Houseboat Solar problem

peter19ue
peter19ue Registered Users Posts: 14
Hi:

I have a houseboat with nine 120w sharp solar panels. The panels are currently only putting out 5amps total and in the past they were putting out 70-90amps. I did have the battery bank go bad and I was wondering if this could have damaged the panels. Any input why the amps dropped so much would be appreciated.

Thx

Comments

  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Houseboat Solar problem

    First, welcome to the forum.

    Second, give us a better over view of your system. How the panels are wired, battery configuration, kind of charge controller etc.

    Once we know some of these answers, we can begin to point you in the right direction. It would be unusual for a battery defect to damage panels. It sounds off the top of my head to be a wiring problem.

    If these panels are wired in parallel it also would be unusual to have the current drop, so my hunch would be in the wiring after the panels, like between the PV and the controller, or a bad controller, or the wiring between the controller and the battery.

    Tony
  • peter19ue
    peter19ue Registered Users Posts: 14
    Re: Houseboat Solar problem

    Hi Tony:

    Thanks for the input. I have an Outback flex 60 controller and 12 x 6v deep cycle batteries wired in series I believe to give me three 24v sections. The panels are also wired in groups of three because I have three legs. Sorry for the bad descriptions but I did not install the system and I'm not that up on solar systems.

    I was going to test each panel individually to see what their output was. Someone told me that if the battery bank goes bad it can actually damage the panels.

    Thx, Pete
  • peter19ue
    peter19ue Registered Users Posts: 14
    Re: Houseboat Solar problem

    Hey Tony:

    If all nine panels are working properly how may amps should they be putting out on a sunny day. I am trying to educate myself.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Houseboat Solar problem

    In 24 vdc configuration, you should be seeing ~ 30 amps

    9*120=1080 watts * .8= 864 watts/24v=36 amps,,

    If you were seeing 70-90 amps something is not figured right. Even wired to 12 vdc, I would be surprised to see more than ~70.

    What do you mean,, "three legs"?

    T
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Houseboat Solar problem

    did you replace the batteries for the controllers must be connected to good batteries?

    can you measure the short circuit current of each pv to be sure each are functional?
  • peter19ue
    peter19ue Registered Users Posts: 14
    Re: Houseboat Solar problem

    I am going to replace the batteries next week. The 9 panels I believe are wired in sets of three. Sorry for the bad description. I was told last week they were putting out 70 amps and now they are putting out only 5 amps. We need to check the wiring and connections but I was told that bad batteries could cause the panels to get damaged and that's why they may be putting out only 5 amps.

    I am going to have someone measure each panel to make sure they are working properly.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Houseboat Solar problem

    Also a DC current clamp meter can be very handy (here is an inexpensive but functional $60 unit).

    Sharp should be good panels and if nobody has pulled on the cables or eaten the insulation--I would be looking for corroded/loose wiring or a failed charge controller.

    You can measure the current through each of your three strings with the DC current clamp to see if it is a general problem or if some of the panels or charge controller are working correctly.

    With the panels, you can measure Voc and Isc (shorting solar panels does not hurt them--but be careful with any connectors--many do not like to be pulled apart under load--the arcs can damage the contacts).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • peter19ue
    peter19ue Registered Users Posts: 14
    Re: Houseboat Solar problem

    When you say charge controller do you mean the Outback flex 80. I was told someone measured the output by the subpanel near the solar panels on the roof and they only got a reading of 5 total amps being generated by all 9 panes. Last week it they got a reading of 70 amps. If a battery bank does go bad is there a chance it can damage the panels. Starting to see how compplicated these systems are. Thanks for all the input.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Houseboat Solar problem

    if that was a short circuit test of the pvs and not how much was being delivered to the controller then it's either the pvs or the wiring. you can't go by how much was being delivered to bad batteries through a controller that hasn't been verified as working correctly either.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Houseboat Solar problem

    The Outback is a MPPT (Maximum Power Point Tracking) Solar Charge Controller...

    Basically it takes the higher voltage/lower current from the solar array and "down converts it" to lower voltage/higher current needed by the battery bank.

    Your issues may be--Solar Panels not able to supply power (not likely whole string fails at once, and the battery should not be able to make a working solar panel fail--unless the solar panel is hooked up backwards directly to the battery bank).

    The Solar Charge controller may not be taking power from the array, or "seeing" the battery bank--and not transferring power to the batteries.

    Or, you could have bad wiring to the battery banks (corrosion, loose/dirty connections, or even a couple failed open or failed shorted cells).

    Pretty much, you are going to have to start from the begining and check the voltages at various points in the system (what is the voltage at the input to the Outback, and what is the battery voltage at the output).

    What does the Outback read for input/output voltages. Does it seem to be "operating"? Any error messages?

    Then you may have to go to the solar array and disconnect or open the breakers/fuses to each string and measure each strings Voc (open circuit voltage). Then (if you know what you are doing) short each individual string and measure its Isc (short circuit current). And if you find a bad string, then break out each panel and measure its Voc/Imp.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • peter19ue
    peter19ue Registered Users Posts: 14
    Re: Houseboat Solar problem

    we took the reading before the controller and panels so either the wiring or panels must be bad. Can bad batteries cause panels to go bad. Just dont know why panels that are only a year old be bad
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Houseboat Solar problem

    I know you wish to know if bad batteries can wreck panels. Bill sort of answered that under odd circumstances they could have, but it is not very common, assuming the system was properly wired and fused.

