3 Volt Solar Panel

Depending on your needs, you may have to use some or all of the following tools and materials: solar panel(s), 12V "car battery" (deep-cycle lead-acid battery), diodes, insulated wire, wire cutters, pliers, wrenches, and screwdrivers.

Let's imagine that you bought a solar panel with a certain maximum output voltage and certain amperage. Now you need to hook it up to a battery. All batteries have specific amp ratings. You will need to determine how many panels will charge your battery adequately.

Once you do the calculations, you will need to either connect the panels straight to the battery, or use a diode in between. It is better to use a diode between your cell(s) and the battery, especially in the systems larger than 12V. If you do not use a diode, your battery may discharge at night. What diode will you need to use? You need a diode of the same (or more) amps as your panel.

3 Solar Panel Battery Wiring Samples

1. Connecting Solar Panel and Battery (Without a Diode):

- Panel's "plus" to battery's "plus".
- Panel's "minus" to battery's "minus".

2. Connecting Several Panels in Parallel (for more power), and then to a Battery:

- Each panel's "plus" to other panel's "plus", and so on.
- Each panel's "minus" to other panel's "minus", and so on.
- The last panel's wires to the battery (follow the two steps from the 1st example).

To calculate the total amperage of your array, add the amp outputs together. Voltage stays the same.

3. Connecting Solar Panel, Diode, and Battery:

- Panel's "plus" to diode's "in".
- Diode's "out" (the end with a black or silvered line) to battery's "plus".
- Panel's "minus" to battery's "minus".

Notes about Solar Panel Battery Wiring:

1. Remember, going below the battery's voltage will not charge the battery fully.

2. Note that a diode will decrease the voltage.

3. Some lead-acid batteries may need a regulator providing certain voltage in order to leave them on forever, without an overcharge damaging the battery. Otherwise you will need to switch your battery off manually when it's fully charged.

When your solar panel starts to produce energy, this energy can either dissipate or be diverted into a battery for your future needs. Many people choose to use systems with batteries, which allow for a power backup. You can also use batteries for your outdoor equipment (golf carts, tractors, motor boats) and various portable devices (laptops, cameras, cell phones, electric fans).

However, remember that you don't necessarily need to use batteries in your home system. You can have the energy generated by the panels fed into the grid, thus eliminating the need for any batteries.

Frequently Asked Questions

  1. QUESTION:
    Can a 3 volt solar panel eventually charge a 6 volt battery?
    Even if it takes a long time, will it EVENTUALLY work?

    Thanks in advance.

    • ANSWER:
      Yes, if you pass the output through a step-up transformer whose output is > 6V.

  2. QUESTION:
    Is a 3 volt solar panel with a 6.5 mA broken?
    well, I've got an old solar panel kit from some relatives of mine. Well, as a kid, you can probably guess that I put in a closed circuit backwards and all sorts of dumb things. well, I tested it with an electrometer and it is capable of giving up to 5 volts, but only 6 mA. I am guessing I fried something because now I can't generate a small motor the size of your thumbnail. I'm not sure that it's something painfully obvious, but it doesn't hurt to ask.

    • ANSWER:
      It would help if you told us the size of the panel. Were your measurements made in bright sun?
      3 volts x 6.5 mA = 20 mW

      The smallest one I found for sale has a power level of 80 mW, 4 times the one you have. It has an area of about 10 cm² or about 1.6 square inches. If your panel is a lot smaller, then that may be normal.

      But I think it is damaged.

      .

  3. QUESTION:
    what is the cost of a 3.0 volt solar Panel?

    • ANSWER:
      depends on the size and power capability.

      One that powers a calculator is about 10 cents.

      Large arrays can cost thousands of dollars.

      .

  4. QUESTION:
    How Long Would It Take For A 3-Watt Solar Panel To Charge A 7-Amp (SLA-Gel) Battery?
    I have been using solar to charge my small electronic devices (cell phones, MP3 players, ect) for a while now, but I recently upgraded to a setup with more power. I'm now using a small 12-Volt/3-Watt Solar Panel and a 12-Volt/7-Amp Sealed Lead Acid Gel (SLA) battery. My question, how long would it take for a 3-Watt Solar panel to charge a 7-Amp battery? Basically is it safe to leave the charger in the sun during the day; so I can then charge my small electronics off of it at night? Is there a possibility that several hours of Day-Light could Overcharge this type of battery?
    Thanks for the help! The setup is really simple for now but I can always change things to make it better. This is the first such kit I have built; so I'm still new to this. The previous Solar Chargers that I have used so far either came with batteries built into the device, or had slots for rechargeable batteries to be Added/Removed.

    So this is the setup as it exists now.

    1. 12-Volt/3-Watt Weather Proof solar charger.
    1. 12-Volt/7-Amp Sealed Lead Acid Gel Battery.
    1. Female Cigarette Lighter socket, adapted with 2-Spade connectors to connect to the battery terminals.
    1. Cigarette Lighter-to-USB adapter.
    1. Cigarette Lighter-to-AC/Inverter adapter.

    Should I change, add or remove anything?
    Oh, and I forgot to mention that I'm not worried about charging the battery completely; I just don't want to overcharge the battery. I just need the battery to soak up what electricity that it can from the solar panel during the day; so I can recharge my personal electronic devices at night. So even if the solar panel only charges the battery 50% that day, that is okay. As long as I'm not running the risk of overcharging. And nothing else will be connected to the battery when it is charging.

    • ANSWER:
      A 7 amp battery is pretty big. I have a 12V 4.5 amp battery and it takes a week to charge with my 12V 0.144 amp solar panel, when placed in direct sunlight.

      In the equasion A= W/V, 3 watts / 12v is 0.25 amps. Thus for 7 amps, you will need about 28 hours (7 / 0.25) of sunlight to charge the battery. That's assuming I used all the correct calculation. As long as the voltages are right there should be no problem with burnout. If you're using an inverter, that will take some energy to maintain so I'd add a couple hours just to be on the safe side.

      That 28 hours is assuming you don't use the battery at all and it goes from empty to full in that time. Using it will obviously require more time, which you can calculate by checking the wattage usage of your devices. Cell phones are usually about 5 watts, mp3s, 1 to 5 for small and more for higher capacity or video models).

  5. QUESTION:
    What's the relationship between a battery(1219mAh, 3.7 volts) and a solar panel (4.2V, 22A)?
    I need to know how long, if even possible, would the solar panel charge the battery. If you need any other information ask.
    Battery: 3.7 V, 1219mAh Solar Panel: 4.2 V, 22 mA

    • ANSWER:
      It is very marginal. It may charge the battery, but only during bright sun, when the sun's rays are perpendicular to the panel. Remember, depending on the battery type, the charging voltage has to be a few volts higher than the battery voltage. And when the voltage from the array drops below 3.7 volts, the battery will discharge through the array.

