MPPT question

2

Comments

  • System2System2 Posts: 6,290 admin
    Re: MPPT question
    BB. wrote: »
    Yes, the voltage is just missing a decimal point for the voltage...

    The reason I am not sure about how long it will take to recharge your system (4.5 days)--is I am not sure of the capacity rating of your batteries and how they are wired.

    There is a lack of complete information here... I don't know how your system is wired (voltage), you have given us the solar panel current (amps) but not the voltage (and with a MPPT controller--we need both the voltage and the current). Not sure about the battery capacity (how many gallons is the gas tank?). And now you have given us the Battery Voltage (~26 vdc), but not the battery current (amps) yet...

    So, we are getting closer--but some of my earlier guesses were wrong (24 vs 48 vdc battery bank)...

    Does not change your system, and you have more information on how to manage and understand your readings from your MPPT controller... All good things.

    And, basically, you are correct on the battery... The deeper your discharge it, the shorter its working life.

    Also, a cool battery has higher voltage readings. A cool battery will last longer (in years). But does have somewhat less ability to store and supply power.

    The link to the battery manual the Jim provided has a whole bunch of information about your batteries.

    Karen, you are doing well here. And I wish my English skills were even 1/2 yours (hence, the reason I choose Engineering--I don't have to talk with anyone-- :roll: )... Or at least so I thought until I had to give training sessions (I threatened to quit the first time) and the long reports, manuals, and design sessions... Gotten over the fear--but my writing is none to pretty.

    Take care Karen,
    -Bill

    What a really nice message, thank you. (I was feeling really down about discharging them so much. Now I feel happier. Thank you.)

    When I had management training with AT&T LONG AGO, there was one week of training with people from all different areas... and in one session we were broken into groups and I remember how cleverly the engineers did their tasks, and they won... I think the idea of that session was that groups always out perform individuals... and my take on it was that engineers were the outperformers of all outperformers. :)

    Thank you again.

    Now, go and have a really good time. :)
  • System2System2 Posts: 6,290 admin
    Re: MPPT question
    icarus wrote: »
    I tried to post this as a PS to no avail,

    PS. I don't know how big your battery bank, or your panel system is, but the relationship between the two is critical. It is even more important that you (the opperator) understand how much energy you should be using. Just because the lights or the computer is on, doesn't mean there is enough "juice" to safely continue to run them. Most people agree that the battery capacity should be big enough for 4-5 days of average use before the batteries reach 50%. Then you need enough panel capacity to bring them back quickly, as using/leaving them partialy discharge will kill them quickly. Most experts (here) recomend that you have 3-5% of battery capacity in solar capacity. They also recomend that before the batteries get close to 50% (most say 80%) they should be fully charged from either grid power, or from a generator. You might consider, if you are not going to to back on the grid, getting a small generator (Honda eu 1000 or similar) to augment you power. Coupled with a GOOD charger you could keep you batteries up, use the generator for your high draw item such as your coffe/tea pot. I use a Honda eu 1000 to top up my batteries. It costs ~$500, plus a Xantrex tc20 charger ~$250. It burns about a quart of gas every 4 hours whilst charging my battery bank.

    I might also suggest that you read through all the threads about "off grid" living on this forum.

    Tony
    I've done a bit of reading, but obviously not enough.

    I have 4 of the 120 Evergreen panels, and 4 183 amp hour gel batteries...

    So, I don't see how the 7 amps an hour for 4 or 5 hours could fill the batteries very much.

    Since I had tetanus I've not been driving. (I got it because I couldn't feel a broken darning needle in my toe... nerve damage... SOOOOO irritating.)

    Meaning: even if I had the money, which I don't, I couldn't easily go out and get the petrol for the generator... I was just very much planning on not overdischarging my batteries... that's why I bought the monitor...

    Without any heat, being on the computer makes the time pass more quickly... but that may still be a bad reason to be using my batteries this evening...
  • System2System2 Posts: 6,290 admin
    Re: MPPT question
    icarus wrote: »
    I'm sorry to say that I think you are correct in your assumption of draining 90% of your battery. It is quite common for people who are new to RE to not understand that even with "deep cycle" batteries, you can't drain them dead (90%) routinely and expect good longevity from them.

    As the link suggests, if you discharge them 20% they will last 10 TIMES as long (as many charge/discharge cycles) than if you discharge them 80%.

    Icarus

    Yes, Yes. I'm afraid so.

    I didn't need to, either.

    The exact reason I bought the monitor was to avoid this.

    So, I am pretty sad about this.
  • BB.BB. Super Moderators, Administrators Posts: 29,980 admin
    Re: MPPT question

    Karen,

    If you want to try a little math to understand what is going one. Your MPPT is like that transmission in a car (or really, an AC electrical transformer--but if you don't know really what that is, don't worry).

    One of the basic equations that we will use here is Power equals Voltage times Current... or:

    P=V*I (voltage is in volts and current is in amps).

    We have energy from your solar panels which equals:

    Ppanel=V*I=V(?)*7amps

    And we have energy to your battery:

    Pbattery=V*I=~27volts * I (?)

    And, for a first approximation, the power going into the MPPT controller equals the power going out of the MPPT controller:

    Ppanel=Pbattery
    V(?)*7amps = ~27volts * I (?)

    The problem is that I have two unknowns here--The PV panel voltage ( V(?) in volts--which you have no way of measuring without a separate voltmeter)...

    And the Battery Charging Current (I in amps).

    Fortunately, the MPPT Controller does allow you to measure both Battery Voltage ("V" in volts) and Battery current ("I" in amps).

    If we know one other value, we can solve for the last unknown.

