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#Post#: 2177--------------------------------------------------
pwm verse mppt
By: happygolucky Date: April 9, 2014, 11:46 am
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i have a small solar setup array consist of 3) 100 watt panels
tied in parallel charging 2 Trojan t-2 130 Ah batteries..
i was given a 30amp PWM charge controller slow charging!......i
want power now..! so i was an have researched MPPT charge
controllers an found by a certain MFG that i bought from t will
work on my panels but do not expect miracles?
here lies the problem i have limited sun at different times of
the day peak sun i do ge but (trees)..clouds etc.an
interfere..have a wire run of 200'
so i bought this..it made since from all my research to own this
verse a 30 amp PWM 15$ china control charger
HTML https://www.youtube.com/watch?v=6q2ICp7acvA
i have this same model for 130$
HTML http://www.ebay.com/itm/140699954876?_trksid=p2055120.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
my solar spec.
solar spec for one panel times 3 in parallel
electrical specifications
Optimum Operating Voltage (Vmp):
18.9 V　
Optimum Operating Current (Imp):
5.29 A
Open - Circuit Voltage (Voc):
22.5 V
Short- Circuit Current (Isc):
5,75 A
Maximum Power at STC:
100 W
Operating Module Temperature:
-40°C to + 85°C
Module Efficiency (%)
14.99%　
Cell Efficiency (%)
17.88%
the vendor said: since it was 12v system not high voltage.. i
should just stay with my PWM? its cheaper!
this is what they said:
Dear watt-dc,
Yes you ordered the PCM3012 (300w) -- that's correct. Thank you.
I should make one thing very very clear here - if you read my
previous message, you will see I advised you to wire your panels
in PARALLEL, not series!
Reason for this is the max input voltage is only 50Voc, so
connecting 3 in series would give you 22.5*3 > 50V which of
course is not a good idea. If you only have 2 panels, wiring in
series would be fine, as 22.5*2 <50V.
It's very important you know why MPPT is more efficient than
PWM, as it's only significantly more effective if you're using
HIGH voltage panels. Now - your panels are all standard "12v
nominal" type, which is what you would use with the traditional
PWM charger anyway, and also the fact that you only have the
option of wiring 3 in PARALLEL (not series), it's clear you'll
be configuring the 3 panels like you would for a PWM controller.
As in my last message - I already said MPPT was introduced for
HIGH voltage panels as using these on a PWM cannot have its
voltage effectively converted into output current. But your
panel is NOT high voltage -- it's "12v nominal" type which is
the same as your 12v battery.
So yeah, you may still get somewhat better efficiency than say
using a PWM, but I would not be expecting any big difference.
That's why I recommended you might as well just buy a 25 or
30amp PWM since the setup is the same, and it'll be cheaper,
too.
Thanks,
Best Regards
-Maximum Solar, Authorized Reseller of MPP Solar Inc.
opinions please... to me the charger controller is the
brain/nucleus of the/ your whole system..
#Post#: 2191--------------------------------------------------
Re: pwm verse mppt
By: happygolucky Date: April 10, 2014, 8:44 am
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question for crazyguy..I' am looking for an ideal inexpensive
charge controller for my small solar array each panel is
described below as follow with spec it is a 12/24v array
depending on which way i wire 24 v is i deal...soi hear.
12 v in parallel is the way i will run because my invert-er is
12v 1000 watt...an my battery bakis wired the same.. unless i
can do some magic to run on 24v converting or stepping down to
12v. with a transformer for lighting an emergency backup to run
a few appliances. with a battery bank.
#Post#: 2192--------------------------------------------------
Re: pwm verse mppt
By: happygolucky Date: April 10, 2014, 8:47 am
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another response from MFG.. of product..
Dear watt-dc,
Hi again
It's not "wrong" to match your setup with the PCM3012, but I'm
just saying there are certainly more ideal setups that would
work better with a MPPT charger. Putting 3 of your panels in
PARALLEL is unfortunately the only way to go in this case, as
the controller cannot take in more than 50V(Voc); but ideally,
with MPPT you want to wire more panels in SERIES (then when you
can't, go in parallel), so you can see the conversion advantage
it has, over PWM ones. When you wire all 3 of them in parallel
and those are 12v panels, there isn't a lot of room to make
conversion.
Long cable runs generally isn't a good idea - the longer the
cable, the higher the voltage drop (more resistance) so would
require you to use thicker, more expensive wires. I would reduce
the wiring distance as much as possible. Or you may find the
high voltage loss can reduce the effect of MPPT charging, i.e.
MPPT requires the pv input to be within mppt range in order to
charge, so minimum 16V is required.
In short, without testing them out I can't "predict" exactly how
the charger will work out in your case, as it depends heavily on
your actual PV input and also system setup, wiring efficiency
etc. But bear in mind that you have the flexibility to change
your setup, as you said you plan to expand with other panels
which may be better suited for this? I can't make the decision
for you but I do want to be honest with you before we complete
this transaction.
Please let us know before Monday if you'd still like us to ship
this out. If not (no worries) we can refund you the full
payment.
thanks
#Post#: 2313--------------------------------------------------
Re: pwm verse mppt
By: crazyguy Date: April 17, 2014, 7:03 am
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Crazyguy knows nothing about solar, sorry.
#Post#: 2317--------------------------------------------------
Re: pwm verse mppt
By: sut Date: April 17, 2014, 8:24 am
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@ sut thinks @cg should get to know them and I know Nothing
about a PWM or MPPT
#Post#: 2321--------------------------------------------------
Re: pwm verse mppt
By: crazyguy Date: April 17, 2014, 2:25 pm
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;D
#Post#: 2324--------------------------------------------------
Re: pwm verse mppt
By: happygolucky Date: April 17, 2014, 5:49 pm
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good day,
If At First You Don’t succeed, Try, Try, Again! , Try, Try,
Again!
Thomas Jefferson
failure is not in my vocabulary
Improvise adapt and overcome ;D Semper Fi :USMC
i learned 2 things today..vinyl an pvc are prone to shrink an
warping an cracking..new some new vinyl windows coming..due to
10 year weathering condition 50 year warranty ;D
dc cable needs thicker wire for a longer run than ac!
#Post#: 2335--------------------------------------------------
Re: pwm verse mppt
By: crazyguy Date: April 18, 2014, 5:57 am
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Adapt.improvise Improvise.. Mount on roof, cut down trees.
#Post#: 2337--------------------------------------------------
Re: pwm verse mppt
By: happygolucky Date: April 18, 2014, 8:11 am
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we need trees for shade an air to breath.. cuts down on my air
condition bill too.. the shade that is. the MPPT should reward
me with efficiency... drawing 100% from my solar panels an the
PWM can go in my Faraday cage with a few extra diodes ...so i
will have solar in case of emp or solar flare brown out...the
reason i put them on the ground was for easy access i'm
handicapped.. solar tracking an easy maintenance is nice .an i
can tip them down an cover so storm damage hail ,falling
objects etc... can be cleaned easy..cannot an do not want to cut
my neighbors tree with my $$$ not mine but will trim mine
that's money! an my shade.. its a trade off!
#Post#: 2339--------------------------------------------------
Re: pwm verse mppt
By: crazyguy Date: April 18, 2014, 9:07 am
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@ HGL
Drawing 100% from my solar panels ??? Really ?
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