      Usually you would put a diode between the array and the battery to prevent this from happening, but there is not enough voltage for that, the 0.7 volts drop across the diode would reduce the array's voltage to 3.5 volts, and the battery would never charge.

      .

  6. QUESTION:
    Help!!!!!!!! i bought a six volt solar panel and it won't light up a 2.5 v light bulb or a 1.5-3 v motor. what?
    i let it soak in the sun, i did the + - both ways, made sure it was hooked correctly, bought a different solar panel with the same result. any help?
    at the time i hooked it up it was in the sun. and i don't have a meter. does anyone know where i can use one. not neccesarily buy but use for a minute or so. and wut is the difference between ac and dc motors

    • ANSWER:
      You need to check the amperage or wattage of the panel as relates to the item that you are trying to connect it to. You need power to drive a load (bulb, motor...). The panel may be underpowered.
      The panel does not store energy so it needs to be in the sun all the time.

      Power (Watts) = Current (Amps) * Voltage (Volts)

      check that the motor is a dc motor as well, not an ac motor
      maybe test them both with a small lantern battery first

  7. QUESTION:
    Can a 12-volt battery be charged from a 6-volt solar panel?
    I asked this before and was told no...
    http://answers.yahoo.com/question/index;_ylt=AlwroSBZWvLJ3KGcoCRYrHDsy6IX;_ylv=3?qid=20080922115433AAr34Rr
    Now I want to know, will it work if a 12-volt capacitor is added. Then the capacitor would charge up 12-volts, and the batteries would recharge from the 12-volt capacitor. I do know a capacitor can charge beyond its input voltage.
    Will this work?

    • ANSWER:
      If you charged two 6-volt capacitors in parallel, then put them in series, you could produce 12 volts. You could theoretically make a DC-DC converter in this way, by using transistors to alternate these logical connections. However, such a circuit would be lossy.

      A much better circuit would be a boost converter using an inductor. The basic idea is that you build up current in an inductor, then quickly switch the inductor over to the battery. In theory, the same current keeps flowing for a while, no matter what the voltage of the battery. There are limits, but you need not worry about them between 6 and 12 volts. Look up the AP34063 on the web, that would be a good part for boosting 6 volts to 12. There should be sample circuits included on the data sheet. You wouldn't even need to set the output voltage, as the battery being charged would do that for you, and you would just be pumping current into it.

      Honestly, if you don't want to fuss, it would be much better to just get a panel designed to charge a 12-volt battery, which would be more like an 18-volt panel.

  8. QUESTION:
    Can you charge a phone with a small solar panel?
    I have a small solar panel that outputs around 3 volts, and it probably doesn't have much amperage. I was wondering if I could simply hook up the solar panel's wires to my phone charger's wires (that plug into the wall) and charge my phone, without any voltage changer or anything. Would this work?

    • ANSWER:
      Check into your phone and find out how many volts it has within the battery. You never know until you try though right? Worst thing that can happen is that the phone takes a while to charge.

  9. QUESTION:
    How much energy you need from a solar panel to charge a battery that has 3.75 volts?
    What is the difference between the "output" and "input" in a charger?
    What do you call the power from the charger that goes to the cellphone? output maybe? or input?
    How much power the charger produces to charge a cellphone?
    Please answer my questions...
    Thank You!

    • ANSWER:
      To make things simple.....
      I would look at the regular cell phone charger (wall plug type), and it says on it, for example, Output 5V DC 0.7 A
      This is what your solar cell should deliver at full sun blast.
      The regulating circuit for charging your cell phone battery is inside the phone, so even if your battery is 3.7Volt, the charger delivers 5 Volt.

  10. QUESTION:
    How many Volts and mA would a solar panel require to charge a 3.7 v li-ion battery?

    The Battery is 1500 mAh at 3.7 volts. So would it be more efficient to use a 6v 60 mA solar panel, or a 2v 200 mA solar panel to charge the battery?

    • ANSWER:

  11. QUESTION:
    Does the solar panel must have the exact formula in the output of the charger to charge a cell phone battery?
    In my case, the output of the charger to charge a cell phone battery with 3.7 volts is 3.7 volts and 355 mA which equals to 1.3135 watts…

    So if I want to charge my cell phone battery thru a solar panel, the solar panel must have 3.7 volts and 355 mA which equals to 1.3135 watts... Is this ok??

    How long (hours) this would take??

    Does the solar panel must have 3.7 volts and 355 mA to charge my cell phone battery OR is it ok that the solar panel will have different volts or only the mA as long as it equals to 1.3135 watts?? If it’s alright, what is the maximum volts or mA it can have??

    I’m very, very confused… Please help me….

    Thank you very much!!!!! : )
    Please answer even just the LAST question... Please!!! Thanks!!! : )

    • ANSWER:
      I wonder how often you are going to ask this same question.....?
      The answer is so simple:
      Look at your "normal" (wall plug) charger for your phone.
      It says there "Output: V= (or DC), mA".
      And this is what your solar panel has to provide.

  12. QUESTION:
    How long will it take to charge a battery by solar power?
    I have a 3 volt, 1000mAh battery that I want to charge with a 1 volt, 100mA solar panel. How do you calculate the time it will take to charge the battery?

    • ANSWER:
      First you have to transform the panel energy to a higher voltage than the battery. Cars charge their 12 volt batteries at around 14 volts. You could do this by running several such panels in a series to make the voltage additive or you could use a transformer. Assuming 100% efficiency (not realistic) then stepping up the voltage to 4 would reduce the solar panel amperage to 25 giving you the same 100mA charging potential. Again assuming 100% efficiency in the charging process it would take 10 hours.

  13. QUESTION:
    I have a solar powered light for a clock but it is always on. How can I make it dusk to dawn or work @12 volts
    The solar panel is 3 volts now and if possible I would better like to tie it in to my low voltage lighting system

    • ANSWER:
      It can be done but you will have to install a on/off switch to the bulb

  14. QUESTION:
    how fast are 3 coleman cl 600 solar panels supposed to charge a car battery?
    I have 3 Coleman CL-600 9 Watt 17 - 24 Volt Solar Panels wired into a coleman cc 4000 charge controller in parallel which is then wired on to my car battery. They aren't charging my battery as fast as I would like (takes a full day of direct sunlight to charge the batter just a little bit). Is this normal? Are my panels generating enough power to charge the battery? How fast should it take to charge a car battery off of a solar powered system? HELP!!!!!!!

    • ANSWER:
      with no load on the battery - no clocks, no lights, it will take about 30 days to recharge a #27 size car or deep cycle battery.

  15. QUESTION:
    what can i power with 36 .5V 3.5A solar panels?
    i plan to make my own solar panel, as a learning experience and im curious to what 36 panels each rated at .5 volts and 3.5 amps would power and for how long.

    • ANSWER:
      What the other guy said, use it to charge a battery, BUT NOTE! The panel you are talking about is big enough to seriously damage even a car-sized battery by overcharging it.

