Solar Problems

Discussion in 'Off Grid Living' started by wpmasterdesign, Apr 2, 2017.


  1. So I live off grid and I have a little problem. I have a 60 watt solar panel connected to a 20Amp charge controller which is also connected to a 12v 35ah battery. The battery is less than a week old. From the charge controllers "load" ports. I am also using a Peak 400w dc inverter.
    Now here is my issue:
    When I connect from the charge controller to the inverter, then plug a load in, the inverter low voltage alarm sounds off almost immediately. At the same time, the voltage tested at the inverter fluctuates quite widely.
    However, if I connect directly from the battery to the inverter, it seems to work fine. No voltage fluctuation, no alarms, it just works.
    So I am trying to determine where the problem is. Every component in this system is brand new., so I am not sure what is going on. Why can't I pull my load from the charge controller?
    In terms of what I have on the load, it is only a laptop computer, which uses about 75 watts. Nothing else.
    Thanks in advance for any thoughts on this.
     
  2. techsar

    techsar Monkey+++

    Since a charge controller is for charging a battery, how are you connecting to it to draw enough power for an inverter? Most of the cheap ones with power "output" won't come close to powering an inverter.
    Hook the inverter to the battery - through a fuse - and hope that you didn't fry something in your CC.
     
  3. duane

    duane Monkey+++

    Your battery has an internal resistance that will drop the voltage that appears across the battery when it is supplying current to a load, With a lead acid battery you can use a proxy that indicates the current draw that is the maximum load allowed. It is usually listed as cranking amps or something similar. At that point a 12 volt source will have a voltage drop of 6 volts across the battery and 6 volts across the load. That will transform the maximum power from the battery to the load for a short period of time, The 35 amp hour is the maximum current supplied over a given discharge time, often 20 hours. That means that your battery will only supply about 3 amps over a roughly 10 hour period. Your solar panel will supply about 5 amps and your inverter will draw abut 30 amps at full draw. Your charge controller is just doings its job and protecting both the battery and the inverter. You will either need a larger capacity battery charged over a longer period of time or a much larger solar panel, 500 watts or so that would supply the 400 watts to the inverter. To run the inverter 24 hours a day would require over 1 k solar and a good sized battery bank. There is a good reason for most systems being grid tie.
     
    Last edited: Apr 2, 2017
    Gator 45/70 and sec_monkey like this.
  4. Well, as I am new to solar power, I am learning as I go. And from everything I found online, the charge controller has 6 ports: 2 for the panel, to for the battery, 2 for "output" Perhaps I understand "Output" wrong, but I thought you were supposed to connect the charge controller to your inverter. Thanks for clarifying that. But I am now confused.

    Do I have to connect and disconnect the battery from the charge controller AND THEN to the inverter each time?
    Do I have the charge controller and the inverter connected to the battery at the same time?
    Do I disconnect the charge controller when i want to use the inverter?

    I know these may seem like stupid questions to you, but this is my first attempt at Solar power, which is why I am starting so small - if I screw something up, I am not out a lot of money. But I need to learn so that I can eventuallly replace my generator with a large solar power system. Thank you for helping a solar rookie!
     
  5. duane

    duane Monkey+++

    Need to change your thinking in order to use inexpensive solar. With a 100 watt light bulb you will need an inverter that draws about 120 watts, 10 amps from your battery, but you can use a led bulb that supplies a similar light output with a 10 or so watt draw and you can get ones that run at 12 volts and thus need no inverter.and thus only draw about 1 amp, Your system will not run using a regular light bulb, but would work very well with a led and the light output would be the same.
     
    Lilikoian and sec_monkey like this.
  6. Sorry, I admit I am not real smart about this stuff. U am a computer geek, but this stuff is just confusing to me and does nto really answer my questions. I am not sure why you are talking about light bulbs and 100 watt panels. I am sure it is related somehow, but doesnt really help me anser the questions I asked. Essentilly, I just want to know what is the CORRECT way for me to connect this small system in order to use it to charge my computer and mobile devices?
     
  7. ghrit

    ghrit Bad company Administrator Founding Member

    Let's start easy and work into the more complex questions.
    What loads are you intending for this "system" besides the laptop?
    What voltage does the panel produce under full sun?
    What make are the cc and inverter?
    What gauge wires are you using?
    At this point, we have to wonder why you are running the laptop off AC if the panel and battery can put out the right voltage.
     
    Last edited: Apr 2, 2017
    sec_monkey likes this.
  8. techsar

    techsar Monkey+++

    Duane was just explaining the need for conservation...the even numbers are easier to work with. :)

    For your particular case, it is perfectly fine to leave the charge controller and inverter connected to the battery. I think you'll find (and I think this was what Duane was aiming for) that your battery is on the small side for any serious run time.

    Don't use the "load" terminals for any high amperage items, such as an inverter. Usually they are ok for a small light or a relay to control another device.

