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ekkesa avatar image
ekkesa asked

Multiplus-II 48/5000/70 Transfer Switch

I would like to confirm my understanding, of the transfer switch rating.

1656950854061.png

I have a SMA-5000TL grid-tied inverter connected to AC-Out1 of my Multiplus-II 48/5000/70.

Can I assume the following:

1. Grid Feedback limit?

  • During low load on AC1, e.g. 600W and grid available, will I be able to feed the total excess back to the grid? Both the solar connected to the Victron MPPT and the SMA-5000TL. Otherwise what will the limit be?

2. Inverter load calculation during day time with grid available (Low Grid Setpoint)?

  • With the grid available, setpoint of 50W, the loads (greater that PV Inverter supply) will first be powered from the SMA-5000TL on AC1-out, should that be insufficient, it will draw from the inverter?
  • Example:
    • Will not cause overload on Multiplus-II 48/5000/70
    • Total Load: 6000W (+-26A)
    • PV Inverter Supply: 4000W (+-18A)
    • Grid Power (AC-In): 50W (+-0.2A)
    • Multiplus-II Inverter: 1950W (+-8.5A)

3. Inverter load calculation during day time (High Grid Setpoint)?

  • With the grid available, setpoint of 10000W, the loads (greater that PV Inverter supply) will first be powered from the SMA-5000TL on AC1-out, should that be insufficient, it will draw from the grid, and not the inverter?
  • Example:
    • Will not cause overload on Multiplus-II 48/5000/70
    • Total Load: 6000W (+-26A)
    • PV Inverter Supply: 4000W (+-18A)
    • Grid Power (AC-In): 2000W (+-9A)
    • Multiplus-II Inverter: 0W (+-0A)

4. Inverter load calculation during day time without grid ?

  • With the grid unavailable, the loads (demand greater that PV Inverter supply) will first be powered from the SMA-5000TL on AC1-out, should that be insufficient, it will draw from the inverter?
  • Example 1:
    • Will not cause overload on Multiplus-II 48/5000/70
    • Total Load: 6000W (+-26A)
    • PV Inverter Supply: 4000W (+-18A)
    • Multiplus-II Inverter: 2000W (+-9A)
  • Example 2:
    • Will cause overload on Multiplus-II 48/5000/70
    • Total Load: 8500W (+-36A)
    • PV Inverter Supply: 4000W (+-18A)
    • Multiplus-II Inverter: 4500W (+-19,5A)

I apologise for the long text, but tried to be as thorough as possible. Should something not make sense, please let me know.

Looking forward to your insights.

Multiplus-IIAC PV Coupling
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2 Answers
Alexandra avatar image
Alexandra answered ·

@ekkesa

The 50a transfer refers to how much can be passed from grid to inverter or through the inverter to grid for feedback. It is the connecting relay you hear clicking on initial connect.

230v x 50A = 11500W max passing through. (The sizing usually allows for battery charging at max and running a 5kva load at full continuous)

Otherwise if you have kept the minimum of 1:1:1 for pv inverter and battery sizing you should be fine.

Max inverting power (no grid connected) should not exceed the 4000W continuous rating. (Well you can but things get and unhappy).

When off grid make sure your inverter can pick up the full load if pv for any reason suddenly drops off (cloud / retracking blips). Hence the 1:1 requirement.

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ekkesa avatar image
ekkesa answered ·

Thank you for the reply.

The 1:1 specification was followed and the system is working perfectly.

"When off grid make sure your inverter can pick up the full load if pv for any reason suddenly drops off (cloud / retracking blips). Hence the 1:1 requirement."

From this, I deduct that my understanding is correct of the power distribution as laid out above - excluding any unexpected behaviour?


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Alexandra avatar image Alexandra ♦ commented ·
Pretty much.

You may find a bit of power assist from the inverter as the battery usually is the most ready source of power.


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ekkesa avatar image ekkesa Alexandra ♦ commented ·
@Alexandra - Awesome! Thank you - Appreciate it...
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