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Thread: Solar beginner 24 or 12 volt panels?

  1. #1
    Junior Member
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    Jun 2009
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    chicago. Ill
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    Default Solar beginner 24 or 12 volt panels?

    I am currently considering buying 160 watt panels that put out 24 volts instead of 12. Will I have added expenses for a 24 volt inverter and battery storage system? Is it worth any advantages vs cost?
    The price is $2.oo a watt but the panels are large about 62" x 24" x 3".
    I live in chicago and would appreciate some guidance.

  2. #2
    Solar Skipper
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    May 2009
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    Jakarta [Lat:06:08South Long:106:45East] Indonesia
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    Default Welcome and congratulation for having new 160w panel

    First of all welcome onboard and thanks for joining the forum.
    And, don't worry, we have a lot of friends here who could share experience and knowledge about installing.
    I'm beginner too, so let's wait more experienced members will explain in detail.

  3. #3
    Solar Fanatic
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    Jun 2009
    Location
    Deland, Florida
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    Default

    The 160 watts solar panel is a 24 volt. You need 4 six volt batteries or two 12 volt batteries. The solar panel puts out 6.6 AMPS at peak. The converter will use up from 5% to 10% of the 160 watts. Or 8 watts to 16 watts. Don't get upset because you are loosing wattage. Really you are producing wattage for free. Now for Chicago. The yearly avg. per day is 3.86 hours of sun light to produce power. June is 6.7 hours. What this means is that your solar panel system will produce in one day in June this is just over 1 KW a day. The worst month is Jan. You will not produce too much power. But for the year your average will give you 194,180 watts produced over a years time. Not much but it is better than paying for electric power.

  4. #4
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    off grid retirement in Northern Calif
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    Default

    Quote Originally Posted by Firermancfd View Post
    I am currently considering buying 160 watt panels that put out 24 volts instead of 12. Will I have added expenses for a 24 volt inverter and battery storage system?
    24V panels CANNOT charge 24V batteries. You need several more volts than the batteries, to pump a charge into them. 12V systems have an EQ cycle at nearly 15V. 24V systems EQ at nearly 30V, and you should have at least 33V to power the charge controller for a 24V system.

    The advantages are, you can use smaller wire, and have less voltage loss.

    Rule of Thumb:

    12V 1,000W max
    24V 2,000W max
    48V 4,000W max
    Otherwise, the battery cables become as thick as a garden hose, and the batteries internal resistance limits the power output.
    Since the dawn of time it has been mankind's dream to blot out the sun.
    Montgomery Burns

    "Always listen to experts. They'll tell you what can't be done and why. Then do it."

    spreadsheet based voltage drop calculator:
    http://www.solar-guppy.com/download/...calculator.zip
    http://www.solarpaneltalk.com/showth...oss-calculator

    http://www.mike-burgess.org/PVinfo_2.html

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,
    battery lugs http://tinyurl.com/LMR-BigLug
    Setting up batteries http://tinyurl.com/LMR-NiFe

    gear :
    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 || || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

  5. #5

    Default

    Quote Originally Posted by Mike90250 View Post
    24V panels CANNOT charge 24V batteries. You need several more volts than the batteries, to pump a charge into them. 12V systems have an EQ cycle at nearly 15V. 24V systems EQ at nearly 30V, and you should have at least 33V to power the charge controller for a 24V system.

    The advantages are, you can use smaller wire, and have less voltage loss.

    Rule of Thumb:

    12V 1,000W max
    24V 2,000W max
    48V 4,000W max
    Otherwise, the battery cables become as thick as a garden hose, and the batteries internal resistance limits the power output.
    Normally the 160W module's Voc is higher than 40V. And the Vmp is higher than 33V. So 160W is ok to charge the 24V battery.

