Solar pond shed

I have a pond that is nearly a half mile from the nearest electrical service. I was considering the possibility of setting up a solar electric system to run an aerator pump, an electric fencer to keeps the cows away and to perhaps recharge my trolling motor battery. I thought about setting this up on/in a small shed.
The aerator would be powered by a 1/3 hp motor.
The electric fencer can run off of 12 v DC.
They make windmill power aerators, but they don't run when you need them most, when it is still.
I had originally considered also using a wind generator so that the batteries could be charged at night when the aerator will often be running, but after lurking on this sight for awhile a small wind powered generator sounds like more trouble than it is worth.
So, let me have it, what do I need? How many watts of solar panels? How many batteries? What type of inverter?

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar pond shed

    You are right about the general consensus of opinion on small-scale wind: more trouble than it's worth.

    They make solar power fence chargers, so that's an easy solution.

    Running a 1/3 HP pump from solar ... is difficult. If we're talking about a standard, "large frame" 1/3 HP water pump you're looking at the need for a 2kW system to make it go because the start-up current is high. Depending on the actual load the run current isn't all that low either. Mine draws 600+ Watts pumping 150' from the lake. Start-up is nearly 3X that, for about 1 sec.

    Maybe you want to redefine your pump specs first.
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: Solar pond shed
    If we're talking about a standard, "large frame" 1/3 HP water pump you're looking at the need for a 2kW system to make it go because the start-up current is high. Depending on the actual load the run current isn't all that low either. Mine draws 600+ Watts pumping 150' from the lake.

    Instead of supersizing the solar just for that 1 sec startup current, wouldn't it also be possible to use a battery based system and a large enough inverter? It might work out cheaper 'cause the batteries will only be used for startup and will spend the rest of their life in float.
  • mike95490mike95490 Solar Expert Posts: 9,362 ✭✭✭✭✭
    Re: Solar pond shed

    Several small aerators, small pumps, each on their own panel ?

    Why do you need to aerate ? too warm for fish (can you shade part of it )

    What if you used straight PV water pumps with a linear load equalizer/booster thingie and pumped water 5' up and let it splash back, instead of pumping air underwater?

    I'm trying to think of a way to avoid batteries, and their maintainance and losses.
    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 ,

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar pond shed
    stephendv wrote: »
    Instead of supersizing the solar just for that 1 sec startup current, wouldn't it also be possible to use a battery based system and a large enough inverter? It might work out cheaper 'cause the batteries will only be used for startup and will spend the rest of their life in float.

    It isn't that you need enough solar panels to supply the power, it's that you need enough solar panels to properly charge a sufficient battery bank that supplies the power. Charging at less than 5% of the 20hr rating results in premature battery death.

    How big the battery bank needs to be is yet undetermined, as it is not only dependent on how big the pump is but also how many hours/day it runs and how long between potential re-charges of the batteries (due to inclement weather).

    So basically inverter size is determined by maximum load, battery size by how long you need to run the average load between charges, and panel size by how much charge current is necessary to properly recharge the batteries.
  • BB.BB. Super Moderators, Administrators Posts: 32,013 admin
    Re: Solar pond shed

    If you can, get DC air pumps and just run solar panels during the day. And, if needed, run a "linear current booster" between the panel set and each motor.

    You might also be able to find a DC powered water pump that can draw air down into the water outlet and both mix the water and aerate... This may be more quiet than running the typical electric air pump.

    Also, I would look at bait tank pumps and such (for boating).

    Try to avoid a battery powered air/water pump system... Makes it much more expensive and complex.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Solar pond shed

    Bill, you confuse me with the "just run solar panels during the day". I didn't know that there was a choice. Did you mean "just run aerators during the day"? The problem is night time and early morning when it is dead calm is the time when aeration is needed most. So, I think we are back to batteries.

    Mike, Why do I need to aerate? Do you really want me to get into destratification, anaerobic bacteria, dissolved oxygen and thermocline?

    One of the pumps that I'm looking at is 1/4 horse, 220ac, 1.5 amps, continuous duty. I realize that a 220 inverter would be more expensive than a 110, but would it help with the start up amp problem? I believe that it pumps 5 or 6 CFM.

