Testing started.. got lots of numbers.. need help deciphering..

ywhic
ywhic Solar Expert Posts: 621 ✭✭
in Off Grid Solar & Battery Systems #1
Ok..

I got my single 145w panel setup..

VMP 18v
IMP 8.05 amp

I got numbers for the solar on the TS meter (under diagnostics) from 14.5v up to 16.39 v..

When the sun is OUT I have 15.49V + for the solar volts and thats when its saying 95w..

The basic 1st screen for the TS meter

Shows (so far with sun out and not clouded)

14.1V
6.6 A
95 W
PWM 96%

Pic1.jpg

I was told these are battery numbers..

It switches from PWM to BULK when the sun goes behind a cloud..

Earlier when I first turned the unit on I had numbers on the 1st screen of..

14.9V
6.2 A
88 W
PWM 91%

The 1st screen ALL THE numbers change as the sun goes in and out..

If I use the max numbers I get 102 watts (using 15.49*6.6a).

Help appreciated..
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Comments

  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #2
    Re: Testing started.. got lots of numbers.. need help deciphering..

    Update..

    The sun is out good now..

    1st screen

    14.4V
    7.3A
    105W
    99% PWM..

    IMHO.. me looking at it I would say 105W is the max for the panel.. 72% eff to the battery..

    Does this sound correct??
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #3
    Re: Testing started.. got lots of numbers.. need help deciphering..

    Well its in BULK.. (sun is out and on it..)

    Numbers:

    14.4 V
    7.8 A
    112 W
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #4
    Re: Testing started.. got lots of numbers.. need help deciphering..

    I toggled the 1st screen.. heres what I get.. keep in mind its in BULK with the SUN fully out.. its shows the AH instead of the normal WATTS with the toggle..

    14.3 V
    7.6 A
    8.5 AH
    BULK


    MeterAH.jpg
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Testing started.. got lots of numbers.. need help deciphering..

    Al, I hope you're having fun but basically your wasting your time.

    Some things you have to know bout solar panels:

    1). They are a current source, not a Voltage source. Under full illumination (direct sun) they try to produce their Imp. This will change quite a bit with the angle of the panel to the sun or any clouds. The Voltage can do whatever as far as the panel is concerned. It doesn't really care. I think I mentioned this before that the current is the thing on PWM and the Voltage will be no more than battery charge Voltage. You will always lose potential power this way with that type of controller. Expect no more than Imp * battery charge Voltage; this appears to be what you are getting.

    2). The current will be affected by the load. More load = more current (again under full illumination) up to the maximum. Not enough load (charged batteries as opposed to discharged ones) and they won't produce full current. Again the Voltage can vary, and you will have different Voltage on the input and output of the controller in other than Bulk mode as the PWM function switches the panels on and off to maintain the proper Voltage on the output side for either Absorb or Float.

    3). Trying to test systems "piecemeal" is pretty much a waste of time. You can check individual components, but there really is no point with brand new equipment.

    4). The Voltage difference between battery charge and panel Vmp is not all a loss; when the panels heat up the Voltage goes down (current potential will remain much the same, however) and you must have greater than battery Voltage to perform any part of the charging regime.

    Right now you are seeing things like the beginning of the Absorb stage: 14.4 Volts (Absorb set point) 7.8 Amps (panel Imp). If that could be maintained you would see the numbers change; the Voltage will stay the same, the current will go down. When it finishes Absorb the Voltage will drop to Float setting and the current will fall off more (unless loads are attached).
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #6
    Re: Testing started.. got lots of numbers.. need help deciphering..
    Cariboocoot wrote: »
    Right now you are seeing things like the beginning of the Absorb stage: 14.4 Volts (Absorb set point) 7.8 Amps (panel Imp). If that could be maintained you would see the numbers change; the Voltage will stay the same, the current will go down. When it finishes Absorb the Voltage will drop to Float setting and the current will fall off more (unless loads are attached).

    So that would explain why at 10:30 am I was between 15.55 and 16.39 V showing as the solar voltage (under the diagnostics tab) temp was a little cooler..

    Now thats it 1pm and 85' and warmer the solar voltage (under the diagnostics tab) goes down to 14.9 V or so..

    The front screen says

    14.4 V
    7.6 A
    108 W
    99% PWM


    So based on that 14.4 thats seems to be constant.. and the 7.6 amps I am seeing NOW..

    I am looking at about 110 watts for the panel though correct??

    Does the AH reading mean anything?? (its going up slowly through out the hours and is at 13.2 ..)
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #7
    Re: Testing started.. got lots of numbers.. need help deciphering..

    All seems to be working well...

    The Amp*Hour is how much current*time your charge controller has output (day/since install/etc.--depending on log function). This can be recharging the battery, supplying power to loads, or a combination of both.

    The maximum AH per day is limited by Sun*time*panel efficiency. However, most of the time, your battery will reach absorb/float long before the sun sets (which causes the controller to limit current into a charging battery bank), and you will not have loads that can use 100% of the controller output for the rest of the day... More or less, your daily AH number will simply be a combination of how much sun and how much loads you had in that day plus the amount of AH sent to the battery for recharging.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #8
    Re: Testing started.. got lots of numbers.. need help deciphering..
    ywhic wrote: »
    So based on that 14.4 thats seems to be constant.. and the 7.6 amps I am seeing NOW..

    The 14.4 Volts should be constant through the Absorb stage. The current will go down as the battery charges up.
    I am looking at about 110 watts for the panel though correct??

    At that moment, yes: 14.4 V * 7.6 A = 109.44 Watts. This will change as conditions change. The 145 Watt rating of the panel is under ideal conditions (STC) and is essentially Imp * Vmp. These numbers rarely show up in the real world, but the Wattage still serves as a reference point for comparison to other panels. If you had an MPPT type controller you could squeeze those few extra Watts out of the Voltage "overhead", but even that won't be available all the time as the temp increase will lower the V and the load needs will alter the over-all current output regardless.
    Does the AH reading mean anything?? (its going up slowly through out the hours and is at 13.2 ..)

    Just the way the controller keeps track of the power that passes through it. If it flows an average of 1 Amp for an hour it registers 1 Amp hour. This becomes fairly useless as the batteries charge and the power demand on the panels lessens or if the clouds come in and panel production is curtailed. That's why battery monitors are better, as they keep track of what's actually going in to and out of the battery for a realistic insight into how much power is produced and consumed.
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #9
    Re: Testing started.. got lots of numbers.. need help deciphering..

    Well the meter says 2 hours of run time.. I'm at 16.2 AH.. (to the battery).. (not sure what that means overall).. there was NO LOAD on the battery at all today..

    I had to pull in the setup as rain is looming and my test setup is outside (and the controller and combiner are not waterproof.. LoL..)

    I am happy with this basic test..

    Thanks for the info..
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: Testing started.. got lots of numbers.. need help deciphering..

    Rain kind of spoils solar. I've been running the gen every day for a week now, except yesterday. More of the same in the forecast.
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