    And for your system, you really need to watch the battery current and voltage--that tells us 99% of what we need to know from the solar charger. The Solar Panel Current is not useful for us right now (kind of like watching the engine RPM gauge instead of the car's speedometer or odometer).

    Once we know both Battery Voltage and Battery current (amperage) while charging (can you give us that at noon on a clear day), we can then give you a better estimate on how fast your batteries will charge and how much power you can take out of them on a sunny day.

    The problem with just watching the battery current, it is a lot like watching your speedometer as you drive around town and the freeway and trying to figure out how far you are going... The Odometer is much better at keeping track of mileage (and that is what you don't have in your system--the universal battery monitor). However, we can also read your battery voltage (and temperature) first thing in the morning and tell roughly how much energy is has stored (kind of like reading your gas gauge and guessing how far you can drive today)...

    Anyway, I will stop with the analogies right now--they are probably hurting more than they are helping right now.

    Take care and keep warm Karen,
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: MPPT question

    Couple of questions I have: With your 120X4 panels you should be getting ~18amp @24vdc or ~36 amps @ 12vdc. If you are only getting 7 amps you must be running 48vdc, is that right?

    In that event (48vdc) you are getting ~300watts per hour into the batteries (assuming everything is turned off) 4.5hours/day would be a possible recharge of ~1350 watts/day to use (assuming good sun 7 days a week with no reserve).

    At 48vdc your batteries have a total capacity of ~8700 watts. If you only want to discharge them to 80% you could pull out ~1740 watts perday, BUT, since you can only put in ~1350 every day you use more than ~1350 you will be going backwards.

    In simple numbers a lap top uses ~60 watts X 4 hours=240 wt/hrs
    Simple light bulb (Incandesent) ~60 watts X 6 hours=240 wt/hrs
    Toaster ~1500 wts X .25 hrs=375 wt/hrs
    Crock pot (guess) ~500 wts X 4 hrs =2000 wt/hrs
    Television (guess) ~125 wts X 4 hrs =500 wt/hrs

    You can see from these typical examples that your system can and will be quickly overwhelmed and the batteries will be drained beyond their safe limit.

    There are only 3 solutions.

    1. Reduce the loads
    2. Recharge from outside sources, either grid or generator
    3. Increase the size of the system

    I think you have begun to realize that "aint nothing as easy as it sounds, and aint nothing free"

    It is a lesson that many who are new to RE have learned in equally painful ways. At least you (and I) have the benefit of the combined wisdom (On this forum) of all the learned minds and hard knocks learning of those who have made similar mistakes earlier. (My self included!)

    Good luck, keep warm and keep a good thought.
  • System2System2 Posts: 6,290 admin
    Re: MPPT question
    icarus wrote: »
    Couple of questions I have: With your 120X4 panels you should be getting ~18amp @24vdc or ~36 amps @ 12vdc. If you are only getting 7 amps you must be running 48vdc, is that right?

    In that event (48vdc) you are getting ~300watts per hour into the batteries (assuming everything is turned off) 4.5hours/day would be a possible recharge of ~1350 watts/day to use (assuming good sun 7 days a week with no reserve).

    At 48vdc your batteries have a total capacity of ~8700 watts. If you only want to discharge them to 80% you could pull out ~1740 watts perday, BUT, since you can only put in ~1350 every day you use more than ~1350 you will be going backwards.

    In simple numbers a lap top uses ~60 watts X 4 hours=240 wt/hrs
    Simple light bulb (Incandesent) ~60 watts X 6 hours=240 wt/hrs
    Toaster ~1500 wts X .25 hrs=375 wt/hrs
    Crock pot (guess) ~500 wts X 4 hrs =2000 wt/hrs
    Television (guess) ~125 wts X 4 hrs =500 wt/hrs

    You can see from these typical examples that your system can and will be quickly overwhelmed and the batteries will be drained beyond their safe limit.

    There are only 3 solutions.

    1. Reduce the loads
    2. Recharge from outside sources, either grid or generator
    3. Increase the size of the system

    I think you have begun to realize that "aint nothing as easy as it sounds, and aint nothing free"

    It is a lesson that many who are new to RE have learned in equally painful ways. At least you (and I) have the benefit of the combined wisdom (On this forum) of all the learned minds and hard knocks learning of those who have made similar mistakes earlier. (My self included!)

    Good luck, keep warm and keep a good thought.

    If it is wired for 48, then why isn't the MPPT thing doing a 400 number instead of a 200 number?

    I used candles for all my cooking up until about a week ago when I decided that if I'd never once used more than 10% of my battery energy, I should start using more.

    I used more because the GD monitor said what it said, that I had 90% of my energy left.

    I never thought this was going to be easy, especially with my brain injury, and it sure as H wasn't cheap.

    It's 24 degrees outside and I can't have a light on because the GD monitor was either installed wrong or another fraud to steal my money and leave me hurting.
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: MPPT question

    If you are getting #in the 200, perhaps it is wired 24vdc. In that case 7 amps would be less than 1/2 what the panels should put out. Perhaps the installer should check to see that it is wired and running properly. If you spend as mcuh money as I guess you have, he shuld come and take a look, as well as give you some lessons on how to moniter your metering system

    Icarus

    PS. The "MPPT thing" is just a controller. It's function is to (in essence) turn off the panels when they are fully charged. The meter just tells you how much charge is going in and (depending on the model) how much (In rough numbers) is in the battery.

    PPS. A 24vdc system should show ~25.2 volts AT REST, (an hour after ALL charging and ALL loads have been turned off). Any battery will show a a higher voltage while being charged, and a lower voltage while under load. There is no such thing as a "gas gauge" for a battery, save a hydrometer as discussed on other threads in this forum. The best compromise is the Tri-metric meter, and others like it.
  • BB.BB. Super Moderators, Administrators Posts: 29,980 admin
    Re: MPPT question

    It really depends on how they wired the Solar Panels... Just a quick look-thru on the controller--From the manual:
    Model MPPT500HV operating efficiency has been optimized for 48 volt
    nominal PV input voltage.

