Author Topic: half the amps~! WHYYYYY  (Read 286 times)

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half the amps~! WHYYYYY
« on: December 18, 2019, 12:51:59 PM »
so i installed 6 of these brand new:
Max Power: 100 Watts
Open Circuit Voltage: 21.6v
Short Circuit Voltage: 6.32a
Max Power Voltage: 17.4
Max Power Current: 5.75a
Maximum Series Fuse Rating: 8a

hooked them up 2s3p with a pmw controller.
got 6amps reported, so i chucked the controller and got a midnite.

turned on the midnite
got 6amps reported, so i tried chucking it but it was too heavy and pretty.

so i scratched my head and rewired the panels to 6s
got 7amps reported.

so i checked my 2 gauge wire to make sure the 12 gauges were touching.
yeah...

midnite reports 250 watts of power from my 600 watt system.
my batteries can handle 2 - 16 amps each... and i have 8 of them in parallel!
they can handle more charging amps!

i expect at least 500w from my 600w system at peak...
... that's normal... and i bought a big wire... cost hundreds... plus midnite...
i'm not asking too much am i?

what am i missing?  :'(

FNG

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Re: half the amps~! WHYYYYY
« Reply #1 on: December 18, 2019, 01:37:09 PM »
First thing to know is what is the classic (or Kid) showing for a mode. For example Absorb, Float, Bulk MPPT?

The second item is those small modules are VERY picky about orientation to the sun. So are they mounted at a perfect 90degree angle to the sun? Even if they are most modules will produce about 75-80% of there rating

Lets answer these and I can help get you going

Ryan

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Re: half the amps~! WHYYYYY
« Reply #2 on: December 18, 2019, 03:21:45 PM »
mostly bulk mppt.

on a clear sunny day, i've eyed it across multiple points of the day.
heavily around noonish.
it never peaks out over 250 - 275w ever at any time.
7amps seems to be the limit it ever reaches.

at peak, it shows  between 100v-120v input,
although i'm not sure why it ever goes over the maximum the panels should be able to give it.
but the amps never go above 7.

if every panel produced only 75% of it's peak power (which is a huge lie then),
then i would still expect 450w, but i'm only getting 250w.

FNG

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Re: half the amps~! WHYYYYY
« Reply #3 on: December 18, 2019, 03:33:34 PM »
Modules have a VOC volts open circuit and a VMP volts maximum power point, Your modules would end up being 104.4 volts at max power point so the classic is finding the proper voltage, that's good.

Now the question is why aren't you getting closer to the nameplate. What I would do if it were me:

1- Verify the array is at the proper tilt, As mentioned before these small modules don't tolerate angles to the sun well. Take a 2x4 piece about 2ft long cut perfectly square and place it solid on the array so the 2ft direction points towards the sun, At noon you should have NO shaddow. If the shadow is below or above the angle is off for this time of year. An example here in Maine we need 30 degrees of tilt in summer and 60 in the winter. If one of your modules is set to 30 for summer I would expect a 25-40% reduction in power in winter
2- Verify each module by doing an open circuit voltage test and a short circuit current test. They are likely ok as they are in a single string but.

as for STC standard test conditions vs real world, I wouldnt call it a lie. The module will provide what its rated at when exposed to 1000 watts per meter squared, Unfortunately with real world skies and soiling and other factors that value is more like 750-800 watts per meter squared

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Re: half the amps~! WHYYYYY
« Reply #4 on: December 18, 2019, 04:07:52 PM »
my power loss is actually 58% - 59% of the nameplate.
i was hoping to settle for a 500w or 17 - 18% loss.

i have the panels laying on a flat roof with no trees or obstructions around.
i propped them on a bit on a roof divider, to little bit east to let snow/rain off...
without noticing much (if any) change in output (no loss or gain).
i don't know the angle.

didn't consider that the slight angle at a direction would play that huge of a role...

are you saying that standing them up and facing them south instead at an angle...
will have that much of an impact that it would boost it by 40%?

if so, then i'll be up there next sunny day.
as soon as i decide on the best prop to withstand the weather :/

FNG

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Re: half the amps~! WHYYYYY
« Reply #5 on: December 18, 2019, 04:12:36 PM »
Angle makes a huge difference on the smaller modules, the larger ones have special glass that helps with that.

