charging batteries

[solar blue]

       Hi Vic
   In answer to last want to run the 120v system in house
I do have grid trying to supplement home or even make it off grid
dont knw amount of daily load yet gotta get kw meter used 635kwh from grid lastmonth
I do have plans to add to system have the 10panels 24v wired to 48v
5strings up running to combiner
will be adding 6 more panels latter
greatest load is refridg
batteries are 2vx12 425amp hrs inverter is 2000watt aims modifed
panels wired with 8awg batteries wired with stranded wire two times larger
from batteries to converter using two mc truck battery cables
hope to be off grid thrught the nine months nice days tht are longer and maybe
even winter  thats our goal

[Vic]

Hi solar blue,  thanks for the important info.

First,  the Aims MSW inverter,  being MSW,  will generally not be good for most motors,  especially the one in the refer.   Most other loads would be OK.   Any Well pump would not like MSW,  either ...  think about changing that inverter.   And please,  ask here for opinions on specific inverters.  Many inexpensive inverters consume a lot of energy over a 24 hour period,  without any loads on them at all.   This load really adds up.

The wiring on your PVs,  at #8 AWG Copper should be fine,  unless this run is fairly long.   The wiring from the Combiner to the input of the Classic should be a minimum of #8 AWG Copper.   Normally we use standard,  stranded copper building wire  --  THHN.

For five strings of two of the CS 220s,  the DC breaker for the PV input the Classic would be 50A,  and the cable for the output of the Classic to the battery,  really should be #4 AWG Copper minimum,  with an 80 Amp DC breaker.   THHN #4 AWG (19 strand)  is the largest cable that will fit the blue Classic terminal block.

Your Grid AC loads for last month averaged,  about 21 kWh per day.  To try to use ALL of that power from Solar,  and probably much of it needing to come from a battery,  you would need a 48 V battery system,  and a huge battery.

Generally,  Grid power is cheap,  and  power generated from PV and batteries is very expensive.   So planning on using your existing battery to supplement Grid power is probably the best plan.

You could run an MNPV6 Combiner for now,  and add another later,  for the next 6 PVs,   BUT,  you would need an additional CC,  because 16 PVs  would overload one Classic 150,  on a 24 V battery system.

More later,  and the above are just my opinions ...   Vic

[solar blue]

       Vic
    Your opinion is good by me and greatly valued by me  I know little of inverters give me a thought on good ones having said that its off to the internet mall to hunt 

them the breakers i mean the 50 and 80amp breaker what type bx should i get to mount them in   if im rite i need a mnpv6 six 150bkers for it  two bx to place the 50 and the 80amp in rite
will replace inverter too

[Vic]

solar blue,

The MNPV6 Combiner will have one MNEPV type (DIN Rail) breaker for each string,  so five breakers in that Combiner box.  The MNPV6 has room for only six breakers,  so there would be only one breaker position that might be open (and that remaining slot could be taken up if you added a Surge Protection Device (SPD).

So for just this part of the installation,  you could use the Big Baby Box,  which can accept four DIN Rail breakers,  or the MN DCQuad box,  which uses a different type breaker  --  Panel Mount MNEPV breakers.  The DCQuad might seem preferable,  but it requires crimped lugs on the cables,  as those MNEPV breakers use studs for connections.   The MNEPV breakers use a screw terminal,  so no lug crimping is required.

AND,  if you use the Big Baby box,  there is an 80 Amp DIN breaker,  but it occupies two positions (it is twice the width of the 1 amp through 63 amp breakers).   With the Big Baby box there would be three breaker positions used.   Just thinking about this,  believe that the Big Baby box is rated for #6 AWG cable,  maximum.   These smallish boxes are fairly tight,  and trying to route #4 AWG cable could be a problem.  Believe that you could still route #4 AWG,  if you choose just the right spot for the 80 A output breaker ...   will look at the specs,  this evening.

There are a number of little details ...

More later,   Vic

[Vic]

Hi solar blue,

The Big Baby box is specified for a maximum breaker size of 63 A.  Using an 80 Amp breaker means that #4 AWG cable into and out of that breaker would be required,  and there is not a lot of room to spare to route cable that large.  With an 80 A breaker and #4,  an Inspector might not like that.   Your system will probably not be inspected ...
Here is a Link to the Manual:
http://www.midnitesolar.com/pdfs/big_baby_quad_manual.pdf

The MNEDC Quad box has a bit more room,  and if only two breakers are installed,  it should be fine,  as the MNEDC breakers,  in 80 A and 100 A ratings are the same size as those breakers with lower current ratings.

