MPPT boost - 24vdc to 48v battery bank

[Photowhit]

The truth will set you free,

I don't want to try to follow what is going on with your system. nny

Funny that, I had two smartly dressed people at my door telling me the same thing..

It appears I have answered questions for the "vaporware" questions, so... If you consider them "bitches" don't look at me, I think the wasting of my time would entitle me, but let a community solve real problems, and it works...

Good point.  But I suppose we did learn, yet again, that the Classic is an ongoing development project.  No boost. And no resourses at Midnite  to add this functionality any time soon. 

We did get some interesting off topic discussion about reporting software and cpu hardware. Much better than other message threads that descended into hard liquor or worse still 'the dogs' complete with dog pics 

dgd

dgd, About the 'truth' comment,... I'm a newby here, but have been an active member of solar forums for years, even before the WWW on the Usenet bulliten boards. Incomplete information makes things difficult, but wrong information makes for wrong answers and wastes the time of people who are part of the community. 

[dgd]

dgd, About the 'truth' comment,... I'm a newby here, but have been an active member of solar forums for years, even before the WWW on the Usenet bulliten boards. Incomplete information makes things difficult, but wrong information makes for wrong answers and wastes the time of people who are part of the community.

yes, the information was wrong and time wasting.
From my experience back to Fidonet and Usenet BBS days in the early 90s there are always people asking for advice/help who withold all the relevant info. They are either naive or deliberately mislead and when they eventually tell all  it annoys those who invested their time trying to be of assistance.

dgd
I cannot find any mppt solar controller anywhere that offers voltage boosting.

[Psyfy]

yes, the information was wrong and time wasting.
From my experience back to Fidonet and Usenet BBS days in the early 90s there are always people asking for advice/help who withold all the relevant info. They are either naive or deliberately mislead and when they eventually tell all  it annoys those who invested their time trying to be of assistance.

dgd
I cannot find any mppt solar controller anywhere that offers voltage boosting.

1.) Hi, FYI... I found an MPPT boost controller (an Australian product). Had one of these puppies shipped home last week and will be certain to let you all know how it works out.

-->> http://www.gsl.com.au/bmppt1500.html


2.) Wrong info. Community? Time wasting?. Nah... I call it tarnished pride when someone realizes that Grandma already knows how to suck eggs... <shrug> <wink>


Psyfy

[boB]

1.) Hi, FYI... I found an MPPT boost controller (an Australian product). Had one of these puppies shipped home last week and will be certain to let you all know how it works out.

-->> http://www.gsl.com.au/bmppt1500.html


2.) Wrong info. Community? Time wasting?. Nah... I call it tarnished pride when someone realizes that Grandma already knows how to suck eggs... <shrug> <wink>

Psyfy

Just remember what "NET" means.  Not Entirely True"...   Which is true sometimes.  Or a lot of times ??

This product looks interesting !    It doesn't say if it is MPPT though.  I would imagine that it is.
They don't say specifically if it is also good for charging a higher voltage battery from
a lower voltage battery.

Does it charge a 12V battery from 12V PV ?  Or 24V battery from 24V PV ?  It would have to be a buck-boost to do that I think.

Also, 58 volts maximum for a 48 volt battery is slightly too low.   It still looks
like it has some great uses.

Yes, please let us know how this works.  I will gladly recommend it to those few customers
that really need such a beast.  That is, if it is fairly reliable.

Thanks for finding that !

boB

[dgd]

1.) Hi, FYI... I found an MPPT boost controller (an Australian product). Had one of these puppies shipped home last week and will be certain to let you all know how it works out.

The working voltage limits sort of reduce its potential usefulness, look forward to your review of it.

2.) Wrong info. Community? Time wasting?. Nah... I call it tarnished pride when someone realizes that Grandma already knows how to suck eggs... <shrug> <wink>

Yes, community is correct. Nothing to do with tarnished pride, just a minor annoyance that could have been avoided with better info.
Sadly some in the community may feel less willing to assist in future..   

dgd

[Psyfy]

Just remember what "NET" means.  Not Entirely True"...   Which is true sometimes.  Or a lot of times ??

LOL ! Especially when passed through the filter of the Eastern marketing machine! I'm sure that we are all familiar with that brand of disappointment...

What's interesting is that I met this guy at http://eastsolar2012.com/ last year (Lindsay Jones). What's refreshing is the 'Old School Engineer' values. They demo their products (nothing as pretty as the Classic to look at BTW but solid none-the-less) on the stand with a CRO, Multimeter and C/Vlim PSU so that the informed can determine what's going on straight away.

