What additional Solar Panels for Classic 200

Started by grizzley, June 20, 2017, 10:09:05 PM

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grizzley

Hi,
I need to expand my solar array and the panels that I have are no longer made.  So I need to find something that will work with what I have.  My question is how do I determine as to what would work? 

I currently have a Classic 200 and two strings of 3 Kyocera KD215 panels.  I had hoped to add another 9 panels to the system so the classic could run near its maximum (the sizing tool when I had checked it a few years ago had said I could use a maximum of 3 strings of 5 KD215). 

Thank you for any recommendation, hint or link to info
1300W solar
3kw wind turbine
MidNite Classic 200
Magnum MS-PAE inverters
420 AH 48V battery bank

Vic

#1
Hi grizzley,

First,  the general rules of thumb are;
For adding PV modules in parallel,  the Vmp (or String Vmp) of the added PVs should ideally match within 5% of the other PVs  --  being within 10%  is probaply OK,  not ideal.
For adding PVs in series with existing PVs,  the Imp of the added PVs ideally should be within 5% of the original PVs,  being within 20 is probably OK.

Your existing Kyo PVs are an unusual configuration  --  54 Cells per module.   They are not commonly available now,   and probably have not been made in the past 10 years,  or so.

You could run an unusual Kyo PV,  the  Ku 340  in strings of two,  with your existing strings of three 215s:
https://www.solar-electric.com/kyocera-ku340-8bca-solar-panel.html

Will look some more,   there will be other combinations,  particularly,  if you are flexible in how your racking can be laid out.

More later,    Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

grizzley

Thanks Vic,

Yes I am flexible on the racking or even if I have to retire a panel or two in order for the system to work out.  I would like to get to as much generating power as I can given to controller and panels we have.

1300W solar
3kw wind turbine
MidNite Classic 200
Magnum MS-PAE inverters
420 AH 48V battery bank

grizzley

Hi Vic (or anyone else)

I used your recommended  tolerance on my system and I was wondering if you could double check it and put your two sense to it.  Since you pointed out the string Vmp I went for that a s a possibility.

The Midnite Classic has a maximum ability to run off of 5 KD215 in series without getting into hyperVoc.  So I used that as my base string.  If I used 4 KU265 or alternatively 3 KU340 (which you had suggested), I should be very close to the 5% tolerance you had mentioned.  The KU265 strings would be at 124V and the KU340 strings at 123.6V.  The KU340 would have the added benefit that the Imp would be closer to the the Imp of the original KD215 panels.  Does my thinking here work correctly? If yes, would the Classic 200 be able to handle this?  If my understanding is correct mismatching panels within the string would create to much loss (i.e. 2 KD215 plus 2 or 3 KU265) or?

Thank you
1300W solar
3kw wind turbine
MidNite Classic 200
Magnum MS-PAE inverters
420 AH 48V battery bank

Vic

Hi grizzley,

Had spent very little time considering your situation,  when proposing using your two strings of three of your existing KD 215s ...   was just trying to avoid tossing any of those 215s,   as would be the case in running 5 of the 215s.

Agree that using three KU 340s with five 215s is not out of the question,  just that the difference in string Vmps with this configuration,   is just over 7%.   Not ideal,   but would probably work OK.

You DO have a Classic 200,  so,  perhaps  the distance twix the PV array and the power electronics/battery is fairly great.

Is there a specific reason that you are leaning toward higher String Vmp for this system?  Perhaps you are just trying to reduce the number of strings,   or,  perhaps the need for a Combiner,   ...   or   ...

With parallel strings of PVs,   the Imp difference in any two parallel strings does not really matter.   Individual strings are just parallel current sources.

The time that Imps do matter,   is if PVs were added in series with an existing string of PVs.   Then,   one would want Imps to be within 5% (ideal),   or 10% maximum (probable OK).

You are correct,   trying to add parallel strings with widely different Vmps (exceeding 10 %)   will generally not work well.

Also,   while the KU 340/5 look to be a very good value right now,  recent production 72 Cell PVs,   like the SW 280 - 300s Monos look to be fairly compatible,   due to the Monos having somewhat higher Vmp per cell than do most Poly cells.

If this makes some sense.   Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

grizzley

Hi Vic,

I did not intentionally want a higher Vmp.  I was more looking a using the most bank for the buck on the Classic 200.  I had used the Midnite Sizing tool for the classic to find out the max would be for the Classic 200 and then go back to what might work.  For some reason I had it in the back of my mind that the max I could use is three parallel strings, but that may be wrong.  I will have to upgrade my combiner box anyway as it would only allow for two stings and I need more power than that could provide.  My predicament is coming from the fact that my wind turbine broke down and it may take some time to get it back up and running and so I wanted to max out the solar side to make up for it, as simple as that.  And since we are off grid, I am needing a bit more power.

The distance between the Solar array and the Classic/battery/inverters is about 90 feet, so not very great.