      Use a charge controller:

      http://www.windsun.com/ChargeControls/ChargeCont.htm
      http://www.wholesalesolar.com/products.folder/controller-folder/sunguard4.html

  16. QUESTION:
    Car battery charging with Solar Panel?
    I hooked up a 102 watt solar panel to a 20A charge controller. I hooked it to my 12v lawn mower battery. The battery alone registered 12.3 volts. When hooked to the solar panel controller, it measured 14.2 volts across the terminals. Is that voltage too high for charging? Will I fry the battery? Thanks.

    • ANSWER:
      The charge controller will protect the battery. You might want to think about getting a fuse.

  17. QUESTION:
    Charging batteries with a solar panel?
    13.8 volts is required to fully charge a battery. But at 13.8 volts, the battery can be overcharged without the use of a controller correct? What if I don't care if the battery is fully charged? In the case of our family boat, I just installed a new radio, so I'm a little worried about power consumption. So now for the real question; If I hook a 12 volt panel to the batteries, do I need to worry about overcharging them? Or will the batteries stop the charging process once they reach 12 volt?

    I built the panel myself, it's 18 volts at 3.5 amps open circuit. I have tabs at every 3 volt increment on the panel so that I can use less voltage than 18 if I want to power something directly, (ex:12 volt radio)
    So I'm using the 12 volt tab at 3.5 amps(approx) for a total of approx 48 watts
    But what I'm asking is, if I use 12 volts off the solar panel, can I just leave it hooked up to the battery without fear of overcharging?

    • ANSWER:
      I have been using solar panels for over ten years & never until recently bothered to use a charge controller, it depends really on how much power your batteries can hold & how often they will be drained from use of the connected dc-ac inverters.

      While constant daylight charging at 18v 3.5a/hr is quite heavy it is not excessive, 12v lead acid battery chargers give a voltage output of appx 14.8v but the fluctuating output of a solar panel means you may well charge at 18v for some time but with occasional shade etc it will more likely average at 15v which I think is quite acceptable.

  18. QUESTION:
    How many volts would the solar panel with this shed light be rated for?
    http://www.homehardware.ca/Products/index/show/product/I3646645/name/lamp_shed_solar_led
    It's a 5 watt panel, but I don't know how many volts it puts out. I was wondering because I have 3 of them and just thought of an idea... I'd like to see if I can hook them up together to charge a deep cycle battery if at all possible...

    • ANSWER:
      Not enough info to tell. Hook all three up in series, put them in the sun and take a reading with a DVOM. You will need at least 15 open circuit volts to charge or maintain a 12V battery.

  19. QUESTION:
    How can I charge a laptop and other electronics from a solar power charged 12 volt car battery?
    I live in a village in Africa as a humanitarian aid worker. My only source of power is a 30 volt solar panel. I have it wired into a 3 stage controller and from there into a 12v/150ah car battery. Everything is wired correctly and working. Here is my problem. I would like to be able to take a portable DVD player or my laptop out into the field if possible. Most of my electronic plugs take 110v or higher voltage and have outputs ranging from 9-19v. I do not have an inverter and do not have access to one so that is not an option to increase my voltage. Is there a safe way (for the electronics) to charge them directly from the 12volt battery instead of the factory given plug that requires 110-240v. In your answer consider me ignorant as this is my first foray into solar power and electrical wiring. In short, don't assume I know anything about electricity in your response. Thank you.

    • ANSWER:
      use your lead acid battery as the main charger
      1 battery gives you 12v
      2 batteries gives you 24v ( connect the battery in series of course)
      now how to make the voltage drop to suit your required voltage? use high wattage diodes. One diode drops the voltage by 0.7v. Two in series will give you 1.4v drop.
      e.g. your lap requires 19v dc to charge, you connect 7 diodes in series and wire them to the 2 batteries with 24v output total. Final output voltage will be 24-0.7x7=19.1 roughly

      You can ask your pal back home to send you 10-20 diodes (low voltage, high current 3A-6A) which only cost a few US cents each..

      Your portable DVD also runs on DC, check the DC voltage and adjust the battery voltage by diodes as described above.

      Of course the simplest way is to buy the inverter

  20. QUESTION:
    how big of a solar panel would you need to power a playstation 3?
    i can't stand the amount of power that the ps3 sucks down. i'm thinking of building a small solar panel for my roof. i need to know how big of a solar panel i need. not in size but like watts and volts and amps.

    10pts. for best answer

    • ANSWER:
      you have a manual, what does it say about power requirements? That will give you the watts.

      Assuming you want to run it off 120 VAC, you need a 12 volt battery and a 12 vDC to 120 VAC inverter rated at the power in watts. Then you need a small-medium lead acid sealed marine battery, and a solar array capable of 15 volts and the wattage of about twice the wattage number you have.

      .

  21. QUESTION:
    How do I increase the speed of a solar car ?
    Mine's currently moving 7 seconds per 5 metres, and that's INCREDIBLY slow. I've heard of solar cars moving approximately 2 seconds for exactly the same length. Can anyone please tell me how can I increase the speed of my current solar car? I really am no good when it comes to physics or any of these things.

    What's the best type of tyres, to move on a rubber track?

    How do I increase the volt of my solar panel, without increasing the watt? Can I put together two solar panels, of 3 volts each and 1 watt, in serial instead of 1 solar panel, 1.5 volt and 1 watt? Which one will move faster?

    • ANSWER:
      OK, let me think whether you are out of your mind or not....
      5 meters in 2 seconds equals 2.5 meters in one second. One km has 1000 meters, and one hour has 3600 seconds. So you are asking for a speed of 9km/hr, which equals a fast-walking pedestrian. I would say this is achievable.
      But what makes "fast" solar cars different is that they do not take the juice for the motor directly from the solar panel, but the solar panel charges a battery (with high Amp/Hrs), and the motor is not a "toy-style" 3 Volt DC motor, but a motor that can produce incredible torque (thanks to the battery bank's high current it can supply).
      Therein lies your problem.

  22. QUESTION:
    How many watts does my solar panel need to be if I am running lights only at night?
    I want to use 12vDc rope lighting that is 3 watts per foot and i am looking to use approx 64 ft of light. I am probably only going to have the lights on for 3-4 hours at night. I will be running the lights off a 12 volt car battery. What wattage will my solar panel need to be to recharge the battery during the day. I would appreciate any help, Thank You! I am also looking at led lighting that is only 0.8 watt per foot.

    • ANSWER:
      Here is the math.

      3W/ft * 64 ft = 192W
      4hr * 192W = 768Whr <--- energy needed per day

      768Whr / 12v = 64Ahr
      64Ahr * 200%(d-rate) = 128Ahr <--- Your battery needs to be a minimum 128 Amp - Hour to opperate without damaging itself.

      At Boise, Idaho — Latitude: 43.6 we get 5 sun hours per day average
      If your latitude is less than that, your sun hours will likely be greater.