  6. #6
    Moderator
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    May 2009
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    off grid retirement in Northern Calif
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    Default

    Quote Originally Posted by indalecio.feng View Post
    Normally the 160W module's Voc is higher than 40V. And the Vmp is higher than 33V. So 160W is ok to charge the 24V battery.
    VOC is entirely unknown here, only that "24V" panels are being considered. We don't know if that 24V is max power or what. To equalize, you need at least 33V at the max power, not open circuit.

    To the original poster, what is the model # of the panels you are considering ?

    A specific question = specific advice
    Since the dawn of time it has been mankind's dream to blot out the sun.
    Montgomery Burns

    "Always listen to experts. They'll tell you what can't be done and why. Then do it."

    spreadsheet based voltage drop calculator:
    http://www.solar-guppy.com/download/...calculator.zip
    http://www.solarpaneltalk.com/showth...oss-calculator

    http://www.mike-burgess.org/PVinfo_2.html

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,
    battery lugs http://tinyurl.com/LMR-BigLug
    Setting up batteries http://tinyurl.com/LMR-NiFe

    gear :
    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 || || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

  7. #7
    Solar Fanatic
    Join Date
    Jun 2009
    Location
    Deland, Florida
    Posts
    125

    Default

    24 volt solar panel. 12 volt batteries. Between the solar panel and the batteries is a charge controller. I am only experienced with Outback's MX 60 charge controller. This charge controller is somewhat programmable. A 12 volt batter can hold up to 14.8 volts. The MX 60 comes set at the factory for 12 volt batteries. The goal is to keep the batteries at 14.5 to 14.8 volts at all times. Now the MX-60 can do the rest. The MX 60 can take up to 140 volts DC and control the charging of the batteries all the time. It's digital display can show you the charging of the batteries at all times. The inverter is connected to the batteries. You should use 8 guage marine type insolated copper wire between the solar panel or panels. Red wire for positive and black for negative (DC only) The MX 60 (and I am not selling this product I have first knowedge of this product) looks at the batteries and checks the voltages of the batteries (programmable if you wish) and if the batteries need power it charges the batteries. Now for the batteries connect the positive post of a battery to the second battery. The same with the negative post to the negative post of the second battery. You can use and I recommend that you use a 12 volt inverter. What you are doing is keeping the voltage of the batteries the same and increasing the AMP storeage of the batteries. Electricity is strange in a way on the AC side. lets say you need 100 watts AC. 120 volt system would be less than 1 AMP. It is always better to have more solar than you need because of the loss of watts being used by the charge controller and the inverter. The best feature of this type of system of using batteries you are somewhat storing electric power (DC only). Whithout getting too technical another feature of solar is it is expandable. Today you can use one panel. Later on to add more power just add more of the same solar panels and also you can add more batteries and more charge controllers and even more inverters. The only problems I have found by using just one inverter is that if that inverter fails you will not have AC power at all. There are other systems available that do not use inverters and can be monitored via the intranet for checking the system at anytime. Avoiding shading conditions should be the first function of any solar systems. Please stay away from trees. Also please do not cut down trees to make solar electric systems work. Now for the roof conditions. I never install a solar system on the roof. This is not a good idea or practice. You can purchase a solar stand that is movable so that you can capture 50% more sun light in a day. This solar stand is not stationary at all. You can move it from east to south to west. This will increase your electric production by up to 12 hours a day depending on the time of the year. In winter months will be a lot less than summer months. A fixed solar stand for a solar panel or solar panels can only get 6 hours a day power generation during summer months. The goal should be to produce as much electric power as you can in a day.

  8. #8
    Junior Member
    Join Date
    Aug 2010
    Location
    Chad
    Posts
    2

    Thumbs up Inverter

    Good day Sir!
    I have 1200Watts Inverter that will Convert 12VDC to 220VAC.I was use Solar Power to bring electricity to home 212 Hours a day.I have two(2) Solar Panel of 12V/140W.What will be the Capacities of Batteries?Is there any detail left?
    Thank you.

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