EPEVER Tracer 6420 and 540W panels

maikelmaikel Registered Users Posts: 5 ✭✭
edited September 30 in Solar Beginners Corner #1
Hi,
I'm completely new in solar but it's very interesting and i have an electronic engineering background. Still it's pretty complicated stuff
That's why I would like to ask for some help.
I already bought 2 panels 540W each (JA Solar JAM72S30-540) with;
Voc of 49.6V
Vmp of 41.64
Isc of 13.86A
Imp of 12.97

I also bought an off-grid 2000W inverter
Also I'm planning to buy 2x 100Ah GEL batteries, 12V each, planning to put them in series for 24V

I'm looking to buy an EPEVER Tracer 6420 solar charger that should handle 200V Voc and 60A in total
Now in my thinking when I put 4x 540 panels with an Voc each of 49.6V at 25 degrees, when it's dropping to the coldest of 20 degrees (I live in Bangkok, Thailand) that im dangerously close to that 200V ? However with 3 panels i'll have around 150-170Voc
Why does the manual suggest i only put 2 panels in series? At page 6 for a panel with 96cell (mine supposedly has 144cells) with Voc < 62V at 24V (panels are 24V) they suggest best 1 panel and max 2 panels? I don't understand why. If thats because of a max temperature drop is US or EU below C i do understand and im good to go with 3 panels?

Also the 60 amps mention; is this the charging or input power?

I'm planning 16 panels but it looks like this combination is far from ideal
Also im looking for a solar combiner box which has 15A or 10A automatic fuses, do i need a minimum of 20A per string of is 15A ok?
Edit: Sorry forgot to mention at first i was planning 4 panels in series and for of those (strings?) in parallel, So per string the max Amp is the Isc?
Edit: So with max 3 panels in need 5 strings of 3 panels in series to not get above 200Voc, same isc? (15 panels total)

Sorry so many questions, really hoping someone can help me
Thanks a lot,
Maikel

Comments

  • littleharbor2littleharbor2 Solar Expert Posts: 1,806 ✭✭✭✭✭
    edited September 30 #2
    Your system voltage will determine how many watts of solar you can use. With what you are proposing you need to go with a 48 volt system. Will the charge controller do 48 volts?  Why so many panels and just two small 100 ah. batteries?

    Your 144 cell panels are actually like two 72 cell panels in parallel, so the voltage output reflects that. The suggestion you series wire in strings of three is for the max safe voltage from those panels. You can also series wire two at a time. You need to end up with a total number pf panels that are divisible by 2 or 3. For example 6, 8 10, 12 ect. or 6, 9, 12,etc.

    Your panels should have a max fuse size rating on the back ofthe panel. Use that for each string.

    60 amps is the maximum charging current of the controller. 

    16 540 watt panels sounds like too much wattage for this controller I'm sure the info you got with your controller gives a suggested max wattage.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

  • BB.BB. Super Moderators, Administrators Posts: 32,923 admin
    Just a couple of other questions... Guessing that you have warm to hot climate there? Lead Acid (AGM, GEL, etc.) don't do great if they are going to get >35C pretty consistently (every 10C increase is ~ 1/2 battery aging life)...

    Also--At least in the US--GEL batteries may be charge current limited (to 5% rate of charge in many cases here)--And you usually want 10-20% Rate of Charge cable batteries. Flooded cell lead acid, AGM, and Lithium Ion are usually a better fit.

    And for warm to hot climates--Many times Lithium Ion (LiFePO4 or similar chemistries) can be a much better "fit". However, Lithium Ion batteries have their own issues--Typically need a BMS (battery monitoring system) and a charge controller that can charge Li Ion batteries (and ideally communicate with BMS). Li Ion--You need to do a lot more research (off the shelf vs build it yourself battery banks+BMS, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • maikelmaikel Registered Users Posts: 5 ✭✭
    Your system voltage will determine how many watts of solar you can use. With what you are proposing you need to go with a 48 volt system. Will the charge controller do 48 volts?  Why so many panels and just two small 100 ah. batteries?

    Your 144 cell panels are actually like two 72 cell panels in parallel, so the voltage output reflects that. The suggestion you series wire in strings of three is for the max safe voltage from those panels. You can also series wire two at a time. You need to end up with a total number pf panels that are divisible by 2 or 3. For example 6, 8 10, 12 ect. or 6, 9, 12,etc.

    Your panels should have a max fuse size rating on the back ofthe panel. Use that for each string.

    60 amps is the maximum charging current of the controller. 