      768Whr / 5hr = 153.6W ~ 160W panel required.

      I highly recommend that you get a charge controller in addition to this panel, as it will protect your batteries and enable charging during low light conditions. Some even come with automatic light timers and or motion sensors:
      http://www.aurorapower.net/products/list/1/categoryid/13/level/a.aspx

      For more information on solar electric components and layout visit: http://www.aurorapower.net/alternative-energy/solar-electric.aspx

      Hope that helps!

  23. QUESTION:
    Whats parts do i need to connect a 5W solar panel to a 12v battery?
    I want the solar panel to charge the battery.
    how long will it take to charge the battery ?
    how can i control the out put volts from the battery?
    and if i can control the volts how long will the battery charge last if i'm charging a phone or sumin at 5v.
    how can i prevent battery over charging.?
    battery= 12V 3.4Ah 3.4amp.
    solar palen = 5W 12V

    • ANSWER:
      If the panel hasn't a reverse protector diode, add one. You should use a 12V1A Shottky diode.
      For safety, you should also run a 1 A or so fuse in series. You should also consider a charge controller.

      A 5W panel practically may output 300ma. It might practically take around two days of normal sunlight to fully charge that battery with that panel, longer if you don't have that much sun.

  24. QUESTION:
    will a 5 watt solar panel charge my 12 volt battery enough to turn on the water pump in my rv?
    After reading a ton of info on solar panels for my rv I am even more confused. I don't think I want anything that is technical just the solar panel with the clamps that connect to the battery terminals. I don't have a lot of things in the camper: water pump, water heater (lp heated), 3 lights. I don't spend a lot of time in the camper so how many watts of power would I need to keep my marine battery charged for the week?? (estimated)

    • ANSWER:
      A lot depends on total usage of the pump. 5 Watts is at best marginal even for a small pump. A 15 Watt panel would be almost adequate. 30 Watts would likely work the best. This assumes an on demand pump rather than one that holds pressure on the line.

      At 30 Watts, you are producing only 2.5 amps on a 12 volt system. This enough to replenish the charge on a fully charged battery in light usage.

  25. QUESTION:
    3 volt fixed regulators?
    I'm looking for a part, something like an LM317, but with a fixed output of 3 volts. Something that could received varying input voltages (from a solar panel) but still put out a consistent 3 volts. As long as the input voltage was greater than 3 volts itself.

    • ANSWER:
      If you are looking for a 3-terminal regulator, and don't want to deal with the zener diode & resistor hassle, you should get your hands on an LM7833. These are usually good for 1 Amp, depending on the input voltage.

      Here is a typical datasheet:
      http://www.alldatasheet.com/datasheet-pdf/pdf/173599/UTC/LM7833L-TA3-G-T.html

      Just remember to heat sink the guy.

  26. QUESTION:
    Were can I get solar recharger for a 9-volt battery?
    I already have one that can recharge AAA, AA, C, D, and cell-phones, and I have 3 small 6-volt panels, but the only thing I can find for 9-volts has been discontinued.

    Also, I know this is EXTREMELY unlikely, but does anyone know how I could get panels cheap, ether used or defective is ok, as long as the work a little.

    • ANSWER:
      http://cgi.ebay.com/Solar-Panel-AA-9v-battery-charger-3-6-9-12-volt-sup_W0QQitemZ390032022761QQcmdZViewItemQQptZElectrical_Solar_US?hash=item390032022761&_trksid=p3286.c0.m14&_trkparms=72%3A1205|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A0|293%3A1|294%3A50

  27. QUESTION:
    I just bought 36 solar cells, One cells gives me gives me .5 Volts and 3.5 amps..?
    I want to build a 60 watts, 12 volt panel, and 3.5 amps is given off of each cell .. i bought a charger controller that is for 12 volt but it only says 7 amps.. can i connect that will the panel once finish?

    • ANSWER:
      A 12 volt panel can either be 33 cells or 36. 36 is better. The open circuit voltage will be at least 18 [36 x 0.5v], but likely higher. You want it higher since a 12v battery is fully charged at about 14.2v.

      A 7 amp charge controller is fine. Your panel's actual current output depends on the load it is connected to, in this case the battery. Even at 12v, a 60 watt panel puts out 5 amps. As the battery voltage rises, the current drops.

  28. QUESTION:
    What additional items do I need to make my solar deer stand more functional?
    I have a 6'x8' deer stand, well insulated, made of cedar, 12' high. I already have a BP 120 watt solar panel, small charger, and a 400 watt inverter. Last year I used 3 optma blue top deep cycle/starting batteries in series, giving me 3 12 volt batteries total output of 12 volts. I have a 30 inch flat screen tv/dvd player combo, a small icebox that only draws 1.2 amps, a 750 watt microwave, 2 100 watt light bulbs, and an airconditioner/heater, which draws ac-5.0 amps, and heat 8.0 amps. Tv draws about 100 watts. Last year this system would only run tv & icebox, and run bats. down less than 3 hrs. Panel was on ground running up to charger with small ga. wire, and 20+ ft. Now panel is mounted on top, with largest wire that would fit. What rec. do you have on battery size, inverter size, and charger size? I want to be able to leave all on 24 hrs a day 7d a wk.? no lights tv or ac/heat while not there. Just Icebox while gone. I hunt 3 days at 4 hrs max which would use tv,ac/heat, microwave
    I forgot to mention that I must have the power to run my dish network sat., which uses about 10 watts.

    • ANSWER:
      You don't have a deer stand!!!!!!! you have a condo!!! Get real and go out and hunt like everyone else.

  29. QUESTION:
    Solar panel connected to battery ??
    im doin a science experiment and i have a battery that is 3.6 volts , does it matter wut voltage the solar panel that im connecting it to is . Does it need to match , be less or does voltage have no effect . If so wut does matter when choosing the type of solar panel to power a bettery?

    • ANSWER:
      You really need a little more infomation about your battery. It should have a recommended range of charging current. You should not exceed that range. Your solar cells must be a higher voltage than the battery, but you should not connect the cells directly to the battery. First, you need a diode in the line to keep the battery from draining into the solar cells when there is no light. Second, you need a resistor to limit the charging current. You have a 3.6v battery. Let's say the charging current is 0.1A. Use a 5v solar cell and silicon diode. The diode will drop the cell voltage to 4.3v. The voltage across the resistor will be .7v for .1A current, you need a 7-ohm resistor.

  30. QUESTION:
    Solar powered helicopter help?
    I am trying to make a solar powered helicopter without a controller. It will be attached to a string like a kite. Will that work? And how many volt solar panel do you think I should get? It will be powered by 2 motors from R/C cars. I am not sure how strong they are. They run pretty well on 3 or 4 AA batteries.
    it is going to be very small and thanks for the info

    • ANSWER:
      How large is the helicopter going to be? You are going to have to do some basic engineering with this. You need to keep it as light as possible, and not weigh it down with too many batteries and motors. As far as actual volts go, I'm not sure. How large is it? You also are going to have to evenly distribute the weight, as well as have enough lift being generated by the rotor. You can do this through trial and error. Sounds like a fun project.