    So, for the number to roughly work out, the PV panel voltages are ~48-60 volts nominal and the Batteries are wired for 24 VDC (per the MPPT Controller's voltmeter).

    If so, then the numbers make sense.

    7amps * 50 volts = 350 watts.

    350 watts * 5 hours per day (winter average sun hours) = 1,750 watts*hours per day

    4 batteries x 12 vdc per battery * 183 amp*hours per battery = 8,784 watt*hours of storage

    8,784 w*h battery/1,750 w*h per day = 5 days to fully recharge

    Or, in terms of current:

    I=P/V=350 watts / 28.3 volts = 12.37 amps

    Amount of storage in batteries is two 12 VDC battery strings in parallel:

    AH (at 24 VDC) = 2 x 183 amp*hours = 366 amp*hours

    366 amp*hours / 13.37 amps = 29.6 hours of charging

    5 hours of sun per day (again, these are hours of full sun, I realize that you have sun 8-10 hours per day)

    29.6 hours of charging / 5 hours per day = 5.9 days to fully charge your batteries...

    All around 5-6 days to recharge your batteries. If you use power for your lights, computer, cooking--that will dramatically increase the time it takes to recharge your batteries. (the numbers are not exact, because there are different assumptions made in the several above calculations--adding inefficiencies of battery charging will add ~10-20% more time)...

    Take care,
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Karens' PV System Configuration

    OK. After having monitored Karen’s threads, I believe we can use the BZ Products “MPPT” charge controller’s display to better understand her system.

    Karen,

    There’s a little black slide switch on the front of the MPPT charge controller. The switch positions and corresponding displays are:

    Top: “PV Amps” (current from the PV array to the MPPT controller)
    Middle: “Battery Volts”
    Bottom: “Battery Amps” (current from the MPPT controller to the batteries and loads)

    On a clear and sunny day, please take a mid-day reading for each of the three switch positions. If you’ll send the data to us, we’ll be able to figure out how your system is configured. With this information, we’ll be able to provide some specific pointers on system operation and maintenance.

    More later,
    Jim / crewzer
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Initial Goals

    Karen,

    OK. Good news, and bad news. The good news is that the batteries are gel types, and they can be recoverable after severe discharges. The bad news is that the BZ Products MPPT controller and its instructions are, in my opinion, sub-optimal.

    For example, what the controller calls a "float" mode is really more of an absorb mode, and there is no real float mode. The misapplied terminology and the missing feature are not good things.

    But, it’s what you’ve got, so let’s see if there’s a way to make the best of things with it. I recommend the following immediate goals:

    1) Adjust the MPPT controller so that it matches your batteries’ charging requirements.
    2) Fully recharge your batteries as quickly as possible. This will mean minimizing loads (light, computers, etc.) on your system so that the maximum amount of charge current is delivered to the battery bank. It will also mean keeping the PV array clear of snow and other debris.

    Your four 12 V x 183 Ah gel batteries are very sensitive to overcharging. Accordingly, it’s important that the charge controller be adjusted to match the battery charging specs. The “optimal” absorb voltage spec for the 12 V batteries is 13.7 V at 77 F.

    The MPPT charge controller’s default “float” voltage setting for sealed batteries is 13.8 V. This is close enough to 13.7 V. Assuming the charge controller is set for sealed (gel batteries are a type of sealed battery) and that the controller voltage is set for the right battery bank nominal voltage, this should all be OK. These settings are determined by the SW-1 DIP switch in the controller.

    Since the BZ Products MPPT charge controller does not include separate absorb- and float voltage targets, the recommended strategy is to use the controller’s “float” setting as the batteries’ absorb target and dispense with a traditional float voltage.

    However, your environment is, at present, typically in the mid-40 degree F temperature range, or ~ 7 C. Cold batteries require a higher charging voltage, and the good news is that your MPPT controller includes a feature to do just that ("temperature compensation").

    Applying the controller’s -18mV/C temperature compensation curve, the target “float” voltage should be 14.1 V. Theoretically, once the battery voltage reaches ~14.1 V, the controller’s “Float” LED should light up, and the controller should go into limited current mode. Once the LED has been steadily illuminated for ~ 3hours, the batteries should be fully recharged.

    If your battery voltage is 24 V nominal, then the reference absorption target should be 27.6 V, and the temp comp target 28.2 V. Once we have the data I requested (see previous post), your system is properly configured and calibrated (goal #1), and the batteries are fully recharged (goal #2), we’ll need to discuss way to understand expectations, system behavior and energy management.

    HTH,
    Jim / crewzer
  • System2System2 Posts: 6,290 admin
    Re: MPPT question

    I added large pictures to my page to show how the monitor has always shown that I have a lot of energy in my batteries.

    http://www.health-boundaries-bite.com/Solar.html#space
  • System2System2 Posts: 6,290 admin
    Re: Initial Goals
    crewzer wrote: »
    Karen,

    OK. Good news, and bad news. The good news is that the batteries are gel types, and they can be recoverable after severe discharges. The bad news is that the BZ Products MPPT controller and its instructions are, in my opinion, sub-optimal.

    For example, what the controller calls a "float" mode is really more of an absorb mode, and there is no real float mode. The misapplied terminology and the missing feature are not good things.