    Perhaps instead of "pond" I should have written "lake". This is 15 acres but I just what to aerate small part of it.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar pond shed

    Not that it's actually relevant to the issue (or maybe it is) but why do you want to aerate a small part of the lake? What is the process for? Nobody aerates our lake and it's fine. Have you got a bacteria problem? Trying to promote fish population?

    The larger the lake, the less effective any localize aeration will be.

    That said, have a look at some of these pumps:

    http://store.solar-electric.com/shacdcwapu.html

    It may not be necessary to have an inverter at all for this process.
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: Solar pond shed

    Or this one which includes an MPPT tracker to maximise solar power:
    http://www.lorentz.de/offgrid/en/products/surfacepumps/badutop/_technical_data
  • System2System2 Posts: 6,290 admin
    Re: Solar pond shed

    I want to aerate part of the lake because I only own half of it, and it would cost a small fortune to properly aerate the whole thing.
    Here is a link for those of you who would rather discuss aeration than solar power.

    http://www.pondboss.com/forums/ubbthreads.php?ubb=cfrm&c=6

    Thank you for the links but those are water pumps, not air pumps.
  • BB.BB. Super Moderators, Administrators Posts: 32,013 admin
    Re: Solar pond shed

    Yes, I did mean run the pumps from solar panels only (no batteries) during daylight.

    Very roughly, you can run your solar panel only system for maybe $0.20-$0.30 per kWhr (we can get more exact--based on equipment you need to purchase and how much power you will collect).

    A solar+battery+inverter system can cost (again, very rough numbes) $1.00-$2.00+ per kWhr. Much of the added costs are because of system losses (80% flooded cell battery and 85% inverter efficiencies) and battery replacement every 3-10 years or so.

    If, for your needs, the larger, battery based system is a useful solution--No problem with helping you to spec. it out.

    220 VAC * 1.2 amps * 24 hours per day = 6,363 Watt*Hours per day

    And lets say you live near Minneapolis, Minnesota. Using the PV watts program; pick 1kW of solar panels (just a data point) and 0.52 for Derating--from panel, thru charge controller, to battery, to inverter end to end efficiency (assuming fixed array):
    Results
    
    Month     
    Solar Radiation (kWh/m2/day)     
    AC Energy (kWh) 
    Energy Value ($ at $0.079 per kWhr)
    
    1      3.85          67        5.29   
    2      4.72          72        5.69   
    3      4.97          80        6.32   
    4      4.91          72        5.69   
    5      5.74          84        6.64   
    6      5.91          81        6.40   
    7      5.89          83        6.56   
    8      5.64          80        6.32   
    9      5.21          74        5.85   
    10      4.28          65        5.13   
    11      2.95          44        3.48   
    12      2.85          48        3.79  
    ===========================
    Year 4.74 hrs of sun  849kWr/yr   $67.07
    

    Let us start and assume that you want the system to operate 24 hours per day 9 months out of they year from solar/battery only.

    That would leave out Oct, Nov, and Dec... That leaves Jan at 67 kWhrs per month per 1kW of solar panels (this is power available at the 220 VAC socket). Or

    And your pump requirements are 6,363 Watt*Hours per day or 6.4 kWhrs per day. Or divide by 30 days per month, 2.23 kWhrs per day per 1kW of solar panels.

    (6.4kWHperday/2.23 kWhrs per day) * 1kW of panels = 2.9 kWatts of solar panels (2,900 watts)

    Battery bank size... We start with assuming 3 days of no sun, and 50% maximum discharge for long(er) battery life.

    Battery bank size (assume 12 volt for now--just to give you an idea of how many 12 volt 100AH batteries we are talking about--higher voltage would be better for several reasons):

    6,363 WH per day * 3 days * 1/0.50 disch * 1/0.85 inv eff * 1/12 volts = 3,742 Amp*Hours at 12 volt battery bank.

    Or roughly 37x 100AH 12 volt batteries (large car-sized batteries).