    Like Bill and Neil have suggested, you are going to have to check everything from PV to battery. My hunch is that you have a bad connection somewhere. In a marine environment corrosion on connectors would not surprise me. You are going to have to check each wiring junction, and each panel.

    Tony

    PS It would be curious to know why the batteries failed. Were they chronically over or under charged? Were they chronically over drawn, and improperly recharged? It is very much more likely that the bad batteries are a symptom of a bigger problem, including the learning curve of the operator.

    A must read for all battery owners:

    http://www.batteryfaq.org/

    http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries
  • peter19ue
    peter19ue Registered Users Posts: 14
    Re: Houseboat Solar problem

    Generator did not work for a while so they were not getting charged properly. I also now know how to monitor them since I've been educated so hopefully these will last longer
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Houseboat Solar problem

    According to the math, that 1080w array can only produce 45a @ 24v. And that's the theoretical max. If you factor in the derating for system inefficiency, as Tony did, then it's even lower.

    9 * 120w = 1080w / 24v = 45a

    You say your batteries are rigged for 24v, but if that is so, then I doubt anyone ever saw 90a, or even 70a. They could have if the batteries are rigged for 12v though.

    9 * 120w = 1080w / 12v = 90a


    As to why you would only see 5a - solar panels only produce power when there is someplace for the power to go. If the batteries can't absorb power for whatever reason - they are bad or disconnected or simply fully charged - then there is no place for the power to flow to, and so there is no amperage flowing to measure.

    That 5a could be (probably is) only however much power is needed to supply parasitic loads, such as the control board for a propane fridge and a couple of lights or smoke detectors or an idling inverter or whatever.

    Even if everything were working correctly, when the battery is full if there is only a 5a draw on the electrical system, then 5a is all that will flow from the solar panels.


    Personally, I don't trust the interpretation of the measurements. Who took the measurements and what sort of meter did they use?

    A clamp meter that goes around the wire will only show how much amperage is flowing through the wire, and as I just described it's perfectly reasonable to only see 5a flowing on a meter like that if that's all the load that is on the array.

    If the battery bank was rigged for 12v and was really low, then a clamp meter could have shown 70a or 90a flowing while the bank was being charged - that would of course drop off to almost nothing (like maybe 5a...) once the bank was fully charged.

    If the solar array was disconnected from the charge controller, then a clamp meter would should 0a - because there is no power flowing because there is no place for it to go (no loads connected).


    To test the actual output of the solar panel requires a multimeter. It can test the open circuit voltage (Voc, i.e., no load), the voltage under max power (Vmp, i.e., while under load) and the amperage.

    However, most multimeters can only handle up to 10a for a load test. More than that and they blow their internal fuse. Some can handle up to 20a, but they aren't as common. Such a meter simply cannot measure the amperage output of the whole array. It can measure the amps that each panel produces, but not all together.


    So...


    The stated measurement of 70a or 90a almost certainly did not come from a multimeter - it came either from a clamp on meter, or from the display of the charge controller.

    In which case, seeing 5a would be perfectly normal if the batteries are charged and not much else is turned on.


    So no...the solar panels are almost certainly not bad. Now the question is - are the batteries actually bad? Seeing 5a flowing on the clamp meter could just mean that they are fully charged.
  • peter19ue
    peter19ue Registered Users Posts: 14
    Re: Houseboat Solar problem

    Thanks for the input. I had an electrician tell me that he was seeing 5 amps at the subpanel that the solar panels are connected to. The is on the top deck before it ties into the controller/inverter. We are going to test each panel induvidually to see if the panels are good or bad. I know that the batteries are bad because they have been run down and not charged or filled properly over the past two years. Some of that was operator error (now I know what to do) and I also did not have the generator working last year. He also told me that when he ran the generator the Flex80 did not come out of the absorption mode.

    Thanks for all the in depth info. I really appreciate it. I'm hoping that I just need to replace the batteries and there is just something wrong with the solar panel wiring and that is why we are only seeing 5amps from the solar panels at the subpanel close to the solar panels before the inverter/controller.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Houseboat Solar problem

    Peter,

    Please describe how you know what current is flowing from the panels, how you know the batteries are " bad", and what you have done in the interim. For example, if only one cell in one battery is bad, it will pull down the entire string, or if one battery is bad, it too will pull down the entire string.

    What you might try is removing all the batteries from the circuit except for one string of the best, to make a single string of 24 vdc. (assuming that is the system voltage) That way you cut down on the number of possible faults while you look for a solution.

    It would also be helpful if you could actually describe how your system is wired, what are the load side devices like inverters and chargers etc. The clearer you can be, the easier it is for someone to diagnose from afar. I still don't understand what you mean by "having three legs".