  31. QUESTION:
    How many white 9-LED's flashlight (1.5vx3) can i run off a solar panel generating 60w storing in a car battery?
    http://www.amazon.com/Sunforce-50044-60-Watt-Solar-Charging/dp/B000CIADLG
    -------
    Like most manufacturer’s specs, the sunforce 60 watt claim is hard to realize. The panels’ current output is about 3.2 amps under bright sun, which yields only about 45 watts into a 12 volt gel cell battery at 14.2 volts. The panels can output about 20 volts which would indeed yield 60 watts, but not while connected with the included charge controller

    • ANSWER:

  32. QUESTION:
    Using a solar panel to charge a 6 V. electric childs car battery?
    I have a childs electric car, for the 4-6 year old. It runs on a 6V 4.5 Ah sealed lead acid battery. This car came from Spain and has only a 220V charging unit that cannot, of course, plug into a standard American outlet. When I got it the battery was at 5.4 V and the motor wouldn't run. I initially recharged it with my car charger that had a 6 volt setting. I disconnected it at 6.7 V and checked it on the motor and the motor ran fine, though not under the load of a child riding around. I removed it from the motor hookup and after 24 hours the battery dropped to 6.37V this morning and seems to be decreasing slowly (to 6.35 after two more hours).

    Since my grandson comes every two weeks and will be using it only for at most 1-2 hours or less.

    Instead of looking for any adaptor or adapting an American adaptor to the wiring, I would like to know if I can use a solar charger. It sits on the dashboard of a vehicle and plugs into the cigarette lighter outlet. It puts out 19 V. in full sun and the solar panel part is 3.5x11.5 inches.

    The plan is to buy a cigarette lighter outlet, hook it to the wiring of the battery, and use the solar charger between his visits while the car sits in the patio.

    1. Do I have to worry about the 19V output of the solar charger?
    2. Do I have to worry about harming the battery if I just leave it plugged in during the two week interim (or more) when he is not visiting in order to keep it topped off?
    3. Is there anything else I should know about this idea.

    Thanks.

    The European charger is 230V ~50Hz 18.4W and outputs to 6V 1000mA 6VA
    Here is the link to the solar charger:

    http://www.4lots.com/browseproducts/Battery-Saver-Plus-1.0-Watt.html
    I also found in my computer box two power supplies for stuff long gone: one has an output of 6V 800mA and the other is 6V 200mA. Would either of these work? My question about the solar panel still stands with the new info in the link.

    • ANSWER:
      The battery is doing what good sealed lead acid batteries do; slow decline in voltage after being disconnected from the charger.. Battery sounds good.

      There are several things you can do:

      Use the 220v you have in your house wiring, just get the right plug adapter by asking at a GOOD hardware or electric store. I think things that are designed at 50 cycle work fine at 60 cycle.

      BEST:Get a European to USA adapter rated at 25 watts or More.

      Buy a second identical battery for the car, hook them in series and top off their charge using the solar charge on trickle after doing the bulk charge with the 6v charger.

      Using the present 6v charger on a timer.

      Buy a decent 6v smart SLA charger on-line or at Batteries Plus, which also might be a good resource for your situation.

      Do not use the solar charger for two weeks without modification to the circuit, it could really shorten the lifetime of th battery depending on the solar's output.

  33. QUESTION:
    How do you make a good solar panel?
    I'm thinking about making a nice little solar panel (not cell), any help?

    Allowed:
    Purchases of solar cells
    purchase of other stuff (ie copper flashing's, wires, etc.)
    usage of basic non-electric tools
    purchase of any material you can find at a local Home Depot/Walmart

    Not allowed:
    purchase/usage of electric tools (They scare me)
    kits <(this is the big one)

    I'm not sure if I can get my hands on a battery or meter thing or whatnot

    No kits!

    Anyways, I'm planning to buy cells on ebay, that might help

    The panel doesn't have to be macho, it's just a little experiment... I'll be perfectly fine with anything that makes over 3 volts/watts/whateverthestandardunitis and it doesn't have to last more than a year

    • ANSWER:
      you can learn how to build yours by visiting http://hubpages.com/hub/DoItYourselfSolarPanels

  34. QUESTION:
    Is it better to recharge batteries in series or in parallel?
    I have 2 6-volt rechargeable lantern batteries, and 1 6-volt solar panel.
    Would it be better to recharge then in series or in parallel?

    I asked this 3 times in the environmental groups and never got a single answer, so maybe one of these "scientifically enlightened" evolutionist can answer. I will just have to make sure I do the opposite of what they say so that I will have it right.

    • ANSWER:
      You can charge batteries in either series or parallel - the issue is not just the method of connection but also the voltage you can apply.

      Two 6-volt batteries connected in parallel requires 6 volts of charge because each battery "sees" the charger individually. In series, they need 12 volts to charge because the charging current passes through both batteries before completing the circuit.

      So you need to recharge from your solar panel either one at a time, or both in parallel.

      http://www.sinetech.co.za/battchrgselect.htm

  35. QUESTION:
    How many watts are there in 3.7 volts and 355 mA?
    I know that the formula in finding the watts is W = V * A. But is there any limitations based in this formula? If there is, can you please tell me. But if that’s the formula, then the answer will be 1,313.5 W.. Is that right?
    Likewise, can you please tell me where I can find a solar panel that produces this power (3.7 volts and 355 mA)?
    Is 355 mA the same as 355 mAh?
    Is this power from the solar panel ok to use (to charge) in a cell phone?
    Please answer my questions..
    Thank you & God Bless!

    • ANSWER:
      You clearly weren't listening when you were told that the formula W = V*A is W (in watts), V (in volts) and A (in amps). 355 mA is 355 milliamps which is .355 Amps so the power is 1.3135 W.

      Do a web search for 'solar cells' to find people who sell them.

      No, 355 mA is -not- the same thing as 355 mAh. 355 mAh is a battery specification indicating how much current the battery can supply at a particular current draw.

      Yes, power from a solar panel is the same as any other DC electrical power. But I wouldn't use it directly to charge a battery without some sort of charging regulator to limit the battery charging cycle. Overcharging a battery is a sure way to kill it or, at the least, damage it and reduce it's useful life.

      I'm glad to be able to help the both of you.

      Doug

  36. QUESTION:
    Solar Panel: Watts, Amps, Volts? mA?
    What do these mean? I'm interested in doing a solar panel project. The problem is I know nothing about electricity, wiring, or panels so I've bought a small panel to experiment with first.

    I don't know what amps, watts, or volts are; what I should be reading on the batteries I will be charging? Or on the small appliances I will be running?