Anyway, what I am trying to say is that his claims are on the conservative side. However, I don't have one in my hands right now to be 100% convinced but time will tell.

This product looks interesting !    It doesn't say if it is MPPT though.  I would imagine that it is.

The model is a BMPPT1500. So yes, it translates to 'Boost Max Power Point Tracking @ 1500w' or some such.

They don't say specifically if it is also good for charging a higher voltage battery from
a lower voltage battery.

Does it charge a 12V battery from 12V PV ?  Or 24V battery from 24V PV ?  It would have to be a buck-boost to do that I think.

This is an interesting point. On the list of website product specs it mentions that the Min(Vmp) as being 14vdc and that lower values are possible but subject to MOQ's. In any case, does it 'Boost' or 'Buck' or 'PWM'? Can't be certain but I did just send an email to GSL with the question.

The product cost me USD417.00, shipped (converted from 395- Aussie bananas).

Also, 58 volts maximum for a 48 volt battery is slightly too low.   It still looks
like it has some great uses.

Apparently, this param is adjustable via firmware and the included app. Up to what point though, I don't yet know.

Yes, please let us know how this works.  I will gladly recommend it to those few customers
that really need such a beast.  That is, if it is fairly reliable.

I sneaked a peek inside one of the boxes at the Expo and it's built with 2oz Cu PCB, STMicro's, generous cooling, solid connectors etc. Don't worry. The first thing thing that I will do when I have the chance is to put a CRO on it and see what makes it tick.

Thanks for finding that !

boB

Too easy.

[Psyfy]

Yes, community is correct. Nothing to do with tarnished pride, just a minor annoyance that could have been avoided with better info.
Sadly some in the community may feel less willing to assist in future..   

dgd

John Boy n community, y'all grab ya pitch forks now an follow me an Jenny Sue to the field where we gonna have ourselves a right proper lynching an a hoedown after wid dem good ol boys.


Seriously though, don't sweat it. Small towns (communities) make a lot of us nervous. LOL!


Psyfy.

[boB]

Thanks Psyfi !

There is another thread on this same CC on the NAWS forum...

http://www.wind-sun.com/ForumVB/showthread.php?18653-DC-DC-Boost-converter-MPPT

I just posted this and will repeat it here just because...

boB

A boost type of charge controller would certainly be interesting ! Instead of worrying about PV input voltage drop from array to charge controller, the opposite might be the case if the batteries are a long ways away from the batteries... Instead of putting the CC near the batteries and optimizing the PV input wiring, you'd want to place the CC near the array and optimize the cable run to the batteries in which case the wire size would be larger and cost more than it would with a typical buck type charge controller.

Doesn't sound like the most efficient method but I suppose it has its uses.

boB

[Psyfy]

Thanks Psyfi !

I just posted this and will repeat it here just because...

Doesn't sound like the most efficient method but I suppose it has its uses.

boB

Everything is a compromise. Ohm, Voltaire, Tesla, Faraday and whoever else will attest to that! 

I think that in a previous post I may have mentioned that my HV strings (+200vOc) are fed into an AC coupled MPPT Grid-Tie inverter. This obviates the entire LVDC voltage drop/distance equation. The Sunny Boy is about 99% eff. on the MPPT side and ~96% eff. electrically. Think about it, -4% and builders three core instead of 4/0 @ ~1%+? Take your pick...

My interest in 'Boost' is to solve a problem, today. Later it will not be as important but it is right now. So, when I did a product search and Googled the specs for the Midnite Solar Classic 150 and learned that it had 'Boost', I yelled Eureka. However, this was not to be... I still don't understand why this function was discussed nearly three years ago and given a bit of a rave by you guys in print. If it was a software-only issue, why it didn't make the grade? Must be, has to be, a more complex issue than software...

As an aside, a Classic 150 LITE arrived in the post today with my name on it. Nice looking unit and surprising in it's compactness and bantam weight. Now, if you'll excuse me, I have Mango and an Acer A500 to setup in lieu of the LCD.



Psyfy

[boB]

If it was a software-only issue, why it didn't make the grade? Must be, has to be, a more complex issue than software...