I will check out the SW panels and see what I can come up with.

Thank you again for your inputs.  Any hints suggestions and corrections are very welcome! 
Newbie = steep learning curve :)
1300W solar
3kw wind turbine
MidNite Classic 200
Magnum MS-PAE inverters
420 AH 48V battery bank

Vic

Hi grizzley,

Agree that running STC String Vmps around 125 or so volts is probably not needed ...

If you stuck with your STC String V of about 80 V,  you should be OK.

Assume that you are running a 24 V battery bank (?).   On a 48 V battery  80 Vmp strings could be slightly low for 48 V Flooded batteries,  under certain conditions.

Recent production Mono 72 cell PVs have relatively high Vmps,   and could do OK  with strings of two of them in parallel with strings of three of your 54 cell PVs,   although this would mean about 7% difference in string Vmps compared to three 215s.

...   More later,  back to project work.    FWIW,  Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

grizzley

Hi Vic,

sorry that I am such a novice, but I have to ask, what certain conditions? We are running a 48 V battery bank with flooded acid batteries and have been running the two strings of 3 KD215 (80 VDC) for several years.  I have not noticed anything but your comment makes me curious.

Hope your project is going well.
1300W solar
3kw wind turbine
MidNite Classic 200
Magnum MS-PAE inverters
420 AH 48V battery bank

Vic

#8
Hi grizzley,

First,  we ALL are learning,   so we all are novices in designing PV systems.

When we use the String Sizing Tools,   it is important to enter the highest and lowest temperatures for the site where the system will be installed.   This will help the user understand the effects of temperature on system performance,   etc.

Have attached the Classic Sizer output for two strings of three KD-215 Kyo PVs,  using the Default high and low temps.

It is recommended that the String Vmps for a system be not less than 130% of the highest battery voltage (when temp compensated) that the system will ever need.   So,  with Flooded batteries that may be cool/cold,  the String Vmp needs to be sufficiently high to allow an EQ on a warm/hot day (perhaps with cool batteries).

What battery manufacturer and model number will your system be using?   This will help drive the selection of a good String Vmp for the system.

Thanks for any added data of the temperature range for this system.

Also,  note,   at bottom of the Sizer output,   there is Note 2,
"   ...   Most all MPPT controllers will want to see a minimum of 130% of the actual high battery voltage. So if we have a 48v battery and it has an Equalize voltage if 62.3 volts than we would multiply that by 130% and we would need a minimum of 81 volts on the input on the hottest day of the year in order to have enough headroom for the MPPT to work   ...   "

Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

grizzley

Hi Vic,

Our max temp here is 95F and the lowest about -30F. 

The batteries are in the temp controlled environment and kept anywhere between 65 and 70F

We are currently using a 48V bank made up of 8 US Battery L16HC-XC batteries.  I will have to add a second string soon, but that is another project.

I am using the default Classic setting on the EQ, Float etc.  I also have a back-up generator and use the Magnum MS-PAE inverter/charger.

So far the 2 strings of (3) KD215 have worked fine and as far as I know I have not had any issues.

Thank you
1300W solar
3kw wind turbine
MidNite Classic 200
Magnum MS-PAE inverters
420 AH 48V battery bank

Vic

#10
Hi grizzley,

Thanks for the info on temperatures.

The Default charge settings on the Classic are very conservative  --  on the low end for Absorb voltage (Vabs),   and essentially,  the EQ voltage default is the same as Vabs  --  57.2 V on a 48 v battery bank.   Vflt appears to be a bit too high for your  USB L-16s.

SO,  it is possible that you might not be able to see an issue with EQ on a warm/hot day,  with cool batteries.

US B  recommends a Veq of about 61.2-ish volts,   and a Vabs of about 58.8,  at the Reference temperature of about 80 F.

Your Hydrometer should be used to check to see how well charger settings are doing at fully-charging your batteries.

Also,  if you have not done so,  yet,  you will want to start a Battery Logbook,  where you record normal maintenance,  charge settings/changes to them,   SG readings of EACH cell (soon),   Amount of (only) Distilled Water added to the bank,   etc.

You will want to mark each battery and cell with (usually)  battery number,   and a letter ( A,  B,  C)  for each cell (this is a common approach).   Use a Sharpie type marker,  as is quite indelible.

You would choose at least one Pilot Cell,  from the lowest SG cells when the bank is fully charged.   You will want at least one Pilot for each battery string.

Here is a good Article on Measuring SGs from Surrette Battery:
http://support.rollsbattery.com/support/solutions/articles/4347-measuring-specific-gravity

Would suggest that you check your Charge settings in the Classic ,  to those noted in the US B  data sheet,   and see how those perform on your batteries.   You will want a good Hydrometer  --  ideally one with a glass outer tube,   and a glass float with SG numbers on it.

Charge parameters may need to be changed,   based upon the SG readings on the bank ...

More later,   Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!