Am I being paranoid...

Johnny Portugal
Johnny Portugal Registered Users Posts: 9
about my charge controller LEDs?

Hello,

I have 2x 130w 12v 10A kyocera panels wired in parallel to a Morningstar ProStar 30A charge controller - this is charging a 12v battery bank (3x 12v 220ah batteries). We have recently set this up and are using it to run the lights in the house (currently incandescent bulbs, used about 2 hrs a day)

We are based in Portugal and it's the start of the summer - long hot sunny days. We had a couple of gloomy days recently and the battery status LED on the morningstar was red (battery voltage had dropped below 11.7V - it was about 11.4V in fact when I measured it). I was a bit surprised - I thought red would not be so easy to get to with just running a few lights on an evening. Anyway...

Now we have had an OK day the next day, light back up to yellow (12.6V attained), and today has been a scorcher - sun all day, but the LED is still yellow! In the manual it says that the light will only go green if the voltage has gone up to 13.1 (charging voltage I assume) - does it sound right that 2 130w panels could be sat there all day in the sun and not reach that? The panels seem to be working OK - the open voltage was about 19V and they were putting out 2.5Amps (this was late in the afternoon and they were not pointing at the sun much).

It's now evening and the battery bank reads 12.3V - so it is charging, but it seems really slow. Or am I just being unrealistic (this is my first bit of PV experience)?

Thanks for any advice! PS. im GMT time so my answers maight be a bit late coming

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Am I being paranoid...

    No, you are probably not being paranoid--You are, most likely, simply drawing more power from your system than the solar panels can recharge in a day.

    First, how much power can this generate... Using the PV Watts website, pick Coimbra Portugal. 260 watts of solar panels, assume 0.52 derating factor. We have to use 1kW as the minimum value for the PV Watts program... We get for May:

    80 kWhrs per month * 1/30 days per month * 260 watts/1,000kWperW= 693 Watt*Hours per day

    If you have 4x 100 watt lights * 2 hours per day = 800 watts (just an example)...

    So, how much power are you using per day vs how much power you are generating.

    You need a generator and charger to quickly recharge your battery bank (and equalize if flooded cell battery).

    If you leave your batteries severly discharged for over a day--it will damange the battery bank.

    You have 660 AH of batteries, you should be charging at ~5-13% of battery capacity.... Very roughly, you should have between 33 amps and 86 amps of 12 volt charging current.

    Your ~20 amps of solar panels is not really large enough to fully charge your battery bank... However, if you use a genset with charger every few days to every few weeks--you can be OK (at the cost of extra fuel and generator noise).

    Monitoring voltage on your battery bank is not the best way to determine state of charge... You need to let the batteries "rest" for 3 hours or so, then measure with an accurate voltmeter. Measuring the battery voltage while under charge or under load is much less accurate.

    You can also use a hydrometer (temperature compensated) if you have flooded cell batteries.

    wind-sun_2056_14433211Freas HD98C Precision Hydrometer Set
    How to take Specific Gravity Readings


    And, the ideal is to use a Battery Monitor which is almost the equvalent of a gas (petrol) gauge for your fuel tank.

    You can start reading about how to best maintain your battery bank at the Battery FAQ.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Am I being paranoid...

    Why on gods green earth are you using incandescent light bulbs,,, instead of clfs or leds?

    You could increase you efficiency by at least four fold!

    As we say all too often here,, conservation is your cheapest PV $$. Just changing two 6 watt bulbs to two 15 watt cfls will yield a savings of 90 watts every hour!, that from a system that 260 watts of panel. Using my rule of thumb,, these panels will give you about 250 watt hours of useable power on a perfect day,,, net/net out of the batteries. That means enough to run the above 90 watts of light bulb for 2.7 hours,,, or the said same cfls for 8.3 hours!