    Tony

    PS As Dhw suggests, if your batteries are "bad" it is entirely possible that they are fully charged as far as the charge controller is concerned, ~ 12.7vdc. Even if they can't hold a charge, the voltage may come up to "full" very quickly, and the controller will dial back the current. Another simple test would be to put the batteries under load, like fire up a bunch of light bulbs under full sun and see what the output of the controller is.

    T.
  • peter19ue
    peter19ue Registered Users Posts: 14
    Re: Houseboat Solar problem

    Hi Tony:

    I wish I could explain it better but I am a novice to all of this and am trying to educate myself. This system is alot more complicated that I originally thought or was told. By three legs I mean the the nine panels are wired in sets of 3 so I have three sets of 3 panels suppling power to the subpanel. The batteries I know are bad for sure because they are over three years old and were overused and not charged properly or filled with water on a timely manner. I am hoping that by replacing the batteries everything will start functioning properly. Still not sure why we are only seeing an output of 5 amps from the 9 solar panels. They are less that 3 years old.

    Now that I know what to look for and how to maintain the batteries and operate the solar system I am hoping I can avoid these problems going forward.

    Sincerely,

    Pete
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Houseboat Solar problem

    That is a bit clearer...

    In simple terms, you are not seeing more than 5 amps because of one of two things. Again, even if the batteries are "bad" they may come up to full voltage and the controller shuts off the panels. The second reason is that there is a problem with the wiring. Don't jump to conclusions, you will have to work through this systematically.

    When you get new batteries, (and indeed you might only get one set to get for testing, then add in the others later). I would also suggest that perhaps you get a qualified installer to help you trouble shoot the system. If you don't trust the folks that did the initial installation then perhaps find someone else who is qualified. You are dealing with potentially dangerous voltages, and certainly dangerous currents, and an errant short of some wire could either damage your hardware, or injure someone,,, or both.

    Tony
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Houseboat Solar problem
    peter19ue wrote: »
    By three legs I mean the the nine panels are wired in sets of 3 so I have three sets of 3 panels suppling power to the subpanel.

    We would say, "3 strings connected to a combiner box". :D

    Still not sure why we are only seeing an output of 5 amps from the 9 solar panels. They are less that 3 years old.

    You will only ever see however many amps as what loads there are.

    If the battery charger thinks the batteries are full, and you aren't running your microwave or whatever, then there will be very little load and so very little amps are flowing.

    A solar panel by itself makes 0 amps. Now if you hook up a 1a load to it - like a lightbulb - now it makes 1a, but only as long as the lightbulb is turned on. Turn the light off, and the amps goes back to 0.

    So the reason you are only seeing 5a, is because that is all the load that is on the panels. To see 70a, you have to have 70a worth of load (like a big battery charger bulking up a battery) IN USE.


    I'm a journeyman electrician with 12 years in the trade before I moved on to another profession. If I went back to the trade, I would qualify to move up to master electrician. If another electrician said to me, "I'm only seeing 5a at the combiner box"...I'd say, "Yea...so? What are the loads?"

    Now if he said he was only seeing 5 VOLTS at the combiner, then that WOULD mean there's a problem.
  • peter19ue
    peter19ue Registered Users Posts: 14
    Re: Houseboat Solar problem

    I agree. I like tinkering with things but this is well beyond my comfort level. I don't want to blow anything up or electrocute myself. I'm not having the original guy that did the install work on the system any longer. I've got someone else who is knowledgeable and has been doing this for a long time. First step is to replace the batteries since I know they are bad. Then he is going to check the solar panel wiring and test each panel individually. I'm hoping that there is nothing wrong with the panels and replacing the batteries will solve the problem.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Houseboat Solar problem

    are there any fuses or breakers inline that could've blown as well?
  • peter19ue
    peter19ue Registered Users Posts: 14
    Re: Houseboat Solar problem

    one circuit breaker was tripped but I set in back to the on position
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Houseboat Solar problem

    A tripped breaker is indicative of something.

    Tony
  • peter19ue
    peter19ue Registered Users Posts: 14
    Re: Houseboat Solar problem

    that's what I was thinking. Hopefully its and easy obvious fix like a loose wire or something of that nature
  • peter19ue
    peter19ue Registered Users Posts: 14
    Re: Houseboat Solar problem

    so if I am only using 5 amps of power you are saying that the solar panels will only generate 5 amps of power. If that is the case I'll turn on the fridge and micro and see if the output from the panels increases
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Houseboat Solar problem

    If your batteries are toasted, I would try a smaller load first, like a few light bulbs. Your batteries may be at full voltage, but not have the capacity to run a fridge or micro. Put 200 watts of load, ~ 9 amps at 24 vdc, and see if they produce the 5 that you are seeing now, plus the 9.

    Tony
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Houseboat Solar problem
    peter19ue wrote: »
    so if I am only using 5 amps of power you are saying that the solar panels will only generate 5 amps of power.

    Exactly. That's how much will flow through the wire, and that's what a meter that clamps around the wire will measure - how much is flowing "at this moment".
  • peter19ue
    peter19ue Registered Users Posts: 14
    Re: Houseboat Solar problem

    got it. thats what I'll do then.