    16 540 watt panels sounds like too much wattage for this controller I'm sure the info you got with your controller gives a suggested max wattage.
    Thanks for your quick reply. 
    Yes the charge controller can handle 48V
    i didn’t explain but I’m planning to do a first setup with these two panels I have and with two hell batteries. Then I would like to buy more panels and as a last step I would like to get rid of the GEL batteries and get a few lifepo4 batteries (the charger also supports those)

    The reason I would like to serie wire 3 panels is that I understood that a higher voltage has better efficiency especially in longer wire. Our roof is quite high so I expect long wires. 

    I will check the max fuse size. Actually the panels themselves have fuses too but I read that automatic fuses before the charge controller is for extra safety. What is your opinion/knowledge on that?

    I just triple checked the manual and specifications but they only mention max charge power but that in the output/battery side
    they only talk about max voltage (68v) and max open voltage (200v)
    the max current they mention (60a) is again for charging. Doesn’t make sense to me

    i try to add some pictures 

  • maikelmaikel Registered Users Posts: 5 ✭✭
    BB. said:
    Just a couple of other questions... Guessing that you have warm to hot climate there? Lead Acid (AGM, GEL, etc.) don't do great if they are going to get >35C pretty consistently (every 10C increase is ~ 1/2 battery aging life)...

    Also--At least in the US--GEL batteries may be charge current limited (to 5% rate of charge in many cases here)--And you usually want 10-20% Rate of Charge cable batteries. Flooded cell lead acid, AGM, and Lithium Ion are usually a better fit.

    And for warm to hot climates--Many times Lithium Ion (LiFePO4 or similar chemistries) can be a much better "fit". However, Lithium Ion batteries have their own issues--Typically need a BMS (battery monitoring system) and a charge controller that can charge Li Ion batteries (and ideally communicate with BMS). Li Ion--You need to do a lot more research (off the shelf vs build it yourself battery banks+BMS, etc.).

    -Bill
    Hi Bill, thanks for your quick reply,
    yes warm to hot climate. Minimum temperature not lower than 20 degrees in winter. Hottest around 50 degrees. Reason why I use GEL batteries is to get started cheap. I plan on buying 2 x 12V so I have 24V and can run the AC in the bedroom at nighttime first. Later I will buy lifepo4 batteries instead but they’re expensive so the gels are stepping stone. 
    They’re vented gel batteries and I read they’re safe in the Livingroom so I plan to put them there. Temperature is a pretty constant 27 degrees
    Oh btw I talk in Celsius sorry

    Im aware of the low efficiency of the GEL batteries but that why they’re relatively cheap
    i read about bms for lifepo4 batteries. I think the charge controller doesn’t include this. Is however includes charge programs for them
    research on this topic I definitely have to do in a later stadium
  • littleharbor2littleharbor2 Solar Expert Posts: 1,806 ✭✭✭✭✭
    Maikel,
     The max controller working voltage relates to acceptable battery voltage range.

     As I mentioned, If going with series strings of three panels you need all strings to be 3 panels. Actually @ 48 volts you really need 3 panels in series. These new high wattage panels have high enough voltage you might get high enough voltage from two panels to do a 48 volt system. Since your controller is a 200 voc  model I would go with 3 in series and not worry about voltage loss on your longer wire run.

     Interesting that each panel has it's own fuse. That would make wiring simpler if this fusing is in fact suitable for series strings. You still want a means of shuting down the incoming PV power before the CC. Typically used are DC rated circuit breakers. I prefer to use Midnite Solar Mini Baby Boxes with Midnite Solar breakers.(all available on the forum host's store) This two circuit box  will accommodate a second breaker for the CC output to battery line..

    I see the manual shows 3,000 watts as max PV input. It is common knowledge that MPPT controllers can be over paneled, to some extent. This might help. It is a bit older now but is put out by the mother company of your controller.

     

     

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

  • maikelmaikel Registered Users Posts: 5 ✭✭
    Maikel,
     The max controller working voltage relates to acceptable battery voltage range.

     As I mentioned, If going with series strings of three panels you need all strings to be 3 panels. Actually @ 48 volts you really need 3 panels in series. These new high wattage panels have high enough voltage you might get high enough voltage from two panels to do a 48 volt system. Since your controller is a 200 voc  model I would go with 3 in series and not worry about voltage loss on your longer wire run.

     Interesting that each panel has it's own fuse. That would make wiring simpler if this fusing is in fact suitable for series strings. You still want a means of shuting down the incoming PV power before the CC. Typically used are DC rated circuit breakers. I prefer to use Midnite Solar Mini Baby Boxes with Midnite Solar breakers.(all available on the forum host's store) This two circuit box  will accommodate a second breaker for the CC output to battery line..