    As Bill suggests,, read all you can here, (and elsewhere) and especially read the battery FAQ he linked, Welcome to the site,, good luck and keep in touch,

    Tony
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Am I being paranoid...

    in addition to what they said, that i concur with, is to say you underestimated your usage and maybe overestimated the battery ah for just using a few hours for lights per night. in any case you need to add amps to those batteries by either more pvs and/or supplement with a generator with a good 3 stage charger capable of the current you need in addition to changing to a light source that does not consume as much power. incandescents are the pits in using energy wisely and the bulbs don't last long either.
  • Johnny Portugal
    Johnny Portugal Registered Users Posts: 9
    Re: Am I being paranoid...

    Many thanks for your comments!

    We are going to change over the lights to compact florescents (I already have the bulbs, but we need to change the light fittings as the old bulbs were GU10 halogens) so we should see a significant saving there.

    It sounds like I don't have enough amps going into the battery bank - before I go out and grab another panel, do you think it would be better to upgrade to a MPPT controller to get better charging from my existing panels?

    Also, thanks for the info on the Battery FAQ - very interesting. As I should be charging at "5-13%" of battery capacity, would it be wise to disconnect one battery so I only have 440ah so as not to leave the battery bank in a state of discharge? I could reconnect the other battery when I have more amps going into the system?

    cheers!
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Am I being paranoid...

    you would still be left with the problem of charging up the one you leave out. if you have a generator and a battery charger i suggest getting some amps back into the batteries as soon as possible to avoid damage due to sulfation. the extra pvs and mppt controller are also good, but you need something fast as delaying those batteries from getting fully charged will result in sulfation setting in and you will get a shorter lifespan from the batteries. 3 pvs exceeding the 30a rating of the controller means you need another controller.
    halogens probably drained much more than you had figured on and that switch to cfls may mean an over abundance of battery power available, but this will allow for shallower dods and will result in a much longer lifespan for your batteries, not to mention a reserve to allow for those bad weather days. the exact configuration will need to be figured out by you as to loads vs power sources. power sources should at least slightly exceed loads by about 10-15% on a daily basis to ensure proper battery charging as they must be able to get a full charge on a regular basis. be very sure the pvs you wind up with will supply all the power you will need during a typical 24hr period. technically you also have that 5% minimum charge required for your batteries even if you reduce loads below the need of 3 pvs, but it is possible to reduce that % somewhat under some circumstances and never lower than 3%.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Am I being paranoid...

    The first thing I would do is reduce your loads. Charging in the 5-15% guideline is optimal, but more important is getting the batteries essentially full every few days,, how ever you have to do it. Adding Pv capacity is certainly the preferred option,, but you could also add the amp/hours via a generator or grid charger.

    Keep in mind that you have to have a roughly equal number of ah coming in and going out,,, plus ~20% going in to stay even to allow for net efficiencies. So if you use 100 ah for example,, you will need to generate ~120 ah just to stay even.

    My rule of thumb,, which is a paraphrase of Bill's in depth math,,, is to take the name plate rating of the PV array,, in your case 260 watts, divide in 1/2 for net efficiencies, (130) multiply that number by the average number of hours of "good" sun,, usually ~4 and that equals the number of watt hours you can sort of count on on an on going basis (520) in your case,,, enough to run a 15 watt cfl for ~34 hours, or a 60 watt incandescent for ~8.5 hours!

    As we say,, do the math on both the charging and the loading side.

    Tony
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Am I being paranoid...
    icarus wrote: »
    The first thing I would do is reduce your loads. Charging in the 5-15% guideline is optimal, but more important is getting the batteries essentially full every few days,, how ever you have to do it. Adding Pv capacity is certainly the preferred option,, but you could also add the amp/hours via a generator or grid charger.

    that was 5-13% as some batteries do not like more than 13%. many manufacturers can take a higher rate, but 13% is on the safe side unless one knows otherwise.