    But, it’s what you’ve got, so let’s see if there’s a way to make the best of things with it. I recommend the following immediate goals:

    1) Adjust the MPPT controller so that it matches your batteries’ charging requirements.
    2) Fully recharge your batteries as quickly as possible. This will mean minimizing loads (light, computers, etc.) on your system so that the maximum amount of charge current is delivered to the battery bank. It will also mean keeping the PV array clear of snow and other debris.

    Your four 12 V x 183 Ah gel batteries are very sensitive to overcharging. Accordingly, it’s important that the charge controller be adjusted to match the battery charging specs. The “optimal” absorb voltage spec for the 12 V batteries is 13.7 V at 77 F.

    The MPPT charge controller’s default “float” voltage setting for sealed batteries is 13.8 V. This is close enough to 13.7 V. Assuming the charge controller is set for sealed (gel batteries are a type of sealed battery) and that the controller voltage is set for the right battery bank nominal voltage, this should all be OK. These settings are determined by the SW-1 DIP switch in the controller.

    Since the BZ Products MPPT charge controller does not include separate absorb- and float voltage targets, the recommended strategy is to use the controller’s “float” setting as the batteries’ absorb target and dispense with a traditional float voltage.

    However, your environment is, at present, typically in the mid-40 degree F temperature range, or ~ 7 C. Cold batteries require a higher charging voltage, and the good news is that your MPPT controller includes a feature to do just that ("temperature compensation").

    Applying the controller’s -18mV/C temperature compensation curve, the target “float” voltage should be 14.1 V. Theoretically, once the battery voltage reaches ~14.1 V, the controller’s “Float” LED should light up, and the controller should go into limited current mode. Once the LED has been steadily illuminated for ~ 3hours, the batteries should be fully recharged.

    If your battery voltage is 24 V nominal, then the reference absorption target should be 27.6 V, and the temp comp target 28.2 V. Once we have the data I requested (see previous post), your system is properly configured and calibrated (goal #1), and the batteries are fully recharged (goal #2), we’ll need to discuss way to understand expectations, system behavior and energy management.

    HTH,
    Jim / crewzer


    Look, the monitor didn't work. It was 18 degrees last night and I don't have heat and now I don't even have light.

    I wonder if those wires should be hanging loose the way that they are:

    http://www.health-boundaries-bite.com/Solar.html#space

    and I wonder if the batteries are properly wired...

    Clearly my solar panels were installed in the right place.

    I guess it's ironic that the installer is married into the privy pit problem I had that has so devastated my life.
  • System2System2 Posts: 6,290 admin
    Re: MPPT question
    icarus wrote: »
    If you are getting #in the 200, perhaps it is wired 24vdc. In that case 7 amps would be less than 1/2 what the panels should put out. Perhaps the installer should check to see that it is wired and running properly. If you spend as mcuh money as I guess you have, he shuld come and take a look, as well as give you some lessons on how to moniter your metering system

    Icarus

    PS. The "MPPT thing" is just a controller. It's function is to (in essence) turn off the panels when they are fully charged. The meter just tells you how much charge is going in and (depending on the model) how much (In rough numbers) is in the battery.

    PPS. A 24vdc system should show ~25.2 volts AT REST, (an hour after ALL charging and ALL loads have been turned off). Any battery will show a a higher voltage while being charged, and a lower voltage while under load. There is no such thing as a "gas gauge" for a battery, save a hydrometer as discussed on other threads in this forum. The best compromise is the Tri-metric meter, and others like it.

    I'm just really depressed about this at this point, and I was really hurt by what you wrote yesterday.
  • System2System2 Posts: 6,290 admin
    Re: MPPT question
    BB. wrote: »
    It really depends on how they wired the Solar Panels... Just a quick look-thru on the controller--From the manual:



    So, for the number to roughly work out, the PV panel voltages are ~48-60 volts nominal and the Batteries are wired for 24 VDC (per the MPPT Controller's voltmeter).

    If so, then the numbers make sense.

    7amps * 50 volts = 350 watts.

    350 watts * 5 hours per day (winter average sun hours) = 1,750 watts*hours per day

    4 batteries x 12 vdc per battery * 183 amp*hours per battery = 8,784 watt*hours of storage

    8,784 w*h battery/1,750 w*h per day = 5 days to fully recharge

    Or, in terms of current:

    I=P/V=350 watts / 28.3 volts = 12.37 amps

    Amount of storage in batteries is two 12 VDC battery strings in parallel:

    AH (at 24 VDC) = 2 x 183 amp*hours = 366 amp*hours

    366 amp*hours / 13.37 amps = 29.6 hours of charging

    5 hours of sun per day (again, these are hours of full sun, I realize that you have sun 8-10 hours per day)

    29.6 hours of charging / 5 hours per day = 5.9 days to fully charge your batteries...

    All around 5-6 days to recharge your batteries. If you use power for your lights, computer, cooking--that will dramatically increase the time it takes to recharge your batteries. (the numbers are not exact, because there are different assumptions made in the several above calculations--adding inefficiencies of battery charging will add ~10-20% more time)...

    Take care,
    -Bill

    Yes... I think you got it, I think that might be what it is. But now that I was taking the readings of the three different things, I saw that there was brilliant sunshine outside and I was hardly getting any amps, so I looked out the window and my bottom panel was installed so that at this time of year it's half in the shade for a couple hours each day.

    In the end, I'm not surprised that there's a connection between the installer and my privy pit problem... and I'm just feeling USED.

    I added pictures to my web page:
    http://www.health-boundaries-bite.com/Solar.html#space

    Overall, ... it just will never be very good in the winter, and my batteries are probably relatively wrecked, and it was not my fault just the way the privy pit wasn't, but there's been NO due process and so I am in proverty because of this and I'm just so angry and it's useless because there's no rule of law here, there's just rule by the rich for the rich.
  • System2System2 Posts: 6,290 admin
    Re: Initial Goals
    crewzer wrote: »
    Karen,

    OK. Good news, and bad news. The good news is that the batteries are gel types, and they can be recoverable after severe discharges. The bad news is that the BZ Products MPPT controller and its instructions are, in my opinion, sub-optimal.