    The panel I bought has four settings:
    1. 3V ---- 200mA
    2. 6V ---- 100 mA
    3. 9V ---- 50mA
    4. 12V ---- 50 mA
    (What is mA?)

    Also, will you give examples of what I can run with this? Make up any scenarios with whatever amps/volts/watts.
    Stephen M:
    I knew I wouldn't be able to run big devices, that's why I said, "*what I should be reading on the batteries I will be charging? Or on the small appliances I will be running?"

    I meant *"what should I" by the way. I bought this small panel to experiment with and learn some basics, wiring, conversions, etc. Then I will move on to bigger projects, maybe using some deep cycle batteries to power bigger devices that use more juice.

    • ANSWER:
      A great project to help you understand electricity is get some LEDs which you can hook up to your solar panels. Some of the LEDs have a forward voltage of 2 volts DC and some have a forward voltage of 3.5 volts DC, but they only require 20 mA of current. The LEDs have a positive and negative terminals just like your solar panels.

      You could hook 5 to 10 LEDs each in series with a 50 ohm resistor and then hook these LED-resistors in parallel and connect them to your 3 volt--200 mA setting. The maximum current for the LEDs is 50 mA so the 50 ohm resistor will limit the amount of current that can flow through the LEDs.

      You could then re-arrange your circuit and hook 4 LEDs in series with a 50 ohm resistor to the 12 volt --50 mA setting.

      PS: The 9 volt setting should be 66.6 mA to make 0.6 watts. I am assuming that the LEDs are 2 volts DC forward voltage.

      See our blog http://brutuscontry.com/ to see our solar panel project.

  37. QUESTION:
    Solar Panels?
    How many solar panels would i need to charge 4 AA batteries, each produce 1.2 volts. The solar panel delivers about 0.3-amps at 0.55VDC in full sunlight. How long would it take to charge them with the fewest amount of solar panels?
    The batteries get 90ma or 900mah

    • ANSWER:
      are you sure about those numbers?
      0.55VDC is too low to charge any battery. The voltage has to be at least 2 volts.

      The 0.3 amps is enough, more than enough to charge AA cells.

      If those are correct numbers, you could put 3 in series and get 1.6 volts, barely enough. If you really get 300ma out of the panels, then it should charge the a battery in 3 hours. 12 hours for all 4. But monitor voltage and current carefully.

  38. QUESTION:
    using 2 x 12v 4 watt solar panels in series?
    hi can you use 2 x 12v 4 watt solar panels connected in series to power 2 x 120mm 12V DC Ball Bearing Fans as i got a small 2 by 3 mtr shed and i want to keep it cool during summer as in the side of my shed i have a aluminium vent with 2 x 120mm thin 12v dc ball bearing fans bolted to it and i have the two solar panels connected to the fans and the panels on my shed roof will this work ok? here is the specs of the fans and the solar panels

    IP55 Rated 120mm 12V DC Ball Bearing Fan

    IP 55 rating on a fan which is extremely important, particularly when the fan is located in an environment where dust, fine dirt particles, soot etc can quickly clog up a standard fan and bring it to failure early in life.

    Air volume: 3 cubic m/min
    Noise: 45dB(A)
    Input: 7 watts
    Size: 120 x 120 x 25mm
    Impeller: Plastic, fibreglass filled
    Housing: Plastic, fibreglass filled
    Bearing system: Ball
    Speed: 3,000 RPM
    Current: 60mA
    Voltage: 12 VDC
    Flylead connection

    4 Watt 12 Volt Solar Panels - Amorphous

    * Size: 315 x 315mm
    * Voltage: 13 - 18V
    * Current: 200 - 280mA
    * Power- watts peak: 2.5 - 5W
    * Temp range: - 50°C to +70°C
    * Depends on light intensity.
    * 1 Year Warranty

    the reason i want to do it this way as it will be energy efficent

    • ANSWER:
      You want them in parallel, not series.

      Series (connecting the plus from panel 1 to the minus of panel 2) will increase the voltage to 24V.

      Parallel (connecting plus from panels 1 & 2, and minus from panels 1 & 2) will increase the current, and keep it at 12V.

      Two 4W panels will output 8W under Standard Test Conditions. This is not usually the same as real world conditions, so actual results may vary.

      Also note that the current output of the panels is up to .28A (280mA), so two of them in parallel would be .56A (560mA). The fan requires .6A. There's a chance that the fan may spin at a lower amperage, but just slower, so in theory it may work. Ideally, you should get a slightly larger panel.

      (If you are interested in why the current is low, note that the panel voltage is up to 18V. 18V x .22A = 4W.)

  39. QUESTION:
    12volt PC FAN Problems?
    hie guys i just bought two 12volt pc fans from centrecom. for a project. i tested them on 3 volts and they started up fine and even better on 6 volts. I then tested them on 18 volts and they spun really fast for like 5 seconds then they started to slow down. i immediately removed the 18 volt transformer. I then tested them again on 3 and 6 volts they do work but they spin slower and they require me to spin the blades to get them to spin. is there any way to fix these fans? i spent big money on this please help. and also i was planning to buy a 7.5 volt solar panel to run them but now since they are slower do i need to buy a 12volt solar panel? thanks in advance guys.

    • ANSWER:
      You probably have partially burned out some of the windings on either the armature, or field, or both. In short you have ruined the fans by using a higher voltage than rated for

  40. QUESTION:
    Building a SOLAR PANEL with ebay SOLAR CELLS?
    Hello all and thank you for helping!

    I'm building a solar panel with solar cells from ebay and I wanted to know what supplies will I need other than 1.Solar Cells 2.Soldering Gun 3.Solder 4.Flux Pen 5.Tabbing 6.Tabbing Wire 7.Bus Wire 8. Materials for the frame 9.12 Volt Batteries

    What kind of power inverter do I need if I'm trying to charge 12 Volt Car Batteries? I need these supplies to be-able to handle a moderate amount of power because I want to keep adding on cells to my panel. I pretty much know how to make the panel but what all do I need to connect the home built Solar Panel to the batteries? I'm willing to spend around 0.00 to 0 for all the parts total a side from the solar cells. I have 140 3x6 cells I should be buying another 60 and want to make a panels that will charge car batteries. I need to know what parts and equipment I will need aside from the solar panels to to charge them. Equipment that that tells me how much power is flowing and if the batteries are charged are not. Thank you all for viewing my question I am very appreciative to all who help and answer.
    -John

    • ANSWER:
      the wattage of your power converter will depend on how much power you want to be able to use at any given time. buy one as big as you can afford, you could always add another converter in parallel later if the first one you buy isn't big enough. the power converter will be used to convert the 12 volts from the batteries into 120 volts to power light, etc. solor panels should produce 12 volts and basically directly connect to the batteries.

  41. QUESTION:
    will a 15v 52watt solar panel charge four 12c dv 55ah batteries?
    I have made a 15v dc 52watt solar panel and I going to be trying to charger 4 12v dc 55ah batteries. I get about 6 hours of sun on my panel. Spec below, is that a big enough panel to charge the batteries???