    Remember to use wire or cable that is capable of the current draw...larger is ok, but never smaller. Your 400 watt inverter is likely to require up to 45 amps...this means 8 gauge wire. A smaller wire will result in voltage drop...it also means that at full output, the battery will be 50% discharged in less than 30 minutes.
     
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  9. Thank you for staying simple for me.
    This particular system will stay small since it is just intended for a "learning" system. So I will be using it to prodice only the power I need to do my job (I work as a remote tech supprt rep).
    1. Load will be Laptop and 2 cell phones only.
    2. Panel produces between 20-23 volts in full sun
    3. Here are links to the cc and inverter I have:
    CC: Amazon.com : Sunix 20A 12V/24V Solar Charge Controller Charge Regulator Intelligent, USB Port Display Overload Protection Temperature Compensation : Patio, Lawn & Garden
    Inverter: Amazon.com: Peak PKC0BO 400-Watt Tailgate Power Inverter: Automotive
    4. 12 guage wire
    5. I honestly didnt know there was any other option but to use an inverter. How exactly would I plug my laptop into the system without one?
     
  10. Thank you for clarifying that Techsar!
    I only have the laptop plugged in when it needs to charge, which takes about 45 minutes. So far, I have been able to run it for about 2 hours without dropping the battery below 11 volts. According to what I have learned so far, I should not let it drop below 10.5. B ut I have decided to err on the side of caution, and never go below 11.0.

    I have 12 guage wire, so I should be good based on what you just told me, right?
    Another question that pops up after your remarks: my CC has 2 USB ports built into it. Can I use these SAFELY to charge my 2 phones? What are the rosks (if any) and the do's/dont's on that?
    Also, what is your battery recommendation? I have a neighbor who uses a couple of Marine batteries. Is that a good idea or shouls I spend the extra money on an actual solar storage battery?

    You guys have been so helpful and I truly am grateful!
     
    Last edited: Apr 2, 2017
  11. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    First. Thing to change is the 12 Ga. wire between the Battery & The Inverter, to #8 Minimum, and make it as Short as Possible... Then make the wire between the Charge Controller and the Battery, some Good # 10 Minimum... Next, look at more Solar for your System, as the Panels are getting cheaper all the time. A nice 240 watt Panel would be a GOOD Investment.. That way you will mostly be in a Positive Power Budget, with the loads you men chained....@TnAndy @Cruisin Sloth
     
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  12. I do plan on increasing my system to be much larger. I currently run primarily on a 5000W generator, but I want to get rid of that eventually. That said, I am starting with this small, very basic system in order to learn. I don't want to invest thousands of dollars into a system only to do the wrong thing and destroy my investment! My eventual goal is a 1500-2000 watt system.
     
  13. techsar

    techsar Monkey+++

    No problem :)

    12 ga. from the battery to inverter really is too small, and if you plug in a heavier load you could have a fire due to heating. It is also likely to decrease the inverter input voltage...sort of like a big resistor.

    As far as what could go wrong with using the sub ports....well, if the voltage regulator goes bad, you could end up putting 12 volts on a 5 volt circuit = smoke, or an exploding phone battery. That's one reason that these inexpensive Chinese products won't get a glowing review from me (or many others I suspect). Poor quality control and cheap parts don't give a reliable end product. So, that's one of those "you take your chances" decisions.

    Marine batteries come in different flavors. Starting, deep cycle, and kinda in-between. You want deep cycle for this application. The cheaper ones are usually flooded cell, so you have to periodically check the electrolyte level and add distilled water if necessary. The acid vapor will also rust or corrode items close to them if you don't have excellent ventilation...not to mention the chance of explosion.

    What type of battery do you have now? AGM, flooded cell, gell ?

    BTPost is spot on about the wiring...and the panels. The last 300 watt panels I bought were about $110 each.

    ETA: take a look through the alternate energy section...lots of good info there!
     
    sec_monkey likes this.
  14. Wwll, I am glad I havent used those USB ports! LOL!
    I agree with you 100% on cheap equipment. I wanted a system I could build for $100 or less, just to learn on When I am ready to build my big system, I will invest in quality components. I know that I am looking at several thousand dollars to buid my full system, so I just want to make sure I do it right the first time.

    So I need 8ga and 10 g because 12 ga is too small? So I take it the lower the guage the bigger the wire?

    The battery I have is a deep cycle AGM.

    Where did you get 300 watt panels for that cheap? Everything I find is $100-150 for a 100 watt panel. Apparently I am looking in the wrong place! My 60 watt cost me $50. So if you can point me to a good source that would be amazing.

    So, the panel I have now is poly. Which is better? Poly or Mono? Is it true I should avoid thin film?
     
  15. techsar

    techsar Monkey+++

    Yes...the smaller the gauge number, the larger the wire...12 ga is smaller than 10.