    I see the manual shows 3,000 watts as max PV input. It is common knowledge that MPPT controllers can be over paneled, to some extent. This might help. It is a bit older now but is put out by the mother company of your controller.

     

     

    Thanks so much Littleharbor2,
    The battery input voltage range mentioned for this solar charger is from 8 to 68 V. Can i interpret that as that i can choose 24V battery bank (at first as startup setup) and later change bank and settings to 48V for a more efficient setup??
    Or do  need 48V at battery bank anyway?

    For the panels i understand i can series 3 panels and parallel them until the maximum of rated pv arraypower
    of 3000 W this would be (considering a slight overpanelling) of 6 panels, so two parallel strings of 3 panels (in series) for the Tracer 6420AN
    Is that correct??
    If so than i can buy another one of this charge controller later and parallel them as EPEVER mentions in their information

    It starting to make sense now, thanks again for all your effort, really appreciate it
  • littleharbor2littleharbor2 Solar Expert Posts: 1,806 ✭✭✭✭✭
    edited October 3 #8
    Your controller can be configured for any of the listed voltages and, down the road, be used for another voltage system. The first thing you always do with the controller is connect to the battery bank, in which it boots up and figures out the nominal system voltage by itself. Then you connect the PV input second. If you want to chang system voltage you need to, again, connect the battery  and allow the controller to boot up. After boot up you can set any parameters you need. Battery type would be on the top of the parameter list. Of course changing system voltage will require a new inverter. One bonus in stepping up your system voltage is the fact  you can increase the PV array size by double for each step upward. If you went from 12 to 24 volts you double allowable PV. If going from 12 to 48 you can quadruple array size. And because you are raising voltage and not amperage your wiring from PV tp controller doesn't need to be replaced with larger wiring.

    Yes you need a 48 volt bank to operate at 48 volts. Depending on how many batteries you have in your 24 volt bank you may be able to simply change your wiring configuration without necessarily needing more batteries.

    As to overpanneling, if you have good unobstructed sun on your panels and favorable year round weather you may not need to overpanel. If OTOH your array isn't in the bestposition you could add another string. Your controller won't put out more than its rated amperage. It would clip any over power to 60 amps but in bad sun you will get more power out of your system if overpaneled. Don't expect to get more than 2200 - 2300 watts at mid day from your 3000 watt array. That's just the nature of PV The panels heat up in hot sun and power output decreases.

     Something to consider, With your proposed two strings you don't need to fuse each string. Once you add a third string you will need to fuse all three strings.


    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

  • maikelmaikel Registered Users Posts: 5 ✭✭
    Your controller can be configured for any of the listed voltages and, down the road, be used for another voltage system. The first thing you always do with the controller is connect to the battery bank, in which it boots up and figures out the nominal system voltage by itself. Then you connect the PV input second. If you want to chang system voltage you need to, again, connect the battery  and allow the controller to boot up. After boot up you can set any parameters you need. Battery type would be on the top of the parameter list. Of course changing system voltage will require a new inverter. One bonus in stepping up your system voltage is the fact  you can increase the PV array size by double for each step upward. If you went from 12 to 24 volts you double allowable PV. If going from 12 to 48 you can quadruple array size. And because you are raising voltage and not amperage your wiring from PV tp controller doesn't need to be replaced with larger wiring.

    Yes you need a 48 volt bank to operate at 48 volts. Depending on how many batteries you have in your 24 volt bank you may be able to simply change your wiring configuration without necessarily needing more batteries.

    As to overpanneling, if you have good unobstructed sun on your panels and favorable year round weather you may not need to overpanel. If OTOH your array isn't in the bestposition you could add another string. Your controller won't put out more than its rated amperage. It would clip any over power to 60 amps but in bad sun you will get more power out of your system if overpaneled. Don't expect to get more than 2200 - 2300 watts at mid day from your 3000 watt array. That's just the nature of PV The panels heat up in hot sun and power output decreases.

     Something to consider, With your proposed two strings you don't need to fuse each string. Once you add a third string you will need to fuse all three strings.



    Thanks a ton Littleharbor2, I think everything is clear now. Will soon order the solar-charger.
    If i have any questions later on could i ask them here or is it better practice to make a new topic?
    Also a big thanks to Bill
  • littleharbor2littleharbor2 Solar Expert Posts: 1,806 ✭✭✭✭✭
    Best to start your own, new thread. Good luck and feel free to ask.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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