    For example, what the controller calls a "float" mode is really more of an absorb mode, and there is no real float mode.

    I don't really know what this means, because I don't know the difference. I think that if the battery monitor had worked this would be less of a problem. I don't know if what you've written means that it allows my batteries to overcharge.

    The misapplied terminology and the missing feature are not good things.

    But, it’s what you’ve got, so let’s see if there’s a way to make the best of things with it. I recommend the following immediate goals:

    1) Adjust the MPPT controller so that it matches your batteries’ charging requirements.

    I don't understand well enough to know what to do.

    2) Fully recharge your batteries as quickly as possible. This will mean minimizing loads (light, computers, etc.) on your system so that the maximum amount of charge current is delivered to the battery bank.

    I'm not using any lights. I never used the Crock Pot until it was winter and there appeared to be so much energy that I could be using.

    It will also mean keeping the PV array clear of snow and other debris.

    Yes, well since the PV array was installed so that the bottom panel is in the shade for a couple hours each morning, the snow will melt off by the time the panel's in the sun. Up until then even with the panels totally clear and great sunshine I get about an amp. And clearing snow in the cold when I don't have heat is not going to do enough good to be worth how cold I'll get doing it.

    Your four 12 V x 183 Ah gel batteries are very sensitive to overcharging. Accordingly, it’s important that the charge controller be adjusted to match the battery charging specs. The “optimal” absorb voltage spec for the 12 V batteries is 13.7 V at 77 F.

    This looks like I better do this, but I didn't see any thing that looked like I could adjust it, and I now wonder what the loose wire hanging from the MPPT thing is...
    http://www.health-boundaries-bite.com/Solar.html#space

    The MPPT charge controller’s default “float” voltage setting for sealed batteries is 13.8 V. This is close enough to 13.7 V. Assuming the charge controller is set for sealed (gel batteries are a type of sealed battery) and that the controller voltage is set for the right battery bank nominal voltage, this should all be OK. These settings are determined by the SW-1 DIP switch in the controller.

    You mean I'm supposed to open it up?

    Since the BZ Products MPPT charge controller does not include separate absorb- and float voltage targets, the recommended strategy is to use the controller’s “float” setting as the batteries’ absorb target and dispense with a traditional float voltage.

    Can't figure out what this means. I'm stuck on worrying about if my batteries have been overcharging every sunny day since I got them

    However, your environment is, at present, typically in the mid-40 degree F temperature range, or ~ 7 C. Cold batteries require a higher charging voltage, and the good news is that your MPPT controller includes a feature to do just that ("temperature compensation").

    Automatically? or is it thinking I'm going to come and direct it with a switch nudge?

    Applying the controller’s -18mV/C temperature compensation curve, the target “float” voltage should be 14.1 V. Theoretically, once the battery voltage reaches ~14.1 V, the controller’s “Float” LED should light up, and the controller should go into limited current mode. Once the LED has been steadily illuminated for ~ 3hours, the batteries should be fully recharged.

    Okay, but this is effectively what I was waiting for anyway... right?

    If your battery voltage is 24 V nominal, then the reference absorption target should be 27.6 V, and the temp comp target 28.2 V. Once we have the data I requested (see previous post), your system is properly configured and calibrated (goal #1), and the batteries are fully recharged (goal #2), we’ll need to discuss way to understand expectations, system behavior and energy management.

    HTH,
    Jim / crewzer

    I can put todays readings on my site, but I think I need another cup of coffee first. It's really distressing to learn all the things about my system that I've just learned.

    Thank you. I don't mean you... I mean about my panels being in the shade and the lose wires and the Monitor saying 100% when 10% would be overstating it.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: MPPT question

    I looked at your pictures ... Your wired for 24 volts ..

    On your Charger Controller ( white box that your recording your reading from ) the number when batt volt is selected is the voltage of your batterys is in tenths of volts, so for example 274 is 27.4 volts

    The manual for your battery monitor

    http://bzproducts.net/db5/00461/bzproducts.net/_download/LPM10uINSTRUCTIONMANUAL.pdf

    indicates it needs to be configured for the batterys its connected to as the monitor can be used for 12, 24 or 48 volts batterys ... I would hazzard a GUESS, your installers did not configure the meter and is set for 12V, which would explain the 100% reading. Looks like its about 1 minute with a phillips screw-driver to check and reconfigure to have it working correctly.

    Your readings from yesterday would indicate your array is 48 volts and is putting out its rated power ... When you do check PV array amps then Batt amps, you will find the battery amps will be ~2x as the MPPT controller is doing its thing. Also, on your amps, again its 1/10th amps, so 71 would be 7.1amps.

    As for the shadowing, it appears to hit you between your 2-3 pm readings, while not ideal, you still are getting a good 5-6 hours with strong amp readings. Its not uncommon to have some shading as to have dawn to dusk year round is hard to do.
  • System2System2 Posts: 6,290 admin
    Re: MPPT question
    I looked at your pictures ... Your wired for 24 volts ..

    On your Charger Controller ( white box that your recording your reading from ) the number when batt volt is selected is the voltage of your batterys is in tenths of volts, so for example 274 is 27.4 volts

    Oh, yes... I thought I learned that yesterday... but clearly I've forgotten. Thank you for reminding me.

