wayyy too new to this, but wana learn

System Posts: 2,511 admin
Hi everyone, im very new to this but im interested in learning. I want to build a solar panel, i found a web site that sales broken solar cell and i wana buy a couple of boxes and put them together http://www.goldmine-elec-products.com/prodinfo.asp?number=G4497

and i already have some sources that will help me put them together but my question are the fallowing,

1. are those cells worth buying from that site?as in the quality of those cells.
2.i have a 36 watt fish tank that i keep on for about 8 hours a day, how big (LxWxH) would i need to achieve this (if possible)
3. what else would i need to know to make this happen (type of battery,wires,controller etc...)

thanks for any advice and info provided,again im new to this but really want to learn thanks :D


  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    Re: wayyy too new to this, but wana learn

    Do a search on this forum for posts of others building panels.

    Simple answer is don't waste your time or money. You can't build a quaility panel for less than buying a manufactured one, no "if's" "or's" or "Butts" about it.

    As for powering a FishTank ... quick math would suggest about 300 watt/hours and you'll need about 120 watts of solar to handle that with a very little margin. Also, pumps should be run 24/7 on Fish Tanks or your Fish could have some serious health issues
  • System2
    System2 Posts: 6,290 admin
    Re: wayyy too new to this, but wana learn

    wow 300 watts/hour thats crazy lol, y isnt it worth buying broken n puting together (not to be disrespectfull just curious), i mean if u buy enough but i know the time to put them together would looooots,is there any cheap 1's out there? (like 200 bucks)

    and as for the fishs i have the pumps running 24/7 but its just the lights thats killing my bills and want to see if theres an alternative solution to powering them up, pluse dont those solar panel produce an DC current and not AC current?? so im assuming that i would need some converter if i where to do this right??

    thanks again
  • BB.
    BB. Super Moderators, Administrators Posts: 33,404 admin
    Re: wayyy too new to this, but wana learn


    If you want to play with solar cells--go ahead and buy some loose ones and mount them under window glass.

    If you want the system to last longer than 6 months, purchase commercially made mono or poly silicon panels. These will last well over 25 years without anything more than being washed off once in a while.

    Since you apparently want your solar panels to power your tank for more hours than there is full sun in a day--then you need an off-grid type system. Solar panels + charge controller + batteries + inverter + wiring + fuses...

    For 40 watts in NY City--see this link and enter 1kW for solar panels and 0.52 for system derating (off grid)...

    1 kW of panels will generate a minimum of 60 kwhrs per month or 2kWhrs per day for 9 months of the year...

    Your system, 40 watts * 8 hours = 320 watt*hours of power usage.

    Using the 1kW of panels makes >=2kW of power per average day:

    1kW/2kW * 0.320kW/day=160 watts of solar panels (panel Vmp >= ~17 volts)

    Use this page
    to pick a charge controller... 160w/15v=10.6 amps (size of controller). If you can justify the price--this Morning Star MPPT type controller is the best for your system and you can learn a lot from using it. Would allow you to use high voltage panels (Vmp >> 17 volts). For best results, always get the remote battery temperature sensor option.

    Then, you would probably need an inverter... Staying in the Morning Star product family--this is a very nice one. Very power efficient at low loads and also is a "pure sine wave" type... For a fixed/permanent installation, usually better to go with pure sine vs Modified Square Wave types... MSW types tend to waste power when running motors/inductive and some electronic loads--plus some sensitive equipment will not last long when supplied with MSW power.

    Next, a battery... Get a true storage battery instead of an "RV" type--will last much longer. The battery should be 6x your daily use (estimate--but very good starting place--3 days for no-sun and do not drain below 50% for long life).

    6*320 watts*hours / 12 volt bank = 160 amp*hour rating at 12 volts.

    Two of these 225 amp*hour batteries would be good (a bit larger than you need--but you can find "golf cart" batteries in your local stores too).

    Lastly, you will need some sort of timer to turn on/off your inverter for the lights... Something like this, tied to the "remote power" switch on the MorningStar inverter would work nicely.

    Add a mount for your solar panel (so it is not blown off by wind), some UV rated wiring (and/or conduit), fuses, etc. and you are ready to go.

    The above system will not be cheap--you can probably save about 50% by looking around for alternatives (used panels, non-MPPT controllers, use MSW inverter, cheap RV batteries, mechanical timer)... But each change will introduce other issues/problems and may impact other parts of your system. (example, MSQ may use 20-25% more power on electric motors, so your solar panels will have to be 25% larger).

    Also, you can make the system more expensive. Install a battery monitor (a very good piece of equipment to make sure you are treating your expensive batteries correctly) or at least a good hydrometer/DVM.

    Batteries generate hydrogen gas--so they need to be vented (not just put under a bed--plus they do let out some acid mist too... So, you may wish to look at AGM batteries instead--a much "cleaner" solution (still need venting for safety, but much less gassing/acid with proper operation). But again, these cost more money.

    At least the above is a start....

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: wayyy too new to this, but wana learn

    bb, he also mentioned the light for the tank. now irving, this will add to the needs even if the lights are dc. dc light choices are straight bulbs(consume much power), cfls, and leds (lower total light and directive, but lowest consumption of watts) with the latter 2 being somewhat high in costs.
    do check the archives as there was another in depth discussion related to a fish tank. do some reading so you can learn before jumping into this even if you don't make the pv. there have been threads on making them as well and, even though high priced, you won't beat the quality for the price of commercial pvs.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,404 admin
    Re: wayyy too new to this, but wana learn


    Yea, those post where while I was typing my reply...


    Basically, if you are trying to save money--you need to look at grid tied solar--that is the only one that will even come close to possibly saving you money...

    Basically, a grid tied system is going to cost you around $0.30 per kWhr (in New York, you may get some good rebates--check them out). May get you under $0.15 per kWhr. (no interest charges, no property taxes taken into account).

    Off-grid with battery--over $1.00 per kWhr...

    Look at your power bill--$$/kWhr... Otherwise, if you have, for example, a saltwater + coral aquarium... The lights are going to be expensive to run.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: wayyy too new to this, but wana learn

    i don't think anybody is going to invest in a solar grid-tie arrangement for a fish tank as that would be overkill and out of the price range don't you think?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,404 admin
    Re: wayyy too new to this, but wana learn

    Seen some pretty elaborate setups that have included some very expensive fish/coral/specimens. My father in law has a 2,000 pond with koi--pump and UV lights constantly running.

    And grid tie can reduce the power usage of the entire home... And with the 75% rebate that somebody else here was getting from New York--sure makes it worth a look.

    Plus grid tie is much less than off-grid for fish tanks/ponds that have been asked about here. However, there seems to be little out there for small grid tied systems--tends to push the price up ($/kWhr generated).

    In the end, I agree, there are no $200 solar PV systems out there that will save anyone very much money vs grid electric power...

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: wayyy too new to this, but wana learn

    > solar grid-tie arrangement for a fish tank

    Well, if you factor in the long view of 20+ years, you can break even.
    If you have an exotic fish business, you may get a insurance discount, if you install a PV battery system, and then after a disaster, you will be the only stocking dealer in town as folks rebuild their tanks. High demand, short supply.....
    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 ,