    Keep in mind that you have to have a roughly equal number of ah coming in and going out,,, plus ~20% going in to stay even to allow for net efficiencies. So if you use 100 ah for example,, you will need to generate ~120 ah just to stay even.

    it may not be exactly 20% as efficiency does depend on too many things and is why i gave the answer of 10-15% or more for that, but it is essentially correct that watts in must equal or exceed watts used plus all losses.

    My rule of thumb,, which is a paraphrase of Bill's in depth math,,, is to take the name plate rating of the PV array,, in your case 260 watts, divide in 1/2 for net efficiencies, (130) multiply that number by the average number of hours of "good" sun,, usually ~4 and that equals the number of watt hours you can sort of count on on an on going basis (520) in your case,,, enough to run a 15 watt cfl for ~34 hours, or a 60 watt incandescent for ~8.5 hours!

    again, this may be over simplifying and may not be an accurate one size fits all statement to make even though figuring more on the worst case may help to insure it will work. there is no substitute for the real math that is not always easily figured as each individual component must be accounted for. btw, the 4hr period is also a reaching generalization as this is totally dependent on the location and time of year and even typical weather patterns for that area.

    As we say,, do the math on both the charging and the loading side.

    Tony

    tony,
    i had to address some of your statements as some are misleading or inaccurate and definitely too simplified.
  • Johnny Portugal
    Johnny Portugal Registered Users Posts: 9
    Re: Am I being paranoid...

    Hello all, again thanks for the info - worth it's weight in gold.

    I'm still not 100% convinced that the charge controller is totally OK - we had another hot one today, sunshine hits the panels about 9am and sets about 8pm - no clouds at all. So the panels should be producing at least about 600w of power based on BBs maths in the first reply. But the batts are still at 12.3v and the LED is still yellow on the morningstar, and that's with hardly any load applied (2 60w bulbs used for 1.5 hrs).

    I think i'm going to disconnect the inverter so there is definitely no load, then check the voltage and amps at the panels, then at the controller, then finally at the batteries to see just what is going in - I only have a standard multimeter so I will have to do each 10A panel separately (hopefully without too much sparking!).

    One word on the batteries, the ones I bought were "carbon fibre" Elecsol 220s - they can apparently do 1000 deep discharges at 80% DOD and have a 5 yr guarantee. So hopefully I haven't screwed the pooch on them yet. I don't know what they mean by carbon fibre, maybe they won't suffer the sulfation problem?
  • Johnny Portugal
    Johnny Portugal Registered Users Posts: 9
    Re: Am I being paranoid...

    Oh one other thing - can anybody please tell me if those Elecsol batteries are "flooded" or "sealed"..?

    They are sealed in the sense that you have no holes to top up the distilled water, but I read they are still a type of flooded acid battery just with carbon fibre plates instead of lead. So they are a sealed flooded battery...:confused:

    The morningstar controller has a switch to set your battery type, and this can affect the charging voltages.

    Thanks
  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    Re: Am I being paranoid...

    assuming your really getting 600 wHrs , that's about 48 aH on a battery pack of 600+ah .... your not going to have the voltage budge much

    Further, you had all most 1/3rd of that on your 120 watts of lights, what ever the inverter draws 24/7 ect ect

    So you gave it maybe a 5% charge best case ... you have a big difference here between expectations and what you have for actual hardware
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Am I being paranoid...