    The manual for your battery monitor

    http://bzproducts.net/db5/00461/bzproducts.net/_download/LPM10uINSTRUCTIONMANUAL.pdf

    indicates it needs to be configured for the batterys its connected to as the monitor can be used for 12, 24 or 48 volts batterys ... I would hazzard a GUESS, your installers did not configure the meter and is set for 12V, which would explain the 100% reading. Looks like its about 1 minute with a phillips screw-driver to check and reconfigure to have it working correctly.

    I'm so nervous today, I don't think I'd better try it. I'm so upset with the installer I don't think I'd better call him.

    Your readings from yesterday would indicate your array is 48 volts and is putting out its rated power ... When you do check PV array amps then Batt amps, you will find the battery amps will be ~2x as the MPPT controller is doing its thing.

    They've never been 2x as high... but a couple extra amps higher, which I thought was good. (now that I know what to look for)

    Also, on your amps, again its 1/10th amps, so 71 would be 7.1amps.

    Thanks! I knew enough about amps to guess that one. :)

    As for the shadowing, it appears to hit you between your 2-3 pm readings,

    Well, it was this morning I noticed it, and it explains why I don't get much energy from sun up till about 9:30 or 10 in the morning. He said the shadow wouldn't hit it in the winter...

    while not ideal, you still are getting a good 5-6 hours with strong amp readings.

    It's not really very many hours... I'm so sad about this. I think I'm getting less than three hours of full sun readings. 10-11 a.m. is good, as are 12-2, but then the shadow kicks in. But the full strength doesn't kick in till 10:15...

    Its not uncommon to have some shading

    Perhaps, but all it would have taken was to set the pole a few inches further away...

    as to have dawn to dusk year round is hard to do.

    Thank you for your comprehensive answer.

    I'll read the manual now, and then maybe tomorrow I can try to fix the thing that takes a phillips screw driver...
  • System2System2 Posts: 6,290 admin
    Re: MPPT question
    As for the shadowing, it appears to hit you between your 2-3 pm readings, while not ideal, you still are getting a good 5-6 hours with strong amp readings. Its not uncommon to have some shading as to have dawn to dusk year round is hard to do.

    I just checked, and it's already in the shade again at the bottom... and it looks as if it has been for a bit. There's great sunshine outside... but...

    So I guess I get about 3.5 hours.

    I read somewhere about a prisming thing that focuses the sunlight... maybe when I'm not so impoverished, like if I get my condo or its value back, I can look into something like that.

    But this way... it's very sad.

    He was very late most days, but the day of the pole he was especially late and the cement set up before it was poured, and ... he wasn't there to direct the hole digger, and he didn't have the right shovel for the hole digger.

    So now all that's got consequences that affect me.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: MPPT question

    As the Sun rises and falls so does the amps, ... Looking at your recordings, you are getting the energy expected till somewhere from 2-3pm ... With the short days this is expected, on the plus side, you have cold weather ( good for pv's as they harvest more energy when its cold )

    PV panels only put out full power when the sun directly overhead and at the same angle, any other time it will be less. While it may be "light" out for 12 hours, the panels will harvest ~4-5 hours of full power .. hence where all these numbers for watt/hours expected and such come from.

    After Dec 15th, the days will start to get longer and the sun higher in the sky ... the shading you are seeing probably will stop happening by Feburary

    If your energy meter doesn't get fixed, you can use the white MPPT box to see roughly your energy reserve. For your system as you read the display selected for batt volts, this list will show an estimate of energy availble. Please note, if the solar is providing energy, that values can be more tha 254 as the batterys are being charged.

    100% 254
    90% 250
    80% 248
    70% 246
    60% 244
    50% 241
    40% 238
    30% 235
    20% 231
    10% 226
    0% 210

    If I am failing to explain this for you to understand, its me, not you ... I'm a technical type and not the best in making things easy to understand.
  • System2System2 Posts: 6,290 admin
    Re: MPPT question
    As the Sun rises and falls so does the amps, ... Looking at your recordings, you are getting the energy expected till somewhere from 2-3pm ... With the short days this is expected, on the plus side, you have cold weather ( good for pv's as they harvest more energy when its cold )

    PV panels only put out full power when the sun directly overhead and at the same angle, any other time it will be less. While it may be "light" out for 12 hours, the panels will harvest ~4-5 hours of full power .. hence where all these numbers for watt/hours expected and such come from.

    After Dec 15th, the days will start to get longer and the sun higher in the sky ... the shading you are seeing probably will stop happening by Feburary

    If your energy meter doesn't get fixed, you can use the white MPPT box to see roughly your energy reserve. For your system as you read the display selected for batt volts, this list will show an estimate of energy availble. Please note, if the solar is providing energy, that values can be more tha 254 as the batterys are being charged.

    100% 254
    90% 250
    80% 248
    70% 246
    60% 244
    50% 241
    40% 238
    30% 235
    20% 231
    10% 226
    0% 210

    If I am failing to explain this for you to understand, its me, not you ... I'm a technical type and not the best in making things easy to understand.


    Oh, no! You've explained it perfectly. I get it. I think the battery monitor is rather ... extraneous at this point. I bought it so that this wouldn't happen.

    I love the numbers, and I think I'll put them on my page. I often use my pages to supplement my memory.

    During the summer I got good power input even at off times. But as soon as the shadow hits the panels, I now see, the power falls off. Yesterday I was a little confused because it was a bit cloudy, but today is brilliant sunshine... so it's all wasted as far as my panels are concerned.

    Thank you SO much for your help. I really appreciate it. I'm sad right now because this was many thousands of dollars for so little power when so much more power is available.

    And ... but grousing doesn't make an improvement.

    Did you happen to notice if my batteries were wired right?

    And I take it the loose wires didn't seem important to you...