Psyfy

Yes, that is exactly it.  Just harder to do (properly) than expected.  It can still be done and has been done but it is a bit too dangerous at the moment
to call it a feature until we can regulate the voltage and power a bit better.  Most of that is just software.
Boost mode is still on the list of future features though.  Just not yet.

boB

[Psyfy]

A boost type of charge controller would certainly be interesting ! Instead of worrying about PV input voltage drop from array to charge controller, the opposite might be the case if the batteries are a long ways away from the batteries... Instead of putting the CC near the batteries and optimizing the PV input wiring, you'd want to place the CC near the array and optimize the cable run to the batteries in which case the wire size would be larger and cost more than it would with a typical buck type charge controller.

Doesn't sound like the most efficient method but I suppose it has its uses.

boB

Just as a follow up on all of this;

1.) For sure! I think that AC coupling is a better solution to the issue of 'PV to Battery Bank' voltage drop, conductor costs and system weight over that distance. So, what about if, just for shits and giggles we were to;

  a.) Take the output of a given PV array and feed all of it's output into the MPPT inputs of a size-matched GTI.
  b.) Send the GTI AC output from point A to point B via standard building flex and into a subpanel that also has a forward facing OGI feeding into it.
  c.) Distribute the AC to loads from that subpanel and dynamically calculate the Demand/Load ratio with a uP.
  d.) Take and post-load AC surplus and feed it back into a 3KvA5 CLim AC/DC SMPS with a stable 'Drooper' curve of ~96% eff. and a Nom. 67vdc/65A output.
  e.) Feed that SMPS CLim DC output into the DC PSU input of a CC ,such as a Classic LITE 150 and charge a 48v battery bank.
  f.) Use the aforementioned uP to also calculate at a DC shunt and do two things with that info;
      1.) Dynamically adjust the SMPS output to match the AC load surplus.
      2.) Divert any AC surplus into the booster of a SHWS, instead of just wastefully dissipating into the open air as most seem to do.

Oh hang on... I just described my setup....


Of course there are losses;
~1% GTI MMPT.
~4% GTI elec. eff.
~6% OGI @ 92%(Load)
~4% SMPS.
~2% Misc sys. losses.
Then there's the ~-20% on the 50KWh AGM battery bank but hey, what can one do...

On a 6KvA PV array that's ~4 250W panels (or $800 @ ~$0.80c p/watt or about 10c per day over 25 years (taking reduced panel output into account) to cover those losses but on the upside, you save a lot in copper, can locate the array away from the batteries and enjoy ~10KvA when the sun is shining and ~5KvA when it's not.


Psyfy.

[dgd]

OMG and I thought my system was complicated 
What a relief to find there are others further up the looney tune scale than me 

dgd

[dbcollen]

Seriously though, don't sweat it. Small towns (communities) make a lot of us nervous. LOL!


Psyfy.

And the flawed logic of most of the big city folks that have lost any connection to nature and how the world really works scares the holy crap out of most of us country folks, especially considering the city is the population base and the ones who decide the new laws.

[Psyfy]

And the flawed logic of most of the big city folks that have lost any connection to nature and how the world really works scares the holy crap out of most of us country folks, especially considering the city is the population base and the ones who decide the new laws.

Ahem, off topic reply but I do enjoy Social Philosophy too <coughs into hand>.

You can have the best of both worlds you know... <shrug> Let it be known that the flawed logic of which you speak extends to those parents who move out of the cities to raise their family. Ironically, only to have their children fight tooth-and-nail to get back into the city that the parents ran away from in the first place. The challenging ones will always want leave the cows behind to immerse themselves in and imbibe the city's myriad inherent sophistications. Not all parents encourage this as they tend to too easily forget that it's not about them anymore and project their own needs and wants onto the shoulders of the hapless next generation.

The cycle repeats ad-infinitum.

Fact is, if you want easy access to toys like those spoken about on these forums and associated gadgets, along with a few other ones at the same time, you know, like homes, travel, cars, skiing/boarding, good wines etc. and if you choose to learn a skill at the highest eschelon, then IMHO, one really does have somewhat broader choices regarding profession and lifestyle offered in the cities, generally.
However, it's all about balance isn't it. Spend too long in the CBD's of the World and one day you wake up to find that you're out of touch with reality and grow weaker. Conversely, choose to suck a Hayseed from day one and that's about as far as it goes... I think that these are both called 'missing the boat'. Life's about decisions isn't it...

So personally, when I'm ready for whatever reason to stop answering to people, then I'll swap my city and country realities but cities are for the young and that time is not forever. Who was it that said, "Everybody is somebody's slave"?

Just sayin'... 


Psyfy


NB. Now, back to electronics and technology.