    if your batteries have no means of adding water then they are sealed, but which type of sealed i don't know.
    as to your battery bank voltage you have to understand that you are undercharging your batteries due to a low charge current from your pvs. if you have 20a from pvs going into depleted batteries with a 660ah capacity this would take at least 660/20=33 hours with no loads on. you will also not get your full charge rate when the sun is near sunrise or sunset and is based on 1000w/m^2 of solar radiation hitting the pvs and i like to refer to that level as 1 full sun. my guess is you may be seeing 6 full suns with no clouds and there may even be a slight reduction in pv output if the ambient heat is high or hot. this translates to at least 33/6=5.5 days without any other losses or loads. 20a represents a 3% rate of charge to 660ah batteries and when loads are on it too this percentage drops. another pv may get you closer to the 5% minimum, but again that is without any loads running at the same time. an inverter set on and not running any lights or appliances will still be a load to the system as it needs some power to just idle there. if you followed me here properly you now know you need to get them charged up asap and if the pvs is the only means you have to do this that this will take time and no loads should be introduced until it is 100% charged.
  • Johnny Portugal
    Johnny Portugal Registered Users Posts: 9
    Re: Am I being paranoid...

    Hello Solar Guppy,

    I did a volts \ amps check on the panels at midday, and each panel was giving 13V and 8.5A. So that should mean the panels gave 220wh over that midday hour (im assuming that the wattage then was the highest as facing directly the sun).

    It just seemed a bit odd not that the panels did not up the voltage at all - the inverter draws less than 1amp when not under load (which it isn't during the day) - how much sun do you need to get these batteries charged back up !?!
  • Johnny Portugal
    Johnny Portugal Registered Users Posts: 9
    Re: Am I being paranoid...

    Hi Niel,

    yes i'm with you on this one - it's going to be a grid powered battery charger to get them pumped back up tomorrow while I swap out the lights to cfls. Thanks for explaining the voltage time charging etc.. Looks like the key here is to keep your dod to a shallow discharge!
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Am I being paranoid...

    with that added bit of specs it is even worse as you are getting 17ah from both pvs together and need to subtract 1a tare loss from the inverter for 16a. 16/660=2.4% charge rate and it would take 660/16=41.25hrs and if 6 full suns each day that is 41.25/6=6.875 days to go from 0 to 100% soc minimally.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Am I being paranoid...

    Note to Niel,

    You are absolutely right that my example is too simple.

    On the other hand,, for the purposes of general discussion,, especially with newbies, it is a my 50% no name plate rating times hours of sun comes pretty darn close,,, close enough for a general discussion IMHO

    My 5-13% rule is also pretty close as a place to start a discussion

    Finally,, my 120% rule is also pretty close

    My point is that while there is certainly a place for gnat's a** math, many if not most newbies who ask the question "How much can I power using such and such hardware?" are looking for an answer that is easily arrive at. After that, the real, engineer's detail can be added to get to the "real answer"

    The truth is,, many of us,, yourself and Bill included, spend a lot of time explaining to newbies that they are off by at least one order of magnitude in their assumptions. If my explanation gets to within ~10% then I think that is close enough for the discussion. (Having said that,, when I do,, and I do often make factually incorrect statements,, I need to be corrected,,, I also need to be corrected when my math is wrong,,, as it also often is!)

    I think sometimes we get can get caught up in the minutia at the expense of the general.

    Solar Guppies post just before this one states the general pretty well, "So you have a 5% charge case best case,,,you have a big difference between expectations and what you have hardware for" The 5% may not be exact,,, but the general explains the problem.

    Tony

    PS I'm not upset by this,, I just wanted to explain my logic.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Am I being paranoid...

    ok, but there's too much leeway as there's a big difference between 3 and 5% when you are talking about a battery rate of charge and add that to all of the others with room to play and this can backlash on you for using it. maybe you need a disclaimer when doing so?
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Am I being paranoid...

    Neil,

    I will write disclaimer,,

    I think it will have to include battery types especially since that is where the biggest danger lies,

    Thanks,

    T
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Am I being paranoid...
    Hello Solar Guppy,

    I did a volts \ amps check on the panels at midday, and each panel was giving 13V and 8.5A. So that should mean the panels gave 220wh over that midday hour (im assuming that the wattage then was the highest as facing directly the sun).

    It just seemed a bit odd not that the panels did not up the voltage at all - the inverter draws less than 1amp when not under load (which it isn't during the day) - how much sun do you need to get these batteries charged back up !?!