    Well, thank you again, VERY MUCH!
  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: MPPT question

    looking at the way the panels are mounted I would expected a smaller reduction in your amps when the lower panel is shaded ..

    I have a feeling this is the BZT MPPT controller, not re-tracking when the panel gets shaded. If there is a switch or circuit breaker that you can toggle on/off that would reset the BZT MPPT, I think you will find it will start producing more power ( after the reset ) as the unit will restart and re-track to the lower PV panel voltage ( shaded module, lowers the total voltage , so instead of say 48V it would be 36V as an example )

    The BZ is the lowest cost unit on the market and I have a hunch is not as robust to shading as more costly unit might be
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: MPPT question
    I'm just really depressed about this at this point, and I was really hurt by what you wrote yesterday.

    Karen,

    It is (was) never my intention to hurt you. If I did I am indeed sorry. My point in this whole conversation has been to illustrate to everyone who may come later the potential pitfalls of getting into RE. I know in my case, a little knowlege is a dangerous thing. I have learned many of the hard lessons presented in this forum. The hope is the next guy coming along can learn from our collective mistakes. I know I have.

    Once again, I'm sorry if I have offended you in any way,

    Tony

    PS. I think that Solar Guppy may be on the right track. If the meter "thinks" it is a 12vdc system, and it is a 24vdc system, it won't show "dead" until ~11vdc. Very dead for a 24 vdc system. I would call the installer.

    Icarus
  • System2System2 Posts: 6,290 admin
    Re: MPPT question
    icarus wrote: »
    Karen,

    It is (was) never my intention to hurt you. If I did I am indeed sorry. My point in this whole conversation has been to illustrate to everyone who may come later the potential pitfalls of getting into RE. I know in my case, a little knowlege is a dangerous thing. I have learned many of the hard lessons presented in this forum. The hope is the next guy coming along can learn from our collective mistakes. I know I have.

    Once again, I'm sorry if I have offended you in any way,

    Tony

    PS. I think that Solar Guppy may be on the right track. If the meter "thinks" it is a 12vdc system, and it is a 24vdc system, it won't show "dead" until ~11vdc. Very dead for a 24 vdc system. I would call the installer.

    Icarus

    It was nice of you to write that. I'm better at dealing with things... I can make changes, like living in this indoor tent, and go on, but I am just so so so tired of people telling me I should have known about the privy pit, that it's my fault I bought a bad property, and too bad if hydrogen sulfide isn't the best thing for nerves. I'm just so tired of it, and I'm tired of being denied due process.

    So when you wrote that about how I didn't think it would be hard or costly, it hurt. because I do think. I make a huge number more errors than I used to because my mind confuses things and sometimes I catch it and sometimes I don't. It is extremely frustrating. Talking, explaining things to people, used to be a real talent. Now, I can write if I'm not under a lot of stress. Writing is much slower than talking, so it's easier for me to do ... it feels a lot more normal than talking.

    Plus, I bought the battery monitor because I know I have this problem. And I explained to the guys who put everything in that I have this brain injury and I need to be very ... take more time and be more conscious of how I can make mistakes if I don't have help, I thought the monitor would help. But now... my batteries have been drained. DRAINED and my panels are in the wrong place by a few inches, which reminds me that there's a lot of cement on the front of my house and garage because they weren't careful.

    I'm just tired. And I'd like to watch some telly, but now I don't have the electric for that. Even though I have a system which should have been able to allow me to watch a tad of telly.

    Dang nab it!

    Still, thanks for writing.

    But... really, I don't think this battery problem was my fault.
  • System2System2 Posts: 6,290 admin
    Re: MPPT question
    looking at the way the panels are mounted I would expected a smaller reduction in your amps when the lower panel is shaded ..

    I have a feeling this is the BZT MPPT controller, not re-tracking when the panel gets shaded. If there is a switch or circuit breaker that you can toggle on/off that would reset the BZT MPPT, I think you will find it will start producing more power ( after the reset ) as the unit will restart and re-track to the lower PV panel voltage ( shaded module, lowers the total voltage , so instead of say 48V it would be 36V as an example )

    The BZ is the lowest cost unit on the market and I have a hunch is not as robust to shading as more costly unit might be

    There's a lever to the whole system, that I think would shut off the power to the MPPT thing... but as far as I can tell there's no reset button on it... Should I try the lever?

    I didn't have the money for the Outback one. There was a great guy in the California Real Goods store, who was good on actual facts, as opposed to sales spiels, and he thought that would be the best one to get, but I just didn't have the money.

    I needed electric. I figured that if I got my condo back (small chance since they've denied me due process repeatedly) that I could then get the components I really wanted... and in between I'd have electric.

    But now... I'm just really taking it hard about the shade and the monitor not working at all.

    Sorry.

    I think I'll go get you guys a thank you card.

    :)
  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: MPPT question

    Sure, turn the level off and see if the Mppt display goes blank, and then turn the lever back on. It won't hurt anything to try. If the MPPT display does turn off/on you should then get 3/4's of the power as only one panel is getting shaded.

    It's possible though turning off the switch will not help as the unit is still getting power from the solar panels ... in which case what is needed is a way to disconnect the solar, only for a moment to have the MPPT reset for the lower voltage .. you would have to ask your electrican friend if there is a fuse that can be pulled to do this safely
  • System2System2 Posts: 6,290 admin
    Re: MPPT question
    Sure, turn the level off and see if the Mppt display goes blank, and then turn the lever back on. It won't hurt anything to try. If the MPPT display does turn off/on you should then get 3/4's of the power as only one panel is getting shaded.

    It's possible though turning off the switch will not help as the unit is still getting power from the solar panels ... in which case what is needed is a way to disconnect the solar, only for a moment to have the MPPT reset for the lower voltage .. you would have to ask your electrican friend if there is a fuse that can be pulled to do this safely


    I'll go try it.