    I have 30 3x6 solar cells wired together Cell Specifications: (Watts): 1.75 Wp (Amps): 3.5 Imax (Volts): 0.5 V max which is where I got my 15g 52watt max (if math is wrong plz tell me) The Battery type: 12Volt 55.0ah NB Sealed Lead Acid Battery. I am using a mppt solar charger.

    • ANSWER:
      >will a 15v 52watt solar panel charge four 12c dv 55ah batteries?

      Eventually. But the panel seems way undersized. Some rough calculations assuming you live in a nice sunny desert:

      Under ideal conditions the mppt charger should supply about 4 amps into the 12 volt batteries. Lets say 70 hours to do a complete charge. Optimistically lets say you get half of that for 6 hours per day and don't use any power from the batteries.

      (140 hours to charge)/(6 hours per day)= 23 days Actually it will be longer because the batteries have a self discharge rate and the charging isn't 100% effecent.

      Another way to look at it is from a power standpoint.

      (26 watts) X (6 hours per day) = 156 watt-hours per day. So maybe you can run a 26 watt (100 watt equivalent) CFL for 2-3 hours per day plus charge the batteries enough to make up for the self discharge rate of the batteries.

      Of course, if you don't live in a nice sunny desert, the situation is worse. And even in nice sunny desert, things will be worse in the winter.

      Info from your second question:
      ---------------------------------------------

      Now has three 52 watt panels
      Needs 12 volts at 93 amps to run all his equipment 12 hours per day.
      671 amp-hr of 12 volt batteries
      three 60 watt charge controlers
      Located in PA, USA

      OK, your equipment needs 1120 watts to operate (12 volts X 93 amps= 1116 watts)

      That's 13.4 kWH per day or 402 kWH/month

      Under ideal conditions your three 52 watt panels produce 156 watts. Figure 1/2 that under ideal conditions in PA.

      1120 watts/ 78 watts = 14.4

      In other words, you would need about 15 times as many panels to just directly operate your equipment on at noon on a sunny day in PA! That should give you an idea of how far off your calculations are.

      There is a calculator at http://sunelec.com/index.php?main_page=page_2 for estimating how big a system you need. I punched your numbers in, it came back with a 4444 watt minimum system. Their 4500 watt system includes twenty two 205 watt solar panels. http://sunelec.com/index.php?main_page=4510_watt_off_grid_system

      >OK here is my idea that i am in to far to back out

      For this kind of project, you need professional guidance.

  42. QUESTION:
    How much power does a solar cell collect per square foot?
    I'm just asking regarding ordinary solar cells/panels, not anything new, special or over-priced. See, I have this idea, but I want to make sure they produce enough to actually accomplish something. I want to know:
    1. Amps
    2. Watts
    3. Volts
    I'm not very electricly-minded, so I always forget which of those does what. But this is just so I can run a few numbers. Thanks in advance.

    • ANSWER:
      That depends on different factor s
      Manufacturer the max efficiency of solar cell is not more than 20% under ideal conditions
      The temperature plays a big roll in the efficiency.
      Angle of the light on the solar cell panel.
      The time of the year because the son is not at the same distance from earth at all times.
      Power in watt = currant (amps)*volts cos ф
      Usually a solar cell is low voltage 12volte or 24 Volte
      One very important thing that with solar cells you can accomplish nothing its so expensive that you will get your capital back after 20 years a 50 watt panel cost around 1000 $ do the math.

  43. QUESTION:
    Can I use a solar panel to charge a deep cycle wheelchair or scooter battery?
    I have a solar panel with the following specs:

    Material: Monocrystalline

    PM: 2w

    Voc: 22.28 V

    Isc: 0.15 A

    Vmp: 18V

    Imp: 0.14 A

    Size: 14.9cm x 15.5cm

    Gross weight: 0.3 kgs

    Max system Voltage: 1000v

    and I want to know if I can use that solar panel to charge a 7 amp, 12 volt electric wheelchir battery or if I have to buy another kind. It is for use on a blackout to charge my laptop, and stuff. I have a dc meter and input, but do I need an inverter? Thanks. I would appreciate it if anyone could answer any part of this question.

    • ANSWER:
      I'm not positive, but I think the other answerer might be a little off. You really should check either the manual if you have it (for your panel) or research it on the net and try to find it. It should say what to use it on, and what not to use it on. I can't answer your question either way just from my head knowledge, but i do know that voltage means little compared to amps. Amps is what will charge or overcharge a battery to a dangerous level. If I were you I would ask a reputable source and not an anybody's-guess website like this. You dont want to get hurt, that's for sure. Good luck.

  44. QUESTION:
    DIY Solar Panel. How many watts will it emit?
    How many watts will a panel i want to create with 36cells withe the following specifications emit?
    Average Power (Watts): 1.8 W
    Average Current (Amps): 3.6 Amps
    Average Voltage (Volts): 0.5 V
    Its making some sense.
    So this is true also
    0.5V*36Cells*3.6W per cell = 64.8 Watts? (series)

    • ANSWER:
      Watts add up. If one cell can produce 1.8 W, then thirty six cells can produce 36×1.8 W.
      Volts add up for cells that are wired in series. Amps add up for cells that are wired in parallel. If you put all of the cells in series, then you'll get 36×0.5 V, at 3.6 A. Etc.

  45. QUESTION:
    70w Solar Panel wattage calculation?
    I recently bought a 70 watt solar panel with specifications as 17.5 volts / 4 amps. The thing is that I am unable to get more than 2.7 amps per hour, even when the sky is clean. I once got 3.0 and 3.3 amps. Is there something to do with the solar panel. I keep it to he south with approx 25 degrees inclication as per my country (India). I also see a small crack in one of the chips. But it seems to be parallely connected to the circut so I am not sure its because of that. Is it true that 4 amps would only be possible in very perfect / or lab conditions. Some more information would be helpful. Thank you.
    Normally the volatge from the panel is 17 to 18 volts at which I get 3 amp max at 12 / 1 noon. Amps through the day are 8am 1.5 / 9am 1.8 / 10 am 2.0 / 11am 2.5 / 12pm 3.0 (max) / 01pm 2.7 / 02pm2.5 / 03pm 2.0 / 04pm 1.5 / 05pm 1.0 and below. I use a solar 5a solar charge controller to charge a 42ah SMF battery and my load is my 65w laptop that consumes 65w while charging and normally i guess about 25-30 watts.

    • ANSWER:
      I'm not exactly sure of the answer, but I would ask this question at a solar forum

  46. QUESTION:
    How to use solar panel to charge this device?
    I have a 12v, 5w solar panel that I typically get 8-19 volts out of with current between 30-200ma depending upon conditions. I would like to use it to charge an electric razor. The charger on the razor is outputs 6vdc at 150ma. And it's a li-on battery within the razor.