But,  with breakers that have stud-terminals, you would need to do good crimps on the terminal lugs that connect the cables to the studs.

Later,   Vic

[solar blue]

      Hi Vic
    Ok the quad it will be with an 80 and 50 amp breakers and the combiner box 15 amp breakers ok for that
what size power surge protector should  I get  Ill call solar electric and get this stuff on the Grey Hound 

[Vic]

Hi solar blue,

OK,  the SPD that could mount in the MNPV6,  will usually need one additional breaker.

Your maximum PV string  voltage with 2 PVs in series is about 85 - 90 V,  Voc,  depending on your temperatures.

Am in the middle of a project,  will check back later,   Vic

[solar blue]

  Hey Vic
       Got it all coming now. Get back at you when it all arrives thanks for helping
hope your project does well
talk with you when it all gets here


                                                                                        again much thanks
                                                                                              solar blue

[Vic]

Hi solar blue,

Thanks for the update.

All the Best for the New Year.

Vic

[solar blue]

     Hey Vic 
   battery bts arrived today plugged it in think its working .  didnt show  temp where would i find it?
I hooked up a shunt meter from another charge controler and checked it with a ge volt meter they agree the midnite is 2.5 greater can i calabrate the charger to that?
At night dark  the controler shows voltage coming in on input side with panels on   turn them off its goes down well almost away. what you think.

[Vic]

Hi solar blue,

Good that  you got the BTS.

On the Classic display (called the MNGP),  there  is a Temps menu.  If you are on the main status page,  press the Right soft button (the rectangular one,  above the other buttons.   "Network"  should show on the display.  Press the Left arrow button once.   The display should say Temps (or something similar).  Press Enter,  and on the lower right there should be an indication of the battery temperature.   If there is NO BTS,  this display should say "NO BTS",  or similar.

Am not certain just what you are saying regarding Calibrating the Classic.   Were you measuring current with that "shunt meter".   Did you add an external Shunt?   Or were you measuring a voltage?  Which voltage or current is it that you feel that needs a calibration?

It  is normal after Sunset for the Vin to show some voltage.   With a small - medium size PV array,  this voltage reading is about two thirds of the battery voltage.   Some PV arrays,  particularly larger arrays (IMO),  will show a lower voltage.   This is normal,  and should be of no concern.

Vic

[solar blue]

       Hi Vic
  Got ya on bts   and input  load after dark 
  hooked up a volt meter from another charge controler to batteries it shows 25.4 next i checked voltage with GE volt meter these two agree 25,4 now looking at batt voltage at same time on midnite classic it shows 1,5volt higher thats the best way i can explain it   do they sometimes require a calabration   

[Vic]

Hi solar blue,

Thanks for the added info.

While it is not unheard of,   it seems really uncommon,  that a Classic's battery voltage reading needs recalibration.

I have never seen a Classic that required recalibration.

Normally one would want to use a known-accurate Digital Multi Meter (DMM).  I would trust my Classic's battery voltage reading,   compared to a $30.00  DMM.

We do have a Lab Grade DC Voltmeter that is used as a Standard,  that other DMMs are compared against.

Think that this was asked before;

Did you purchase this Classic as a previously used one,  or was it new?   It could be,   that if it was used,  that the  previous owner had adjusted the Calibration.

Also,  check the Tweaks menu,  to see if any of the Offsets have been changed.   The Classic ships with voltage Offsets set to 0.0V.

Vic

[solar blue]

        Hi Vic

    Bought it new from missiouri wind and solar this nov
If offsets arent 0.0v should i set it there?
just set to 0.0 yep that did it beside offset  what is vpv what should it be it is set at .05 i think



                                                                                                 Thanks Vic

[Vic]

Hi solar blue,

OK on the Classic being new in November.   But,  seems to me,  that the BTS should have been included,  as the info on the MidNite Solar site states that it is still included ...   hope that  you did not have to pay for the BTS.

Normally the Offsets are used to allow adjustments in how well multiple CCs work together.   These adjustments can help fine-tune when each CC (when there are multiple CCs) go to Float,   etc.

At least you should check the Offest values.   You should find them to be set to 00.0 V (IMO).

Thanks,   Vic