    If you are charging 660 Amp*Hours (at 12 volts of batteries), and you are running around 11.4 volts (assuming that these are Lead Acid batteries and the "Carbon Fiber" is just in the plates to make them stronger)... From the Battery FAQ, 11.4 volts at ~25C is near 15% state of charge.

    So, to "refill" your battery just using the solar panels (and no extra loads for lights), would take:

    660 amp*hours * (100%-15%) = 561 amp*hours to recharge.

    561 AH / (8.5 amps + 8.5 amps per panel) = 33 hours of "full sun"

    Which, allowing for inefficiencies and such... is at least 5 hours of sun per day:

    55 hours / 5 hours of full sun per day = 11 days (minimum) to fully recharge from solar panels

    The above answer is probably accurate to within +/- 20% (since we now have to add "error bars" to all of our assumptions :roll: ).

    The above assumes that your batteries are at 25C, that the 11.4 volts was measured when the batteries where at rest for at least several hours (no charging or discharging), and that your meter was calibrated, and that "carbon fiber batteries" are really just a form of standard (sounds like) AGM or Gel Cell type batteries.

    If you are charging your battery at C/10 (capacity of bank at 10% charge current)--it will recharge the bank by 10% every hour (10 hours = 0-100% charge). C/20 or 5% rate of charge, will take 20 hours to recharge a dead bank (not that you ever want to take your batteries to "dead").

    And I will be redundant again--You really need to get a Battery Monitor for your system. As you batteries appear to be sealed--there is only one way--the battery monitor--that you can know your bank's accurate state of charge at any time.

    For most users, a Battery Monitor will save them from giving their batteries an early death (BM is usually cheaper than a bank of batteries). And it will answer most of your system specific questions (how fast will the bank discharge with XX load, how fast will it recharge with YY charging current, am I using more power than I replace, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nigtomdaw
    nigtomdaw Solar Expert Posts: 705 ✭✭
    Re: Am I being paranoid...

    Hi Jonny P I paid a visit to Elecsol website at http://www.elecsolbatteries.com

    From there literature your batteries can be topped up and from the data within the site it would appear that the voltage settings are close to standard flooded lead acid at 14.8 bulk 14.4 absorb.

    You have been guilty of long term under charging and really need to invest in a proper 3/4 stage deep cycle battery charging system whether a standalone charger or an inverter charger. A standard car battery charger will not cut it. I suspect that your inverter is a modified sinewave ?

    If you are off grid and need to keep costs low have a look at Magnum Energy they do a small 12v modified sinewave inverter euro spec 230 50 hz with a power factor corrected 4 stage charger charger .Wind and Sun should have them , not totally sure.

    Xantrex do a generator friendly range deep cycle battery charger also TrueCharge

    Look at some of the small Suitcase Inverter Style generators around the 2000 w range

    (Honda Kipor and other budget brands are available in Spain so guess Portugal as well they are excellent with the smaller Inverter Chargers.

    To look after your batteries they need to get a full absorption cycle mimimum twice a week and whilst Elecsol claim to have greatly deminished the risk of sulphation with there batteries I bet you wont get them replaced on there five year warranty if you keep them in this discharged state .

    If you have a portugal landline I can ring you for free if you need any further help,
    also according to Elecsol they have a lower SG reading compared to standard Flooded cells its all on thier site

    HTH Nigel
  • Johnny Portugal
    Johnny Portugal Registered Users Posts: 9
    Re: Am I being paranoid...

    Thanks Bill,

    I was looking into getting a NASA BM1 battery monitor, a lot of marine suppliers stock them but so do a few of the solar suppliers in Europe. Problem is they are rated to handle battery banks of up to 650Ah - mine is 660Ah - do you think I'll get away with the extra 10Ah?. If not, any advice on a good battery monitor to go for?

