!

    That's just about what i'm doing right now, using a standard well pump, in a pond, to pump water 160' high on a hill to a tank for gravity pressure.

    As Bill says, it's expensive. PV. inverter that can start a pump, batteries, backup genset,

    Poke around in my .Sig, lots of stuff there.

    Mike
    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 ,

  • MIDGAPATRIOTMIDGAPATRIOT Registered Users Posts: 5
    Re: Need Info On A Small Solar System

    Thanks for that info. This is gonna be a SHTF system. Just wanting to keep a good size tank full of water and run a refrigerator/freezer to keep meat from hunting from going bad. This would not be used to provide the house with it's normal water usage, I know that would be really expensive. Just to fill up the tank, maybe 300 to 500 gallons. And have a float valve/switch to shut off the pump when the tank is full.
  • mike95490mike95490 Solar Expert Posts: 8,471 ✭✭✭✭✭
    Re: Need Info On A Small Solar System
    Thanks for that info. This is gonna be a SHTF system. ....

    If you are real good the batteries will last 5-9 years. Then, it's only power when the sun shines. So depending on the size/wattage of your pump, you should have twice that in solar PV to make sure the pump will run.
    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 ,

  • MIDGAPATRIOTMIDGAPATRIOT Registered Users Posts: 5
    Re: Need Info On A Small Solar System
    mike90045 wrote: »
    If you are real good the batteries will last 5-9 years. Then, it's only power when the sun shines. So depending on the size/wattage of your pump, you should have twice that in solar PV to make sure the pump will run.

    Like I said I know nothing about this stuff, what is PV? :confused:
  • KamalaKamala Solar Expert Posts: 452 ✭✭
    Re: Need Info On A Small Solar System

    PV = PhotoVoltaic

    That is, solar cells/panels. They convert the energy of massless photons (the "conveyors" of light, or better said, electromagnetic radiation) into electromotive force, more commonly called voltage.
  • BB.BB. Super Moderators, Administrators Posts: 29,736 admin
    Re: Need Info On A Small Solar System

    PV = Photo Voltaic = Solar Electric Panels/Solar cells

    Roughly:
    • Solar panels generate voltage and current (typically >17.5 volts and 5-15 amps) of unregulated electricity.
    • A solar charge controller takes the power/current from the solar panel and dolls it out to the battery... Adjusting the amount of current required to get the battery fully charged (~14.5 volts full charge, drop back to ~13.7 volts for float/storage charge on a 12 volt battery). Two types of charge controllers PWM (pulse width modulation--less expensive) and MPPT (maximum power point tracking--more expensive).
    • Battery--Stores energy and regulates the system DC voltage. Typically from ~11.5 volts to ~15 volts (depending on charging/discharging/state of charge). Rated in Volts and Amp*Hour (or Watts*Hours--how much useful energy is stored in a battery bank).
    • Inverter--Takes the DC voltage (from 10.5-15.5 volts) and turns it into 120 VAC. Two types of inverters MSW (modified square wave--less expensive and not "clean sine wave power") and TSW (true or pure sine wave power--same as utility power--more expensive).
    Each of these, ideally, should be sized to support the daily loads you wish to operate...

    To design a system without knowing your loads is pretty difficult... We could guess that your minimum load is 1.5 kWH per day (Energy Star Refrigerator) plus a few small lights.

    Or we could guess 2x that at 3.3 kWH would give you enough power to live a pretty reasonable life style (washer, water pump, radio, some lights, etc.).

    Assuming you will install the system somewhere around Macon Georgia--Using PV Watts website, 1,600 watts of solar panels, 0.52 over all system derating, fixed solar array tilted at latitude (note--1,600 watts or 1.6kW of solar panels is just a starting guess--nothing magic about that number):
    "Station Identification"
    "City:","Macon"
    "State:","Georgia"

    "Lat (deg N):", 32.70
    "Long (deg W):", 83.65
    "Elev (m): ", 110
    "PV System Specifications"
    "DC Rating:"," 1.6 kW"
    "DC to AC Derate Factor:"," 0.520"

    "AC Rating:"," 0.8 kW"
    "Array Type: Fixed Tilt"
    "Array Tilt:"," 32.7"

    "Array Azimuth:","180.0"

    "Energy Specifications"
    "Cost of Electricity:"," 7.9 cents/kWh"