    Can I just attach the solar panel directly to the charger (cut off AC plug so it's just wire leads attaching to alligator clips off the solar panel) and let it charge the battery for say 5 hours when current off the panel is around 150ma or less and about voltage in the neighborhood of 15 to 18v?

    I don't have a charge controller and want to make sure the li-on battery doesn't overcharge or explode. I know they're more prone to this than nicad or ni-mh batteries. And that's why I'm more concerned about this being a lithium-ion.

    My guess at this point is that I should be ok because the current rating on my panel vs the razor battery is matched nearly perfectly. But I don't know if the double to triple voltage would be a big problem. And if so, then whether or not a 12v charge controller would be needed.

    Thanks in advance for all your help!

    NOTE: I also have an older li-on razor that is 3v and 100ma. If I wanted to charge this one, separately from the one above, using the same solar panel, would I need a charge controller? Or am I going to be ok by simply attaching the panel to the charger for about 3-6 hrs at 14-18v and 150ma on the high end?
    Thanks for the answers. As a follow-up and general question, let me ask you this.

    When you have a solar panel that's not matched voltage and current-wise to a device's needs, how would you regulate both the current and voltage at the same time?

    I know a voltage regulator can be used with resistors to maintain either a constant voltage or current.

    But how would you regulate both voltage and current levels at the same time? For instance, reduce a 12v panel down to 6v. And at the same time, lower current from 100ma to 20ma?

    • ANSWER:
      Bad idea it won’t work

      a 6 volt battery should be charged steadily at 7 volts

      Your 8-18 volts will let the smoke out or boil your battery

      A voltage regulating charger controller would fix this problem but you’re never going to find one

      Just forget the whole thing

      edit
      The type of voltage regulator you would need world have to be full electronic and spastic to exactly what your trying to do (you won’t find one to buy and you can’t make one its way to complicated)

      Resisters won’t work
      with a your variable solar voltage which means you’re getting a varying current as well this wont work at all.

      Just for get it and chard your razor from the wall

  47. QUESTION:
    Help with a simple electronic circuit.?
    I have a 6v 50 MAh solar panel and a 3v dc motor. How do I reduce the voltage of the solar panel to 3 volts in order to power the dc motor safely?
    http://www.radioshack.com/product/index.jsp?productId=2102822
    http://www.radioshack.com/product/index.jsp?productId=2131051

    • ANSWER:
      No such thing as a "6v 50 MAh solar panel". Perhaps 6 volt 50 mA.

      You will get less voltage if the panel is not directly perpendicular to the sun's rays. And the voltage may go above 6 volts under very bright sunlight.

      Are you sure that 50mA will run the motor?

      You can use a 3 terminal regulator like a LM338. Download the data sheet and study it. You will need two resistors to set the voltage.

      .

  48. QUESTION:
    Solar panles, voltage conversion, and usage?
    I have a two (2) small solar (~9 x 12in) panels each one stores energy in a 3.5 volts battery. I want to know how many LED's I would be able to power with these panels and for how long?

    Solar panels allows us to capture light energy and store it elsewhere until we can use it, so...the size of the panel wouldn't matter as much as does the time it will take to charge a larger power storage unit, in my case a 3.5 battery...then I can power a 9 volt battery but it would take more time to fully charge...Is my this right?

    Is it possible to power a 60 watt light bulb with these solar panels? given my last question, do you think it is possible to use a battery battery that can store more energy?

    Let's assume the solar panels are in constant sun light all day no cloudy conditions. I want to thank everyone in advance. Thank you!
    Thanks you both for responding to my inquiries. The battery looks like an AA and the package says 250 mAh. I will confirm this once I am home.
    Okay so the panel has a LiFe Cell rechargable battery 3.5 , 250 mAh

    Does this help?

    • ANSWER:
      1. The panel only gathers energy. - You need a battery to store it.
      Those units you have store energy at 3.5V.
      You might connect them in series to get 7V., but without some form
      of converter, that's all you get.
      2. Those panels probably produce about 5W. total in full direct sun.
      (Figure 20 -25 W./Hr.s on a good day.)
      3. You can't charge a 9V. Battery with a 3.5V. or a 7V. (Series), source.
      4. LEDs take very low wattage at very low voltages, and you could run
      quite a few of them from that source, but you'll have to learn a heck of
      a lot more about the subject than you now know to do it.

  49. QUESTION:
    DC electric wiring battery solar voltage help?
    If I have (6) 12 volt batteries wired in series for a total of 72volts. I am thinking about buying a solar charger that is 18 - 24 volts. Do I have to have 3 of these solar panels wired in series to charge the batteries? What will happen if I purchase one charger and put the put the pos+ on the first battery and the neg - on the 6th battery? Will it charge, just slower? Do I have to match the charger output to the battery voltage. I do want to have to unhook the batteries that are in series because I am lazy. Thank you in advance for your help. I hope I explained it well enough.
    Sorry for the typo, I don't want to have to disconnect the 6 batteries that are wired in series.
    The batteries are in a golf cart. Can I just trickle charge them with 18-24 volts. Doesn't a regular charger trickle charge batteries at a lower voltage?

    • ANSWER:
      When a panel says 18 volts out, that's the most you'll get out of it. So if you connect it to 72 volts, either no current will flow, or worse, current will flow the wrong way.

      I suspect the panel you have in mind is very low power. Six golfcart batteries is equivalent to what someone might have in a cabin, and charge with a 600W (minimum) array. A smaller array would not generate enough current to get the batteries to absorb charge.

      If all you want to do is maintain the batteries with a trickle charge, best to just run an extension cord to a trickle charger.

  50. QUESTION:
    Solar Panels: Watts, Amps, Volts, mA?
    Solar Panel: Watts, Amps, Volts? mA?
    What do these mean? I'm interested in doing a solar panel project. The problem is I know nothing about electricity, wiring, or panels so I've bought a small panel to experiment with first.

    I don't know what amps, watts, or volts are; what I should be reading on the batteries I will be charging? Or on the small appliances I will be running?

    The panel I bought has four settings:
    1. 3V ---- 200mA
    2. 6V ---- 100 mA
    3. 9V ---- 50mA
    4. 12V ---- 50 mA
    (What is mA?)

    Also, will you give examples of what I can run with this? Make up any scenarios with whatever amps/volts/watts.

    • ANSWER:
      Watt is the unit of measure for power used.
      Ampere is the unit of measure for current.
      Volt is the unit of measure for electromotive force.
      mA is simply a miliamp, or one thousanth of an amp.

      for the settings, waht they mean is that at:
      3volts, you can pass 200mA of current
      6volts you can pass 100mA
      9volt-50mA etc.
      The best use for solar panels is to charge batteries, then run whatever load you want off the batteries. whatever small appliance you want to use, should have on it something that will look the same as where you got the settings for your solar panels. Look at several and that will give you a sort of idea as to what you can run with the things.


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