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semiraue avatar image
semiraue asked

MPPT controllers for Pylontech us3000c battery bank and system advice

Hi All,

I'm currently building my second off-grid setup for house in very remote area. I already purchased 4x pylontech US3000C batteries for this project. But now I'm in strange situation where I cannot import any other components for this project due to import restrictions by the government :(

Same project I was try to build with much smaller capacity before (with 1xus3000c) but later decided to got with this larger setup as this will be my only power source for next 10 years may be.

Items that I already purchased


Items that I'm planning to buy

  • 1x Smart Solar MPPT 150/65
    • -or
  • 3x MPPT 100/20-48V
  • 2x 540w Jinko Panels - same model


This is for 48v system which needs to support 230-240v mains

Project was all set to install with 6x Jinko modules (3x series and 2x parallel strings) and 1x 150/60 MPPT SCC. then for my bad our country went in to bad financial situation and we suddenly cannot import most of the things anymore.

Now my only option is, ask someone outside to buy smaller 100/20-48 models for me. and setup each controller for 2x series strings

And if you say go for other brands. No I need victron somehow. And the reason behind the meanwell is that's the only quality brand inverter I can get on my hands at the moment.


Below are some of the calculations I did for 100/20-48 model using this site (https://www.explorist.life/solar-charge-controller-calculator/)

  • Solar Panel Wattage (W)* - 540w
  • Battery Bank Voltage - 48V
  • Estimated Low Temperature (℉)* - 68 (lowest recorded for my place in Sri Lanka)
  • Panel STC (T= ℃)* = 21
  • Solar Panel Open-Circuit Voltage (Voc)* = 49.42
  • Solar Panel Maximum Power Current (Imp):* = 13.27
  • Temperature Coefficient of (Voc) (%/℃)* = -0.28
  • Temperature Coefficient of (Pmax) (%/℃)* = 0.35
  • Panels in Each Series* = 2
  • Panels/Strings in Parallel* = 1
  • Calculated Number of Panels in your Array = 2


DETAILED RESULTS

  • Max Voltage Per Panel at Estimated Low Temperature = 49.55v
  • Solar Panel Array Max Voltage = 99.11v
  • Max Amps Going Into the Charge Controller = 13.27A
  • Max Amps Coming out of Solar Controller = 22.83 A



My questions are

1. Is it ok go with 3x 100/20-48 controller plan and use one controller for 2x series panels ? and is that safe even with the given environmental conditions ? (I know these results are on the edge of what 100/20-48 can do. but if I have no other options will this work?)

2. I don't think I can get GX device at this time. If that's the case, can I charge my pylontech without any issues directly from the 100/20-48 controllers? Anything that I need to be aware of if I'm going with this route ?

3. Even though my meanwell inverter is rock solid, It cannot communicate with any victron devices. Will this be a problem ? Meanwell comes with some kind of com port and I may be able to write small script or program myself to extract the data out of it. but this will take time and for the start I need to connect the inverter to battery bank and SCC without any comms.

4. If this is not the Ideal setup, please suggest me alternate way to do this ? if only suggestion is to go with bigger SCC like 150/60 or 250/60, I need to delay this project may be more than 1 year. and that timing also not guaranteed.

I would thankful anyone who can input even tiny bit of information to this.

Thank you all.


MPPT ControllersPylontechoffgrid
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1 Answer
wkirby avatar image
wkirby answered ·

MPPT 100/20 is really too close for the Voc of two PV modules in series. This Voc Voltage will be higher with temperatures going below 25°C which will risk damaging the controller.
The only sensible option is 250/60 controller with three PV modules in series and two strings in parallel. Again the 150/60 is too close for 3 PV modules in series.

The CerboGX's CAN-bus connection is necessary in order to the battery to hear the keep-alive message and also for it to communicate the various limits to the system for any given time. Pylontech battery would shut down without the keep-alive message.
Is there a way to shut the inverter down in case of a low battery Voltage? In the Victron ecosystem the CerboGX will instruct the Victron inverter to stop discharging if battery gets low, for example.

Sorry, this is not much good news here, but better to not ruin your existing equipment that you already have.

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semiraue avatar image semiraue commented ·

Thanks for your reply.

I am trying to purchase CerboGX device and I may be able to solve this issues where I can connect the batteries.

250/60 is not an option for me unfortunately. If I use 2x panels 100/20-48 will shutdown if the voltage = 100 ? or do they have some safe margin to shutdown like VOC reach 95% of the SCC capacity ? (like 95V) ?

One more thing I need to mention that currently I have another smaller 12v setup using 2x 460w JA panels and 100-20/48 controller with 12v battery. for this I use 2x panels parallel. This panel VOC is 50v but it never reach beyond 46V. does this means the new panels also even advertised as 49v will it give something below that value ?

I was actually thinking to do some experiments with 100/20-48 and 540w panels. like covering up small portion of the panels to lower the voltage. but not sure it will work.

but, if any of these are not not possible, can I use 150/35 scc with 2x540w panels in series and 2xparrarel ? I need to buy 2x 150/35 this way





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semiraue avatar image semiraue semiraue commented ·

I would thankful if you could add any input on this

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