Thoughts about integrating the battery voltage maintenance algorithm into the MPPT controller.
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MPPT controllers are not the end all be all of PV charge controllers. They are only worth the cost with a big PV array comprised of identical modules or iden…
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Caleb Engineering, LLC says:
January 3, 2015 at 12:34 pm (UTC 0)
As far as battery maintenance, are you simply trying to float the voltage
at 13.5 volts? Or do you have some sort of charge profile? I was thinking
of doing something similar for a wind turbine.
Also, I noticed that your pencil was from the Centre for Alternative
Technology. Are you associated with that organization?
jusb1066 says:
January 3, 2015 at 1:08 pm (UTC 0)
question about internal clock, kind of… for battery charging, its usual
to boost the voltage to 14.4 for a short period once a day assuming ithas
been at or below 13.6v all day, does your board have the ability to count
to 24 hours with reasonable accuracy? i dont know if you have an internal
clock
xanataph says:
January 3, 2015 at 1:12 pm (UTC 0)
I think you’re on the right track there Julian. 🙂 From what I understand
most commercial units drop out ov MPPT mode once they hit the absorption
stage.
joseph jonatas says:
January 3, 2015 at 1:50 pm (UTC 0)
can you please post your latest sketch for this MPPT project. thanks and
more power
Jim M says:
January 3, 2015 at 1:57 pm (UTC 0)
Julian,
I recently started “playing” with the Arduino boards, an UNO and an MEGA
2560 for a project with XBee Pro radios. I did a fair amount of work
several years ago with Atmel Microcontrollers using the STK-500 and Atmel
AVR Studio 4 IDE. This project turned into a four layer PCB with an
ATMega1280 TQFP-64. It was a huge learning curve and a pretty fair price
after adding it all up.
I’ve been viewing your videos for some time now and they’ve got me
interested again in some ideas I’ve had for some time, plus a friend of
mine’s idea that he asked me to develop. I like the idea of the Arduino
boards as a rapid prototyping platform with multiple shields you can stack.
Watching your video this morning, and my own frustrations with the Arduino
IDE, reminds me of what I really liked about Atmel AVR Studio 4. The
Arduino IDE is designed for learners, I’m not a big fan of it, but it does
work, and you can do more advanced things than what are documented as shown
in you video.
I really like what you’ve developed so far, I think you’ve got something
good going on with the MPPT/PWM idea.
Thanks for the videos,
Jim
tobortine says:
January 3, 2015 at 2:17 pm (UTC 0)
You wouldn’t need to poll in night mode but instead use a rising edge
external interrupt to detect when you have some power coming in from the
solar panel. It’ll save you consuming power only to realise it’s still
night.
Andy Crofts says:
January 3, 2015 at 2:19 pm (UTC 0)
Now I’m confused…
Intuitively, I was going the opposite way, looking at MPPT to get the
battery upto optimum voltage (13.5) as fast as possible, THEN switch to
battery voltage hold mode with PWM, until Vbatt drops to, say, 12.5, then
back to MPPT.
Thought the whole point of MPPT was that it’s more efficient than PWM, and
gives more ‘grunt’ to the battery, faster.
Don’t get your reasoning, Julian. But you’ve been doing this far longer
than me!
(Oh, and for night mode, I’ve heard of a library called ‘Narcoleptic’ for
the arduino. It’s at https://code.google.com/p/narcoleptic/ with a trivial
example at http://www.willowdesign.info/blog/digistump-cricket-generator/
).
abyssunderground says:
January 3, 2015 at 3:05 pm (UTC 0)
This makes me want to complete my PWM controller now but I just don’t have
the time!
Nice idea about doing the mixed mode. I hadn’t thought of that before in
the same way. My idea for the PWM was to look at current and when it was
below a certain point if it’s reached the bulk charge voltage (14.5v) it
would then back down to float mode (13.6v) until the voltage dropped below
a certain point then it would flip back to bulk mode again. Rinse and
repeat. I didn’t dive into that too much though as I didn’t get the rest of
the code to a state I was happy with.
Simon Parkinson says:
January 3, 2015 at 4:04 pm (UTC 0)
Can you not just continue with the MPPT buck converter running at 15kHz,
but just add the battery voltage setpoint into the algorithm so that the
PWM% is reduced to achieve the target voltage?
On the surface of it, this could provide some useful efficiency gains when
you have both solar charging and a load connected simultaneously.
Giulio Berti says:
January 3, 2015 at 4:17 pm (UTC 0)
Glad you are looking again at the mppt project
Simon Parkinson says:
January 3, 2015 at 4:53 pm (UTC 0)
Can you not just continue with the MPPT buck converter running at 15kHz,
but just add the battery voltage setpoint into the algorithm so that the
PWM% is reduced to achieve the target voltage?
On the surface of it, this could provide some useful efficiency gains when
you have both solar charging and a load connected simultaneously.
Giulio Berti says:
January 3, 2015 at 5:24 pm (UTC 0)
Glad you are looking again at the mppt project
Julian Ilett says:
January 3, 2015 at 6:08 pm (UTC 0)
Arduino MPPT Solar Charge Controller #21 – Battery Maintenance
Larry Witte says:
January 3, 2015 at 6:46 pm (UTC 0)
Would the harbor freight box be ok with a 100 watt 5.6 amp panel ?
Alan Heath says:
January 3, 2015 at 7:01 pm (UTC 0)
I also had problems with PayPal.