    I pulled the middle battery out of the bank so the panels just had the 2 to charge, and charged the loose battery with a normal battery charger. The batteries today are 100% full (according to the charge controller) as it's gone into PWM mode.

    Lessons learned by me

    1. dont take the panel rating at face value as to how much power you'll get
    2. understand that amps is important (not just watts) when seeing how much juice your panels can put back in
    3. realise that 11.4 volts is nearly a flat battery (not just a "bit low" as I assumed):blush:

    Thanks
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Am I being paranoid...

    add number 4 in that your batteries need to achieve a full charge periodically or sulfation will occur from undercharging and damage the batteries to one degree or another.
    also note that amps is a component of watts as watts = volts x amps.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Am I being paranoid...

    I don't know about the BM you are asking about (I am certainly no expert in the solar hardware area)--but 650 vs 660 AH is no problem.

    Perhaps Nigel (Nigtimdaw) can give you some information on good solar suppliers in your area (links/information that point to other solar suppliers as part of discussions/Q&A are fine here).

    And, even when the charge controller just goes into PWM mode--the battery is still only (approximately) 80-90% charged.

    Follow the battery charging instructions from the mfg. in Nigel's link.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Johnny Portugal
    Johnny Portugal Registered Users Posts: 9
    Re: Am I being paranoid...

    Thanks Nigel,

    the elecsol batteries I have are definitely sealed (the lower rated 110s are open flooded and can be topped up) - these sealed ones apparently will be permanently damaged if overcharged, as too much heat, loss of water etc..

    Interestingly, these batteries apparently don't suffer from sulfation (quote from the manufacturer's website)

    "Batteries fail in cycling life due to a permanent encapsulation of PbSO4 on the plates (lead sulphation). The capacity loss is more rapid with these battery types, the deeper that the battery is discharged, and the quicker lead sulphation builds up. Upon recharging the battery, not all of this sulphation is converted back to lead (PB0). The result is a gradual loss of capacity.

    Another major reason for premature battery failure is due to the oxide shredding from the plate. Standard lead plates are bound only with acrylic and polyester fibres they do not serve as reinforcement of the plate. The cycling life of the ELECSOL battery is much greater than all other battery types because THE CARBON FIBRE ELIMINATES LEAD SULPHATION OF THE PLATES PERMANENTLY. Upon recharging, the original capacity will be replenished. Carbon Fibre acts as a mechanical reinforcement fibre to the lead grid and paste reducing oxide shredding."

    and

    "Q.6 - WHAT HAPPENS IF I LEAVE MY ELECSOL BATTERY IN A DISCHARGED STATE?
    A. Unlike conventional batteries, the Elecsol range does not suffer from permanent lead sulphation, which is caused by leaving your battery in a discharged state or by overcharging."

    They also say the battery is fully charged at 14.4V, so I will change my morningstar charge controller to "flooded" battery type. I think this is a 3 stage charger - the grid battery charger was just an emergency measure to ease the job of the panels and get some amps back into the batteries to avoid sulfation (which it appears they don't suffer from anyway! Sheesh!;))
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Am I being paranoid...

    At least one other AGM vendor (Concord?) says that their AGM's don't suffer sulfation either.

    The killer for AGM's is overcharging... So, make sure that your charger does not go above the recommended voltages--and if the charger has an equalization setting--that it is turned of or the voltage is programmed per the operator's manual.

    Even with AGM, I would not want to let them sit for long periods near dead.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • peterako
    peterako Solar Expert Posts: 144 ✭✭
    Re: Am I being paranoid...

    Hi there,

    You can leaf your GU10 fittings and install leds from Phillips , osram or lexman. the 3 watt type are like 25 Watt halogeen and brighter. saving energy will be your first plus after one year i am more aware that the cfl. are not surviving the inverter even a full sinus inverter is heating them up.

    second at a nice generator to full charge your battery a battery needs to wake up by charge discharge.

    Greetings From Greece8)