Relatively New to Solar

dbaxter78109
dbaxter78109 Registered Users Posts: 2
Hi all, and thank you for letting me in to your community.

I have a couple questions. But first, let me tell you what I have, a mish-mash of things so far.

I have 1 - 200 watts 24v solar panel, a 24v wind turbine.

2 - each Harbor Freight 45 watt solar panel kits (12v), 2 Everstart Marine Deep Cycle batteries (29 group).

Also have 20 each 24v UPS batteries that have been tested and are good. and finally I have about 50 each 12v UPS batteries.

We have a small place very remote (no electric, water or cell service) and want to expand a bit our energy collection. I know I will probably get a bit of a ribbing/chastising from folks on here especially for the Harbor Freight purchase but so far the HF panels have worked well for lighting and, laptops and c-pap with the two Everstart batteries. Also that is all I can afford at this point. Anyway, now I want to incorporate the large panel and wind turbine in to the system or even into another separate system all together. At least one question I have is regarding charge controllers. I am thinking that I need an MPPT type controller and one that will support both 12v and 24v but the question is, will multiple controllers be required being that I have both 12v and 24v? Or can the multi-voltage controller support both voltages at the same time?

I appreciate any suggestions with configuring my current setup and also we do plan on expanding as we go, probably more piecemeal.

Thank You, Dave

Comments

  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Oh so many things and so little time...

    First is your 200 watt panel really a 24 volt panel? most are26-30volt VMP which is too low to charge 24 volt battery bank. You will want to charge around 29volts and after losses from distance, heat, and through the charge controller you won't get there. you can count the cells on your panel, 60 and it will be too low 72 and you have a true 24 volt panel.

    20-24volt UPS batteries, most often these are made up of 6 or 12 volt batteries, so I might question 24volt...

    How do you know they are good? Load tested and capacity checked? or just the voltage is good? You can have near zero capacity and still have good voltage. What size and type are these? if they are high amperage and designed for cycling and not just float with a load now and again, you might consider load testing a few and using them...Mostly we like to see few parallel strings of batteries so 3 strings at what ever amperage that adds up to... if it's large enough to be functional...

    MPPT controller are expensive and generally speaking you will need 2 to charge separate 2 and 24 volt banks... I'd suggest starting with a small PWM CC and see how things go...

    What do you want to do?
    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.
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Welcome, there are several good threads here on using solar for a CPAP. just do a search in the top right corner..
    hth
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    I am a little confused about what components you have and what you want the system to look like in the end.

    In general, I like to define the loads (amps * hours per day, peak amps, voltage, etc.). The loads tell us what size battery bank (AH and Voltage) is needed. Then the battery bank size and amount of sun you get (across the seasons) tells us the solar array size.

    Or, you tell us how much "something" you have, and then we can help you with the balance of equipment... And predict how much energy the system will produce.

    I like to think of the battery bank as the "heart" of the system. Starting batteries (car/truck) / Marine Batteries generally do not make very good batteries for solar power systems (they are not really deep cycle batteries).

    Similar for many UPS batteries (they are usually designed to "float" until there is a power failure, run for minutes to an hour or so, do that several times then get replaced). Also, many UPS batteries are GEL type--Which (at least in the US) do not accept very much in the way of charging current (5% rate of charge--I.e., a 100 AH GEL battery bank would have a maximum of 5 amps rate of charge--Turns out not to match very well with the relatively few hours of sun per day--leaves batteries under charged).

    If you are looking to "step up" for solar power... 6 volts @ ~220 AH batteries (aka "golf cart" type) deep cycle batteries are pretty nice (cheap, pretty rugged and forgiving--If you take care of them). You can usually get them from Walmart or Costco for something like $80-$100 or so each (as I recall).

    2x 6 volt batteries in series gives you a 12 volt @ 220 AH battery bank.

    2x 6 volt batteries in series, with two parallel strings gives you a 12 volt @ 440 AH battery bank.

    or 4x 6 volt batteries in series, gives you a 24 volt @ 220 AH battery bank.

    But even a pair of golf cart batteries requires a fairly large solar array. 5% to 13% or so recommended (4 batteries would be 2x larger solar array):
    • 220 AH * 14.5 volts charging * 1/0.77 panel+controller derating * 0.05 rate of charge = 207 Watt array minimum (weekend/seasonal use system)
    • 220 AH * 14.5 volts charging * 1/0.77 panel+controller derating * 0.10 rate of charge = 414 Watt array nominal (full time off grid system)
    • 220 AH * 14.5 volts charging * 1/0.77 panel+controller derating * 0.13 rate of charge = 539 Watt array typical "cost effective maximum" array
    Your Everstart is probably something like a 100 AH @ 12 volt battery (20 Hour Discharge Rate). So a pair of 6 volt golf cart batteries would be about the same AH rating of your pair of Everstart's.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dbaxter78109
    dbaxter78109 Registered Users Posts: 2
    First let me thank each of you for you reply.

    Photowit - the label on the 200 watt panel states: Max Power 200W, Current 6.95A, Voltage 28.7V, Series Fuse 12A, Open Circuit Voltage 36.2V, Short Circuit Current 7.56A and finally Max System Voltage 600V.

    As for the 24v batteries, it does appear that each 24v battery is a serials of 2 12v. There are no specs on the batteries other than the part number of 911-0050A. As far as if they are functional all I did was measure voltage.

    Westbranch - thanks for the heads up concerning my CPAP.

    BB - Thanks for the recommendation concerning golf cart batteries, and those are actually the way we plan on going but with the exception of the two EverStart batteries we didn't pay a cent. Just waiting until we can get the money to purchase.

    ALL- We are not looking to conquer the world with energy production but we would like to be able to use a small frig, a small LED TV and lighting (and CPAP of course). Currently we only go to our property 2-3 times a month for 1-2 days sometimes more if the weekend is in conjunction with a holiday. We are located in central Texas so typically we have a lot of sun year round. We are located on what Texans call a mountain (just a hill to me) with no obstructions to the sun or wind for the turbine.

    Again, I really do appreciate everyone's input. --Dave
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    A fridge will generally put you in the 1000 watt array area by it's self, If it's just run on the weekends, you might get by with less, Is this in a cool area or how do you intend to deal with heat? regular fridges run more in heat, a freezer conversion might be more cost effective particularly if you're in a hot area... Small fridges use nearly as much energy as larger 'Small full size" brothers. No fans? Radio, battery charging...

    The panel is obviously not a 24 volt nominal panels, if sold that way the seller should be drawn and quartered... or maybe give some lessons in solar energy and battery charging.

    I did a quick search for the battery, might be a sealed hopefully AGM battery around 18 amp, Do you have the weight of one of them? or dimensions? Might give use the UPS # that it came out of, I'm guessing its that size used often in jump packs singles in the small cheap ones and sometimes as pairs in larger ones and often in UPSs for car starting and such. not a lot of storage...
    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.