    The above should give you a rough idea of the size of a "rule of thumb" designed system... Of course, I have made assumptions that may not be true in your case.

    Also, you can adjust some of the numbers/requirements up or down by using fewer batteries (1 day of sun vs 3), using a 6 hour On / 6 hour off Timer (1/2 pumping requirements), etc...

    The 6kWHrs per day--comes pretty close to the amount of power I use for my entire home (near SF California, 8kWhrs per day or less, use natural gas for heating, cooking, hot water, etc.).

    24 hour a day pumps just consume a lot of power. Anything you can do to reduce the demand (more efficient, but expensive pumps, changing the pumping requirements/assumptions, etc.) can help.

    Also, I may have guessed wrong where you live will be installing the system. Solar PV array output is very dependent on location and local weather conditions.

    I have not priced the costs of running a 1/2 mile of buried or on-pole wiring to run a 1/4 hp pump--but it might be similar to the costs for this size of solar system ($15,000-$30,000??? plus battery replacement every 3-10 years).

    Questions? Answers?

    Again, the above is a really rough first pass at a solution... Your requirements and how much you will do yourself can affect the sizing/costing of the system by a factor of 2--and I am not a retailer or solar design engineer to give you exact costs/requirements.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 9,362 ✭✭✭✭✭
    Re: Solar pond shed

    bottop of page are some kits:
    http://www.livingwateraeration.com/pondaeration.html
    plan to spend some bucks.

    Other links:
    http://aquahabitat.com/index.html
    http://www.noble.org/Ag/Research/Wildlife.htm
    http://wfs.sdstate.edu/wfsdept/Pond%20Web%20Page/Ch8.pdf

    But if you only own half of it....
    If you cared enough to tell us the problem (water stinks, full of geese, dead fish, choked with algae) We could come closer with suitable solutions (pump air, not water, Water splasher driven by PTO on tractor. Solar power to run day and night, 24/7 is pretty expensive. Daytime solar is about 1/4 the price.
    Whatever.
    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. Super Moderators, Administrators Posts: 32,013 admin
    Re: Solar pond shed

    Just from a simple logistic point of view--

    3kW of panels can drive your 1/4 hp pump for 24 hours per day in January...

    Or 3kW of panels (without batteries) can drive a 1-4 HP pump almost 4 hours per day (equivalent, sun is up for 10, useful for maybe 6, "full power" equivalent for ~4 hours) for 1/2 the costs (no batteries, no charge controller, no battery replacements, no battery maintenance, etc.).

    You know better than I what you need (how fast does oxygen get absorbed, do you need "small" water turns/oxygenation 24 hours per day vs a "large" water turn/oxygenation just a few hours a day, etc.).

    :confused:

    You may be correct to discuss the details about water quality in the forum dedicated to it... Some here may be able to help you will the pump selection (there are some very nice DC powered pumps that play nice with solar panels available--but they are certainly more costly than a run-of-the-mill AC pump)--or even the pond/lake issues itself--but that leaves you answering similar questions in two (or more) forums.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar pond shed

    Couple of points.

    You can pump water up into the air and let it fall back and it becomes aerated.

    Sometimes starting an air compressor is easier than a water pump, as you can let the pressure drop to zero before the motor restarts making it much easier than trying to restart against a load. Pushing air doesn't require as much power as pushing water.

    If this is a matter of wanting aeration to improve the quality of water for usage (rather than the lake itself) then you could lessen demands further by only treating water on an as-needed basis.

    Lots of possibilities here, but you're going to want to get your power requirements down to the minimum to provide the service you're after before trying to run with solar.
  • BillFBillF Solar Expert Posts: 48 ✭✭
    Re: Solar pond shed

    For my garden pond (8'x8'x4'), I use a 12vdc bilge pump powered by a 85 watt Sharp panel and fed through a old time vehicle ballast resistor. Sun comes up-pump comes on-sun goes down-pump slows and turns off. The pump I use will flow at 600 to 800 gph w/o a problem. Of course your flow rate will vary with lift a available power. I have about a 18" lift to the waterfall. The pump usually needs replaced after one season due to the sleeve bearings not designed for full time operation.
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