    Here's hoping!!!!!!
  • System2System2 Posts: 6,290 admin
    Re: MPPT question

    Well, the screen went blank... it was quite scary, actually. I left it off about as long as I'd leave off my computer or modem if I were resetting them.

    (the battery monitor was unaffected, it stayed lit, happily showing that my batteries are 100% charged)

    I turned the power back on... and ... I think it's too late in the day, the sun is almost down.

    So, this is the most exciting thing... I now have something to really look forward to for tomorrow morning. : ) And, since I took all the readings yesterday and today, I will be able to see if there is a difference.

    (I love doing things that may make a difference, and I love it when they do make a difference.)

    Thank you SOOOOO much!
  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: MPPT question

    OK, Next project, when you feel upto it.

    Looking at your pictures, the battery monitor has a grey wire that drops down to and looks like a blue and grey wire nut. Blue connects to the fat red wire, grey to the back wire.

    To check/configure the battery monitor do the following

    1) remove the grey wirenut, do this by holding the wires and twist off the grey nut counter clock wise ... so only take a couple of turns

    2) untwist the wire ( its ground, not to worry ) and when apart, the battery light will turn off

    3) unscrew the 4 black phillips screws ( I somewhat guessing based on the manual ) on the 4 corners of the battery monitor face

    4) the front of the unt should come apart from the base , when it does, turn it around and look for the dip-switchs as discussed in the manual. If the dip switch is ON for 12 volts, flick it off and turn the ON marked for 24V turn in on

    5) reverse assemble as you took everything apart ... you should be then good to go.

    Working slow, its at most 2-3 minutes ... if you have questions or something doesn't match the instructions, take a picture and upload so I can see what more instructions could help you with


    At a minimum, if you not planning to use the meter, you should do #1 & #2 and then put the cap back on the black wire. The battery monitor uses power 24/7, while not much, for you every little bit helps

    I can imagine this would seem overwhelming, but trust we are guiding you to make what you have work, all you have to do it follow what I've written up and ask questions if something isn't right. YOU CAN DO IT and will fell empowered as you become familar with your system and master its upkeeping
  • System2System2 Posts: 6,290 admin
    Re: MPPT question
    OK, Next project, when you feel upto it.

    Looking at your pictures, the battery monitor has a grey wire that drops down to and looks like a blue and grey wire nut. Blue connects to the fat red wire, grey to the back wire.

    Okay, I've got the picture next to me, and yes... I can see what you are talking about.

    To check/configure the battery monitor do the following

    1) remove the grey wirenut, do this by holding the wires and twist off the grey nut counter clock wise ... so only take a couple of turns

    2) untwist the wire ( its ground, not to worry )

    You told me this at exactly the right time... I was getting all nervous in advance of the actual event...

    and when apart, the battery light will turn off

    Oh, that's exciting. I wanted to rip the whole thing out yesterday when I turned off the inverter and the monitor was still eating electric... (I know it's not its fault and I shouldn't be angry at it.)

    3) unscrew the 4 black phillips screws ( I somewhat guessing based on the manual ) on the 4 corners of the battery monitor face

    I can clearly see where those are in my other picture...

    4) the front of the unt should come apart from the base , when it does, turn it around and look for the dip-switchs as discussed in the manual. If the dip switch is ON for 12 volts, flick it off and turn the ON marked for 24V turn in on

    Okay... but when I read the manual it didn't make sense to me... so maybe when I see it, it won't be so ... hard to grasp.

    5) reverse assemble as you took everything apart ... you should be then good to go.

    "reverse assemble" -- love the sound of that! it's just a fun sound. : )

    Working slow, its at most 2-3 minutes ... if you have questions or something doesn't match the instructions, take a picture and upload so I can see what more instructions could help you with

    I wonder if I could turn the light on in there and do it now... I think maybe I'll wait for tomorrow ... darn, I don't know what to do... I think I better wait because I'll be between the light and the monitor, so I'll be casting a shadow on it and I want to be able to see it. Oh... but I could go disconnect it... that would feel good... I'll go do that... all I have to remember is the grey cap, the small one, and counterclockwise... Checking the picture... and... I'm on my way. : )


    At a minimum, if you not planning to use the meter, you should do #1 & #2 and then put the cap back on the black wire. The battery monitor uses power 24/7, while not much, for you every little bit helps

    I can imagine this would seem overwhelming, but trust we are guiding you to make what you have work, all you have to do it follow what I've written up and ask questions if something isn't right. YOU CAN DO IT and will fell empowered as you become familar with your system and master its upkeeping

    more soon. : )

    It's telling me my message is too short...
  • System2System2 Posts: 6,290 admin
    Re: MPPT question

    Well, that was pretty easy. I couldn't see the colors in the dim light, but the one was smaller... so I was pretty sure it was the grey one.

    I unscrewed it and the light stayed on... I'd forgotten what you had said... so I was thinking the light would go off. I decided I should unscrew the wires, because I knew you'd mentioned that... but I couldn't remember... and I thought the light would already be off, showing me it was safe...

    I touched the wires tentatively... and no shock, so I happily unscrewed them and then the light went out. Happiness!!!!!! Happiness!!!!!! Happiness!!!!!!

    I didn't put the grey cap back on because I either didn't remember you said that or I thought I was supposed to do it tomorrow.

    Wow, this is very exciting! Thank you VERY much.

    Here's what I think about the battery monitor... it wasn't useful when I needed it, and now I know how to read the MPPT thing so I don't need it anymore... is that about right?

    And... I don't quite understand why I would put the grey cap back on the wires... wouldn't that put them together again?
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