Where are you located so i can calculate angles?

ClassicCrazy

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Re: half the amps~! WHYYYYY
« Reply #6 on: December 18, 2019, 05:07:06 PM »
There are a bunch of tilt calculator apps for android  on Playstore .

Yeah tilt makes big difference .  Amy at Alt E made a video about it too
https://youtu.be/m_YuPfShbCo

Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

mike90045

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Re: half the amps~! WHYYYYY
« Reply #7 on: December 19, 2019, 02:02:50 AM »
And, if your batteries are 90% full, they won't take much of a charge regardless how bright the sun, or well aimed the panels are.   You will have to put a beefy 600w load on the system, at noon, to see how it manages that.
http://tinyurl.com/LMR-Solar

Classic 200| 2Kw PV, 160Voc | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph )| Listeroid 6/1, st5 gen head | XW6048 inverter/chgr | midnight ePanel & 4 SPDs | 48V, 800A NiFe battery bank | MS-TS-MPPT60 w/3Kw PV

FNG

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Re: half the amps~! WHYYYYY
« Reply #8 on: December 19, 2019, 11:39:23 AM »
Generally speaking the classic works like this:

Puts out as much power as it possibly can regardless of anything when it is in the following modes:
Bulk MPPT
Float MPPT
EQ MPPT

Then it regulates the power out and decreases it because the battery is close to or is full in these modes:
Absorb
Float
Equalize

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Re: half the amps~! WHYYYYY
« Reply #9 on: December 19, 2019, 08:43:58 PM »
my batteries haven't been much full since i upgraded the system.
i bought 600w, factoring 500w, because i can easily use between 100-300w.
2kw bank tends to hover at 30% full and some days the alarms beeping on empty...
...because i'm not getting the extra juice i expected and need to bank on dim days.

it's been an annoying game of choosing to chill vs straining in pitch black.
toggling back and forth trying to figure out why the juice isn't flowing.

that being said, the tilt suggestion here really motivated me.
it brough back the motivation for going solar that i had lost.

thank you for that.  ;D

as for the results,
i did go on up and adjust the tilt a bit today.
there was immediately an amp or so added to my peak,
bringing me above the 300w mark.

that was a summertime tilt, though
(which was the only angle readily available up there)

i wasn't prepared to construct equipment for this,
...and i sidetracked myself while getting things together,
so i missed the final result after i added a little more tilt.

i don't think i'll be breaking 400 with the new tilt i have.
(angle is between summer and spring time)
i can't get the optimal tilt safely on this flat roof...
...without fairing well out of my territory into a new field.

i guess i'll have to wait till late spring to really see the results.
and even at this current new tilt,
i'll have to wait until at least next week to measure the gain!  :-\
« Last Edit: December 19, 2019, 08:52:26 PM by . »

ClassicCrazy

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Re: half the amps~! WHYYYYY
« Reply #10 on: December 19, 2019, 10:13:17 PM »
Have you used the Midnite string calculator to evaluate the best way to wire up your panels ?
Not sure where you are located but up here in the north the sun is so low now , there isn't a lot of hours to charge.
Any solar system  should have a generator to keep the batteries healthy when there isn't enough light to charge. Cutting back on usage isn't  a very good option to battery longevity.

Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

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Re: half the amps~! WHYYYYY
« Reply #11 on: January 06, 2020, 12:51:24 PM »
sorry this took so long. i changed my schedule.
i haven't been able to be around the controller as often and we've been getting mostly cloudy days.

i can now confirm that the tilt has made a huge difference.
due to limitations, I could only angle 5 of the 6 panels...
...and then still not at recommened tilt for my area this season.

given that, and finally having a sunny day and being able to check the controller,
i can report that the watts have gone from 250w, in full sun, to 450w.
come the next season, I'm sure it will be exactly at my tolerance range.

this is within the logic that I was aiming for!
i'm really enjoying this Midnite now!
thank you.

FNG

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Re: half the amps~! WHYYYYY
« Reply #12 on: January 06, 2020, 01:31:09 PM »
Glad it worked out, Hopefully you can work out a way to get them angled.

Ryan