    AGM is the type I use...although a bit bigger ;) Nice to not have the worries of spilled electrolyte.

    Solar Blvd has some killer deals...just have to watch for them. Shipping is the worst part, but that's anywhere.

    Poly vs. mono....these days there doesn't seem to be a whole lot of difference, but try to stay with major brands. I haven't dealt with thin film, so I'll reserve comment on that issue.
     
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  16. ghrit

    ghrit Bad company Administrator Founding Member

    OK. Upgrade your wire as BT suggests. Then, get out your laptop wall wart and see what it's rating is, that should also be in the O&M manual for the lappy with the onboard battery specs. You are particularly interested in the battery charging (out put from the wall wart.) Some lappys can be charged directly from a 12 volt source, and you MAY be able to do that by directly wiring to the charge controller that will regulate (your storage battery) charging voltage. BE VERY CAREFUL HERE, SOME LAPPYS USE A LOWER VOLTAGE AND USING A HIGHER CHARGING VOLTAGE WILL PERMAF**K YOUR COMPUTER.

    If you can't find the wall wart specs, plug it in and read the voltage with your VOM. (You DO have one of those, no? Get one, the 13 dollar hardware store types are close enough for this. When you go a bit higher in knowledge, you might get a Fluke meter that will nearly pick your nose for you.) Bear in mind that the wall wart will show a higher voltage measured this way, but will tell you quite closely what the lappy wants for its onboard battery.

    I am totally unfamiliar with the hardware you have, so will pass that to the guys who live with solar.

    Yes. 12 ga wire has a higher resistance to amps than the larger sizes at a given voltage.. When you are dealing with low voltage, wire size must be larger to carry higher current for any given power rating. You can safely and easily stuff 30 amps thru 12 ga wires at 120 volts. *Check codes before trying that, I think the legal limit is 20, but I've been wrong before.* Try to stuff 30 amps thru 12 ga, and your apt to get the wire to glow ---

    OHMS Law rules ---
     
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  17. I actually have some 10g wire already, but I will need to get some 8. Thank you guys.
    Output for my wall wart is 19.5V / 2.31A and yes, I actually have a very nice VOM. Got it as a gift from my wife last year. This one will ALMOST pick your nose and brush your teeth. lol.
    So with my 60w panel and 35ah battery, I THINK I have enough to power my laptop and 2 phones. Agreed? BUT if I want to power anything else, I should get a larger battery AND a larger panel?

    So can I safely wire directly to my battery or will I permaf**l my lappy as you say?
     
  18. ghrit

    ghrit Bad company Administrator Founding Member

    You need to confirm that the onboard battery is 12 volts, but at this point, I'm guessing not, could be like 15 or 18 with that high an open circuit voltage. If it is either, you won't be too successful directly wiring to the storage battery, and you'll need to fall back on the inverter. If the onboard battery is nominally 12 volt (see your O&M for that spec) you can directly wire the lappy to the storage battery. Now, saying that, you will need to watch the lappy state of charge, because the wall wart may also have a charging current controller in it as well as a rectifier.

    If you are seriously thinking to directly wire to the storage battery (I would, voltages permitting) order up a replacement wall wart and cut off the wart so you have the connector. Or do some creative connections with the wart you have.

    Now, so far as powering phones and lappy, think about what the demand will be at oh-dark-thirty. 75 watts tells us zilch if we don't know the onboard battery voltage. (We know the battery will run the lappy, but we do not know for how long, or we could figure that out.) Anyway, once the demand amperage is known it's easy to add the capacity of both the onboard and storage sources and see how long you can operate with the sun off line. Charge the phones at noon.

    Observe, the 60 watt panel will NOT power the lappy by itself, you will need to ration the time on line to accommodate recharging the batteries. There will also be losses in the controller and invertor that are not yet accounted for.
     
  19. Ok, I think I have enough info to go on. Ya'lls help combined with the books I downloaded today, I think I have a pretty good idea of what I need to have and do for this small system. And I think I am pretty well on my way to learning enough to build my new system before next winter (which was my goal) I will be so happy when I do not have to listen to this stupid genny run anymore!

    So, the panel I have now is poly. Which is better? Poly or Mono? Is it true I should avoid thin film?

    Last note before I consider this thread resolved: If anyone has any good solar panel supppliers/recomendations that will give me what I need at an affoordable price, I would love to hear it!
     
  20. Cruisin Sloth

    Cruisin Sloth Special & Slow

    WOW
    Sir you have all your math wrong & your forgetting time , losses , and storage . and 60 watt panel makes 45W max . The numbers all not True , BUT the first level Of a gauge .
    First is to know the level & a standard (as with anything ) ...

    Sloth

    Now for asking such a question POST all info on what you got sold !!
    ALL INFO of who made watt/what ;)
    you have a LED light setup as I see it , but depends where you are !
    Im west coast canada , so we get winter shade
    SlothA
     
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