SpockMcoy Issmart says:
January 3, 2015 at 7:27 pm (UTC 0)
nice video. on the side, as soon as you started talking, the audio quality
reminds me of the old NASA videos while NASA talked to the astronauts in
space……..
ytugtbk says:
January 3, 2015 at 8:22 pm (UTC 0)
It’s always important–whenever making a video where your hands are
present–to include a bandage.
randacnam7321 says:
January 3, 2015 at 8:48 pm (UTC 0)
For mixed module arrays, PWM charge controllers are better. It would be
possible to use multiple small MPPT controllers (one for each module in
your case), but doing so is more expensive than getting more modules to
make up the difference between using a PWM controller and an MPPT
controller.
electrodacus says:
January 3, 2015 at 9:45 pm (UTC 0)
Wellsee are all fake MPPT and even they will be free I will not recommend
them. EPSOLAR is good not sure about the model you have but I have some
nice one with graphic LCD and programmable parameters. A good PWM will be
much cheaper and more reliable than an MPPT and with the difference in
price you can get more solar panels to compensate for efficiency.
Dan Frank says:
January 3, 2015 at 10:11 pm (UTC 0)
I think your question is fundamental in nature, so I think I can explain
your observations. A charge controller restricts flow of current to the
battery. For example in the morning battery charge is low so the controller
allows all available current to go to the battery, thereby charging it up.
after a few hours of increasing sunshine producing more current going to
the battery, the battery gets charged up resulting in increased voltage
seeing this the controller restricts current! hope helps!
Maverik says:
January 3, 2015 at 11:06 pm (UTC 0)
i have one mono and one poly, 100 watts each =200watts, i also have the
harbor freight 45 watts, … 245 total,.. i have a wincong 30 amp charge
controller, im sure you seen those, cheap chinese, but it is a 30 amp, i
have i have 240 amp hours, zero gauge battery cables throughout the bank,
whats your thoughts?
randacnam7321 says:
January 3, 2015 at 11:25 pm (UTC 0)
You would be better off using multiple smaller modules, as modules that big
need multiple guys to move and are very expensive. Also, one big module is
a single point of failure.
richardesh94 says:
January 4, 2015 at 12:03 am (UTC 0)
just wondering if a person can two charge controllers in paralell to the
batteries, ?,would they have to be a pair of identicle units?…I know
someone can answere this……?…luv yer vids!
Maverik says:
January 4, 2015 at 1:03 am (UTC 0)
what size breaker do you recommend to use between the panels and the charge
controller
whateverspycity says:
January 4, 2015 at 1:32 am (UTC 0)
AIMS has them on sale right now! Just got mine and it’s super! 40 amp 192
volt input MPPT totally adjustable everything. may be pricey for some new
comers but in the end it will be on the watch list. Had it with cheap SCC’s
they will ruin your battery in no time at all.
SDubensky says:
January 4, 2015 at 1:44 am (UTC 0)
Does anyone have recommendations for a 300w 36.55v 8.22a solar panel (a
single one)?
randacnam7321 says:
January 4, 2015 at 2:15 am (UTC 0)
@groundzerofm I would not try more than 70W of modules on a Harbor Freight
charge controller.
randacnam7321 says:
January 4, 2015 at 3:04 am (UTC 0)
@jffgrumpy It works OK for what it is.
randacnam7321 says:
January 4, 2015 at 3:26 am (UTC 0)
MPPT is only worth it with arrays or modules over a hundred watts or so.
Also, you can get a pair of 60W modules or a 120W module for less than the
Harbor Freight kit nowadays.
Jason Reeves says:
January 4, 2015 at 3:57 am (UTC 0)
Absolutely correct, the Wellsee product is not a real MPPT. Wellsee make
very good PWM controllers, actually quite reliable, but Wellsee should hang
their heads in shame calling this MPPT!
randacnam7321 says:
January 4, 2015 at 4:47 am (UTC 0)
Depends on the wire used and on operating current and operating potential
of the array. For example, if 12AWG wire was used for the PV array home
run, then the fuse or breaker can be rated for at most 20A as that is the
most that 12AWG wire can handle. And remember that any fuses or circuit
breakers MUST be rated for DC use.
randacnam7321 says:
January 4, 2015 at 5:24 am (UTC 0)
@electrodacus The BZ Products MPPT controllers are actually not much more
expensive than a comparable PWM controller, and are in some cases cheaper.
I got these EP Solar controllers as they were cheap and I did not need all
of the bells and whistles that the LCD versions have. And yes, the WellSee
crapola unit sucks, although it does work as a halfway decent PWM unit and
my improved inductor gives it a 1.4% current gain.
randacnam7321 says:
January 4, 2015 at 5:48 am (UTC 0)
Assuming that you mean what type of charge controller to get, that depends
on the modules.
kiingAli says:
January 4, 2015 at 6:06 am (UTC 0)
And how exactly do you claim that these are fake MPPT controllers?
randacnam7321 says:
January 4, 2015 at 7:02 am (UTC 0)
In addition, derating may be required depending on how the home run is
wired. There are books out there that give a better explanation of what to
do WRT system fusing.
solarpowergetics says:
January 4, 2015 at 7:30 am (UTC 0)
Great analysis. Would it be possible to do a presentation on YouTube for my
solar controllers? Please contact me. MH at Solarpowergetics.
rollbruce says:
January 4, 2015 at 7:39 am (UTC 0)
i bought one of these wellsee all it did was rase my volts to about 15
volts but the amps were only 2.2 at high noon i have over 300 watts of
solar why would this controller do this my old one the volts were 12.5to 13
volts but at 10 to 15 amps my sytem is a mix betten harbor and other solar
pannels dose this sound wright to you thanks
Chris Treb says:
January 4, 2015 at 7:45 am (UTC 0)
Great video! I would like to put two harbor freight 45 w kits together. Can
the stock harbor freight charge controller handle both kits. I am running
about 35 w night and day. thank you