    "Results"
    "Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
    1, 3.59, 86, 6.79
    2, 4.66, 103, 8.14
    3, 5.46, 129, 10.19
    4, 5.88, 132, 10.43
    5, 5.82, 130, 10.27
    6, 5.47, 116, 9.16
    7, 5.60, 122, 9.64
    8, 5.52, 121, 9.56
    9, 5.01, 108, 8.53
    10, 5.38, 123, 9.72
    11, 4.58, 105, 8.29
    12, 3.73, 90, 7.11
    "Year", 5.06, 1365, 107.84
    So, if you "want 100 kWH per month" from solar--1.6 kW of solar panels will supply you that amount of energy (or more) for ~10 months of the year.

    Battery Bank size should be around 1-3 days of energy storage and a maximum of 50% discharge. For 3.3 kWH of power use per day... Assuming 12 volt battery bank (24 or 48 volt may be better for your needs--but use 12 volts as a start):
    • 3,300 WH per day * 1/12 volts * 1/0.85 inverter efficiency * 1 day of no sun * 1/0.50 max discharge = 747 AH @ 12 volts minimum
    • 3,300 WH per day * 1/12 volts * 1/0.85 inverter efficiency * 3 day of no sun * 1/0.50 max discharge = 1,941 AH @ 12 volts maximum
    The above are just rules of thumb--you may choose somewhere in between or more or less... But this gives a roughly balanced system between solar panels, battery bank, and energy use.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • MIDGAPATRIOTMIDGAPATRIOT Registered Users Posts: 5
    Re: Need Info On A Small Solar System
    BB. wrote: »
    PV = Photo Voltaic = Solar Electric Panels/Solar cells

    Roughly:
    • Solar panels generate voltage and current (typically >17.5 volts and 5-15 amps) of unregulated electricity.
    • A solar charge controller takes the power/current from the solar panel and dolls it out to the battery... Adjusting the amount of current required to get the battery fully charged (~14.5 volts full charge, drop back to ~13.7 volts for float/storage charge on a 12 volt battery). Two types of charge controllers PWM (pulse width modulation--less expensive) and MPPT (maximum power point tracking--more expensive).
    • Battery--Stores energy and regulates the system DC voltage. Typically from ~11.5 volts to ~15 volts (depending on charging/discharging/state of charge). Rated in Volts and Amp*Hour (or Watts*Hours--how much useful energy is stored in a battery bank).
    • Inverter--Takes the DC voltage (from 10.5-15.5 volts) and turns it into 120 VAC. Two types of inverters MSW (modified square wave--less expensive and not "clean sine wave power") and TSW (true or pure sine wave power--same as utility power--more expensive).
    Each of these, ideally, should be sized to support the daily loads you wish to operate...

    To design a system without know your loads is pretty difficult... We could guess that your minimum load is 1.5 kWH per day (Energy Star Refrigerator) plus a few small lights.

    Or we could guess 2x that at 3.3 kWH would give you enough power to live a pretty reasonable life style (washer, water pump, radio, some lights, etc.).

    Assuming you will install the system somewhere around Macon Georgia--Using PV Watts website, 1,600 watts of solar panels, 0.52 over all system derating, fixed solar array tilted at latitude (note--1,600 watts or 1.6kW of solar panels is just a starting guess--nothing magic about that number):

    So, if you "want 100 kWH per month" from solar--1.6 kW of solar panels will supply you that amount of energy (or more) for ~10 months of the year.

    Battery Bank size should be around 1-3 days of energy storage and a maximum of 50% discharge. For 3.3 kWH of power use per day... Assuming 12 volt battery bank (24 or 48 volt may be better for your needs--but use 12 volts as a start):
    • 3,300 WH per day * 1/12 volts * 1/0.85 inverter efficiency * 1 day of no sun * 1/0.50 max discharge = 747 AH @ 12 volts minimum
    • 3,300 WH per day * 1/12 volts * 1/0.85 inverter efficiency * 3 day of no sun * 1/0.50 max discharge = 1,941 AH @ 12 volts maximum
    The above are just rules of thumb--you may choose somewhere in between or more or less... But this gives a roughly balanced system between solar panels, battery bank, and energy use.

    -Bill

    Thanks for the info. I don't understand any of it but I'm gonna look stuff up and try to figure it out.
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